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Susceptibility Test Methods: Dilution and Disk Diffusion Methods

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... Gingerols present in ginger have analgesic, sedative, antipyretic, antibacterial and gastrointestinal tract motility effects [13]. The rapid development of multidrug resistant bacteria has become threatens the effective prevention and treatment of infections caused by bacteria that requires action across all government sectors and society [16,17,18,19,20,21]. ...
... The antibiotic susceptibility test was done by determining MIC value using broth dilution method and using Kirby-Bauer disk diffusion method Antibiotics used were amoxicillin (25μg), Augumentin (30μg), co-trimoxazole (25μg), gentamicin (10μg), nalidixic acid (30μg), nitrofurantoin (300μg), ofloxacin (30μg), and tetracycline (30μg), After 24/48 hours of incubation at 37°C, the diameter of the zone of inhibition was measured around each antimicrobial disk on the plate. On the basis of zone size around each antimicrobial disk results were interpreted as sensitive, intermediate or resistant according to current NCCLS standards in accordance with WHO requirements [20]. ...
... Plants were collected and the hot and cold extracts were obtained by standard methods. Agar well diffusion method was used to test the antimicrobial activity [20]. One loopful of the microorganism was inoculated into 50ml of nutrient broth. ...
... Bacteria are able to grow in the presence of antimicrobials when the concentration is not able to totally kill or inhibit the organisms, allowing them to reach a critical mass that is able to overcome the lethal action of the antibiotic. The time taken to reach this critical mass depends on the organism and is affected by temperature and the media (Jorgensen and Turnridge, 2007). The zones are in themselves meaningless (Jorgensen and Turnridge, 2007). ...
... The time taken to reach this critical mass depends on the organism and is affected by temperature and the media (Jorgensen and Turnridge, 2007). The zones are in themselves meaningless (Jorgensen and Turnridge, 2007). The interpretation of resistance or susceptibility is done through in vivo blood and urine test to establish the obtainable level of an antibiotic that is capable of resolving an infection. ...
... The discs draw water from the surface of the media to diffuse the antibiotic into the agar slowly depending on the diffusion and solubility properties of the drug in the MH agar(Bauer et al., 1966). As a result, a logarithmic reduction in drug concentration occurs farther away from the disc; the immediate surroundings of the disc are subsequently of a higher concentration(Jorgensen and Turnridge, 2007). Molecules with smaller molecular weights and structures diffuse faster than molecules with larger ones. ...
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Pig production in Ghana is increasing at an unprecedented pace under intensive farming conditions. With this shift, farmers have adopted the use of antibiotics for the prophylaxis and treatment of pig diseases; creating a concern that their handling practices could affect the susceptibilities of pathogens to these antibiotics. Due to the public health hazard posed by the antibiotic handling practices of these farmers, a total of 110 pig farms from five districts within the Ashanti Region of Ghana, were surveyed using validated questionnaires and observations to assess the husbandry practices and prevalence of resistance among microbes isolated from the pigs. Interviews were held with veterinarians and animal scientists. Enterobacteria isolates from collected pig faecal samples were analysed for their susceptibility. Tests showed that more than 80% of all isolates were susceptible to the fluoroquinolones and gentamicin (which have less patronage among the farmers). Susceptibility to amoxicillin and streptomycin was observed among at least 25% of all isolates whiles 40-50% of the isolates were susceptible to the tetracyclines and Sulphamethoxazole-trimethoprim (antibiotics commonly patronised by the farmers). Most (78%) of the resistant organisms were multi-drug resistant. Bosomtwe and Atwima Kwanwoma districts had the greatest prevalence of resistant isolates, followed by Ejisu Juaben district. E. coli and Salmonellae from all the districts showed resistance to clinically important antibiotics. Educational level of farmers, the type of farm manager, antibiotic storage site, the use of protection, body washing after antibiotic handling, routes of antibiotic administration and dosage form, type of antibiotics used and source of farm water were all found to significantly impact on antibiotic resistance. However, types of protection used during antibiotic handling had no effect on bacterial resistance to antibiotics. Consequently, pig farms are harbouring resistant bacteria which are a threat to public health. Stricter regulations and supervision regarding the sales and use of antibiotics, promotion of probiotics and vaccinations, periodic education of farmers through workshops and seminars and periodic surveillance studies to follow the trend in antibiotic resistance in pig farms are necessary measures to check the development and spread of resistant bacteria.
... There are a broad range of laboratory antimicrobial susceptibility testing (AST) methods and parameters that can be used to evaluate the susceptibility of bacteria isolated from the CF airway to certain drugs [37][38][39] (Fig. 1). The most widely used methods comprise standardised dilution, concentration gradient and disk diffusion tests, which measure antimicrobial activity by assessing the growth of a clinical isolate in vitro in the presence of a particular antibiotic. ...
... Likewise, in the disk diffusion (or Kirby-Bauer) method, antibiotics are diffused into a pre-inoculated agar plate via filter paper disks impregnated with a single, specified antibiotic concentration [38]. Qualitative assessment of susceptibility is determined by measuring the diameter of the growth inhibition zone, with the size of the zone inversely related to the MIC [39]. ...
... Broth dilution assays have also been adapted for high-throughput clinical use in the form of automated AST systems (e.g. VITEK® 2, Microscan WalkAway, BD Phoenix™) [39]. Automated AST is not recommended for CF-derived isolates of P. aeruginosa and other non-fermenting Gram-negative species due to high error rates and/or a lack of validation data [40][41][42][43]. ...
Article
Antimicrobial resistance (AMR) can present significant challenges in the treatment of cystic fibrosis (CF) lung infections. In CF and other chronic diseases, AMR has a different profile and clinical consequences compared to acute infections and this requires different diagnostic and treatment approaches. This review defines AMR, explains how it occurs, describes the methods used to measure AMR as well as their limitations, and concludes with future directions for research and development in the area of AMR in CF.
... The anti-bacterial activity of each fruit extract was determined using the disc diffusion method (Jorgensen et al., 2007) with a slight modification. The methanol extract (100 mg) was dissolved in 2 ml of dimethyl sulfoxide and sterilized through a membrane filter (0.22 µm). ...
... The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) in the methanol extracts of fruits were determined according to the reported protocol of Kitzberger et al. (2007). ...
... MIC is defined as the lowest concentration of the plant extract that inhibits the microbial growth after 24 hours of incubation (Kitzberger et al., 2007). MBC is the minimum amount of plant extract to completely kill the respective microorganism after 24 hours of incubation on the freshly inoculated agar plates (Kitzberger et al., 2007). The lower MIC and MBC values indicate higher anti-bacterial activities (Cowan, 1999 ...
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Background: Wild fruits have traditionally been important food sources for rural population which are known to contain many biologically active compounds that can help in the prevention of several diseases. Objective: To investigate the anti-bacterial property and anti-nutritional contents of Grewia sapida Roxb. ex DC., Ottelia alismoides (L.) Pers., Aporosa dioica (Roxb.) Muell.-Arg., Antidesma bunius (L.) Spreng., and Eugenia operculata Roxb. fruits obtained in Assam, India. Methods: The methanolic extracts of five wild fruits were studied for anti-bacterial activities against two strains of gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and two strains of gram-negative bacteria (Escherichia coli and Proteus vulgaris) using the disc diffusion method. The anti-nutritional contents such as oxalate, phytate, tannins, saponins, and alkaloid were also assessed following the reported procedures. Results and Conclusion: All the fruit extracts exhibited different degrees of anti-bacterial activities. E. operculata, A. dioica, and O. alismoides extracts were the most effective extracts, which showed strong anti-bacterial activities against the studied bacteria. The five wild fruits showed varied concentrations of anti-nutritional factors and very high levels of anti-nutritional compounds were not observed.
