Molecular Characterization of Community-Associated Methicillin-ResistantStaphylococcus aureusIsolated from Skin and Pus Samples of Outpatients in Japan

Abstract

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is now endemic in the United States. In Japan, CA-MRSA infections and CA-MRSA surveillance have been scarcely reported. In this study, we conducted a nationwide survey of CA-MRSA in Japan. We collected MRSA strains isolated from outpatients with skin and soft-tissue infection (SSTI) at 107 medical facilities from 24 prefectures in 2010 and 2012. Among 10,385 clinical samples from SSTI patients, 3,581 S. aureus isolates (35%) were obtained and 673 of the S. aureus strains (19%) were identified as MRSA. Among 625 MRSA strains tested in this study, 266 strains (43%) and 114 strains (18%) were classified as SCCmec types IV and V, respectively. Detection of virulence genes was as follows: Panton-Valentine leukocidin (PVL) gene (57 strains, 9%), exfoliative toxin (ET) gene (179 strains, 29%), toxic shock syndrome toxin-1 (TSST-1) gene (195 strains, 31%), or none. PVL-positive strains were classified into eight sequence types (STs) (i.e., ST1, ST5, ST8, ST22, ST30, ST452, ST59, and ST154) and six clonal complexes (i.e., CC1, CC5, CC8, CC22, CC30, and CC59). Only 10 PVL-positive strains (2%) were pulsed-field type USA300 clone. There were a wide variety of CA-MRSA clones in Japan, which were different from the situation in the United States.

Molecular characteristics of methicillin‐resistant Staphylococcus aureus isolated from skin and soft tissue infections collected in the Japanese nationwide surveillance

“…From our genetic analysis, the percentage of SCC mec type II was higher than that of SCC mec type IV. On the other hand, in the previous nationwide surveillance of CA‐MRSA isolated from skin and pus samples of outpatients in Japan, the most frequent SCC mec type was IV and the second was II . However, there were some differences in study design between the two nationwide surveillances.…”

“…In this study, the susceptibility rate of fluoroquinolone was lower in HA‐ than in CA‐MRSA, but there was no significant difference. Previous studies reported that antibiotic susceptibility was different between HA‐ and CA‐MRSA …”

“…On the other hand, in the previous nationwide surveillance of CA-MRSA isolated from skin and pus samples of outpatients in Japan, the most frequent SCCmec type was IV and the second was II. 4 However, there were some differences in study design between the two nationwide surveillances. MRSA strains were collected from only outpatients in the first nationwide surveillance while MRSA strains were collected from both outpatients and inpatients in this study.…”

“…Although most methicillin‐resistant Staphylococcus aureus (MRSA) infections are categorized as health‐care‐associated (HA‐MRSA) infections, those caused by community‐associated MRSA (CA‐MRSA), which usually carry staphylococcal cassette chromosome mec (SCC mec ) types IV or V, have been reported from all over the world for over 10 years . However, the molecular characteristics of MRSA isolated from SSTI in Japan remain unclear because there are only a few multicenter studies on molecular epidemiology of MRSA isolated from SSTI in Japan …”

“…1,2 However, the molecular characteristics of MRSA isolated from SSTI in Japan remain unclear because there are only a few multicenter studies on molecular epidemiology of MRSA isolated from SSTI in Japan. [3][4][5] To reveal the molecular epidemiology of MRSA isolated from patients with SSTI in Japan, we performed genetic analysis of MRSA collected in the nationwide surveillance conducted by the Japanese Society of Chemotherapy, Japanese Association for Infectious Diseases and Japanese Society for Clinical Microbiology. 6 Additionally, we investigated the differences between HA-and CA-MRSA based on classification through genetic analysis.…”