Prevalence, Antibiotic Resistance and Molecular Characterisation of Staphylococcus aureus in Pigs at Agricultural Fairs in the USA

September 19, 2012 — 

Fairs and petting zoos have been associated with outbreaks of zoonotic disease. Previously, the presence of methicillin-resistant Staphylococcus aureus (MRSA) was documented in commercial pigs; therefore, it was hypothesised that antibiotic-resistant S aureus may also occur in pigs exhibited at agricultural fairs. To test this hypothesis, 157 pigs were swabbed at two state fairs in 2008 to 2009. Both nares were sampled and cultures were grown in enrichment broth, then plated onto selective MRSA plates and blood plates. S aureus was confirmed using phenotypic and molecular methods, and was analysed using spa typing, gene-specific polymerase chain reaction and antibiotic susceptibility testing. The presence of S aureus was confirmed in samples collected from pigs exhibited at USA pig shows. Twenty-five of 157 (15.9 per cent) samples were positive for S aureus. Two isolates (8 per cent) were resistant to methicillin; 23/25 (92 per cent), 14/25 (56 per cent) and 15/25 (60 per cent) were resistant to tetracycline, erythromycin and clindamycin, respectively. spa typing revealed multiple isolates of spa type t034 (9/25, 36 per cent) and t337 (7/25, 28 per cent) and singletons of t002, t209, t526, t1236, t1334, t1683, t3075, t5784 and t5883. These results verify the presence of antibiotic-resistant S aureus in pigs exhibited at USA fairs, suggesting that pigs are a potential reservoir for S aureus within this environment.

Dressler AE, Scheibel RP, Wardyn S, Harper AL, Hanson BM, Kroeger JS, Diekema DJ, Bender JB, Gray GC, Smith TC; Prevalence, Antibiotic Resistance and Molecular Characterisation of Staphylococcus aureus in Pigs at Agricultural Fairs in the USA; Vet Rec. 2012 May 12;170(19):495. Epub 2012 Apr 14.

PMID: 22505242 [PubMed - indexed for MEDLINE]