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Robert N. Oglesby DVM
Moderator
Username: dro
Post Number: 21267
Registered: 1-1997
| | Posted on Wednesday, Aug 27, 2008 - 7:50 am: |   |
Almost weekly someone posts about a horse going on to antibiotics for ill defined or worst poorly supported reasons. These posts include diagnosis of foot abscesses, cough and/or nasal discharge, performance problems, etc... Here we see one of most important adverse consequences of antibioic administration whether justified or not: the growing incidence of serious pathogens in the background population of bacteria that live on your horses.
DrO
Vet Microbiol. 2008 Jul 5;
High occurrence of methicillin-resistant Staphylococcus aureus ST398 in equine nasal samples.
Van den Eede A, Martens A, Lipinska U, Struelens M, Deplano A, Denis O, Haesebrouck F, Gasthuys F, Hermans K.
Department of Surgery and Anaesthesiology of Domestic Animals, Ghent University, Faculty of Veterinary Medicine, Salisburylaan 133, B-9820 Merelbeke, Belgium.
Methicillin-resistant Staphylococcus aureus (MRSA) infections do occur in equine patients. Little is known, however, about their origin and the general equine MRSA colonization status. In West European horses in particular, neither the colonization rate nor the present strains or their antimicrobial susceptibility patterns are known. In the present study, a sample of 110 (Belgian, French, Dutch and Luxemburg) horses presented at a Belgian equine clinic was screened for nasal MRSA carriage. An indirect culturing protocol using a 0.001% colistin and nalidixic acid containing broth was compared to a direct agar method. Phenotypic identification following growth on a chromogenic MRSA screening agar (ChromIDtrade mark MRSA) was combined with genotypic analysis (PCR, PFGE, SCCmec, spa, and MLST typing). Antimicrobial susceptibility was tested through disk diffusion. Twelve (10.9%) horses carried MRSA, with the enrichment protocol resulting in a significantly higher isolation rate. None of the isolated strains were typeable through SmaI PFGE. They all harboured SCCmec type IVa or V and belonged to spa type t011 or t1451 of the ST398 lineage. All isolates were tetracycline resistant and sulfonamide and enrofloxacin susceptible. Macrolide, lincosamide, trimethoprim and aminoglycoside susceptibility varied and in total five different antimicrobial resistance patterns were distinguished. These results show that ST398 is certainly present in West European horses. Due to its known interspecies transmission and the structure of the equine industry, the presence of this clone in horses poses a substantial health hazard for both animals and humans. |
