from november 2008 through december 2011 , mrsa of companion animal origin was routinely isolated from specimens submitted for diagnostic purposes to vet med labor gmbh in ludwigsburg , germany , or to the institute of microbiology and epizootics , freie universitt berlin , in berlin , germany . s. aureus was confirmed as described ( 7 ) and stored in glycerol stocks at 80c . pcr routinely used to confirm methicillin resistance and species identity had failed to produce a positive signal for meca in 10 mrsa isolates from companion animals ( 2 isolates from dogs , 7 from cats , and 1 from a guinea pig ) ( 8) . we screened these 10 isolates for the meca homologue by using the pcr method published by cuny et al . ( 5 ) and sent the amplicons obtained to lgc genomics gmbh ( berlin , germany ) for sequencing . automated antimicrobial drug susceptibility testing was performed by using the biomrieux vitek 2 system ( nrtingen , germany ) according to the manufacturer s instructions . the following drugs were tested according to clinical and laboratory standards institute guidelines m31a3 : penicillin , ampicillin sulbactam , oxacillin , gentamicin , kanamycin , enrofloxacin , marbofloxacin , erythromycin , clindamycin , tetracycline , nitrofurantoin , chloramphenicol , and trimethoprim  sulfamethoxazole , ( 9 ) . all isolates were further characterized by spa typing , multilocus sequence typing , and microarray hybridization by using the alere identibac s. aureus genotyping chip ( alere technologies gmbh , jena , germany ) as described ( 1012 ) . all pcr amplicons demonstrated 100% identity with the dna sequence of mecalga251 ( national center for biotechnology information no . the strains originated from geographically diverse areas ( 5 federal states of germany ) and were isolated from different infection sites ( table ) . all strains were identified as mrsa by the vitek 2 system ( growth in the presence of 6 g / ml cefoxitin according to the vitek 2 advanced expert system ) , although oxacillin mics were rather low ( 0.5 g / ml ) or moderately high ( 4 g / ml ) ( table ) . imt , institute of microbiology and epizootics , freie universitt berlin , berlin , germany ; oxa , oxacillin ; st , sequence type ; vb , vet med labor gmbh , ludwigsburg , germany . all isolates were positive for nuc and negative for meca according to pcr to detect mrsa ( 8) , and all were positive for mecalga251 according to pcr to detect the novel meca homologue ( 5 ) . as has been described for atypical mrsa , 4 strains belonged to st130 and 1 strain belonged to st1945 ( differs from st130 by 1 allele ) ( 35 ) . the remaining 5 isolates were assigned to st599 ( differs from st121 by 2 alleles ) ( table ) . st599 has been reported for methicillin - susceptible isolates from humans in europe , asia , and africa ( www.mlst.net ) . the figure shows a minimum spanning tree based on 4,197 entries of the s. aureus multilocus sequence type database ( http://saureus.mlst.net/ ) as of january 19 , 2012 ( figure , panel a ) and a detailed view of the branches and sts harboring strains with the novel meca homologue published ( figure , panel b ) ( 35 ) . minimum spanning tree based on multilocus sequence typing data from 4,197 staphylococcus aureus strains ( a ) and an enlarged view of 1 phylogenetic group ( b ) . each circle represents a distinct sequence type ( st ) , and circle size is proportional to st frequency . green indicates mecalga251-positive s. aureus strains of companion animal origin reported in this study and sequence data from published multilocus sequence typing results ( 35 ) ; red indicates st599 methicillin - resistant s. aureus ; and blue represents st2024 methicillin - sensitive s. aureus isolated from a wild rat . microarray hybridization data revealed that the agr type i and capsule type 5 seem to be associated with st599 and agriii and that clonal complex ( cc ) 130 isolates harbor the capsule type 8 encoding gene . cc130 and st599 isolates were positive for the surface - associated proteins clfa , clfb , fnba , and bbp . all st599 strains produced a positive hybridization result for 1 of the gene variants encoding the toxin responsible for toxic shock syndrome ( tst1 or tst - bov ) , and all but 1 of them harbored the enterotoxins c ( sec ) and l ( sel ) , indicating the presence of an s. aureus pathogenicity island that encodes superantigens ( 13 ) . positive or ambiguous hybridization signals for ccrb1 , ccra3 , and ccrb3 were obtained for 5 isolates , suggesting the presence of the sccmecxi in those strains , according to the results of shore et al . our findings of cc130 and st599 mrsa harboring mecalga251 in several companion animal species suggest that in germany , the presence of the meca homologue in mrsa is not exclusively associated with cc130 . this finding supports the hypothesis that some , if not all , mrsa strains that harbor the novel meca variant can cause infections among a broad variety of hosts , as has been shown for mrsa of human , equine , canine , and other companion animal origins ( 1,7 ) . all currently known mecalga251carrying mrsa were observed in a distinct section of the s. aureus population ( figure , panel b ) . whether this phylogenetic group possesses the ability to integrate the novel meca variant needs to be further investigated . in the past however , all isolates were correctly identified as mrsa by the vitek 2 system , as reported ( 4 ) . of the 10 isolates , a recent study identified cats as a potential natural reservoir for s. aureus of cc133 , a genetic lineage that has also been reported for s. aureus of ruminant origin ( 14 ) . moreover , we have identified a cc130 strain ( mssa_st2024 , t8403 ) from a wild rat ( imt21250 ; id4035 ) ( www.mlst.net ) . in addition , cc130 mrsa containing the meca homologue has only recently been reported for isolates from humans in germany ( 5 ) . although many investigators focus on livestock - associated mrsa , and because particular companion animal lineages of mrsa seem to be lacking , transmission of mrsa between companion animals and human family members in close proximity might be underestimated , especially in cases of recurrent infection ( 15 ) . the emergence of mrsa harboring the novel meca homologue has consequences for the verification methods for mrsa used in veterinary medicine ; implementation of new methods will be inevitable . their supposed restriction to only a few genetic lineages and the potential risk for interspecies transmission of atypical mrsa between companion animals and their owners in household environments needs further elucidation .
methicillin - resistant staphylocoocus aureus ( mrsa ) harboring mecalga251 has been isolated from humans and ruminants . 
 database screening identified this mrsa variant in cats , dogs , and a guinea pig in germany during 20082011 . 
 the novel mrsa variant is not restricted to ruminants or humans , and contact with companion animals might pose a zoonotic risk .