Open Access Research article

High diversity of genetic lineages and virulence genes in nasal Staphylococcus aureus isolates from donkeys destined to food consumption in Tunisia with predominance of the ruminant associated CC133 lineage

Haythem Gharsa1, Rym Ben Sallem1, Karim Ben Slama1, Elena Gómez-Sanz2, Carmen Lozano2, Ahlem Jouini1, Naouel Klibi1, Myriam Zarazaga2, Abdellatif Boudabous1 and Carmen Torres2*

Author Affiliations

1 Laboratoire des Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Université Tunis-El Manar, Tunis, 2092, Tunisia

2 Departamento de Agricultura y Alimentación, Área de Bioquímica y Biología Molecular, Universidad de La Rioja, Madre de Dios 51, Logroño, 26006, Spain

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BMC Veterinary Research 2012, 8:203  doi:10.1186/1746-6148-8-203

Published: 29 October 2012

Abstract

Background

The objective of this study was to determine the genetic lineages and the incidence of antibiotic resistance and virulence determinants of nasal Staphylococcus aureus isolates of healthy donkeys destined to food consumption in Tunisia.

Results

Nasal swabs of 100 donkeys obtained in a large slaughterhouse in 2010 were inoculated in specific media for S. aureus and methicillin-resistant S. aureus (MRSA) recovery. S. aureus was obtained in 50% of the samples, being all of isolates methicillin-susceptible (MSSA). Genetic lineages, toxin gene profile, and antibiotic resistance mechanisms were determined in recovered isolates. Twenty-five different spa-types were detected among the 50 MSSA with 9 novel spa-types. S. aureus isolates were ascribed to agr type I (37 isolates), III (7), II (4), and IV (2). Sixteen different sequence-types (STs) were revealed by MLST, with seven new ones. STs belonging to clonal clomplex CC133 were majority. The gene tst was detected in 6 isolates and the gene etb in one isolate. Different combinations of enterotoxin, leukocidin and haemolysin genes were identified among S. aureus isolates. The egc-cluster-like and an incomplete egc-cluster-like were detected. Isolates resistant to penicillin, erythromycin, fusidic acid, streptomycin, ciprofloxacin, clindamycin, tetracycline, or chloramphenicol were found and the genes blaZ, erm(A), erm(C), tet(M), fusC were identified.

Conclusions

The nares of donkeys frequently harbor MSSA. They could be reservoirs of the ruminant-associated CC133 lineage and of toxin genes encoding TSST-1 and other virulence traits with potential implications in public health. CC133 seems to have a broader host distribution than expected.

Keywords:
Staphylococcus aureus; Donkey; spa types; CC133; Virulence genes; Tunisia