Süheyla Türkyilmaz

Molecular epidemiology and antimicrobial resistance mechanisms of methicillin-resistant Staphylococcus aureus isolated from bovine milk.

The aim of this study was to identify methicillin‐resistant Staphylococcus aureus (MRSA) strains gathered from 2002 to 2006 from milk samples in Aydin region in Turkey. Among 93 S. aureus strains isolated from bovine milk with mastitis, 16 were resistant to methicillin. Methicillin‐resistant S. aureus strains were studied further for their staphylococcal cassette chromosome mec (SCCmec) types, pulsotypes, spa and MLST types, antimicrobial susceptibilities, mechanisms of resistance and presence of Panton–Valentine leucocidin (PVL) toxin gene. The MRSA strains were multi‐drug resistant. The susceptibility rates to antimicrobials tested were 0%, 0%, 0%, 0%, 6.25%, 16.25% and 56.25% for erythromycin, clindamycin, chloramphenicol, gentamicin, tetracyclin, ciprofloxacin and vancomycin, respectively. All tetracycline and gentamicin resistant strains carried tet(M) and aac(6)‐aph(2) gene, respectively. Among macrolide‐resistant isolates, nine had erm(A), and seven had both erm(A) and erm(B) genes. The molecular characterization by pulsed‐field gel electrophoresis showed presence of three pulsotypes with their variants. The pulsotype B strains were type IV with SCCmec typing, and representative of pulsotype B was t190 by spa typing and ST8 by MLST typing. The strains with pulsotype A and C were SCCmec III, and representative of these pulsotypes was t030 by spa typing. The MLST type of pulsotype A was ST239 and pulsotype C was one allele variant of ST239. None of the isolates harboured the PVL gene. Presence of hospital‐related MRSA strains may indicate transmission of these strains between human and animals. In case of clonal spread beside the infected animals’ treatment of MRSA carrier, farm workers should also be considered. Hygienic measures and rational antibiotic use may avoid resistance selection, clonal dissemination of resistant strains and decrease losses because of mastitis in dairy herds.

Investigation of plasmid profiles of Enterococcus faecalis isolated from mastitic cow milks

Bulgular: Plazmid izolasyonu sonucunda, izolatların 19’unun bir ile sekiz arasında plazmid taşıdığı, plazmid boyutlarının da yaklaşık olarak 0.6 kb ile 41 kb arasında değiştiği tespit edildi. Çalışmada, 5 izolat tek plazmid ve 14 izolatın ise birden fazla plazmid taşıdığı saptandı. Plazmid izolasyonunu takiben, profil içerikleri kontrol edilerek, plazmidler arasında kümeleme analizi yapıldı. Benzer plazmid profilinde olan iki veya daha fazla suş içeren 6 küme belirlendi.

Distribution of Antibiotic Resistance Genes in Enterococcus spp. Isolated from Mastitis Bovine Milk

Abstract In this study, determination of enterococcus species that were isolated from mastitic milk samples, investigation of their susceptibilities to antibiotics and identification of the existence of resistance genes in resistant strains were conducted. The specimens consist of 600 mastitic milk samples that were collected from 242 cows. Isolation of enterococcus was carried out in selective media and 94 (15.6%) Enterococcus spp. were isolated. A total of 94 species of Enterococci were identified using both sequencing and polymerase chain reaction (PCR). Enterococcus spp. isolates belong to 5 different species (E. faecalis, E. faecium, E. durans, E. hirae, E. mundtii) in sequence analysis and 4 different species (E. faecalis, E. faecium, E. durans, E. hirae) were identify by PCR method with specific primers. Analyzing 94 enterococcus strains by antibiotic sensitiveness test a high rate of resistance to tetracycline in 77 (81.9%) isolates was shown. The tet resistance genes were identified as follows: 54 were tetM positive, 23 were tetK positive and 17 were positive on tetM and tetK. Resistance to erythromycin was established in 27 (28.7%) isolates (25 ermB) while the chloramphenicol resistance gene was found in 10 (10.7%) of isolates and the cat gene was identified in nine samples and one isolate was resistant to vancomycin (1.06%) with the VanA gene confirmed. In conclusion, it was shown that E. faecalis has the biggest role in enterococcus originated mastitis and these strains were found to be mostly resistant to tetracycline. One vancomycine resistant isolate that had the VanA gene was also determined.

Development and characterization of new polymorphic microsatellite loci for Trionyx triunguis(Testudines: Trionychidae) in the Mediterranean Basin

The Mediterranean subpopulation of T. triunguishas been listed by IUCN as critically endangered (European Reptile and Amphibian Specialist Group 1996, category CR C2A). There are very few studies for determination of distribution and population genetics of this species in the world. A total of 13 polymorphic microsatellite loci were isolated from 42 samples of T. triunguisby using biotinylated (GT) 10, (CT) 10, (GATA) 5-enriched library. The range of observed heterozygosities was 0.000-0.833 with a mean of 0.274, and the range of expected heterozygosities was 0.081-0.607 with a mean of 0.374. It was found that four loci deviated significantly from Hardy-Weinberg equilibrium after Bonferroni correction analysis. There was no evidence for large allele dropout. Null alleles may be present at ttmed-6, ttmed-8, and ttmed-9 loci, as suggested by the general excess of homozygote for most allele size classes. Designed microsatellite loci could provide a powerful tool for the population structure and conservation genetics studies of the Nile soft-shelled turtle and for captive breeding programs or to detect species illegal trade.