title: Detection and new genetic environment of the pleuromutilin-lincosamide-streptogramin A resistance gene lsa(E) in methicillin-resistant Staphylococcus aureus of swine origin.
abstract: OBJECTIVE
  To investigate the genetic basis of pleuromutilin resistance in porcine methicillin-resistant Staphylococcus aureus (MRSA) and to map the genetic environment of the identified plasmid-borne resistance gene.
  
  
  METHODS
  Seventy porcine MRSA isolates, which exhibited high MICs of tiamulin, valnemulin and retapamulin, were investigated for pleuromutilin resistance genes and mutations. They were characterized by staphylococcal cassette chromosome mec (SCCmec) typing, spa typing and multilocus sequence typing (MLST). Plasmid DNA was extracted from the lsa(E)-positive strains and transferred to S. aureus RN4220 for selection of resistance plasmids. The plasmid-borne lsa(E) gene region was sequenced and 10 overlapping PCR assays for the analysis of the genetic environment of lsa(E) were developed.
  
  
  RESULTS
  All 70 MRSA isolates were ST9 (MLST)-t899 (spa)-IVa (SCCmec). Sixteen isolates carried the lsa(E) gene; all others were negative for known pleuromutilin resistance mechanisms. An lsa(E)-carrying plasmid of ∼41 kb was detected in a single isolate. Sequence analysis revealed that the lsa(E) gene was located in a multiresistance gene cluster, which showed partial homology to clusters identified in MRSA, methicillin-susceptible S. aureus (MSSA) and Enterococcus faecalis. PCR analysis of the remaining isolates revealed a partly deleted multiresistance gene cluster in 6/15 isolates and solely the lsa(E) gene without the known flanking regions in 9/15 isolates.
  
  
  CONCLUSIONS
  We identified the pleuromutilin-lincosamide-streptogramin A resistance gene lsa(E) in porcine MRSA isolates. The multiresistance gene cluster in which lsa(E) was located differed from the previously described ones found in human MRSA/MSSA or in E. faecalis. The location of lsa(E) on a multiresistance plasmid facilitates its persistence and dissemination.
authors: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China.
authors: Beibei
authors: B
authors: Li
authors: Sarah
authors: S
authors: Wendlandt
authors: Jiannan
authors: J
authors: Yao
authors: Yiqiu
authors: Y
authors: Liu
authors: Qing
authors: Q
authors: Zhang
authors: Zixue
authors: Z
authors: Shi
authors: Jianchao
authors: J
authors: Wei
authors: Donghua
authors: D
authors: Shao
authors: Stefan
authors: S
authors: Schwarz
authors: Shaohui
authors: S
authors: Wang
authors: Zhiyong
authors: Z
authors: Ma
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002681:China; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004224:Diterpenes / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D013293:Enterococcus faecalis / Q000187:drug effects; D055231:Lincosamides / Q000494:pharmacology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D010957:Plasmids / Q000235:genetics; D011083:Polycyclic Compounds; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology* / Q000662:veterinary*; D025364:Streptogramin A / Q000494:pharmacology*; D013552:Swine; D013553:Swine Diseases / Q000188:drug therapy / Q000382:microbiology*; D014169:Transformation, Bacterial; D000097567:Pleuromutilins
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004224:Diterpenes; D055231:Lincosamides; D011083:Polycyclic Compounds; D025364:Streptogramin A; D000097567:Pleuromutilins
keywords: ABC transporters; MRSA; multidrug resistance; plasmids