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In the study on antimicrobial activity of rose geranium oil (GEO), 167 bacterial strains belonging to 22 genera and 49 species were tested. In total only seven strains were sensitive to GEO. Out of 15 reference strains included in the study only one (Streptococcus equi ssp. equi MTCC-3522) and six of the 120 isolates from clinically sick animals were found sensitive. None of the 26 isolates from environment (soil, water and air) and six from healthy animals was sensitive to GEO. All resistant strains (160) had minimum inhibitory concentration (MIC) more than 2µL of GEO / mL of medium. Sensitive strains’ GEO MIC ranged between 0.2 µL/ mL to 2µL/ mL. The minimum MIC was for Pasteurella langaensis (0.2 µL/ mL) strain followed by strain of Streptococcus equi ssp. equi MTCC-3522 (0.4µL/ mL), Strept. intestnalis and Strept. pyogenes (0. 4µL/ mL), Strept. equi ssp. equi (0.8µL/ mL), Bacillus polymyxa (1.5 µL/ mL) and Pseudomonas aeruginosa (2.0µL/ mL). The study emphasizes need for evolution of some short of central universally accepted guidelines to perform and report antimicrobial activity of herbal antimicrobials so that the comparable data can be analyzed for future meta-analytical and clinical purposes.
Bhoj R Singh et al., Asian Journal of Pharmaceutical Technology & Innovation, 03 (13); 2015; 01 - 05
Asian Journal of Pharmaceutical Technology & Innovation
ISSN: 2347-8810
Research Article
Received on: 11-05-2015
Accepted on: 17-05-2015
Published on: 15-08-2015
Corresponding Author
Antimicrobial Activity of Rose Geranium
(Pelargonium roseum) Essential Oil on
Bacteria of Veterinary Clinical Origin
*Dr. Bhoj R Singh
Act. Head of Division of Epidemiology,
Indian Veterinary Research Institute,
Izatnagar-243122, India, Ph. No. +91-
Bhoj R Singh*1, Ravi Kant Agrawal2, Sakshi Dubey1, Monika
Bhardwaj1, Prasanna Vadhana1
In the study on antimicrobial activity of rose geranium oil (GEO), 167
bacterial strains belonging to 22 genera and 49 species were tested. In
total only seven strains were sensitive to GEO. Out of 15 reference
strains included in the study only one (Streptococcus equi ssp. equi
MTCC-3522) and six of the 120 isolates from clinically sick animals
were found sensitive. None of the 26 isolates from environment (soil,
water and air) and six from healthy animals was sensitive to GEO. All
resistant strains (160) had minimum inhibitory concentration (MIC)
more than 2µL of GEO / mL of medium. Sensitive strains’ GEO MIC
ranged between 0.2 µL/ mL to 2µL/ mL. The minimum MIC was for
Pasteurella langaensis (0.2 µL/ mL) strain followed by strain of
Streptococcus equi ssp. equi MTCC-3522 (0.4µL/ mL), Strept. intestnalis
and Strept. pyogenes (0. 4µL/ mL), Strept. equi ssp. equi (0.8µL/ mL),
Bacillus polymyxa (1.5 µL/ mL) and Pseudomonas aeruginosa (2.0µL/
mL). The study emphasizes need for evolution of some short of central
universally accepted guidelines to perform and report antimicrobial
activity of herbal antimicrobials so that the comparable data can be
analyzed for future meta-analytical and clinical purposes.
Key-words: Pasteurella, Brucella, Klebsiella, Escherichia,
Streptococcus, Staphylococcus, Geranium oil
Cite this article as:
Bhoj R Singh, Ravi Kant Agrawal, Sakshi Dubey, Monika Bhardwaj, PrasannaVadhana, Antimicrobial Activity of Rose
Geranium (Pelargonium roseum) Essential Oil on Bacteria of Veterinary Clinical Origin, Asian Journal of Pharmaceutical
Technology & Innovation, 03 (13); 2015.
1Division of Epidemiology, Indian Veterinary Research Institute, Izatnagar-243122, India.
2Division of Livestock Products Technology, Indian Veterinary Research Institute, Izatnagar-243122, India.
Bhoj R Singh et al., Asian Journal of Pharmaceutical Technology & Innovation, 03 (13); 2015; 01 - 05
Geranium oil is extracted from fragrant plants of Pelargonium species especially P. graveolens, however,
much appreciated rose fragrance of rose geranium may also be obtained from P. roseum. Main constituents of
geranium essential oil1 include citronellol (~26.7%) and geraniol (~13.1%), nerol (~8.7%), citronellyl formate
(~7.1%), isomenthone (~6.3%) and linalool (~5.2%). Composition does not vary significantly among geranium
essential oil (GEO) of different origin2.
Due to its antidepressant, anti-inflammatory, antiseptic, astringent, cicatrisant, cytophylactic, diuretic,
deodorant, haemostatic, insect repellent, styptic, tonic, vermifuge and vulnerary properties GEO has widely
been used for therapeutic purposes3. The GEO is oil of choice in aromatherapy to treat acne, sore throat,
anxiety, depression, and insomnia. Due to its anti-inflammatory property GEO is used to reduce pain and
inflammation. For its antiseptic properties it has been used on wounds, burns, frostbites, fungal infections,
athlete’s foot, eczema and hemorrhoides. It not only protects as a natural insect repellent but its topical
application helps to heal insect bites and stop itching4.
Antibacterial, antifungal, and antioxidant properties of GEO have been explored all over the globe. It has
been shown to inhibit many food-borne microbes and reference strains of Aspergillusniger, Candida albicans,
Basillus subtilis, Brevibacterium linens, Enterobacter aerogenes, Enterococcus faecalis, Escherichia coli, Klebsiella
pneumoniae, Listeria monocytogenes, Mycobacterium smegmatis, Proteus mirabilis, Proteus vulgaris,
Pseudomonas aeruginosa, Salmonella Enteritidis, Salmonella Typhi, Salmonella Typhimurium, Staphylococcus
aureus, Staph. epidermidis, Streptococcus mutans and Yersinia enterocolitica5-11. However, contrasting reports of
its non activity on gram positive bacteria12 are also cited in literature. The wide range of variation in its
affectivity as antimicrobial leads to confusion due to use of only limited number of bacterial strains to test and
also variation in amount of GEO used (1.5 µL to 15µL) in disc diffusion assay1, 8, 9, 11. Therefore, this study was
planned to do an elaborate testing using 15 reference, 26 environmental, 120 clinical and six commensal (from
healthy animals) bacteria isolates and testing them all at the same level of GEO concentration (2 µL) of discs.