... Cat#. 260661) as described by[28][29]. The dispenser was loaded with six antimicrobial cartridges each containing the individual antimicrobial disks and placed onto the inoculated plate following the manufacturer's instruction (BD BBLTM, 2006). ...
... After the disks were placed onto the plate, the plate was covered, inverted, and incubated for 18 to 24 hours[28]. The diameters of the complete zones of inhibition were measured to the nearest millimeter using a standard measuring ruler as described by[28][29]. The zone diameters of the duplicates and their averages were recorded and used to determine whether the organism was resistant (R), intermediate (I), or susceptible (S), to the tested antimicrobial based on the zone diameter interpretive chart provided by the BD BBL TM Sensi-Disc Antimicrobial Susceptibility Test Discs, adapted from the CLSI (BD BBLTM, 2007a). ...
... The gold-standard methods focus on the determination of the minimum inhibitory concentration (MIC) or the qualitative growth curve using a simple readout method for which the unaided eye is generally sufficient. Goldstandard methods are standardised by various organisations, such as the Clinical and Laboratory Standards Institute (CLSI) and the International Organization for Standardization (ISO) [12,[14][15][16]. The interpretation of test results is, among others, standardised by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) [17]. ...
... The Autobac 1 system [106] was introduced in 1975 as an RAST method. Other machines, such the Vitek2, BAXTER MicroScan Walkaway, BD Phoenix Automated Microbiology System and Sensititre ARIS 2X, followed and are FDA-approved for clinical application [14,[107][108][109][110]. All use similar techniques, including microdilution trays or small cards that are inoculated with a known concentration of bacteria. ...
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In the field of orthopaedic surgery, bacterial invasion of implants and the resulting periprosthetic infections are a common and unresolved problem. Antimicrobial susceptibility testing methods help to define the optimal treatment and identify antimicrobial resistance. This review discusses proven gold-standard techniques and recently developed models for antimicrobial susceptibility testing, while also providing a future outlook. Conventional, gold-standard methods, such as broth microdilution, are still widely applied in clinical settings. Although recently developed methods based on microfluidics and microdroplets have shown advantages over conventional methods in terms of testing speed, safety and the potential to provide a deeper insight into resistance mechanisms, extensive validation is required to translate this research to clinical practice. Recent optical and mechanical methods are complex and expensive and, therefore, not immediately clinically applicable. Novel osteoblast infection and tissue models best resemble infections in vivo. However, the integration of biomaterials into these models remains challenging and they require a long tissue culture, making their rapid clinical implementation unlikely. A method applicable for both clinical and research environments is difficult to realise. With a continuous increase in antimicrobial resistance, there is an urgent need for methods that analyse recurrent infections to identify the optimal treatment approaches. Graphical abstractTimeline of published and partly applied antimicrobial susceptibility testing methods, listed according to their underlying mechanism, complexity and application in research or clinics.
... Essential oils are biological products with high variability (Kaya et al., 2013). For example Karami-Osboo et al. (2010) registered antibacterial effect of thyme oil, carvacrol and thymol on Pectrobacterium by measuring of inhibition zones of agar diffusing method, but this process say very small data about MIC of tested compounds (Jorgensen and Turnidge, 2015). Disc diffusion method is useful method for qualitative preliminary screening of antimicrobial activity (Jorgensen and Turnidge, 2015). ...
... For example Karami-Osboo et al. (2010) registered antibacterial effect of thyme oil, carvacrol and thymol on Pectrobacterium by measuring of inhibition zones of agar diffusing method, but this process say very small data about MIC of tested compounds (Jorgensen and Turnidge, 2015). Disc diffusion method is useful method for qualitative preliminary screening of antimicrobial activity (Jorgensen and Turnidge, 2015). In our test, quantitative microdilution method was used. ...
Article
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Essential oils are volatile substances from plants and many of them have antimicrobial activity. For that reason, they have become known as a useful alternative to chemical preservatives and pesticides. In this study, we tested essential oils of four aromatic plants. Cinnamon (Cinnamomum zeylanicum), thyme (Thymus vulgaris), oregano (Origanum vulgare) and clove (Syzygium aromaticum) essential oils were investigated for their composition and antimicrobial effect against plant pathogenic bacteria (Pectobacterium spp. and Pseudomonas spp.). Both are commonly associated with diseased fruit trees in orchards and gardens. The chemical composition of the tested essential oils was identified by gas chromatography coupled with mass spectrometry. The cinnamon essential oil was most effective form tested oil. The experimental results indicated that the wild strains of tested bacteria are more resistant to essential oils than commonly used laboratory strains. In conclusion, certain essential oils could be used for the control of postharvest bacterial pathogens. The findings of the present study suggest that the essential oils have a potential to be used as antimicrobial agents.
... A broth microdilution method was performed as described by Jorgensen et al. [41]. In brief, bacterial isolates (i.e., Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa) were freshly cultured on 5% blood agar plates (LabM Ltd., Heywood, UK). ...
... The MIC assay is a standard method used to determine bacterial susceptibility and identifies the lowest dose at which a compound is inhibitory to the growth of bacteria [41]. All the clay leachates (see Supplementary Materials, Table S1) failed to show any effect on methicillin-resistant Staphylococcus aureus (MRSA) and P. aeruginosa at concentrations of 300 g/L. ...
Article
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Clays attributed to have medicinal properties have been used since prehistoric times and are still used today as complementary medicines, which has given rise to unregulated “bioceutical” clays to treat skin conditions. Recently, clays with antibacterial characteristics have been proposed as alternatives to antibiotics, potentially overcoming modern day antibiotic resistance. Clays with suggested antibacterial properties were examined to establish their effects on common wound-infecting bacteria. Geochemical, microscopical, and toxicological characterization of clay particulates, their suspensions and filtered leachates was performed on THP-1 and HaCaT cell lines. Cytoskeletal toxicity, cell proliferation/viability (MTT assays), and migration (scratch wounds) were further evaluated. Clays were assayed for antibacterial efficacy using minimum inhibitory concentration assays. All clays possessed a mineral content with antibacterial potential; however, clay leachates contained insufficient ions to have any antibacterial effects. All clay leachates displayed toxicity towards THP-1 monocytes, while clay suspensions showed less toxicity, suggesting immunogenicity. Reduced clay cytotoxicity on HaCaTs was shown, as many leachates stimulated wound-healing responses. The “Green” clay exhibited antibacterial effects and only in suspension, which was lost upon neutralization. pH and its interaction with clay particle surface charge is more significant than previously understood to emphasize dangers of unregulated marketing and unsubstantiated bioceutical claims.
... Respiratory isolates of NTHi and S. pneumoniae with specified antimicrobial susceptibility patterns were selected for evaluation of solithromycin. MIC values were determined using tube-dilution methods (7,8), and the minimal bactericidal concentration (MBC) determinations were performed as recommended in CLSI M26-A (9). The MBC is defined as a 3 log reduction in CFU per milliliter compared to the inoculum. ...
