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|Title:||Polymerase chain reaction (PCR)-directed analysis of the genetic environment of the lincosamide-pleuromutilin-streptogramin a resistance gene lsa(E) in methicillin-resistant staphylococcus aureus of food, animal and human origin|
|Source:||23rd European Congress of Clinical Microbiology & Infectious Diseases, Berlin, Germany, 27-30 Apr, 2013 How to cite?|
|Abstract:||Objectives: In a study by Li et al. one MRSA ST9 isolate of porcine origin from China was identified, which carried the novel lincosamide-pleuromutilin-streptogramin A resistance gene lsa(E) on a ca. 41-kb plasmid. Sequence analysis revealed the location of lsa(E) in a multiresistance gene cluster. The aim of the present study was to investigate MRSA isolates of various origins that exhibited this resistance phenotype for the presence of lsa(E) and to comparatively analyse its genetic environment.|
Methods: Eleven clindamycin- and tiamulin-resistant MRSA ST9 isolates (eight from chicken meat, two from pigs and one from a butcher) originating from seven different markets in Hong Kong were investigated in this study. The presence of the lsa(E) gene was confirmed by PCR. Based on the sequence of the so far analyzed lsa(E)-carrying resistance plasmid from the porcine MRSA ST9, overlapping PCR assays were developed, which covered the entire lsa(E)-comprising multiresistance gene region.
Results: All 11 MRSA isolates were positive for lsa(E). Ten PCR assays for a rapid analysis of the genetic environment of lsa(E) were validated using the 41-kb plasmid as template. Four PCRs covered about 5kb downstream of lsa(E), including the resistance gene lnu(B). The remaining six PCRs covered about 10kb upstream of lsa(E) and included the antimicrobial resistance genes aadE, erm(B) and aacA-aphD. All 11 MRSA isolates had the gene lnu(B) immediately downstream of lsa(E). Nine MRSA isolates – six from frozen or chilled chicken, two from pigs and the single isolate from a butcher – exhibited the same downstream region as detected on the 41-kb plasmid which also included the insertion sequence IS257 about 3kb downstream of lsa(E). However, only one chicken isolate showed the same upstream region for about 1.5kb. One of the frozen chicken isolates with the same downstream region and one additional isolate from chilled chicken showed the same upstream region of lsa(E) for about 5kb including aadE. In addition, all 11 isolates were positive for aacA-aphD, a single porcine isolate was positive for aadE and none of the isolates for erm(B).
Conclusions: The novel resistance gene lsa(E) was identified in MRSA isolates of different origin from Hong Kong wet markets. However, the lsa(E) gene appears to be present in different genetic contexts as confirmed by the PCR assays applied and the variability in the resistance genes present.
|Appears in Collections:||Conference Paper|
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