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Antimicrobial Activity of Mandelic Acid Against Methicillin-Resistant Staphylococcus aureus: a Novel Finding with Important Practical Implications
Abstract and Figures
Background: Staphylococcus aureus is a major health concern worldwide especially in cutaneous diseases. The aim of this study was to determine the in vitro antimicrobial activity of mandelic acid against Staphylococcus aureus isolates. Methods: In this study, the susceptibility of mandelic acid against two type strains and nineteen clinical isolates of Staphylococcus aureus was assessed in vitro. Results: Mandelic acid in different concentrations of 40, 80 and 160 mg/ml showed in vitro antibacterial activity against all tested clinical isolates of Methicillin-resistant Staphylococcus aureus (MRSA) as well as the tested type strains in disk diffusion method with inhibitory zones of 11-20 mm. The minimum inhibitory concentration and minimum bactericidal concentration (MIC/MBC) for methicillin-sensitive staphylococcus aureus (MSSA) and MRSA type strains were 20/20 and 40/40 mg/ml respectively. For the nineteen clinical MRSA isolates, MIC50 and MIC90 were 20 and 40 (mg/ml) respectively and MBC50 and MBC90 were 20 and 80 (mg/ml) respectively. Conclusion: Our results suggest that mandelic acid has an antibacterial activity against MRSA and might be a useful addition to anti-MRSA armamentarium. Further investigations regarding the use of mandelic acid in a suitable moisturizer for atopic skin, to exert the dual effects of lubrication and MRSA eradication is recommended.
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... It acts as an antiseptic against various microbial pathogens such as Staphylococcus aureus, E. coli, Proteus sp., Pseudomonas sp. [19][20][21]. Nowadays, dermatologists suggest mandelic acid as a useful agent for a wide variety of skin problems, from acne to wrinkles. Mandelic acid has been studied extensively for its possible uses in treating common skin problems such as photoaging, irregular pigmentation and acne [19]. ...
... Nowadays, dermatologists suggest mandelic acid as a useful agent for a wide variety of skin problems, from acne to wrinkles. Mandelic acid has been studied extensively for its possible uses in treating common skin problems such as photoaging, irregular pigmentation and acne [19]. ...
... MA derived compounds were tested for their antimicrobial activity against a few Gram-positive and Gram-negative bacteria by the disk diffusion method. They demonstrated the antimicrobial effect of MA at concentrations of 20-160 mg/mL against MRSA [19]. Thus, mandelic acid could be an effective treatment for MRSA and other bacterial skin infections. ...
Antimicrobial hand gels have become extremely popular in recent years due to the COVID-19 pandemic. Frequent use of hand sanitising gel can lead to dryness and irritation of the skin. This work focuses on the preparation of antimicrobial acrylic acid (Carbomer)-based gels enhanced by non-traditional compounds—mandelic acid and essential oils—as a substitute for irritating ethanol. Physicochemical properties (pH and viscosity), stability and sensory attributes of the prepared gels were investigated. Antimicrobial activity against representative Gram-positive and Gram-negative bacteria and yeasts was determined. The prepared gels with mandelic acid and essential oil (cinnamon, clove, lemon, and thyme) proved to have antimicrobial activity and even better organoleptic properties than commercial ethanol-based antimicrobial gel. Further, results confirmed that the addition of mandelic acid had a desirable effect on gel properties (antimicrobial, consistency, stability). It has been shown that the essential oil/mandelic acid combination can be a dermatologically beneficial hand sanitiser compared to commercial products. Thus, the produced gels can be used as a natural alternative to alcohol-based daily hand hygiene sanitisers.
... aeruginosa), and Candida albicans (C. albicans) (17,18). ...