Article
Background: Solithromycin is a fourth generation macrolide with in-vitro activity against multidrug-resistant Streptococcus pneumoniae (SP) and non-typeable Haemophilus influenzae (NTHi). Objective: The objective was to evaluate pharmacokinetics (PK), middle ear fluid (MEF) concentrations, and microbiologic efficacy in a chinchilla model of EOM due to isolates of SP or NTHi. Methods: Plasma PK (C max and AUC 0-24 ) and MEF concentrations were determined. Isolates with specified antimicrobial susceptibility patterns were inoculated directly into the middle ear (ME). Plasma and MEF were collected for PK and MEF cultures performed to determine efficacy. Results: Solithromycin at 150 mg/kg/day resulted in: C max and AUC 0-24 of 2.2 μg/mL and 27.4 μg⋅h/mL in plasma and 1.7 μg/mL and 28.2 μg⋅h/mL, in extracellular MEF on day 1. By day 3, C max and AUC 0-24 increased to 4.5 μg/mL and 54 μg⋅h/mL in plasma and 4.8 μg/mL and 98.6 μg⋅h/mL in extracellular MEF. For NTHi EOM, three isolates with MIC/MBC [BCH1:0.5/1; 1247: 2/2 and 1213: 4/4 μg/mL] were selected. The MEF of > 85% of animals infected with BCH1 and 1247 was sterilized. For NTHi 1213, > 85% of MEF cultures remained positive. For SP EOM, 3 isolates with MIC/MBC [SP 331: 0.06/0.125; SP CP-645 (MLS B phenotype):0.125/1 and CP-712( mef A subclass mef A resistance): 0.5/2 μg/mL] were selected. Solithromycin sterilized MEF in 100% of animals infected with SP 331 and SP CP-645. ME infection persisted in 60% of animals infected with CP-712. Conclusions: In a model of EOM, solithromycin sterilized MEF in >85% of animals challenged with NTHi with MIC≤ 2 μg/mL and 100% of ME infected with SP with MIC≤ 0.125 μg/mL.
... Being a gradient diffusion test, E-test strips make it possible to determine MIC values between the conventional two-fold dilution values suggested by breakpoints. 44 It is important to note that the AST-like protocols used in this study were for research purposes only, and the MIC values obtained might not reflect actual drug concentration for therapeutic use. It is essential that the clinical applications be based on the most current breakpoints from international organizations such as CLSI and EUCAST. ...
Article
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Standard antimicrobial susceptibility tests are performed in vitro under normal room oxygen conditions to predict the in vivo effectiveness of antimicrobial therapy. The aim of this study was to conduct a comprehensive analysis of the effect of different oxygen levels on the antibiotic susceptibility of two strains of Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae. It was found that anoxic conditions caused reduced sensitivity of bacteria to aminoglycoside antibiotics in four of six bacteria used in the study. In addition, oxygen limitation decreased the susceptibility of P. aeruginosa strains and K. pneumoniae strains to piperacillin/tazobactam and azithromycin, respectively. In contrast, five of six bacteria became more susceptible to tetracycline antibiotics under oxygen-limiting conditions. Our data highlight the importance of considering the potential in vivo oxygen levels within the infection site when setting susceptibility breakpoints for evaluating the therapeutic potential of a drug and its effect on antibiotic sensitivity of the pathogen.
... The antibiotic susceptibility of the pathogens was tested using Kirby-Bauer disk diffusion method on Mueller-Hinton agar (Jorgensen et al. 1997). Briefly, the overnight broth culture of collected swabs was adjusted to obtain approximately 1x10 8 CFU/ml. ...
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To assess the most common bacterial causes of pneumo-enteritis in small ruminants in three Egyptian provinces, a total of 248 rectal and nasal swabs and 19 tissue samples were collected from diarrheic and dead lambs and goat kids and examined by the standard bacteriological techniques. All the isolates were examined for their antibiotic sensitivity. Finally, the virulence genotyping of E coli serogroups was carried out by PCR. The data showed that 90.34% and 73.79% of the rectal and nasal swabs were bacteriologically positive respectively, with the highest percentage of positive samples were observed in neonates (85%) comparing with 80% in adult samples. Escherichia coli was the highest percentage followed by Staph. aureus and then Salmonella (70.99%, 5.34%, and 3.82% respectively). While, in the case of tissue samples, the highest percentage of bacteria were isolated from the liver with E. coli is predominant (31.58%). The isolated aerobic bacteria showed a multi-drug resistance. The common E .coli serotypes are O114, O103, O8, O26, O108, O148, O86, O78, O111, O18. These serotypes were further examined for the presence of Shiga toxin (Stx1) and attaching effacing (eaeA) encoding genes. The data showed that Stx1 and eaeA genes were produced by 64.85% (9/14) of and 42.85% (6/14) of these serogroup respectively. The production of both was noticed in only 35.71% (5/14) of E. coli serogroups, while 21.43% (3/14) serogroups did not contain any of these genes. The data collectively showed that E. coli is the main cause of pneumo-enteritis amongst small ruminants and severity of infection mainly depends on the production of certain virolence encoding genes including Stx1 and eaeA genes. Further investigations are still required to verify their precise role in pneumo-enteritis pathogenesis.
... large zones of inhibition indicate that the organism is susceptible, while small or no zone of inhibition indicate resistance. An interpretation of intermediate is given for zones which fall between the accepted cutoffs for the other interpretations [20,21]. ...
Article
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Proteus vulgaris resistant to beta-lactam and quinolone drugs, is widely recognized as an opportunistic pathogen causing urinary tract and septic infections; often nosocomial. The resistance property is obtained by acquisition of mobile element-encoded bla TEM and qnr genes. The aim of this study was to document the prevalence of these resistant genes in Proteus vulgaris.The susceptibility of isolates to a variety of antibiotics has been investigated. It has been found that all the isolates had the highest percentage of resistance (100%) to ampicillin, amoxicillin, cephalothin, chloramphenicol and ceftazidime, and some isolates had lower frequencies of resistance to ceftriaxone (89%), ciprofloxacin (82%) and cotrimazole (92.8%).Whereas, all the isolates were sensitive (100%) to amikacin, gentamycin, nitrofurantion,imipenem, meropenem, and norfloxacin. bla TEM and qnr genes were detected in 100% and 50% of isolates, respectively. The results suggest the spread of resistance genes among strains of Proteus vulgaris.
... Broth microdilution method. The minimum inhibitory concentration (MIC) of all extracts, subextracts and essential oils for antibacterial testing was determined by broth microdilution method according to that approved by NCCLS [20]. Each fraction was first dissolved -in 1 ml of dimethyl sulfoxide (DMSO), than in Mueller-Hinton broth to a 200 mg/ml concentration. ...
Article
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The aim of this study was to determine the antibacterial and antifungal properties of the extracts, subextracts and essential oils of Bidens tripartita flowers and herbs. In the study, twelve extracts and two essential oils were investigated for activity against different Gram-positive Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Gram-negative bacteria Escherichia coli, E. coli (beta-laktamase+), Klebsiella pneumoniae (ESBL+), Pseudomonas aeruginosa and some fungal organisms Candida albicans, C. parapsilosis, Aspergillus fumigatus, A. terreus using a broth microdilution and disc diffusion methods. The results obtained indicate antimicrobial activity of the tested extracts (except butanolic extracts), which however did not inhibit the growth of fungi used in this study. Bacteriostatic effect of both essential oils is insignificant, but they have strong antifungal activity. These results support the use of B. tripartita to treat a microbial infections and it is indicated as an antimicrobial and antifungal agent, which may act as pharmaceuticals and preservatives.