Material and Methods:
Bacterial isolates tested: Bacterial strains either reference (15) or isolated from different sources (from
apparently healthy animals 6, sick animals 120, air 10, water 7, soil 9) and available in different laboratories at
Indian Veterinary Research Institute, Izatnagar (Table. 1) were revived and checked for purity and identity
using standard bacteriological techniques13, 14. Pure cultures were stored on nutrient blood agar (BBL, Difco)
slants for the period of testing for sensitivity assay for GEO.
Sensitivity assay for GEO: All the bacterial strains were tested in duplicate using disc diffusion method15, 16 on
Mueller Hinton (MH) agar (BBL, Difco). However, for Streptococcus, Brucella and Pasteurella strains brain heart
infusion (BHI) agar (BBL, Difco) was used for sensitivity assays. The GEO discs were prepared to contain 2µL of
GEO in each disc as described earlier16. The rose geranium oil (GEO) used in the study was purchased from
Shubh Flavours and Fragrances Pvt. Ltd. New Delhi.
Minimum inhibitory concentration (MIC) determination: It was determined using agar well diffusion assay16
as it is done for antibiotics. Geranium oil (GEO) dilutions (8) were made in sterile dimethyl sulphoxide (DMSO)
to contain 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.5, 2.0 µL of GEO in 50 µL of DMSO. The eight dilutions of GEO in DMSO
were aseptically transferred to 8 peripheral wells of pre-inoculated (with 1:1000 diluted overnight growth of
test strain) while central well was filled with 50 µL of sterile DMSO. Plates were incubated under desired
atmosphere (5% CO2 enriched for Brucella and aerobic for other bacteria) for 24 h. Plates were read for growth
inhibition zone and results were interpreted16.
To find out the statistical significance in association of sensitivity of bacteria and source of bacteria χ2
test was performed using MS Office Excel-2007.
Of the 167 bacterial strains tested with disc diffusion assay for GEO sensitivity inhibition zone of 6 mm
to 20 mm was evident for only seven strains. Only one of the 15 reference strains of 11 species belonging to
nine genera tested, a strain of Streptococcus equi ssp. equi (MTCC-3522) was sensitive to GEO (Table. 1). Out of
120 isolates of 32 species belonging to 16 genera of potentially pathogenic bacteria from clinically sick animals
only six isolates were sensitive to GEO. None of 26 isolates from environment (soil 9, water 7, and air 10)
belonging to 8 genera and 9 species was sensitive to GEO in the study. Similarly of the six isolates from
apparently healthy animals (belonging to 6 species of four genera) none was sensitive to GEO. Of the 101 Gram
Bhoj R Singh et al., Asian Journal of Pharmaceutical Technology & Innovation, 03 (13); 2015; 01 - 05
negative bacterial isolates and 66 Gram positive isolates only two and five strains were sensitive to GEO.
Maximum zone of inhibition (20 mm) was recorded for Pasteurella langaensis and minimum (6-7 mm) for
Bacillus polymyxa and Pseudomonas aeruginosa while for all the four streptococci, sensitive to GEO, inhibition
zone was 7mm to 10 mm.
All GEO resistant strains (160) had GEO MIC more than 2µL/ mL while for sensitive strains it ranged
between 0.2 µL/ mL to 2µL/ mL (Table. 1). Minimum MIC was for P. langaensis followed by that for Strept. equi
ssp. equi MTCC-3522 (0.4µL/ mL), Strept. intestnalis and Strept. pyogenes (0. 4µL/ mL), Strept. equi ssp. equi
(0.8µL/ mL), B. polymyxa (1.5 µL/ mL) and Pseudomonas aeruginosa (2.0µL/ mL).
Table 1. Sensitivity of some reference and bacterial isolates for rose geranium (Pelargonium roseum) essential oil
Source of
Strains (Nos.)
for test
Bacterial strains resistant to GEO(Nos.)
Bacterial strains
sensitive to GEO
animals (6)
One strains each of Staphylococcus capitis
ssp. urealyticus, Staph. caseolyticus, Staph.
chromogenes, Agrobacterium tumefaciens,
Klebsiella pneumoniae, Pseudomonas
sick animals
to 2µL/mL
strains and
Aeromonas caviae (1), A. sobria (1), Bacillus
marcerans (1), B. polymyxa (1), Bacillus spp.
(5), Brucella abortus (3), Burkholderia spp.
(5), Dermatophilus congolensis (2),
Enterobacter agglomerans (2), Erwinia
ananas (1), Escherichia coli (37), E.
fergusonii(3), Hafnia alvei (1), Klebsiella
oxytoca (1), Pasteurella canis (1), Proteus
mirabilis (1), Proteus vulgaris (3),
Pseudomonas aeruginosa (2), Staphylococcus
aureus (3), Staph. capitis ssp. urealyticus (2),
Staph. haemolyticus (1), Staph. hyicus (1),
Staph. intermedius (2), Staph. sciuri (6),
Streptobacillus moniliformis(1),
Streptococcus equi ssp. zooepidemicus (16),
Strept. Intestinalis (4), Strept. Milleri (1),
Strept. pneumoniae(1), Strept. Pyogenes (5)
One strains each of
Streptococcus equi ssp.
equi, Pseudomonas
aeruginosa, Bacillus
polymyxa and
Pasteurella langaensis
strains (15)
0.4 µL/mL
and for
Bordetella bronchiseptica (MTCC3838),
Brucella abortus strain 19 (S-19, and BS-
19)1, Burkholderia cepacia (MTCC438), B.
gladioli (MTCC1888), B. pseudomallei
(MTCC7183 and MTCC7259), Erwinia
herbicola (MTCC7100 and MTCC7100/1),
Pasteurella multocida (P-52 and SORON)2,
Salmonella Gallinarum (E-79)3, Staph.
aureus (BM-100)4, Yersinia enterocolitica
Streptococcus equi ssp.
equi (MTCC3522)
4Air (10)
E. coli (1), Pseudomonas aeruginosa (1),
Staph. epidermidis (8)
4Soil (9)
E. coli (3), Enterobacter agglomerans (2),
Proteus mirabilis (1),
Pseudomonasaeruginosa (3)
4Water (7)
Citrobacter freundii (1), E. coli (1), Erwinia
chrysanthemii (1), Klebsiella pneumoniae
(3), Proteus vulgaris (1)
Strains numbers prefixed with MTCC were procured from The Microbial Type Culture Collection and Gene Bank (MTCC),
Institute of Microbial Technology (IMTECH), Chandigarh, 1National Brucella Centre, 2Pasteurella Laboratory, 3National
Salmonella Centre (Vet.), 4Division of Epidemiology, Indian Veterinary Research Institute, Izatnagar, Bareilly.
