Virulence properties of Staphylococcus delphini strains isolated from domestic pigeons

Virulence properties (biofilm formation, antibiotic susceptibility, inducible clindamycin resistance, extracellular protease-lipase productions and presence of virulence genes) and genetic-relatedness of 18 Staphylococcus delphini strains (8 group A and 10 group B), isolated from domestic pigeons, were investigated. All strains were susceptible to vancomycin, oxacillin, cefoxitin, novobiocin, sulphamethoxazole/trimethoprim, gentamicin, teicoplanin, amoxycillin/clavulanic acid, rifampicin, cephazolin, linezolid, imipenem, chloramphenicol and tobramycin. However, 15, 13, 12 and 6 strains were found to be resistant to erythromycin, tetracycline, clindamycin and penicillin G, respectively. Although 12 strains showed constitutive resistance, inducible clindamycin resistance was detected in 3 strains by D-test. In addition, ermABC genes related to inducible or constitutive resistance were detected in 9 strains (ermA), in 5 strains (ermC) and in one strain (ermB). Biofilm formation results demonstrated that 9/18 strains showed high adherence to microplate surfaces in tryptic soy broth (TSB) supplemented with 1% sucrose. None of the strains harbored virulence genes, including enterotoxins, toxic-shock syndrome toxin, exfoliative toxins, heamolysins, methicillin-resistance, set1, lukE-lukD leukocidin and Panton-Valentine Leukocidine (PVL). Pulsed-field gel electrophoresis (PFGE) analysis revealed that there were two main clusters with 75% homology and only 3 strains showed 100% homology. In addition, 5 strains have strong proteolytic activity and 8 strains showed lipase activity. To our knowledge, this is the first study to investigate the virulence properties and genetic-relatedness of S. delphini strains isolated from pigeons in Turkey.

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