... The stock culture was maintained at 4 ∘ C. All aqueous solutions were prepared with deionized water. To exploit antibacterial potential of the samples Kirby-Bauer diskdiffusion method was performed [41]. In brief, sterile LBA plates were prepared by pouring the sterilized media in sterile Petri plates under aseptic conditions. ...
Article
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Cerium oxide nanoparticles (CeO 2 NPs) in crystalline form have been synthesized by a coprecipitation method. CeO 2 nanoparticles were then embedded in polypyrrole (PPy) films during the electropolymerization of pyrrole (Py) on titanium substrate. The influence of poly(sodium 4-styrenesulfonate) (NaPSS) surfactant used during polymerization on the embedding of CeO 2 NPs in polypyrrole films was investigated. The new films were characterized in terms of surface analysis, wettability, electrochemical behaviour, and antibacterial effect. The surface and electrochemical characterization revealed the role of surfactant on PPy doping process cerium oxide incorporation. In the presence of surfactant, CeO 2 NPs are preferentially embedded in the polymeric film while, without surfactant, the ceria nanoparticles are quasiuniformly spread as agglomerates onto polymeric films. The antibacterial effect of studied PPy films was substantially improved in the presence of cerium oxide and depends by the polymerization conditions.
... Bacteriostatic activity can be shown by the slow growth activity when the treatment was applied. In contrast, bactericidal activity can be shown by no growth activity after treatment (4,27,28). ...
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Background: Goat milk is reported to have antimicrobial activity of several pathogen bacteria that contained on food materials. The research related with antimicrobial activity of Alpha-S2 casein from goat milk is relatively less than other casein components. Herein, we reported the antimicrobial activity of caprine Alpha-S2 Casein (CSN1S2) protein from Ethawah breed goat milk and yoghurt in Gram positive (Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus) and negative pathogen bacteria (Escherichia coli, Salmonella typhi and Shigella flexneri). Those bacteria were known as pathogens that caused gastrointestinal infection. Methods: Serial dilution and agar diffusion analysis with three different concentrations of caprine CSN1S2, 1.25 mg/ml, 2.5 mg/ml, and 5 mg/ml were used to test the inhibition effect of protein on the viability of bacteria cells. The inhibitory activity of caprine CSN1S2 was based on dose dependent manner. Agar diffusion analysis was showed the larger diameter of clear zone at B. cereus and S. flexneri. Results: The serial dilution analysis was shown the inhibition of almost in all groups of bacteria with concentration 5 mg/ml higher by CSN1S2 protein of goat fresh milk than yogurt. The inhibitory activity caprine CSN1S2 protein of fresh milk was shown a vary inhibition clear zone with optimal concentration 5 mg/ml, however CSN1S2 protein of goat yogurt intermediate effectively was only in gram negative bacteria. The weakness bacteria against inhibition activity caprine CSN1S2 protein was B. cereus (Gram positive) and S. flexneri (Gram negative). Meanwhile the strongest bacteria against inhibition activity caprine CSN1S2 protein was S. typhi (Gram negative), may cause in this bacteria has lipopolysaccharide prevent to interact with that protein as proper. Conclusion: This study result concluded that the caprine CSN1S2 protein has inhibition activity in opposition to pathogenic bacteria by optimal concentration 5 mg/ml in all bacteria and indicated caprine CSN1S2 protein as anti-microbial agent.
... Bactericidal activities of the synthesized azo compounds contra pathogenic bacteria are recorded by disc diffusion method [23] and the results are given in (Table 4) and (Table 5).Both azo compound 1, 2 and azo compound 3 exhibit varying degree of antibacterial activity against the test packets caused by frequency resulting by the combination groups vibrations C=O and C=N, which confirm the presence of formulas as a result of the presence of hydrogen ties underlying that work on change lengths ties and the formulas occurs which leads to a displacement of red for the vibration frequency of the carbonyl group for its pure anticipation at frequency region organisms. The azo compound 3 shows the highest antibacterial activity with the inhibition zone of 29 mm against S.aureus at 100 mg concentration. ...
Article
In this study the new azo compounds (3compounds) for nitrogen bases (Adenine and Cytosine) are synthesized through two reaction steps (formation of diazonium salt and coupling reaction). The compounds have been characterized by FTIR, melting point, and ultra-violate (UV) spectra. All synthesized compounds have been estimated in vitro for their antimicrobial activities against two species of bacteria(E.coli, S.aureus)and one kind of fungi ( Aspergillus flavus) .The results show that these compounds have very good antibacterial and antifungal activities especially compounds 1 and 3.To study the effect of these compounds were making some physiological tests on rats are made ,the results of hematological study showed decreasing level of total hemoglobin concentration in all treatment groups specially in group (1).The values of Packed in cell volume (P.C.V) are within normal blood range of rats . Total leucocytes count (W.B.C) decrease in all groups.
... Screening of GNB isolates for inclusion in the study A total of 761 non-duplicate nosocomial GNB were included in the study from North (554; 73 %) and South (207; 27 %) Indian hospitals. All these strains were subjected to Clinical and Laboratory Standards Institute (CLSI) recommended screening tests for detection of beta-lactamases [extended spectrum beta-lactamases (ESBLs), AmpC and carbapenemases] production [3]. Phenotypic screening for ESBL production was done against ceftazidime, cefotaxime, ceftriaxone, cefpodoxime and aztreonam; for AmpC production, against cefoxitin; and for carbapenamases, against imipenem and meropenem, by disc diffusion testing on Mueller Hinton Agar (MHA) using CLSI recommended conditions [4]. ...
Article
Purpose: Resistant Gram-negative bacterial (GNB) infections, apart from tremendously escalating the cost of treatment, are a cause for substantial morbidity and mortality among hospitalized patients. Such bacteria are rapidly acquiring resistance to many antimicrobial agents, especially the beta-lactams which are the most frequently prescribed antimicrobials in hospital and community patient care settings, and now also to colistin; a last-line drug to treat infections with such bacteria. The greatest threat to antimicrobial treatment is the production of metallo beta-lactamases, and plasmid-mediated serine carbapenemases. Methodology: We conducted a two-year study to observe the pattern of beta-lactamase enzyme production (extended spectrum beta-lactamases (ESBLs), AmpC and carbapenemases) among the nosocomial GNB isolated from intensive care units (ICUs) of North and South Indian hospitals. A total of 761 non-duplicate GNB were included in the study from North (554; 73 %) and South India (207; 27 %). All strains were subjected to Clinical and Laboratory Standards Institute (CLSI) recommended screening tests for detection of beta-lactamase production, followed by polymerase chain reaction (PCR)-based detection of clinically important beta-lactamase genes mediating resistant phenotypes among these isolates. Results: Out of the 761 GNB, Acinetobacter spp., Klebsiella spp., Pseudomonas spp., Enterobacter spp. and others were 27, 23 , 21 , 17 , 5 and 7 % respectively. A high prevalence of ESBL was found across all genera in these strains. The carbapenem resistance was higher in North than in South Indian GNB. The level of AmpC production was comparatively lower in both North and South Indian strains. Conclusion: Beta-lactamases showed tremendous variation in geographic distribution. Thus, their detection and characterization is important from a clinical-epidemiological, laboratory and infection control point of view. Knowledge of this epidemiology can predict the empiric antimicrobial treatment.