Bhoj R Singh et al., Asian Journal of Pharmaceutical Technology & Innovation, 03 (13); 2015; 01 - 05
It was apparent from the results that all six isolates sensitive to GEO were isolated from sick animals
only and none from the healthy animals or their environment. It might be due to the fact that none of the type
of bacteria found sensitive to GEO, except P. aeruginosa, was included in the study was from healthy animals
and environment. The P. aeruginosa strain sensitive to GEO had MIC just near the cut off limit to decide
sensitivity. Therefore, the results cannot be compared on the basis of source except for strains of those bacteria
which were detected in healthy as well as sick animals and their environment. Statistical analysis indicated that
source of bacteria could not be associated (p, >0.1) with their sensitivity to GEO.
Both of the Streptococcus equi ssp. equi (one reference and other from strangled horse), only one of the
five Streptococcus intestinalis, one of 6 Streptococcus pyogenes and a Streptococcus pneumoniae isolates, were
sensitive to GEO. However, none of 16 Streptococcus equi ssp. zooepidemicus, one Streptococcus milleri, all from
clinically sick animals, irrespective of the animal source was sensitive to GEO. The observation indicated that it
cannot be predicted even for the streptococci that which one of the strain may be sensitive to GEO. Probability
of being sensitive to GEO can also not be defined for strains of other bacteria. Even for the most sensitive P.
langaensis, it cannot be generalized as it was the lonely isolate in the study and testing of more number of
strains is required. However, from the earlier studies (mostly on reference strains) one may get a false
impression that GEO is an effective antimicrobial acting against wide range of microbes5- 11. Observations in this
study corroborate with only few studies12 indicating the fact that GEO possess very limited antimicrobial utility
similar to so many other herbal antimicrobials17-19.
Our study seems to contrast earlier observations5-11 but the difference in observations might be due to
the fact that most of the earlier studies were done on reference sensitive strains using discs impregnated in to
GEO or disc containing more amount of oil ranging between 3.5 µL to 15 µL1, 8, 9, 11. Besides, in earlier studies
different concentrations of GEO were used in discs for different bacteria in contrast to uniform concentration
used in the present study (2 µL/ disc). Therefore, it is now the time to decide over fixing the amount of herbal
product(s) to be used for determining herbal drug sensitivity similar to the standards available for
antimicrobial drugs15. In lack of standards, confusing literature will keep on emerging giving false impression of
affectivity of herbal drugs on microbes. Besides, the lot of data generated in different labs using different
standards poses difficulty in meta-analysis of the information to draw a useful conclusion for future clinical use
of herbal antimicrobials.
In the present study using cut off limit of 2 µL/ disc or 2 µL/ mL for deciding sensitivity by disc diffusion
assay or MIC through agar well method, respectively was used throughout the study irrespective of microbes
tested. The uniformity in testing provides more lucidity in understanding the comparative sensitivity of
different bacteria to GEO. In earlier studies GEO MIC has been reported to be the lowest for Streptococcus
mutans in range of 0.06µL/ mL to 1.25µL/ mL9, 11, the figures are quite close to our observations on GEO
sensitive Streptococcus strains with MIC ranging from 0.4-0.8 µL/ mL. However, none of the 27 staphylococci
and majority of the streptococci tested in our study was sensitive to GEO and had MIC 2 µL/ mL which is
contrast to earlier observation on MIC (0.25–2.50 μL/ mL) for Staph. aureus1. It might be due to several reasons
including the variation in the genetic background of the strains and origin of GEO used in the study.
The study conclude that GEO is effective as antimicrobial only on few strains of some bacteria. For
evolution of consistent and clinically useful literature on antimicrobial activity of herbal antimicrobials some
central agency should be constituted to guide the researchers to use the standard concentrations of different
preparations based on the scientific data on, method of using (topical/ systemic/ perentral), toxicity in target
tissues, organs and animals/ host, biological availability, serum levels and diffusion in agar or any other testing
media etc. Similarly for determining MIC and minimum bactericidal concentration (MBC) of herbal
antimicrobials, often insoluble in broth media and aqueous environment even after use of tween and other
solvents, suitable methodology needs to be standardized.
Authors are thankful to Joint Director (R) and Director of Indian Veterinary Research Institute, Izatnagar for
providing required funds and laboratory facilities to conduct the research. Authors also extend their
indebtedness to all the laboratory in-charges who provided the needed reference strains in the study. We thank
to Mr. HC Joshi and Mr. Laikur Rahman for laboratory assistance.
Source(s) of support: Indian Veterinary Research Institute, Izatnagar-243122, India
Bhoj R Singh et al., Asian Journal of Pharmaceutical Technology & Innovation, 03 (13); 2015; 01 - 05
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5. Boukhatem MN, Kameli A, Saidi F. Essential oil of Algerian rose-scented geranium (Pelargonium graveolens): Chemical
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oils from Pelargonium graveolens L’Her and Vitexagnus castus L. Iranian J Microbiol. 2012;4:171-6.
9. Jirovetz L, Eller G, Buchbauer G, Schmidt E, Denkova Z, Stoyanova AS, Nikolova R, Geissler M. Chemical composition,
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faecal droppings of common house lizard/gecko (Hemidactylus frenatus). Int J Microbiol. 2013: 8 pages,
19. Singh BR, Agarwal RK, Singh KP, Pawde AM, Sinha DK, Dubey S, Bhardwaj M, Prasanna Vadhana. Antibacterial activity
of Caraway essential oil against bacteria isolated from veterinary clinical cases. Natural Products: An Indian
J. 2015;11:69-74.
... In the study, though only 24.1% strains of microbes were sensitive to ACME this is much higher than several other potential herbs including citronella and geranium oils reported earlier [7,21,22] inhibiting only about 10% of the strains tested. However, Lalfakjuala et al. [23] reported methanolic extract of A. conyzoides much inferior in antimicrobial activity against phosphate degrading bacteria than other weedy herbs including Eupatorium odoratum, Mikania micrantha and Centella asiatic. ...
