Community-Acquired Methicillin-Resistant<i>Staphylococcus aureus</i>Carrying Panton-Valentine Leukocidin Genes: Worldwide Emergence

TLDR

Community-acquired methicillin-resistant Staphylococcus aureus infections have been reported worldwide. The study assessed whether common genetic markers exist among 117 CA‑MRSA isolates from six countries by PCR screening of 24 virulence factors and the methicillin‑resistance determinant. We performed PCR for 24 virulence factors and the methicillin‑resistance determinant, and analyzed the genetic background by pulsed-field gel electrophoresis and multi-locus sequence typing. The CA‑MRSA strains shared a type IV SCCmec cassette and the Panton‑Valentine leukocidin locus, but other toxin genes varied by continent; PFGE and MLST showed distinct genetic backgrounds per geographic origin, mainly agr3, and these backgrounds differed from hospital‑acquired MRSA within each continent.

Abstract

Abstract Infections caused by community-acquired (CA)-methicillin resistant Staphylococcus aureus (MRSA) have been reported worldwide. We assessed whether any common genetic markers existed among 117 CA-MRSA isolates from the United States, France, Switzerland, Australia, New Zealand, and Western Samoa by performing polymerase chain reaction for 24 virulence factors and the methicillin-resistance determinant. The genetic background of the strain was analyzed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The CA-MRSA strains shared a type IV SCCmec cassette and the Panton-Valentine leukocidin locus, whereas the distribution of the other toxin genes was quite specific to the strains from each continent. PFGE and MLST analysis indicated distinct genetic backgrounds associated with each geographic origin, although predominantly restricted to the agr3 background. Within each continent, the genetic background of CA-MRSA strains did not correspond to that of the hospital-acquired MRSA.