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

Abstract

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 companion animals, such as cats, dogs, horses, and pigs, 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 were screened for methicillin-resistance. All MRSA isolates were genotyped by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and spa typing. They were also screened for common staphylococcal enterotoxin 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, rabbits, hamsters and rats. 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%), 6 of 48 cats (12.5%), 5 of 12 horses (42%), and 1 of 2 pigs (50%). The 24 MRSA isolates resolved into 4 PFGE clones: USA100 (50%), USA300 (16.7%), USA500 (20.8%) and USA800 (12.5%) and 6 sequence types (ST5, ST8, ST105, ST830, and ST986) or 2 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 background 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 profiles within a MRSA genotype in these animals suggests the potential of emergence of new MRSA clones by gaining or losing additional virulence genes.

Carriage of Methicillin-Resistant Staphylococcus aureus by Wild Urban Norway Rats (Rattus norvegicus)

“…This ST belongs to clonal complex 5 (CC5), the leading cause of HA-MRSA infection in Canada [30], as well as CA-MRSA colonization in Canada and the United States [30], [31]. MRSA CC5 has also been reported in various domestic animals in Canada [32].…”

Methicillin-Resistant Staphylococcus aureus (MRSA) in Food- Producing and Companion Animals and Food Products

“…The CC8-SCCmec IV genotype in horses was likely from a contaminated veterinary hospital and later spread to various clinics [219]. This genotype was reported in veterinary hospitals in Canada and the USA [118,225]. It was irst found in infected horses in Ireland and thereafter reported in the Netherlands, Austria, and Germany [226][227][228].…”

“…One Belgian pig CC80 strain contained an exfoliatin (etd), an epidermal cell diferentiation inhibitor (edinB), and staphylococcal exotoxin-like protein (setC) and IEC genes (isaB, isdA, hysA1, hysA2) [121]. A comparison of the pvl-positive MRSA isolates (ST8-t008-IVa) from American pig and pet animals indicated the presence of common virulence proiles (lukSF-PV, clfA, clfB, fnbA, and sek) except for the fnbB gene of a canine isolate [118]. Spanish ST1379/CC97 porcine isolates carried an exfoliatin (eta), a leukotoxin (lukE/D), and a gamma-hemolysin (hlg-2) but were negative for etb, etc, tst, pvl, and enterotoxins [255].…”

“…Although some studies suggested that the MRSA present in catle is bovine-speciic, most of the reports indicated that MRSA found in catle were derived from humans [89,92,115,116]. Bovine, porcine, canine, feline, and equine MRSA isolates containing the pvl gene and other virulence factors, such as chp, scn, seb, sek, and seq, toxic shock syndrome toxin 1 (tsst1 or tst) gene [91,117], hemolysin, protease, superantigen-like protein, capsule, and bioilm-associated genes [118][119][120][121], may pose a potential threat to public health. …”

Surveillance of Zoonotic Infectious Disease Transmitted by Small Companion Animals

“…Many of these are true zoonoses spread by direct contact between the species, and others are vector-transmitted (e.g., fleas, ticks, flies, and mosquitoes) diseases for which cats and dogs might act as reservoirs for the pathogen. Reverse zoonoses also occur in which disease is transmitted from the human reservoir to the dog or cat; the most contemporary examples are methicillin-resistant Staphylococcus aureus ( 8 ) and influenza A(H1N1)pdm09 virus ( 9 ) infections.…”