... In the present study, the most sensitive strains to ACME belonged to oxidase positive GPBs (62.5%) followed by oxidase negative GPBs (40.8%), oxidase positive GNBs (27.4%) and oxidase negative GNBs (4.9%). The role of oxidase production ability might be important in herbal drug resistance, similar observation have been made earlier with lemongrass oil [24], Artemesia vulgaris oil [25,26], geranium oil [21] and citronella oil [22]. ...
... Though A. conyzoides is usually not consumed by animals but in scarcity, it may be. Similar views have also been expressed earlier for higher resistance in bacterial isolates from such kinds of animals for A. vulgaris, lemon grass and citronella oil [21,22,[24][25][26]. ...
Full-text available
Ageratum conyzoides, a weed prevalent in India, is known for its several therapeutic uses to control infections. In the present study we compared the antimicrobial potential of its ether extract and methanolic extract with ciprofloxacin on 294 strains of Gram positive bacteria (GPBs), 575 strains of Gram negative bacteria (GNBs), 15 yeast and 5 mould strains of clinical and nonclinical origin belonging to 49 genera and more than 155 species using disc diffusion assay. The microbial strains in the study were isolated from samples of abiotic (41) and biotic (101) environment, foods (81), clinically sick (441), dead (108) and healthy (75) animals and human beings, and 42 were reference strains. The study revealed that there was no appreciable difference in antimicrobial activity of ether extract (ACEE) or methanolic extract (ACME) of A. conyzoides. A total of 214 (24.1%) strains were sensitive to ACME while of the 697 strains tested for ciprofloxacin 551 (79.1%) were sensitive. Sensitivity to ACME among 294 GPBs (44.9%) was significantly (p<0.0001) higher than among 575 strains of GNBs (12.4%). There was no significant difference among GPBs and GNBs for ciprofloxacin (one of the most commonly used antibiotics in India) sensitivity, but oxidase negative GNBs (385) as well as GPBs (238) were about two times more commonly sensitive to ciprofloxacin than 190 oxidase positive GNBs (p = 0.001) and 56 oxidase positive GPBs (p, 0.03), respectively. For ACME oxidase positive strains had 2.4 times more odds (p < 0.0001) in their favour of being sensitive to ACME (53.4%) than oxidase negative strains (18.6%). The most sensitive strains to ACME belonged to oxidase positive GPBs (62.5%) followed by oxidase negative GPBs (40.8%), oxidase positive GNBs (27.4%) and oxidase negative GNBs (4.9%). All Aeromonas, Alcaligenes, Klebsiella, and Proteus species strains were resistant to ACME irrespective of source of isolation or association with illness. In contrast, majority of the strains of Burkholderia (76.9%), Bacillus (66.7%) and Brucella (53.8%) species were sensitive to ACME. The study revealed that A. conyzoides might be containing useful antimicrobial component(s) more active against oxidase positive potentially pathogenic strains often associated with systemic and deadly infections in animals as well as in humans.
... On comparing the E. coli strains of piglet and of calf origin, it was evident that piglet origin strains were more often resistant to cefotaxime clavulanic acid , moxalactam (p, 0.03). The pig E. coli isolates were more often sensitive to tetracycline, nalidixic acid (p, 0.01), cotrimoxazole (p, 0.01), ciprofloxacin (p, 0.002), (Singh et al., 2012a;Singh et al., 2014b), but herbal antimicrobials (Singh et al., 2016a) too including eucalyptus oil (Singh, 2013a), Artemesia essential oil (Singh et al., 2012b), Salinium wallichiarum essential oil (Singh et al., 2012c), lemon grass oil , sage oil (Singh, 2013), caraway essential oil (Singh et al., 2015a), citronella oil (Singh et al., 2015b), Ageratum conyzoides (Singh et al., 2016b), rose geranium oil (Singh et al., 2015c), tea tree oil along with antibiotics (Singh et al., 2016a), kalonji oil (Singh et al., 2017b) and also for multiple herbs antimicrobial and antibiotics (Singh et al., 2016a). ...
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The emergence of drug resistant pathogens has become a crucial problem for humans and animals worldwide. Due to increase in multi-drug resistant bacteria, treatment with conventional antibiotics as well as herbal drugs does not provide desired clinical outcomes. Therefore, there is a need to find an alternative approach to protect humans and animals from bacterial pathogen. Combination therapies using conventional antibiotics and herbal drugs can fulfil our requirement for effective and long lasting therapy. The present study was carried out to reveal the phenotypic and genetic regulation for synergistic activity between trans-cinnamaldehyde (TC, an active component of cinnamon, commonly known as Dalchini) and imipenem, tigecycline, colistin, nitrofurantoin and polymixin B, against E. coli. A total of 430 isolates were screened for synergy between TC and selected antibiotics by disc diffusion method. They have also shown high level of resistance against commonly used antibiotics like ampicillin (65.5%), streptomycin (59.5%), gentamicin (55.8%), trimethoprim/sulfamethoxazole (45.81%), tetracycline (44.8%) and ciprofloxacin (35.11%). Seventy two E. coli isolates have shown synergy between TC and imipenem. The E. coli isolates were confirmed phenotypically as well as genotypically. After their MIC determination, the synergistic activity between TC and imipenem against all the isolates was confirmed by checkerboard method, with the FIC range of 0.25 to 0.5. The ME97 being kanamycin sensitive and with FICI 0.5 was selected for further confirmation by time kill assay for synergism. The combinations, 2MBC (TC-640 µg/ml) + 0.5MBC (IPM-75 µg/ml) and 0.5MBC (TC-160 µg/ml) + 0.5MBC (IPM75 µg/ml) and MBC (TC-320 µg/ml) + MBC (IPM-150 µg/ml) were found synergistic with each other. For identification of gene responsible for synergy, transformation of plasmids from the ME97 strain did not transfer synergy between TC and imipenem to DH5α E. coli cells suggesting that the plasmids may not have any role in induction of synergistic activity. Lastly, to identify the gene responsible for synergistic activity, transposon mutagenesis was performed. Transposon mutagenesis of ME97 strain yielded >2500 mutants, of which only 34 isolates were showing loss of synergy between TC and imipenem to varying degree whereas 10 isolates were showing sensitivity to TC. The transposon insertion was confirmed by detection of kanamycin resistance and transposon cassette by PCR (i.e., 494 bp). The mutant numbered 5H had stability in loss of synergy and 4A and B1 had shown sensitivity to TC. Also, the mutants as well as parent strain were tested for active efflux pump with ethidium bromide cartwheel method. It was observed that efflux pump(s) had no role in TC resistance and synergy in ME97 E. coli. The parent strain and mutants were compared for antibiotic resistance pattern. The mutants have become sensitive to TC and impenem, with slight increase in zone of inhibition for nitrofurantoin and polymixin B. A hypothetical gene in 5H mutant strain was identified by next generation sequencing (NGS) as inactivated due to transposon mutagenesis,. It may possible that the genetic mechanism of synergistic activity is mediated by this hypothetical gene whose function is to be studied further. Finally, the study concluded that TC and imipenem can be used as therapeutics effectively against E. coli.