... Antimicrobial sensitivity testing was done by Kirby-Bauer Antimicrobial Susceptibility Test (disc diffusion method) using Mueller-Hinton agar [15]. Six different antibiotics were tested and the zone size was measured. ...
... Antimicrobial sensitivity testing was done by Kirby-Bauer Antimicrobial Susceptibility Test (disc diffusion method) using Mueller-Hinton agar [15]. Six different antibiotics were tested and the zone size was measured. ...
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This study is to probe the pattern of antibiotic resistance against aminoglycosides and its mechanism in E. coli obtained from patients from Chennai, India. Isolation and identification of pathogens were done on MacConkey agar. Antimicrobial sensitivity testing was done by disc diffusion test. The identification of genes encoding aminoglycoside modifying enzymes was done by Polymerase Chain Reaction (PCR). Out of 98 isolates, 71 (72.45%) isolates were identified as E. coli and the remaining 27 (27.55%) as other bacteria. Disc diffusion method results showed a resistance level of 72.15% for streptomycin, 73.4% for gentamicin, 63.26% for neomycin, 57.14% for tobramycin, 47.9% for netilmicin, and 8.16% for amikacin in E. coli . PCR screening showed the presence of four genes, namely, rrs , aacC2 , aacA-aphD , and aphA3 , in their plasmid DNA. The results point towards the novel mechanism of drug resistance in E. coli from UTI patients in India as they confirm the presence of genes encoding enzymes that cause resistance to aminoglycoside drugs. This could be an alarm for drug prescription to UTI patients.
... The disk diffusion test was performed using standard procedure by Jorgensen et al. [11].The inoculum suspension of each bacterial isolate was swabbed on the entire surface of Muller-Hinton agar (MHA)(pH7.3).Sterile 6mm filter paper discs (Watman No.3) were aseptically placed on MHA surface, and crude ethanolic extract, essential oil , hot -water extraction and coldwater extraction were immediately added to discs in volume of 20 ml. A 20ml aliquot of 10% DMSO and distilled water were also added to a sterile paper discs as a negative control, whereas an antibiotic screening by disc method used as a positive control. ...
... The antimicrobial agents, tetracycline (A.N.B Laboratories Co., LTD., Thailand), vancomycin (Oxoid) and nystatin (T.O Pharma co., LTD., Thailand) were used as positive controls. The minimum inhibitory concentration (MIC) of the compound was determined by the standard microdilution assay described by Jorgensen et al. [13]. Antimycobacterial activity was assessed against Mycobacterium tuberculosis (H37Ra strain) using the Green fluorescent protein microplate assay (GFPMA) [14]. ...
... Aflatoxin producing strain, test organism for investigating inhibition of mycotoxin production, Resistant to flucanazole and amphotericin B MIC determination: MIC (minimum inhibitory concentration) determination was carried out using microbroth dilution method as per NCCLS guidelines (Jorgensen and Turnidge, 2003). Assay was performed in a 96-well microtitre plate. ...
... Aflatoxin producing strain, test organism for investigating inhibition of mycotoxin production, Resistant to flucanazole and amphotericin B MIC determination: MIC (minimum inhibitory concentration) determination was carried out using microbroth dilution method as per NCCLS guidelines (Jorgensen and Turnidge, 2003). Assay was performed in a 96-well microtitre plate. ...
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Extracts of five different plant seeds-Syzygium cumini, Pheonix sylvestris, Manilkara zapota, Tamarindus indica, and Annona squamosa-prepared by Microwave Assisted Extraction (MAE) method were screened for their antimicrobial activity against certain phytopathogenic microorganisms. Ethanolic extract of S. cumini was found to possess highest average total activity against susceptible microbes. Total activity was found to have a positive correlation with the extraction efficiency. Methanolic extract of T. indica exerted bactericidal action against Agrobacterium tumefaciens and Pseudomonas syringae. Ethanolic extract of P. sylvestris was able to protect cabbage leaf against Xanthomonas campestris. Acetone extract of M. zapota was able to reduce aflatoxin production in Aspergillus parasiticus by >50 %. Curcumin proved bactericidal against X. campestris.
... The samples were processed immediately after collection and Enterococcus isolates were identified by standard protocols based on Gram's staining, colony morphology, catalase test, bile solubility, growth in sodium chloride, bile esculin test, and sugar fermentation tests [6]. Antibiotic sensitivity testing of enterococci was performed using Kirby-Bauer disc diffusion method and Mueller-Hinton agar supplemented with 5% sheep blood was used as per CLSI guidelines [7]. The antibiotics discs used were penicillin (10 U), gentamicin (10 í µí¼‡g), ciprofloxacin (5 í µí¼‡g), linezolid (30 í µí¼‡g), vancomycin (30 í µí¼‡g), erythromycin (15 í µí¼‡g), and doxycycline (30 í µí¼‡g), and nitrofurantoin (300 í µí¼‡g) was also added in urinary isolates. ...
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Aims . This study was aimed at knowing the prevalence of vancomycin and high level aminoglycoside resistance in enterococcal strains among clinical samples. Study Design . It was an investigational study. Place and Duration of Study . It was conducted on 100 Enterococcus isolates, in the Department of Microbiology, Pt. BDS PGIMS, Rohtak, over a period of six months from July to December 2014. Methodology . Clinical specimens including urine, pus, blood, semen, vaginal swab, and throat swab were processed and Enterococcus isolates were identified by standard protocols. Antibiotic sensitivity testing of enterococci was performed using Kirby-Bauer disc diffusion method. Results . High level gentamicin resistance (HLGR) was more common in urine samples (41.5%) followed by blood (36%) samples. High level streptomycin resistance (HLSR) was more common in pus samples (52.6%) followed by blood samples (36%). Resistance to vancomycin was maximum in blood isolates. Conclusion . Enterococci resistant to multiple antimicrobial agents have been recognized. Thus, it is crucial for laboratories to provide accurate antimicrobial resistance patterns for enterococci so that effective therapy and infection control measures can be initiated.
... Six antibiotic discs (Nalidixic acid 30 mcg, Nitrofurantoin 300 mcg, Gentamicin 10 mcg, Streptomycin 10 mcg, Tetracycline 30 mcg and Amoxicillin 25 mcg) were used for antibiotic sensitivity test. The agar diffusion method was used according to Jorgensen et al. (1999). Guidelines of using antibiotic discs on the media Mueller-Hinton agar, Antibiotic, Nalidixic acid 30 mcg, Nitrofurantoin 300 mcg, Gentamicin 10 mcg, Streptomycin 10, Tetracycline 30 and Amoxicillin 25 MCG were followed. ...