1,3,4-oxadiazoles are interesting compounds because of their valuable biological effects such as cytotoxic, antibacterial, antifungal, and anti-tubercular activities. Ethyl mandelate was treated with hydrazine hydrate to yield the corresponding acylhydrazide. Some of the 2,5 disubstituted 1,3,4-oxadiazole derivatives were prepared from acylhydrazide using three different procedures. In the first procedure, acylhydrazide was reacted with nitro or chloro aroyle chloride to afford a diacylhydrazide which was cyclized to 2,5-disubstituted 1,3,4-oxadiazole in the presence of phosphoryl chloride as dehydrating agent. In the second procedure, furan-oxadiazole derivative was directly prepared from carboxylic acid and acylhydrazide in one step. In the third procedure, acyl hydrazide was condensed with 5-nitrofuraldehyde to yield 5-nitrofuran-2-yl) methylene)-2-phenyl acetohydrazide intermediate which was cyclized to form the nitrofuran-oxadiazole derivative by acetic anhydride as dehydrating agent. The structures of these compounds have been elucidated by spectral IR and 1 H-NMR analysis. All the newly synthesized compounds were screened for their antibacterial and antifungal activities. Compounds F 3 and F 4 showed remarkable antibacterial activities against Staphylococcus aureus and Escherichia coli bacteria.
... Mandelic acid is responsible for the antibacterial activity in the camel tears [28]. The specific presence of certain amino acids suggests that they may have special functions in the tear film, perhaps helping camels to keep the ocular surface healthy and withstand the ocular discomfort associated with its desert environment. ...
Camel tear metabolomics and elemental analysis are useful in getting the information regarding the components responsible for maintaining the protective system that allows living in the desert and dry regions. The aim of this study was to correlate that the camel tears can be used as artificial tears for the evaluation of dryness in the eye. Eye biomarkers of camel tears were analyzed by gas chromatography-mass spectroscopy (GC-MS) and inductively coupled plasma mass spectroscopy (ICP-MS). The major compounds detected in camel tears by GC-MS were alanine, valine, leucine, norvaline, glycine, cadaverine, urea, ribitol, sugars, and higher fatty acids like octadecanoic acid and hexadecanoic acid. GC-MS analysis of camel tears also finds several products of metabolites and its associated metabolic participants. ICP-MS analysis showed the presence of different concentration of elemental composition in the camel tears.
Ethnopharmacological relevance:
Man has used honey to treat diseases since ancient times, perhaps even before the history of medicine itself. Several civilizations have utilized natural honey as a functional and therapeutic food to ward off infections. Recently, researchers worldwide have been focusing on the antibacterial effects of natural honey against antibiotic-resistant bacteria.
Aim of the study:
This review aims to summarize research on the use of honey properties and constituents with their anti-bacterial, anti-biofilm, and anti-quorum sensing mechanisms of action. Further, honey's bacterial products, including probiotic organisms and antibacterial agents which are produced to curb the growth of other competitor microorganisms is addressed.
Materials and methods:
In this review, we have provided a comprehensive overview of the antibacterial, anti-biofilm, and anti-quorum sensing activities of honey and their mechanisms of action. Furthermore, the review addressed the effects of antibacterial agents of honey from bacterial origin. Relevant information on the antibacterial activity of honey was obtained from scientific online databases such as Web of Science, Google Scholar, ScienceDirect, and PubMed.
Results:
Honey's antibacterial, anti-biofilm, and anti-quorum sensing activities are mostly attributed to four key components: hydrogen peroxide, methylglyoxal, bee defensin-1, and phenolic compounds. The performance of bacteria can be altered by honey components, which impact their cell cycle and cell morphology. To the best of our knowledge, this is the first review that specifically summarizes every phenolic compound identified in honey along with their potential antibacterial mechanisms of action. Furthermore, certain strains of beneficial lactic acid bacteria such as Bifidobacterium, Fructobacillus, and Lactobacillaceae, as well as Bacillus species can survive and even grow in honey, making it a potential delivery system for these agents.
Conclusion:
Honey could be regarded as one of the best complementary and alternative medicines. The data presented in this review will enhance our knowledge of some of honey's therapeutic properties as well as its antibacterial activities.