... Thymian-, Oregano-, Teebaum-, Nelken-, Zimtblätter-, Lemongras-und Muskatellersalbeiöl erwiesen sich in vitro als wirksam gegen Referenzstämme von Staphylococcus (S.) aureus, Enterococcus faecalis, Escherichia (E.) coli, Pseudomonas (P.) aeruginosa, Proteus mirabilis und Klebsiella pneumoniae [18,19]. Eine Studie belegte zwar eine gute Wirksamkeit von Salbeiöl gegen bakterielle Referenzstämme, allerdings eine verringerte bis schlechte Wirksamkeit gegen klinische Keimisolate [20,21]. Damit liegt die Untersuchung klinischer Isolate nahe. ...
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In vitro Antibacterial Activity of Essential Oils against Bacteria of Veterinary Relevance from Clinical Isolates of Dogs, Cats, and Horses Introduction: Essential oils are the basis for aromatherapy. They are supposed to have an antibacterial activity. The aim of this study was to determine the in vitro antibacterial activity of essential oils against a broad range of clinical isolates of bacteria which are relevant for veterinary medicine. Methods: The antibacterial activity of 16 essential oils was detected using the agar diffusion test. Gram-positive and gram-negative bacteria of clinical isolates of dogs, cats, and horses from veterinary routine diagnostic were used. Classification of antibacterial activity in not, lowly, moderately, and highly effective resulted from the size of the zone of inhibition of bacterial growth. Results: Overall, gram-positive and gram-negative bacteria were susceptible against essential oils. They showed an in vitro antibacterial activity against staphylococci including methicillin-resistant strains. Pasteurella multocida was rather sensitive, in great contrast to the totally resistant Pseudomonas aeruginosa. Tea tree, oregano, and winter savory oil seemed to be the most potent oils. In addition, lemongrass oil and thyme oil showed a good activity against gram-positive and gram-negative bacteria, respectively. Conclusion: Essential oils have an in vitro antibacterial activity against clinical isolates of dogs, cats, and horses. This study conducts basic information for the use of essential oils in veterinary medicine. Clearly, tendencies in the spectrum of efficacy of essential oils can be found, but no generalizing assertion about their activity against specific pathogenic bacteria in an individual patient should be made. Thus, before the beginning of a therapy with essential oils, their respective individual activity should be tested by an aromatogram.
... Difference in sensitivity to TTO among strains of different origin observed in the present study further proved the same fact that origin [21,[24][25][26][27][28][29]. Similar sensitivity pattern of bacteria of mithun origin for other antimicrobials as to TTO, i.e., more commonly sensitive to other antimicrobials than strains of other origin further suggested the similar mechanism of emergence of resistance to antibiotics and TTO or probably for other herbal drugs too [29]. ...
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Tea Tree Oil (TTO) is a popular herbal antimicrobial for topical application against many microbes. This study was conducted to determine a spectrum of antimicrobial activity of TTO against bacteria often associated with topical infections and wound infection in human and animals. A total of 550 strains of bacteria and one strain of Candida albicans were tested for their sensitivity to TTO and eight antibiotics including polymyxin B sulfate, gentamicin, nitrofurantoin, tetracycline, chloramphenicol, co-trimoxazole, ciprofloxacin, and novobiocin. Gentamicin was the most effective antibiotic followed by chloramphenicol, ciprofloxacin, nitrofurantoin and polymyxin B inhibiting 87.1%, 84.8%, 76.8%, 75% and 72.8% strains, respectively. Tea tree oil (at 1 μL/ mL) could inhibit the growth of 20.5% strains. Except all strains of Streptobacillus, Sphingomonas, Cytophaga and Brahmnella, 71.4% Brucella, 60% Bordetella and 53.1% Aeromonas species (46.9%), only a few strains of other genera were sensitive to TTO. Only 20.5% strains were sensitive to TTO and multiple drug resistance (MDR) was positively correlated to their resistance to TTO, as 50%, 25%, 12%, 6% and 5% of the strains resistant to 0, 1-2, 3-4, 5-6 and 7-8 antimicrobial drugs, respectively were sensitive to TTO. Sensitivity of bacteria to TTO was positively correlated (p, ≤0.05) with their sensitivity to novobiocin (r, 0.24), tetracycline (r, 0.22), gentamicin (r, 0.21), ciprofloxacin (r, 0.17), nitrofurantoin (r, 0.16), and chloramphenicol (r, 0.14) while correlation was insignificant (p, >0.05) with sensitivity to co-trimoxazole (r, 0.10) and polymyxin B (r, 0.12). Minimum inhibitory concentration (MIC) of TTO varied from 0.001% to >0.512% (v/v) for different strains. The study revealed that TTO is a broad-spectrum antimicrobial active on 26 out of 44 genera of bacteria is a less promising antimicrobial than antibiotics on MDR strains. The study concluded that resistance to TTO, antibiotics and other antimicrobials in bacteria of clinical origin go hand in hand.
... The present study suggested that conclusion based on studies using only a few reference strains may not be always practically useful. Further, detection of sensitivity in a few strains of a bacteria or resistance in a few strains of other bacteria indicated that there might be some mechanism for emergence of resistance against herbal antimicrobials as proposed earlier [16,[24][25][26] . ...