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The current study was conducted to determine the inhibitory effect of the aqueous extract of hornwort Ceratophyllum demersum on Vibrio cholerae bacteria that affects the common carp Cyprinus carpio L. in fish farms. The inhibitory effect of the aqueous extract was determined in petri dishes. The inhibition effects of the extract and six common antibiotics (Nalidixic acid, Nitrofurantoin, Gentamicin, Streptomycin, Tetracycline, and Amoxicillin) were compared; the results showed that the inhibition effect of the aqueous extract of hornwort was higher than the inhibitory effects of the six antibiotics. The stock solution 100% of the aqueous extract showed an inhibition effect reached 35.3 mm compared with 25 mm, 15 mm, 7 mm, 10 mm, 23 mm and 11 mm of Nalidixic acid, Nitrofurantoin, Gentamicin, Streptomycin, Tetracycline, and Amoxicillin antibiotics respectively. A positive correlation was recorded between concentration of aqueous extract and its inhibitory effect. The average of inhibition diameter was 23.3 mm, 27.6 mm, 28.6 mm, and 35.3 mm for the concentrations 25%, 50%, 75% and 100% of the stock solution, respectively.
... The minimum inhibitory concentrations (MIC) of N. sativa and clove oils were determined using the broth micro-dilution method [16]. The concentration of stock solution of the used essential oils was adjusted at 1024 µg/mL DMSO and the inoculum size was approximately prepared as 5x10 5 CFU/mL. ...
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Antimicrobial resistance of methicillin resistant Staphylococcus aureus (MRSA) became on the top list of the serious problems that have a negative impact on public health. Therefore, this study aimed to determine the in vitro antibacterial activities of Nigella sativa (N. sativa) and clove essential oils against multidrug resistant (MDR) methicillin resistant Staphylococcus aureus (MRSA) isolates recovered from different sources with a special reference to their role on the expression of penicillin binding protein (pbp2) and muscle ring finger (murF) genes. Antibiotic susceptibility testing of 51 staphylococcal isolates comprising 34 Staphylococcus aureus (S. aureus) and 17 coagulase negative staphylococci (CoNs) revealed a highest sensitivity against vancomycin (100%) and marked resistance patterns against β-lactam (beta-lactam) antibiotics. The results revealed that 97.1% of S. aureus isolates demonstrated a high level of MDR pattern, being resistant to more than 3 antibiotics of different classes. The in vitro antibacterial effects of clove and Nigella sativa essential oils against 11 MDR isolates using disc diffusion method indicated that both oils exhibited strong inhibitory efficiencies with inhibition zone diameters up to 45 and 20 mm, respectively. Besides, broth microdilution test of both essential oils revealed maximum activities against the tested strains with minimum inhibitory concentrations (MICs) up to 0.5 and 8 µg/mL for clove and N. sativa oils, respectively. Quantitative RT-PCR (real time polymerase chain reaction) analysis revealed the effective role of N. sativa and clove oils on the down-regulation of S. aureus murF and pbp2 genes. In conclusion, the above findings highlight the promising antibacterial functions of N. sativa and clove essential oils in the treatment of emergent resistant S. aureus infections.
... All experiments were performed in triplicate. 23 ...
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Krzysztof Bielawski,1 Katarzyna Leszczyńska,2 Zbigniew Kałuża,3 Anna Bielawska,4 Olga Michalak,3 Tamara Daniluk,2 Olga Staszewska-Krajewska,3 Anna Czajkowska,4 Natalia Pawłowska,1 Agnieszka Gornowicz4 1Department of Synthesis and Technology of Drugs, 2Department of Microbiology, Medical University of Bialystok, Bialystok, 3Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw, 4Department of Biotechnology, Medical University of Bialystok, Bialystok, Poland Abstract: A new class of highly functionalized tetrahydroisoquinolines with a quaternary carbon stereocenter was synthesized starting from an easily accessible l-tartaric acid. Nine strains of bacteria (Staphylococcus aureus, Streptococcus pyogenes, Streptococcus mutans, Streptococcus salivarius, Bacillus subtilis, Enterococcus faecalis, Moraxella catarrhalis, Escherichia coli, Campylobacter jejuni) were used for the determination of minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of synthesized compounds. The influence of analyzed compounds on viability and induction of apoptosis in human skin fibroblasts was determined. A majority of the synthesized compounds showed the strongest antibacterial properties toward some gram-negative bacteria (M. catarrhalis and C. jejuni) with a high level of selectivity. High antibacterial compounds have bactericidal activity ratio MBC/MIC =4. Our studies also proved that the novel compounds do not possess cytotoxic and proapoptotic potential in normal cells. Keywords: quaternary ammonium compounds, tetrahydroisoquinolines, antimicrobial activity, antibiotic resistance
... Pure Antibacterial activity was determined by the method of disc diffusion [19][20][21]. ...
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Aims: This work aimed to investigate the phytochemical constituents of Cameroonian species of Solanum torvum Swartz and to carry out. Antioxidant, enzyme inhibition (urease and glucosidase) and antibacterial activities of methanol crude extract and isolated compounds. Original Research Article Lacmago et al.; SARJNP, 4(1): 16-23, 2021; Article no.SARJNP.65844 17 Methodology: The stems of Solanum torvum were collected and extracted by maceration in methanol. The crude extract was subjected to repeated column chromatographic separation. Their structures were elucidated on the basis of spectral analysis of ESI-MS, 1D and 2D NMR. The methanol crude extract and pure compounds were tested against Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis, Salmonella typhi, Klebsiella pneumonia, Staphylococcus aureus, Streptococcus faecalis, Micrococcus sp. and Saccharomyces cerevisiae using the method of disk diffusion. The radical scavenging (DPPH) and the enzyme inhibition (urease and glucosidase) were perfomed according to the standards methods Results: One new compound neochlorogenin-6-O-β-D-xylopyranosyl-(1→3)-α-D-quinovopyranoside, together with eight known compounds including four steroidal derivatives, neochlorogenin-6-O-β-L-rhamnopyranosyl-(1→3)-β-D-quinovopyranoside, yamogenin-3-O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranoside, diosgenin, chlorogenin; three phytosterols stigmasterol, β-sitosterol, β-sitosterol-3-O-β-D-glucopyranoside and one pentacyclic derivative, betullinic acid were isolated from the stems of Solanum torvum.. Diosgenin was isolated from S. torvum for the first time. All the tested compounds were found to be inactive while methanol crude extract showed moderate urease and significant glucosidase inhibition activities with IC 50 = 61.2± 0.68 and 32.5± 0.87 µM respectively. Conclusion: These results suggested that Solanum torvum might be used as an enzyme inhibition agent particularly for alpha glycosidase inhibition.
... The inocula of the test organisms were prepared by transferring a loopful of culture into 9 ml of sterilized Mueller Hinton Broth (MHB) (Difco) and incubated at 37°C for 5 to 6h, if necessary 12 to 18h. The MHB culture was compared with McFarland 0.5 (Jorgensen et al. 1999) turbidity standards (10 7 CFU/ml) and streaked evenly in three plates with the cotton swab at a 60° angle on the surface of the Mueller Hinton Agar (MHA) plate. Excess suspension was removed from the swab by rotating it against the side of the tube before the plate was seeded. ...
