The bacterial and fungal flora of the external ear canal of dogs with otitis externa and of healthy dogs were studied. The most frequently isolated microorganism from otitic ears was Staphylococcus intermedius (58.8%), followed by Malassezia pachydermatis (30.9%), Streptococcus canis (29.9%), Proteus spp. (14.4%) and Escherichia coli (10.3%). A statistical analysis of our results showed that the prevalence of these microorganisms is significant in dogs with otitis externa. Furthermore, the antimicrobial susceptibility patterns of isolated strains were determined. Majority of all bacterial isolates were most susceptible to gentamicin. Malassezia pachydermatis, the most prevalent yeast in this study, showed an excellent level of susceptibility to all antifungal agents tested.

To determine the prevalence of Streptococcus canis in dogs and cats, a total of 926 swabs were examined bacteriologically in the period from 2003 to 2005. Eighty-six isolates obtained from various anatomical locations were further characterized for their phenotypic properties. The most frequently isolated biotype produced phosphatase, leucine amidopeptidase, arginine dihydrolase, alpha-D-and beta-D-galactosidase and fermented lactose and ribose. Additional identification by species-specific amplification of the 16S-23S rRNA intergenic spacer region was consistent with S. canis. All isolates were susceptible to penicillin G and ampicillin. The least effective antimicrobial agent was found to be tetracycline (only 33.8% of susceptible strains). Prevalence, S. canis, biochemical properties, 16S-23S rRNA intergenic spacer region

Aims. The aim of this study was to evaluate the antimicrobial effects of five natural substances against 50 clinical isolates of Mycoplasma hominis. Methods and Results. The in vitro activity of selected natural compounds, cinnamon bark oil, anethole, carvacrol, eugenol and guaiazulene, was investigated against 50 M. hominis isolates cultivated from cervical swabs by the broth dilution method. All showed valuable antimicrobial activity against the tested isolates. Oil from the bark of Cinnamomum zeylanicum (MBC 90 = 500 μg/mL) however was found to be the most effective. Carvacrol (MBC 90 = 600 μg/mL) and eugenol (MBC 90 = 1000 μg/mL) also possessed strong antimycoplasmal activity. Conclusions. The results indicate that cinnamon bark oil, carvacrol and eugenol have strong antimycoplasmal activity and the potential for use as antimicrobial agents in the treatment of mycoplasmal infections.

ABSTRACT:The aim of this study was to investigate the antibacterial activity and toxicity for sperm cells of the natural substances gallic acid, methyl gallate, ethyl gallate, propyl gallate, octyl gallate, thymol, carvacrol and eugenol. The antibacterial activity of these natural substances and selected combinations of them against bacterial strains isolated from boar ejaculates was determined using the microdilution and macrodilution method in Mueller-Hinton broth. The most effective natural substances against Gram-negative and Gram-positive bacteria included in our study were thymol and carvacrol with minimum inhibitory concentration (MIC) values in the range of 300-600 µg/ml. Gallic acid exhibited the best antibacterial activity against Pseudomonas aeruginosa strains (MIC values of 300-2400 µg/ml), whereas the ranges of MIC values against Escherichia coli, Enterococcus faecalis and Staphylococcus sp. strains were higher. Octyl gallate exhibited stronger antibacterial activity against staphylococci and enterococci (MIC values of 18.8-75 µg/ml) than against Escherichia coli and Pseudomonas aeruginosa strains with MIC values in the ranges of 300-600 µg/ml and 1200-2400 µg/ml, respectively. Thymol combined with carvacrol was the most effective combination against enterococci (MIC values of 75-300 : 150 thymol : carvacrol) and Pseudomonas aeruginosa (MIC values of 75-300 : 300 thymol : carvacrol), bacteria which are known to be frequently resistant to antimicrobials. Similar results were determined for the combination of carvacrol and eugenol against staphylococci and enterococci. The results of the combinations revealed more of an additive rather than a synergistic effect. Thymol and carvacrol were the most effective natural substances against the bacteria included in this study, with a low toxicity for sperm cells compared to other substances, suggesting their possible use for boar semen decontamination.

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