République Tunisienne  
Ministère de l'Agriculture, des Ressources Hydrauliques et de la Pêche

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Genetic characterization of Staphylococcus aureus isolated from milk and nasal samples of healthy cows in Tunisia: First report of ST97-t267-agrI-SCCmecV MRSA of bovine origin in Tunisia.>  Description

 
Date de publication 2018
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 Genetic characterization of Staphylococcus aureus isolated from milk and nasal samples of healthy cows in Tunisia: First report of ST97-t267-agrI-SCCmecV MRSA of bovine origin in Tunisia.

Auteur  M. Khemiri, M. S. Abbassi, N. Couto, R. Mansouri, S. Hammami
Mots clés

Staphylococcus, lait, vache,  bovin, Tunisie, MSSA

Résumé

Objectives: This study aimed to screen for and characterize methicillin-susceptible S. aureus (MSSA) and MRSA in nasal swabs and milk from healthy cows from different regions in Tunisia.
Methods: One hundred and forty-one Staphylococcus spp. isolates were recovered from milk and nasal swabs of cows. S. aureus isolates were further characterized by determining their antibiotic susceptibilities, genes encoding antibiotic resistance and virulence factors, biofilm production, agr type and PFGE. spa-, SCCmec-types and MLST were also determined for a MRSA isolate.
Results: Twenty-seven isolates (19.1%) were identified as S. aureus, of which 26 were MSSA and one MRSA. MSSA isolates were resistant to penicillin (69.2%), fusidic acid (53.8%), clindamycin (30.7%) and erythromycin (26.9 %). The MRSA isolate, from milk sample, was resistant to cefoxitin, penicillin, fusidic acid, amikacin and clindamycin. Twentyfive (92.3%) isolates have at least one enterotoxin. Only three (11.1 %) isolates were positive for the tsst-1 gene. The genes of the exfoliative toxins D and A were detected in 7 (25.9%) and 5 (18.5 %) isolates, respectively. The single MRSA isolate and 22 MSSA isolates were biofilm producers on Congo Red Agar plates. Twelve pulsotypes were identified amongst 25 MSSA isolates revealing the clonal diversity of these isolates; however, one MSSA isolate was identified as CC398. The MRSA isolate was PVL negative and typed as ST97-t267-agr
I-SCCmecV.
Conclusion: Contamination of milk with S. aureus, especially enterotoxin- and TSST-1-positive strains, poses a potential public health threat. This is the first report of MRSA of bovine origin in Tunisia.

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