This article investigated the structure, and the spectroscopic and antimicrobial properties of mandelic acid and its alkali metal salts. The electron charge distribution and aromaticity in the analyzed molecules were investigated using molecular spectroscopy methods (FT-IR, FT-Raman, 1H NMR, and 13C NMR) and theoretical calculations (structure, NBO, HOMO, LUMO, energy descriptors, and theoretical IR and NMR spectra). The B3LYP/6-311++G(d,p) method was used in the calculations. The antimicrobial activities of mandelic acid and its salt were tested against six bacteria: Gram-positive Listeria monocytogenes ATCC 13932, Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, and Loigolactobacillus backii KKP 3566; Gram-negative Escherichia coli ATCC 25922 and Salmonella Typhimurium ATCC 14028, as well as two yeast species, Rhodotorulla mucilaginosa KKP 3560 and Candida albicans ATCC 10231.
Mandelic acid enantiomers are key precursors in the synthesis of valuable chiral products. However, separating enantiomers in reasonable amounts is a challenging task despite advances in chiral chromatography and other discontinuous and expensive techniques. To tackle these problems, we designed and tested a modular microfluidic system working in a fully continuous flow regime. The system consists of two modules, namely (i) a packed-bed microreactor (PBR) with immobilized enzyme lipase and (ii) a membrane microseparator driven by an imposed electric field. The immobilized catalyst converts a racemic substrate, methyl mandelate, into mandelic acid enantiomers. The enzyme preferentially synthesizes (R)-(−)-mandelic acid within minutes. The product stream from PBR is fed into a membrane microseparator operated in a counter-current regime. An inserted dialysis membrane and an orthogonally applied electric field completely separate the electrically charged enantiomers from their mixture with unreacted and uncharged methyl mandelate within 1.5 min. Under improved reaction and separation conditions, approximately 1 g of (R)-(−)-mandelic acid are produced per day with almost 60 % enantiomeric excess. Moreover, the productivity of this system is easily scalable without compromising its excellent reaction-transport characteristics.
The exogenous synthesis of nanoparticles (NPs) by living plant systems was considered a sustainable way to synthesize NPs. It is cost-effective and more eco-friendly compared to the currently used chemical and physical methods. In this study, silver NPs (AgNPs) were exogenously synthesized by the desert Tephrosia apollinea (Delile) DC. living plants under different levels of drought stress simulated by polyethylene glycol (PEG). The phytochemicals capping the AgNPs were characterized by gas chromatography-mass spectrometry (GC-MS). Different phytochemicals, such as palmitic acid, stearic acid, eicosane, oxalic acid, and 1,3-propanediol, were identified as possible capping agents. Hierarchical clustering and principal component analysis of the GC-MS data indicated that the levels and types of phytochemicals encapsulating the AgNPs were affected by the drought stress levels and its duration applied during AgNPs synthesis. Furthermore, the cytotoxic activities of the synthesized AgNPs were varied. The cytotoxic activity was higher with AgNPs synthesized at higher drought stress levels. The lowest half-maximal inhibitory concentration (IC50) toxicity levels were observed at −0.4 MPa, which is 5.66 ± 1.69 μg/mL for human MDA-MB-231 breast cancer cells and 4.65 ± 0.52 μg/mL for human HaCat normal skin cells. Our data collectively indicate that drought stress pre-treatment of living plants could synthesize NPs with variable capping phytochemicals. Hence, variable promising biomedical applications could be possible.
