2021 年 47 巻 6 号 p. 293-300
The isolation frequency of strains with genetic features of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has increased in inpatients. Additionally, the number of infectious diseases caused by Panton- Valentine leukocidin (PVL)-positive highly pathogenic MRSA strains has been increasing in communities. However, the prevalence of CA-MRSA strains in outpatients of hospitals is unknown. This study investigated the prevalence of CA-MRSA including PVL-positive MRSA strains among inpatients (n = 362) and outpatients (n = 184) between 2013 and 2017 at Tokai University Hachioji Hospital. The proportion of staphylococcal cassette chromosome (SCC) mec type IV, which is a major SCCmec type of CA-MRSA, increased significantly in inpatients (P < 0.01). In contrast, SCCmec type IV strains accounted for >50％ in outpatients every year. The isolation rate of PVL-positive MRSA strains in outpatients (12 strains, 6.5％) was significantly higher than that in inpatients (1 strain, 0.3％) (P < 0.01). Furthermore, the incidence of PVL-positive MRSA strains in 2016 to 2017 (8/70 strains, 11.4％) was significantly higher than that in 2013 to 2015 (4/114 strains, 3.5％) (P < 0.05). All PVL-positive MRSA strains were susceptible to minocycline, vancomycin, and linezolid. This study shows that the number of cases of PVL-positive MRSA strains is increasing in outpatients of a university hospital. Surveillance of PVL-positive MRSA strains for both inpatients and outpatients is necessary to prevent outbreaks of highly pathogenic MRSA strains.
