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Abstract  Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA), which is often positive for Panton-Valentine leucocidin (PVL), is increasingly noted as an emerging pathogen worldwide. In Japan, PVLpositive CA-MRSA belonging to multilocus sequence type (ST) 30 has spread and caused, for example, pediatric death due to community-acquired pneumonia and severe pelvic abscesses in an athlete. In this study, we investigated a new rapid screening method for PVL-positive ST30 CA-MRSA and its related clone by a combination of multiplex polymerase chain reaction (M-PCR) and pulsed-field gel electrophoresis (PFGE). For M-PCR, the targets of the assay were the five genes for PVL, collagen adhesin, bone sialoprotein adhesin, methicillin resistance, and S. aureus-specifi c thermostable nuclease. Only PVL-positive ST30 CA-MRSA strains produced all five bands in M-PCR. With PFGE, Japanese strains and most foreign strains of PVLpositive ST30 CA-MRSA shared the same pattern. Moreover, PFGE distinguished current PVL-positive CA-MRSA ST30/spa19 strains from previous PVL-positive MRSA ST30/spa43 strains (which were isolated at the time of nosocomial MRSA outbreaks in the late 1980s and early 1990s) in Japan. Thus, the M-PCR assay rapidly, and the M-PCR/PFGE combination assay more precisely, discriminated between PVL-positive ST30 CA-MRSA (or its related clone) and PVL-positive CA-MRSA belonging to other ST types such as ST1, 8, 59, and 80, PVL-negative CA-MRSA, hospital-acquired MRSA, methicillin-susceptible S. aureus, or coagulase-negative staphylococci (CNS), including MRCNS. This screening method is more useful than genotyping for routine work in many clinical laboratories. [ABSTRACT FROM AUTHOR]

Abstract??Staphylococcus aureusand coagulase-negative staphylococci (CNS) isolated from the nasal mucosa of medical students were examined for susceptibility to 16 antimicrobial agents. No methicillin-resistantS. aureus(MRSA) was isolated, while MRCNS was present in 23.5% of the medical students. CNS exhibited significantly more resistance to antimicrobial agents such as gentamicin, in addition to oxacillin, compared toS. aureus, and 13.1% of the CNS strains (mostly MRCNS) were multidrug-resistant (to five or more drugs). In contrast, ampicillin resistance was higher inS. aureus. The rate of hospitalization or of taking an antimicrobial agent within the past 1 year was lower in CNS+students than inS. aureus+students. The data suggest that CNS could serve as a reservoir of drug resistance by persistent colonization in the nasal mucosa. In this study, MRCNS with multidrug resistance was found in medical students. More attention should be given to nasal MRCNS in medical students as a possible spreader in hospitals. [ABSTRACT FROM AUTHOR]