In the present work we compared the biological activity of mandelic acid (MA) and its Li, Na, K, Rb and Cs salts. The study also investigated the effect of raw wastewaters (RW) and treated wastewaters (TW), comparable to microbial medium (MM) on the biological activity of the tested chemical compounds used in concentrations of 5; 2.5; 1.25; 0.625; 0.3125 mg/ml. In the present experiment the evaluation of the following parameters was performed: E. coli (ATCC 25922) cells viability, growth inhibition of E. coli (ATCC 25922), the inhibition of GFP protein, genotoxicity and ROS generation. Our results showed that three main factors differentiated the antibacterial activity of MA and its Li, Na, K, Rb and Cs salts: study environment (MM, RW, TW), metal forming salt of mandelic acid and concentration of tested compounds. Additionally, raw and treated wastewater, compared to microbial medium, changes the antimicrobial activity of MA and its salts in relation to the E. coli strain. We also detected that both MA and its salts affect the GFP protein and the induction of the recA promoter (genotoxicity test). The activity of the tested salts in relation to these two parameters is strictly dependent on the type of salt-forming metal and the concentration used. The analysis of ROS synthesis suggests that in the majority of the studied mandelic acid salts, oxidative stress is the dominant mechanism of cytotoxicity and genotoxicity. We also showed that both raw wastewaters (RW) and treated wastewaters (TW), compared to microbial medium (MM), change significantly the activity of MA and its salts.
GC-MS-based metabolomics were used to investigate metabolic changes in prawn shell waste during fermentation. Microbial strains Lactobacillus plantarum and Bacillus subtilis were co-fermented in a shake flask comprising of 5% (w/v) prawn shell waste and 20% (w/v) glucose as a carbon source. Analysis of the prawn shell waste fermentation showed a total of 376 metabolites detected in the culture supernatant, including 14 amino acids, 106 organic acids, and 90 antimicrobial molecules. Results show that the liquid fraction of the co-fermentation is promising for harvesting valuable metabolites for probiotics application.
Different contents of mandelic acid (2.5–10 %) were mixed with glycerol-plasticized soy protein isolate (SPI) to prepare mandelic acid incorporated soy protein isolate films. The effects of the mandelic acid content on the morphology and properties of the glycerol-plasticized SPI films were investigated by scanning electron microscopy, dynamic mechanical thermal analysis, differential scanning calorimetry, thermogravimetric analysis, water resistivity and tensile testing. The tensile strength of the mandelic acid incorporated SPI films decreased while elongation at break increased. The results indicated that, at 10 mass% of mandelic acid, strong interactions occurred both between the mandelic acid and the SPI matrix, leading to appearance of endotherms at 148.8 °C. Mandelic acid-incorporated soy protein films were also tested for their antibacterial properties.
The present work aimed to find out the antibacterial activity of Nymphaea nouchali flower on human and plant pathogenic bacteria.
Antibacterial potency of methanol, acetone, ethyl acetate and petroleum spirit extracts of Nymphaea nouchali flower has been tested against four human pathogenic bacteria Bacillus subtilis (FO 3026) Escherichia coli (IFO 3007), Klebsiella pneumonia (ATTC 10031) and Sarcina lutea (IFO 3232) and one plant pathogenic bacterium Xanthomonas campestris (IAM 1671) by disc diffusion assay. Zone of inhibition produced by different extracts against the test bacteria was measured and compared with standard antibiotic disc.
Methanol extract possessed better antibacterial activity against two pathogenic bacteria, B. subtilis (FO 3026) and S. lutea (IFO 3232) than commercial antibiotic nalidixic acid. Acetone extract showed moderate sensitivity whereas B. subtilis (FO 3026), S. lutea (IFO 3232) and X. campestris (IAM 1671) showed resistance to ethyl acetate and petroleum spirit extracts. The minimum inhibitory concentrations of various extracts were ranged between 128--2048 mugml-1.
Nymphaea nouchali flower could be a potential candidate for future development of novel broad spectrum antibacterial herbal formulation.