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The study was conducted to determine antimicrobial activity in ethanolic extracts and aqueous solution of 31 samples of edible gums from Acacia nilotica (17), Buchanania lanzan (7), Sterculia spp. (5), Balanites aegyptiaca (1) and Prosopis juliflora (1) plants. Antimicrobial activity in ethanolic extracts (EE) was determined using disc (2mg EE/ disc) diffusion assay, while antimicrobial activity of aqueous solution (50 mg/ mL) and minimum inhibitory concentration (MIC) of EE was determined through agar well dilution method against 101 bacterial strains including four reference strains (Streptococcus milleri, Bacillus mycoides, E. coli, Salmonella Abortusequi) and 97 clinical/ environmental isolates (34 Gram positive bacteria, GPBs and 63 Gram negative bacteria, GNB). All the strains were also tested for sensitivity to ciprofloxacin disks (10 mcg). None of the 101 strain was sensitive to 4% (w/v) aqueous solution of gums but 50 (49.5%) strains were sensitive to one or other EE of two gum acacia (EEA) and 9 (8.9%) to EE of one gum chironji (EEC) samples. GPB strains were more commonly sensitive to EEA (p, 0.0007) than GNB strains. However, no significant (p, 0.56) difference among GPBs and GNBs was evident for their sensitivity to EEC. MIC of EEA ranged between 80 µg to 2560 µg/ mL for sensitive bacterial strains. MIC of EEC was lowest (160 mcg) for Streptococcus equi but ranged between 640 mcg to 2560 µg/ mL for other sensitive strains. All resistant strains had MIC >2.56 mg/ mL EEA or EEC. Although antimicrobial activity of ethanolic extract of gum acacia and gum chironji had wide spectrum, it could be detected only in 2 of the 17 samples of gum acacia and one of the 7 samples of gum chironji. Though edible gums may have little utility as antimicrobials in therapeutics, might be containing some antibacterial component(s) which needs to be identified.
... Variation in sensitivity to EOME among strains of different species of the same genera was insignificant in most of the cases with only few exceptions as reported in earlier studies on Eupatorium extracts [8,9], other herbal antimicrobials [13,16,[20][21][22][23] and antibiotics [15,19]. Interspecies variation in sensitivity to EOME among strains of Enterococcus, Pasteurella and Salmonella could not be understood without further studies. ...
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Eupatorium odoratum is an invasive weed in most parts of the world. Though toxic to human and animals its leaf juice has been indicated for application on fresh wounds. In the study Eupatorium odoratum methanolic extract (EOME) and crushed leaf extract (EOE) from fresh leaves were tested for antimicrobial activity against 893 strains belonging to more than 140 species of 40 genera. The EOME inhibited 31.9% and EOE inhibited only 5.36% strains. There was no significant (p >0.05) correlation (r, -.02) between antimicrobial activity of EOE and EOME. Instead, strong (p, 0.01) positive correlation (r, 0.245) was evident between sensitivity of strains to EOME and tetracycline. More of the Bacillus, Brucella and Burhkolderia spp. strains were sensitive to EOME than strains of other bacteria. Pasteurella multocida type B (p, 0.01) and Salmonella indica (p, 0.009) strains were more frequently sensitive to EOME than strains of other species of the respective genera. Among bacterial strains of different origin sensitivity to EOME ranged from 12.5% to 50.4%. Bacteria of food (Axone) origin (50.4%) were more frequently sensitive to EOME than reference strains (p, 0.002) and strains of pig (p <0.001), cattle (p, 0.001), human (p, 0.009), horse (p, 0.049), wall lizard (p <0.001), environment (p, 0.007) and zoo animal (p<0.001) origin. There was no difference in sensitivity to EOME in strains isolated from biotic and abiotic environment (p, 0.11) irrespective of their G+ve (p, 0.16) or G-ve (p, 0.42) trait. Significantly more (p, 0.046) number of bacteria of environmental origin were sensitive to EOME than those isolated from animal sources. Of the 287 G+ve and 579 G-ve bacterial strains tested, G+ve bacteria were more frequently (p <0.001) sensitive (87.5%) to tetracycline than G-ve bacterial (69.61) strains. Source of G+ bacteria had no significant (p, 0.4) bearing on their sensitivity to tetracycline (TetS). However, G-ve bacteria isolated from Axone were more commonly TetS type than strains of environmental (0.003) and animal origin (p, 0.024) especially those associated with illness (p, 0.036) and mortality (p, 0.008).The study concluded that crushed leaf extract of E. odoratum (EOE) though effective on many of the bacteria associated with wound infection, was less effective antimicrobial than methanolic extract of the herb (EOME). There was good correlation between sensitivity of bacterial strains to tetracycline and EOME. Markedly good antibacterial activity of EOME on some of the important pathogens of animals including Brucella, Pasteurella and Burkholderia spp. indicated that the herb may be a potential source of useful antimicrobial component(s).
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The antimicrobial-resistance (AMR) is a serious global concern. The development of antimicrobial resistance appeared soon after the discovery of 'Penicillin' in 1928 and at present, the microbes are already equipped to resist against fifth generation of antibiotics available in the market. Antimicrobial resistance is responsible for death of millions of people each year leading to heavy losses to the global economy. This situation is alarming and further intensified due to substantial drop in the invention of new antibiotics. The current antibiotic discovery model is not delivering new agents at a rate that is sufficient to combat emergence of antimicrobial resistance. Therefore, there is need to explore for alternative strategies to combat microbes with special focus on drug resistance microorganisms. Although, development of new antimicrobials is always a first priority, alternative antimicrobials can be effectively used to reduce the dependence on antibiotics to mitigate onset and spread of AMR. One of these alternative antimicrobials is essentials oils. Essential oils are aromatic liquids which have been used in traditional Indian medicine and food production since ancient times. Their importance has resurfaced in the current scenario due to the emergence of drug resistance in microbes and demand for chemical preservative free food from general public.