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This investigation assessed the microbiological quality of various fast foods sold in Dhaka City, Bangladesh. Microbiological analysis was conducted on 55 samples, viz. beef burger, beef patties, egg chop, chicken patties, chicken shaworma, faluda, ice-cream, pasteurized milk, pudding and pastry. The isolates obtained from the samples were provisionally identified as Bacillus cereus, Staphylococcus aureus and Escherichia coli. The highest level of B. cereus count (3.75 ± 0.31) was observed in faluda, while the highest levels of S. aureus and E. coli counts were observed (6.30 ±. 0.05) and (4.50 ± 0.24), respectively in chicken shaworma. Based on the attributes sampling planning for S. aureus, B. cereus and E. coli, all samples under study except ice-cream and pasteurized milk met no bacteriological quality standards, posing potential risk to consumers. Antibacterial activity of essential oils, such as cinnamaldehyde, euginol and carvacrol was carried out against the isolates of B. cereus, S. aureus and E. coli and from the experimental findings it was apparent that the essential oils showed antibacterial activity against the pathogens tested. The Minimum Inhibitory Concentration (MIC) and Minimum Bacterial Concentration (MBC) values of the essential oils against the test bacteria ranged from 2.5 to 10% and 5 to 15%, respectively. Essential oils can be used as alternatives of antibiotics and / or chemical preservatives in the fast foods.
... Evaluation of the minimal inhibitory concentration (MIC): A broth dilution susceptibility testing method was applied for the determination of the (MIC) [55], using a stock solution prepared by adding 15 mg of the organic extract in 3 mL of Trypticase-Soy Broth (TSB). Serial dilutions of the organic extract (3.33 µg/mL, 1.67 µg/mL, 0.56 µg/mL, 0.18 µg/mL, 0.061 µg/mL, 0.0021 µg/mL, and 0.007 µg/mL) and positive control (gentamycin sulfate: 104.5 µg/mL, 35.0 µg/mL, 11.6 µg/mL, and 3.87 µg/mL) were performed. ...
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As a result of the capability of fungi to respond to culture conditions, we aimed to explore and compare the antibacterial activity and chemical diversity of two endophytic fungi isolated from Hyptis dilatata and cultured under different conditions by the addition of chemical elicitors, changes in the pH, and different incubation temperatures. Seventeen extracts were obtained from both Pestalotiopsis mangiferae (man-1 to man-17) and Pestalotiopsis microspora (mic-1 to mic-17) and were tested against a panel of pathogenic bacteria. Seven extracts from P. mangiferae and four extracts from P. microspora showed antibacterial activity; while some of these extracts displayed a high-level of selectivity and a broad-spectrum of activity, Pseudomonas aeruginosa was the most inhibited microorganism and was selected to determine the minimal inhibitory concentration (MIC). The MIC was determined for extracts man-6 (0.11 μg/mL) and mic-9 (0.56 μg/mL). Three active extracts obtained from P. mangiferae were analyzed by Liquid Chromatography-Electrospray Ionization-Quadrupole-Time of Flight-Mass Spectrometry (LC–ESI–Q–TOF–MS) to explore the chemical diversity and the variations in the composition. This allows us to propose structures for some of the determined molecular formulas, including the previously reported mangiferaelactone (1), an antibacterial compound.
... Jorgensen et al. [20] conducted the disk diffusion check by normal protocol. On the entire surface of Muller-Hinton agar (MHA), the inoculum suspension of bacterial insulates was swabbed (pH7.3). ...
... The disk diffusion method was used for an antibiotic susceptibility assay (Jorgensen et al., 1999). Antimicrobial disks impregnated with cefalexin or cefazolin were separately placed onto the inoculated MH agar plates. ...
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A genomic analysis of Comamonas testosteroni S44 revealed a gene that encodes a LysR family transcriptional regulator (here named czoR, czo for cefazolin) located upstream of a putative class A β-lactamase encoding gene (here named czoA). A putative DNA-binding motif of the Fe-S cluster assembly regulator IscR was identified in the czoR-czoA intergenic region. Real-time RT-PCR and lacZ fusion expression assays indicated that transcription of czoA and czoR were induced by multiple β-lactams. CzoA expressed in Escherichia coli was shown to contribute to susceptibility to a wide range of β-lactams judged from minimum inhibitory concentrations. In vitro enzymatic assays showed that CzoA hydrolyzed seven β-lactams, including benzylpenicillin, ampicillin, cefalexin, cefazolin, cefuroxime, ceftriaxone, and cefepime. Deletion of either iscR or czoR increased susceptibility to cefalexin and cefazolin, while complemented strains restored their wild-type susceptibility levels. Electrophoretic mobility shift assays (EMSA) demonstrated that CzoR and IscR bind to different sites of the czoR-czoA intergenic region. Precise CzoR- and IscR-binding sites were confirmed via DNase I footprinting or short fragment EMSA. When cefalexin or cefazolin was added to cultures, czoR deletion completely inhibited czoA expression but did not affect iscR transcription, while iscR deletion decreased the expressions of both czoR and czoA. These results reveal that CzoR positively affects the expression of czoA with its own expression upregulated by IscR.
... The antibiotic susceptibility of isolates was determined as described previously (Jorgensen and Turnidge, 2015). Twenty-one antibiotics were tested: amoxicillin, bicozamycin, cefaclor, cefatrizine, cefazolin, cefixime, cefoperazone, cephaloridine, doxycycline, erythromycin, florphenicol, fosfomycin, kanamycin, lincomycin, oxolinic acid, oxytetracycline, rifamycin, spiramycin, sulfamethoxazole/trimethoprim, sulfamonomethoxine, vancomycin. ...
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Channel catfish (Ictalurus punctatus) are one of the most commercially important fish species cultured in Vietnam, and has been a major driver of Vietnam's rise to become a leading country for fisheries exports in the world. Since 2016, there have been several outbreaks of a contagious disease which in channel catfish has resulted in severe levels of economic loss. In this study, bacterial isolates from diseased fish were sampled and analyzed from 22 farms in four Northern Vietnam provinces experiencing outbreaks. Isolates were identified as Aeromonas veronii based on their bacteriological characteristics, 16S rRNA sequence analysis, and presence of Aeromonas veronii specific rpoB gene by PCR examinations. Subsequently, A. veronii isolates were tested for their virulence to fish via an experimental infection challenge, and their susceptibility to 21 antibiotics was also assessed. Results showed that A. veronii is pathogenic and has probably contributed to the mass mortality of this channel catfish species in Vietnam. Notably, A. veronii also exhibited resistance to four common antibiotics including amoxicillin, bicozamycin, lincomycin, and vancomycin. To our knowledge, this is the first report of outbreaks associated with A. veronii infection in channel catfish in a Southeast Asian country. This report could be used to alert aquaculture farmers and managers in this region to develop an appropriate biosecurity strategy for protecting catfish and other vulnerable species to A. veronii infection, and find alternative solutions to help mitigate occurences of the disease.
... The plates were kept in the oven at 37°C for 24 h. Minimum inhibitory concentration (MIC) was considered as the lowest concentration of antibiotic that completely inhibited bacterial growth (CLSI, 2010) for the diameter of the bacterial growth inhibition halos (BARRY, 1991;JORGENSEN et al., 1999) formed around each hole. The halos were measured and the results displayed in millimeters (mm). ...