The biocidal activity of twelve pure chemical substances and crude extracts of onion and garlic leaves and date palm seeds was investigated against P. marginalis using agar well diffusion method. Sodium chlorite, Cetyltrimethylammonium bromide (CTAB), hydrogen peroxide and crystal violet showed the most promising biocidal activity, sodium dodecyl sulfate (SDS) and methylene blue showed moderate activity, ammonium molybdate and silver nitrate showed very low activity, while sodium molybdate, dinitrophenol, sodium azide and vanillin did not show any inhibitory effect against Pseudomonas marginalis at the concentration of 10,000 ppm. Water, HCl (0.1N), NaOH (0.1N) and methanol (80%) were used for extraction of the agricultural wastes of onion, garlic and date palm seeds. Results indicated that water and methanolic crude extracts had the most promising biocidal activity against P. marginalis.
In the present study, a new series of 2-(1,3-dioxo-2,3-dihydro-1H-2- isoindolyl) ethyl 2-hydroxy-2-(substituted phenyl) acetates 6a-e have been synthesized from the combination of N-(2-hydroxy ethyl) phthalimide 5 and substituted mandelic acids 2a-e which resulted in both anti-inflammatory and antimicrobial activity. These compounds have been characterized by IR, 1H NMR, mass spectral and elemental analysis. Among the compounds tested for anti-inflammatory activity, compound 6b and 6c showed significant activity and compound 6d showed potent antibacterial and antifungal activity. The anti-inflammatory activity has been determined by carrageenan induced acute paw oedema in rats. The results are discussed in the text. The in vitro antibacterial and antifungal activity of the compounds have been evaluated by paper disc diffusion method. The minimum inhibitory concentrations (MIC) of the compounds have also been determined by agar streak dilution method.
Background:
Treatment of melasma and postinflammatory hyperpigmentation is often challenging. No ideal short-term and long-term treatment is available. Vitamin C alone and in combination with iontophoresis has been studied and found to be useful; however, no long-term studies have been published.
Methods:
In this study, 35 patients (34 female, 1 male) were treated with a novel full-face iontophoresis mask (FFIM) and a proprietary vitamin C (ascorbyl glucoside) preparation. Patients received one in-office treatment and 12 to 24 at-home treatments over 1 to 2 months in conjunction with a strict maintenance regimen consisting of a mandelic/malic acid skin care regimen, broad-spectrum ultraviolet A/ultraviolet B sunblock, a wide-brimmed hat, and sun-avoidance behavior. Follow-up after the initial in-office treatment ranged from 1 to 54 months (mean, 26 months). Four independent observers graded improvement of melasma and PIH using a 4-point scale. Before the study, high-performance liquid chromatography was used to verify iontophoretic penetration of vitamin C into the skin to a level of 0.2 cm in healthy volunteers (2 male, 2 female).
Results:
A mean 73% improvement in abnormal pigmentation was observed at the end of FFIM/vitamin C treatment. Greater than 25% improvement was observed in 32 of 35 patients, and greater than 50% improvement in 22 of 35 patients. Melasma Area and Severity Index scores demonstrated substantial improvement from baseline for all patients, with a mean improvement of 15.7.
Conclusions:
Full-face iontophoresis of vitamin C appears to be an effective short-term treatment for melasma and postinflammatory hyperpigmentation. A protocol of strict sun avoidance in combination with a mandelic/malic acid skin care regimen appears to be useful in maintaining the improvement.