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The development of antimicrobial resistance parallels the discovery of the first antibiotic ‘Penicillin’ by Alexander Flaming in 1928. Currently, the fifth generation of antibiotics is in the market but the microbes are already equipped to resist all generations of antimicrobials. Failure of antimicrobial therapy is rampant leading to the death of about 0.7 million people every year and this toll is predicted to rise to 10 million people per year by 2050, costing up to USD 210 trillion to the global economy. This situation is alarming and further intensified due to a substantial drop in the invention of new antibiotics. Antimicrobial resistance (AMR) is now a serious problem of global concern and all concerned expressed the urgent need for new treatment modalities. The current antibiotic discovery model is not delivering new agents at a rate that is sufficient to combat present levels of AMR emergence. This has led to fears of entering into a ‘pre-antibiotic era’. Therefore, there is a need to explore alternative strategies to combat drug-resistant infections. In the last few decades, AMR has led to the generation of “superbugs”, i.e. super-resistant strains with increased virulence and enhanced transmissibility. The factors causing AMR emergence are mainly poor antibiotic stewardship as overuse and indiscriminate use of antibiotics, easy and on-counter availability of all kinds of antibiotics, substandard antimicrobials, poor sanitation, excessive use of newer and potent antibiotics (otherwise reserved for emergency use in severely infected patients), and dissemination of R factors through food and poultry products. Besides, genetic jugglery, intrinsic resistance, the existence of resistome and subsistome, and natural resistance genes are other contributors to the spread of AMR. The decades of experience show that resistance to antibiotics cannot be avoided but can be sufficiently delayed or its onset can be manipulated. The AMR strains are not restricted to human beings rather also constantly extending to economically important livestock and naive ecosystems like Arctic and Antarctic regions, deep seas, and wildlife. Though the development of new antimicrobials is always the first priority, alternate strategies can be effectively used to reduce the dependence on antimicrobials to mitigate the onset and spread of AMR. Alternative to conventional antibiotics will be extremely helpful especially when there are no new antimicrobials in the pipeline in the last few years. The threat of antimicrobial resistance is substantial therefore myriad approaches to circumvent it are to be researched. These include classical approaches, such as searching for natural products in the environment, more synthetic attempts, like the discovery of new compounds with previously unknown mechanisms, rationally mutated bacterial toxins, small molecules designed by virtual docking process, ancient approaches including Ayurveda and herbal antimicrobials, Homeopathy, bacteriophage therapy, bacteriocins, antimicrobial peptides and nanotechnology for targeted delivery of antimicrobial for better efficacy. If some of these methods can successfully be translated to a therapeutic option, the bacteriological apocalypse may yet be averted. This book compiled the research of scientists working for alternative antimicrobials in India and abroad using Ayurvedic, Homeopathic, herbalist approaches, and also the modern methods including targeted phage therapy, antimicrobial peptides, and nanotechnology. Observation of leaders in the different areas of alternative therapies to mitigate AMR and its after-effects seem to solve this imminent global problem. Editors strongly feel that the compilation shall be of immense use to the researchers working in the area in tackling the global problem of AMR.
Introduction: According to the increasing resistance of pathogenic bacteria against antibiotics, searching to find new alternatives to chemical drugs and antibiotics has recently become popular. Therapeutic and pharmaceutical effects of medicinal plants have been considered for decades. The aim of this study was to investigate the effect of alcoholic extract of Geranium plant on the growth of antibiotic resistant bacteria that are prevalent in hospitals. Materials & methods: To investigate the antimicrobial activity of Geranium, clinical and standard strains of Pseudomonas aeruginosa and Escherichia coli bacteria and standard strain of Enterococcus faecalis were treated by 25 and 50 mg/ml concentrations of alcoholic extract of Geranium. For this purpose, disk diffusion method was employed. In order to measure minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), micro broth dilution method was applied. Findings: The most sensitive bacterium was Pseudomonas aeruginosa due to showing the highest diameter of the inhibition zone (24 mm). The results showed that the alcoholic extract of Geranium plant at a concentration of 50 mg/ml had a higher antimicrobial effect. Discussion & conclusions: The results showed that the alcoholic extract of Geranium plant has anti-bacterial properties. According to being indigenous and having therapeutic effects, further are is recommended to identify the therapeutic effects
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Alternative medicines have been practiced for centuries and remained as integral part of many civilizations around the globe. One important aspect of alternative medicine includes herbal medicines/drugs in which locally available plants or its parts are used in treating ailments. Herbal medicines are commonly used for treating both infectious and non-infectious diseases. On the other hand, Antimicrobials used to treat bacterial infections caused by multiple drug resistant (MDR) and total drug resistant (TDR) strains are becoming more common in the clinical setting and world is looking for alternative therapies to treat such infections. Herbal medicines are anticipated to protect us from infections as they are considered as better alternatives for existing and emerging antimicrobial drug resistant (ADR) pathogens. Herbal antimicrobials acts either by killing or restricting the bacterial growth through parallel mechanisms as antibiotics similarly there could be mechanisms of herbal drug resistance just like antibiotic resistance in microbes. However, lack of systematic and standard data on herbal antimicrobial activity neither we could understand the extent of herbal drug resistance nor the mechanism of resistance in microbes. The recent studies on antimicrobial properties of herbal drugs on clinical isolates indicated that there is some insensitivity or resistance in microbes towards some common herbal antimicrobial compounds. This review focuses on recent reports of herbal drug resistance among pathogenic microbes (clinical bacterial isolates) against herbal drugs.
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The study was conducted to determine antimicrobial activity of Artemisia vulgaris essential oil (AVEO), and to see the effect of drying of herb for AVEO extraction on its antimicrobial activity. AVEO was extracted from fresh chaffed herb and dried powdered herb and tested on 1199 strains of 113 species of pathogenic, potentially pathogenic and environmental microbes belonging to 33 different genera, 1172 were bacteria and 27 were yeast and moulds. Although more number of strains was sensitive for AVEO extracted from fresh herb (23%) than AVEO from dried herb (21%), difference was statistically insignificant (p, 0.40) between AVEOs extracted from fresh or dried herb. About 19.9% of bacterial and 25.9% of fungal isolates were sensitive to AVEO. Interestingly, oxidase positive strains (63.7%) including those of pseudomonads (60%), aeromonads (53.6%), spore forming bacilli (71.6%), Pastuerella (83.3%) and micrococci (66.7%) were comparatively more sensitive (p, <0.001) than oxidase negative bacteria (8.3%) to AVEO. Of the 114 clinical isolates (associated with illness in human and animals) belonging to 25 bacterial species, 23 (20.2%) were sensitive to AVEO. Clinical isolates were significantly (p, 0.03) more sensitive than isolates from healthy human and animals (12.6%). Thus for better antimicrobial activity AVEO should be extracted from fresh herb. The AVEO may be an effective therapeutic agent of future either as such or as the source of some novel antibacterial molecule(s) particularly against oxidase positive bacteria.