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The association of natural compounds isolated from medicinal plants with conventional antibiotics, both with similar mechanisms of action, have become a viable alternative strategy to overcome the problem of drug resistance. This study aimed to evaluate the in vitro antimicrobial activity of tannic substances present in the bark of Anacardium occidentale and Anadenanthera colubrina against samples of Staphylococcus aureus when in combination with cephalexin. These combinations were evaluated by determining the minimum inhibitory concentration (MIC). For this purpose, tannins and cephalexin were serially dissolved in distilled water at concentrations ranging from 0.976 mg/mL to 500 mg/mL and 2 mg/mL to 512 mg/mL, respectively. When combined, the compounds inhibited S. aureus growth forming halos ranging from 0.9 to 46 mm with an MIC of 7.8 mg/mL (tannins) and 4 µg/mL (cephalexin). The resulting effect of the combination of natural and synthetic substances with similar mechanisms of action presented better results than when tested alone. Thus, the conclusion is that both the tannins and cephalexin had their antimicrobial action enhanced when used in combination, enabling the use of lower concentrations while maintaining their antibacterial effect against strains of S. aureus.
... For analysis of antimicrobial activity, two Gram negative bacteria (Staphylococcus aureus and Escherichia coli), two Gram positive bacteria (Pseudomonas aeruginosa and Bacillus subtilis) and two fungal strains (Aspergillus niger and Aspergillus oryzae) were employed following Cruick-Cruick-Shank et al., (1975). The zone of inhibition was determined by employing Agar Well Diffusion technique following Jorgensen and Turnidge (2007). ...
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In present study antimicrobial and antioxidant activities of leaf and stem ethanolic extracts of Cissampelos pareira were evaluated. Stem extract revealed good result as compared to leaf extract. The stem ethanolic extract exhibited good zone of inhibition against Escherichia coli and Pseudomonas aeruginosa with 13±0.33 mm and 14±0.58 mm diameter whereas minimum zone of inhibition was observed by leaf ethanolic extract against Bacillus subtilis and Staphylococcus aureus with 7±0.58 mm and 7±0.88 mm, respectively. The available antibiotics such as tetracycline, cefoperazone and erythromycin were used to compare all these results. The fungal strains i.e. Aspergillus oryzae and Aspergillus niger were used and significant results were recorded for stem ethanolic extract as compared with antifungal standard discs such as terbinafine and fungivin. The MIC assay was used for further analysis of leaf and stem extracts that inhibited bacterial and fungal growth. The antioxidant effect was evaluated by using 1,1-diphenyl-2picrylhydrazyl (DPPH) radical scavenging assay, total phenolic content and total flavonoid content. The stem extract of plant displayed good antioxidant potential as compared to the leaf extract. The % DPPH free radical scavenging activity was maximum of the stem extract (1.03±0.19 µg/ml). The maximum result of antioxidant activity was observed by total phenolic content i.e. 0.77±0.09 µg/ml at 1000 concentration. The ethanolic extract of stem had exhibited most elevated level of flavonoid content i.e. 0.70±0.06 µg/ml as compared to the leaf extract of C. pareira.
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A total of 117 Salmonella enterica serovar Typhimurium and 59 monophasic Salmonella Typhimurium (S. enterica serovar 4,[5],12:i:–) strains isolated between 2008 and 2012 from pig, wild bird, rodent, and farm environment samples from the northeast of Spain were characterized by phage typing, antibiotic susceptibility testing, and multiple-locus variable-number tandem repeat analysis in order to evaluate their phenotypic and genetic relatedness. In Salmonella 4,[5],12:i:–, the most prevalent phage types were U311 (40.7%) and DT195 (22%), which did not correspond with the so-called Spanish clone and generally showed a different resistance pattern (ASSuT). Antibiotic resistance was found in 85.8% of the isolates, with 94.1% of them displaying multidrug resistance. Multiple-locus variable-number tandem repeat analysis identified 92 different profiles, six of them shared by both serovars. The minimum spanning tree showed one major cluster that included 95% of the Salmonella 4,[5],12:i:– isolates, which came from different animal sources, geographic locations, and time periods, suggesting high clonality among those Salmonella strains and the ability to spread among pig farms. Overall, isolates of Salmonella 4,[5],12:i:– were more similar to European strains than to the well-characterized Spanish clone. The spread of these new strains of Salmonella 4,[5],12:i:– would likely have been favored by the important pig trade between this Spanish region and other European countries. The overall high prevalence of multidrug resistance observed in these new strains should be noted.
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The objective of this study was to compare the antimicrobial and antioxidant activities of Moringa oleifera and Biden pilosa leaf extracts on ground beef quality from Bonsmara and non-descript cattle during 6 days refrigeration storage. Fresh ground beef form each breed were treated BHT (positive control, 0.02%w/w), M. oleifera (ML, 0.05 and 0.1% w/w) and B. pilosa (BP, 0.05 and 0.1% w/w) leaf extracts and compared with beef samples without any additive (negative control). The pH, instrumental color (CIE L*, a*, b*), oxidative stability, total viable counts (TVC) and lactic acid bacteria (LAB) counts were determined after the storage period. The results revealed higher pH values in control and BHT treatment than ground beef samples treated with extracts (p > 0.05). Addition of ML and BP leaf extracts significantly (p < 0.05) improved the hunter (L*, a* and b*) values and sensory quality of the ground beef compared to control. Similarly, the formation of TBARS in ground beef samples treated with extracts were significantly (p < 0.05) lower compared to control and BHT treatment. Breed had little effect on most parameters except redness (a*) and TBARS formation in which ground beef samples from Bonsmara cattle demonstrated higher oxidative stability than non-descript (p < 0.05). The bacterial counts of beef samples containing ML and BP leaf extract samples were relatively lower than control and BHT treated samples. In conclusion, the addition of M. oleifera and B. pilosa leaf extracts in ground beef show that they are very effective against lipid oxidation and have potential as natural antioxidants.
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The thyme (Thymus vulgaris) essential oil was assessed as antibiotic growth promoter replacement in quail chick diet and in vitro test. In total, 250 day-old Japanese quail chicks (mixed sex) were allocated into 5 dietary treatments of 5 replications (6 females and 4 males in each cage with the size of 40× 90× 25 cm) under a completely randomized design. The dietary treatments were included the control diet, control diet without any additive, control diet plus 100 ppm flavophospholipol as an antibiotic growth promoter, control diet plus 200 ppm TVE, control diet plus 300 ppm TVE, and control diet plus 400 ppm Thymus vulgaris essential oil (TVE). Feed intake (FI), body weight gain (BWG), feed conversion ratio (FCR), organs weight, morphology of intestine, serum lipids, and microbial population were measured on day 35. Lipid oxidation of stored muscle tissue was measured by TBARS test. GC/MS assay, DPPH method, and well diffusion method were evaluated for determination of components, antioxidant, and antimicrobial properties respectively. FCR improved significantly in 400 ppm TVE compared with 200 and 300 ppm TVE (P < 0.05). The serum triglyceride decreased significantly in both sexes receiving 400 ppm TVE compared to control. Villi height increased significantly in duodenum accompanied by decreasing crypt dept at all TVE levels compared with control and antibiotic. The breast muscle tissue of quail fed on 300 and 400 ppm TVE reduced the rate of oxidation during refrigerated storage compared to control. Thymol was the main component (35.40%) of the thymus oil. The considerable antioxidant activity of TVE was identified by IC50 of 58.48 µg/mL. Moreover, zones of growth inhibition of gram positive bacteria and ecoli were numerically greater in different doses of TVE than antibiotics. Therefore, The TVE is suitable alternative component for antibiotic growth promoters by dosing consideration. However, it is possible that antibiotic resistance would increase for these natural compounds along the time.
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