In some hospitals a 1 ~o solution of mandelic acid is used as bladder irrigation fluid to prevent urinary tract infections associated with indwelling urethral catheterization. A 1 ~ solution of mandelic acid (phenylglycolic acid) has a pH of 2.4. This solution is able to dissolve apatite and struvite, two minerals causing concrements and stones associated with indwelling catheters (Froeling, 1978; Goldhoorn et al., 1978). Nearly the same results can also be obtained with a 1 : 10 diluted renacidin solution (see below), which gives less irritation and pain complaints than 1 ~ mandelic acid (Goldo hoorn. 1978). The dissolving activity of the bladder irrigation fluid seems to be more important than its antimicrobial activity (Froeling, 1978; Warren et al., 1978; Documentatie- en informatiedienst KNMP, 1979). On the other hand, irrigation with antibiotics has the risk of superinfection with multiresistant strains. Intermittent irrigation with closed system drainage gives better results than continuous open drainage (Zinner, Kenny and Weinstein, 1970). According to the directions of the Health Council (Advies van de Gezondheidsraad, 1976) oral applications of mandelic acid are advised: 4 times 30 ml Ira ammonium mandelate daily with a large quantity of ascorbic acid to decrease the pH of the urine below 5.5. The acidifying activity of ascorbic acid is poor and the risk is the formation ofoxalate concrements and stones (Documentatie- en informatiedienst KNMP, 1979). This paper reports the results of some experiments on the bactericidal activity of mandelic acid when used in cases of indwelling catheter or of urinary tract infection. The bactericidal activity ofmandelic acid was compared with that of renacidin solution, as used in hospitals and containing 60.4 g citric acid, 0.9 g calcium carbonate, 0.1 g EDTA (Na-salt), 6 g gluconolactone, 27.2 g magnesium carbonate hydroxide in distilled water (ad 1000 ml). Tubes containing 2 ml 1/mandelic acid (pH 2.4) or 2 ml of a 1:10 diluted renacidin solution (pH 3.8) were inoculated with 106 microorganisms of different strains of Escherichia coli, Klebsiella Table 1. Effect on pH on bacterial growth ~ in the presence of 0.5 and 1 ~ mandelic acid.
Many clinicians have used glycolic acid (GA) peels for facial acne, scarring, and hyperpigmentation, mainly in lighter skin types. Salicylic-mandelic acid combination peels (SMPs) are a newer modality, and there have been no well-controlled studies comparing them with other conventional agents.
To compare the therapeutic efficacy and tolerability of 35% GA peels and 20% salicylic-10% mandelic acid peels in active acne and post-acne scarring and hyperpigmentation.
Forty-four patients with facial acne and post-acne scarring and hyperpigmentation were divided into two groups, with one receiving GA peels and the other SMPs at fortnightly intervals for six sessions. The treating physician performed objective evaluation of treatment outcomes. The patients, the treating physician, and an independent observer made subjective assessments. Side effects of both agents were also noted.
Both the agents were effective, but SMPs had a higher efficacy for most active acne lesions (p<.001) and hyperpigmentation (p<.001). Side effects were also lesser with SMPs.
Both the agents were effective and safe in Indian patients, with SMPs being better for active acne and post-acne hyperpigmentation.
Children with atopic dermatitis are more frequently colonized with Staphylococcus aureus than children without atopic dermatitis. However, little epidemiological data exist regarding the prevalence of methicillin-resistant S. aureus among children with atopic dermatitis. Recent studies have revealed an increasing prevalence of community-associated methicillin-resistant S. aureus among patients presenting to hospitals with serious bacterial infections, particularly those with cutaneous and soft tissue infections. As many atopic dermatitis patients are treated empirically with antibiotics for secondary skin infections, an understanding of the epidemiology of bacterial colonization and superinfection is essential for directing proper treatment in the atopic patient population. This study investigates the prevalence of risk factors for community-associated, methicillin-resistant S. aureus colonization among pediatric atopic dermatitis patients encountered at an academic pediatric dermatology clinic. An observational cross-sectional study was conducted at the Children's Hospital of Philadelphia in which 54 patients previously diagnosed with atopic dermatitis were enrolled. A detailed patient questionnaire, a complete cutaneous examination, and an evaluation of eczema severity according to the Eczema Area and Severity Index were completed at the time of enrollment. Bacterial cultures from the skin and nares were obtained to determine the frequency of colonization with either methicillin-sensitive S. aureus or methicillin-resistant S. aureus. Although most atopic dermatitis patients studied were colonized with S. aureus (43/54 [80%]), methicillin-resistant S. aureus was isolated from only seven atopic dermatitis patients (7/43 [16%]). Patients colonized with S. aureus were more likely to be male, to have been previously hospitalized, to have used a topical calcineurin inhibitor in combination with a topical steroid, and less likely to have used topical antibiotics. Bivariable analysis, however, revealed that only previous hospitalization was independently associated with an increased risk of methicillin-resistant S. aureus colonization. We observed that 80% of atopic dermatitis patients were colonized with S. aureus, and that of these patients, 16% of colonized patients were colonized with a methicillin-resistant strain. Methicillin-resistant S. aureus colonization was found to be significantly associated with previous hospitalization. Evidence also indicates that topical calcineurin inhibitors used in conjunction with topical steroids is associated with increased S. aureus colonization, while topical antibiotic use appears to decrease S. aureus colonization.