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Of the 257 strains of bacteria belonging to 75 species of 30 genera isolated from morbid or post-mortem samples of animals, fish, birds and human beings only 15 strains were sensitive to 2 mg discs of caraway essential oil (CEO). Fifteen CEO sensitive strains belonged to 13 species of bacteria namely Bacillus cereus, Bordetella bronchiseptica, Brucella abortus, Dermatophilus congolensis, Erwinia ananas, Escherchia coli, Moraxella canis, Moraxella osloensis, Pasteurella multocida, Proteus penneri, Pseudomonas aeruginosa, Raoultella terrigena and Streptococcus pyogenes. The MIC of CEO for all resistant strains was more than 2.0 mg/ mL while MIC of sensitive strains ranged between 0.20 mg/ mL to 2mg/ mL, minimum for M. osloensis (0.20 mg/ mL) strains. The study revealed only limited antimicrobial activity against clinically important bacteria causing disease or death. The antibacterial activity of CEO was more prominent for some of the strains of high zoonotic significance viz., Brucella abortus, Burkholderia mallei and Bordetella bronchiseptica which might be important in designing antimicrobials for their therapeutic control.  2015 Trade Science Inc. - INDIA,
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The antiseptic qualities of aromatic and medicinal plants and their extracts have been recognized since antiquity, while attempts to characterize these properties in the laboratory date back the beginning of the XX(th) century. In the current study essential oils obtained from Pelargonium roseum (Geraniacea) were analyzed for their antibacterial and antifungal activities. The antimicrobial activity of the Pelargonium essential oil was tested against Gram-negative bacteria (Pseudomonas aeruginosa, Proteus mirabilis, Escherichia coli), Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis) and fungi (Candida albicans). Disc diffusion method was used to study antimicrobial activity. Inhibition zones showed that the studied essential oils were active against all of the studied bacteria. In the case of Candida albicans, the complete inhibition of the fungus's development was observed. In the cases of Pseudomonas aeruginosa and Staphylococcus aureus we observed an inhibition comparable to that obtained by the use of an appropriate antimicrobial substance. The volatile oils exhibited considerable inhibitory effects against all the organisms under test, in some cases comparable with those of the reference antibiotics. There were no considerable differences between the antimicrobial activities of the oil obtained by distillation and commercially available Pelargonium oils.
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The chemical composition of the essential oil from the leaves of Pelargonium odoratissimum (L.) L'Hér., Geraniaceae, was determined and the antimicrobial activities against the Aspergillus flavus CML 1816, Aspergillus carbonarius CML1815 and Aspergillus parasiticus CMLA 817 fungi, as well the Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25 992 bacteria were evaluated. The essential oil was isolated by steam distillation using a modified Clevenger apparatus, and its constituents were identified and quantified by GC/MS and GC-FID analyses. In vitro bioanalytical testing was performed using a completely randomized design. The concentrations of essential oil employed ranged from 0.1 to 2 μL.mL-1 (in dimethyl sulfoxide) for the fungus species and from 1 to 500 μL.mL-1 for the bacteria. The diameters of the inhibition zones formed for bacteria and the mean diameters of mycelial growth in perpendicular directions for fungi were measured, followed by calculation of the percentage of inhibition. The essential oil from the leaves of P. odoratissimum furnished methyleugenol (96.80%), a phenylpropanoid. This essential oil inhibited the growth of fungi (100% inhibition) and exhibited a small effect on the bacteria at the concentrations tested.
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Book contains more than 50 chapters on different aspects of laboratory microbiology.
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In the study except a strain of Dermatophilus congolensis isolated from a dog blood suffering from pyrexia, all bacterial isolates from diseased animals were resistant to discs containing 2 µl sage oil. The only sensitive strain of D. congolensis also showed narrow zone (8 mm) of growth inhibition while the sensitive reference strain of E. coli-382 had 10-12 mm zone of growth inhibition around SEO discs. The MIC for the reference E. coli strain was 0.64 µl/ ml while for D. congolensis strain it was 1.28 µl/ ml with all three methods (agar dilution, broth dilution and agar well methods) of MIC determination. Sage oil MIC for four Streptococcus species strains was 2.56 µl to 5.12 µl/ ml while for three strains of Pasteurella canis and four strains of Plesiomonas shigelloides was 5.12 µl / ml. For screening purpose, disc diffusion assay for antimicrobial activity appeared useful tool. The study revealed that MIC of sage oil could be determined using any of the three (broth dilution, agar dilution or agar well) methods without any significant variation among results.
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From 194 faecal dropping samples of common house geckos collected from offices (60), houses (88), integrated farm units (IFS,18) and hostels, guest houses, and dining rooms of different canteen/mess (HGM, 28), 326 bacterial isolates of enteric bacteria belonging to 17 genera and 34 species were detected. Escherichia coli were the most frequently (39) isolated followed by Citrobacter freundii (33), Klebsiella pneumonia (27), Salmonella indica (12), Enterobacter gergoviae (12), and Ent. agglomerans (11). Other important bacteria isolated from gecko droppings were Listonella damsela (2), Raoultella terrigena (3), S. salamae (2), S. houtenae (3), Edwardsiella tarda (4), Edwardsiella hoshinae (1), and Klebsiella oxytoca (2). Of the 223 isolates tested for antimicrobial drug sensitivity, 27 (12.1%) had multiple drug resistance (MDR). None of the salmonellae or edwardsiellae had MDR however, MDR strains were significantly more common among Escherichia spp. (P = 1.9 × 10(-5)) and isolates from IFS units (P = 3.58 × 10(-23)). The most effective herbal drug, Ageratum conyzoides extract, inhibited growth of only 27.8% of strains tested followed by ethanolic extract of Zanthoxylum rhetsa (13.9%), eucalyptus oil (5.4%), patchouli oil (5.4%), lemongrass oil (3.6%), and sandalwood oil (3.1%), and Artemisia vulgaris essential oil (3.1%).
The aim of this study was to analyse the chemical composition of essential oil of rose-scented geranium (Pelargonium graveolens L.) growing in Algeria and to test the efficacy of the oil against food spoilage and food-borne pathogens.The chemical composition of the oil was analysed by Gas Chromatography-Mass Spectrometry (GC–MS). A total of 45 compounds representing 94.2% of the essential oil were identified. The main constituents were citronellol (30.2%), citronellyl formate (9.3%) and geraniol (7.6%).The antimicrobial activity of essential oil was evaluated against 23 food spoilage microorganisms in liquid and vapour phase at three different concentrations (10, 20 and 30 μl/disc).The oil exhibited promising antibacterial effect against Gram positive more than Gram negative bacteria and provides a good inhibitory effect against Candida strains. Furthermore, the zone of inhibition increased with increasing oil concentration. Significantly higher antimicrobial activity was observed in the vapour phase. This is the first report on the antimicrobial properties of the essential oil of Algerian rose geranium.Our results suggest that rose-scented geranium oil could be used for the development of novel types of antibacterial agents to control food spoilage and food-borne pathogens.