Saturday, 28 August 2010

MRSA - From Vets to Pets

We have seen these reports before elsewhere, but the following Pro Med extract helps underline something pretty important:

Veterinarians can spread MRSA to animals.

The veterinary industry everywhere likes to associate this with people giving it to pets.

Indeed, the British government vets conspired across the Atlantic to makes this a joint Public Relations objective. They made the mistake of publishing the minutes of the phone conferences.

They prefer not to talk about veterinarians moving from farm to farm giving it to livestock.

The vets don’t even like to think about taking home MRSA and other superbugs and giving them to their kids.

Difficult subjects, difficult problems, but not something that can be avoided in Britain, merely because some veterinarians are making fortunes from drug dealing aided by corruption in the agricultural ministry Defra.

Clin Med Res. 2010 Aug 25. [Epub ahead of print]

Evidence of Multiple Virulence Subtypes in Nosocomial and Community-Associated MRSA Genotypes in Companion Animals from the Upper Midwestern and Northeastern United States.

Lin Y, Barker E, Kislow J, Kaldhone P, Stemper ME, Moore FM, Hall M, Fritsche TR, Novicki T, Shukla SK.

* Molecular Microbiology Laboratory, Marshfield Clinic Research Foundation, Marshfield, Wisconsin, USA.


Objective Not much is known about the zoonotic transmission of methicillin-resistant Staphylococcus aureus (MRSA) in companion animals in the United States. We report the rate of prevalence of S. aureus and MRSA recovered from clinical samples of animals requiring treatment at veterinary clinics throughout the upper midwestern and northeastern United States. Design We compared phenotypes, genotypes, and virulence profiles of the MRSA isolates identified in cats, dogs, horses, pigs, etc., with typical human nosocomial and community-associated MRSA (CA-MRSA) genotypes to assess implied zoonotic transmission or zooanthroponosis. Five hundred thirty-three coagulase positive staphylococci (CPS) isolates recovered between 2006 and 2008 from a variety of animal-source samples were screened for S. aureus by S. aureus-specific 16S rDNA primers and for methicillin-resistance. All MRSA isolates were genotypes by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and spa typing. They were also screened for common staphylococcal enterotoxin toxin and adhesion genes by multiplex and singleplex PCR. Results Among the 533 CPS isolates recovered, 66 (12.4%) were determined to be S. aureus and 24 (4.5%) were MRSA. The percent of animals that were positive for S. aureus were as follows: 6.6% (32 of 487) dogs, 39.6% (19 of 48) cats, 83.3% (10 of 12) horses, and 100% of pigs, rabbit, hamster and rat. Notably, 36.4% of all S. aureus identified were MRSA. Methicillin-resistant S. aureus was present in clinical samples from 12 of 487 dogs (2.5%), six of 48 cats (12.5%), five of 12 horses (42%), and one of two pigs. The 24 MRSA isolates resolved into four PFGE clones (USA100 (50%), USA300 (16.7%), USA500 (20.8%) and USA800 (12.5%) and six sequence types (ST5, ST8, ST105, ST830, and ST986) or two clonal complexes, CC5 and CC8. Five major virulence profiles (clusters A to E) were observed in these MRSA isolates. Genotypic and virulence profiles of cats and dogs were more similar to each other than to those of horses. A Panton-Valentine leukocidin positive isolate with ST8:USA300 was identified in a pig causing skin and soft infection. Conclusion The presence of human MRSA clones in these animals suggests possible reverse zoonotic transmission. This study reports the first case of a USA300 genotype in a pig. Presence of multiple virulence profile within a MRSA genotype suggests the potential of emergence of new MRSA clones by gaining or losing additional virulence genes.