Staphylococcus aureus colonization is accepted to be an important triggering factor in patients with atopic dermatitis (AD) and antibiotic resistance has been recognized to be a serious problem as a consequence and for the management of AD treatment.
To investigate the antibiotic resistance pattern of S. aureus strains isolated from patients with AD with apparent (lesional and nonlesional skin areas) and recurrent skin colonization and strains obtained from healthy nasal carriers.
Eighty-seven patients (age 23+/-11.5 years) with mild to severe AD (SCORAD 46.9+/-16.6), 21 patients (age 19.8+/-6.7 years) before antistaphylococcal treatment and 177 healthy nasal carriers (age 27.5+/-8.4 years) were microbiologically assessed for carriage of S. aureus. Colonization of lesional and nonlesional skin areas was quantified by counting the number of colony forming units on the skin surface (log(10) CFU cm(-2)). Antimicrobial susceptibility and resistance phenotypes of 179 S. aureus strains were assessed with the agar disc-diffusion method.
Staphylococcus aureus was isolated from 87% of lesional and 44% of nonlesional skin samples from patients with AD. The colonization density of S. aureus was markedly higher in lesional than in nonlesional skin (P<0.001), and was positively correlated with AD severity (P<0.001) and total serum IgE (P<0.05). Patients with AD had a significantly higher prevalence of chloramphenicol-resistant S. aureus than nasal carriers (P<0.01). Similar rates of resistance were expressed to tetracycline, erythromycin, mupirocin, clindamycin and penicillin. Nearly 35% of S. aureus strains from the lesional skin demonstrated different antimicrobial sensitivity pattern compared with strains from nonlesional skin of the same patients with AD. The trend of increasing resistance to chloramphenicol, erythromycin and fusidic acid was observed among S. aureus strains recovered from patients after approximately 75 days of antibiotic treatment. Methicillin-resistant S. aureus isolates were cultured from two patients, one during exacerbation and the other after subsequent bacterial recolonization.
Discrepancies in antibiotic sensitivity pattern were observed among S. aureus strains colonizing different sites of AD skin (lesional and nonlesional areas), and also in AD patients with prior antibiotic treatment. Therefore, clinicians should consider repeat microbial susceptibility testing on different body sites of patients with AD when clinically indicated.
As part of a programme to establish the relative merits of antiseptics that are used as bladder instillations to control urinary tract infections in patients with indwelling catheters, the activity of five such formulations were tested against dense (10(9) cfu/cm2) mixed biofilms composed of Citrobacter diversus, Pseudomonas aeruginosa and Enterococcus faecalis growing on silicone discs. All three species were resistant to chlorhexidine (200 mg/l) and povidone-iodine (1% v/v) in the biofilm mode of growth, whereas these agents rapidly eliminated viable cells from urine suspensions of the mixed community. Lactic acid (1% v/v) produced a 1 log reduction of the biofilm population within 30 min of exposure. The mandelic acid (1% w/v) and mandelic acid (0.5% w/v)/lactic acid (0.5% v/v) mixture proved to be the most effective in eliminating the biofilm organisms. It is suggested that these latter solutions should now be tested for efficacy in bladder washouts against urinary tract infections in catheterized patients.