Detection of Legionella pneumophila serogroup 7 strain from bathwater samples in a Japanese hospital.

Hospital-acquired legionellosis is one of the serious problems in nosocomial infection. For risk assessment of nosocomial Legionella infection, we surveyed samples from bathrooms for public use in three hospitals and two nursing homes to determine whether Legionella pneumophila was present. A total of 70 hot bathwater samples and samples wiped from bathtubs were collected at 1-h intervals. Fifteen shower-water and 15 inner-head samples were obtained at the start of a bath. Water samples were cultured using the Legionella spp. selective medium, and discrimination between L. pneumophila and other Legionella spp. was performed by PCR analysis. L. pneumophila serogroup 7 was detected in 1 bathwater and 1 wiped sample, both of which were collected 1 h after daily use from the same bathtub in a hospital. However, L. pneumophila SG7 was not detected in any other samples. Furthermore, the concentrations of free residual chlorine in most bath- and shower-water samples were lower than 0.1 mg/l. These results suggest that L. pneumophila has become a potential pathogen for nosocomial infections in public-type hospital baths. From the point of view of an infection-control program, it might be advisable to hold the concentration of free residual chlorine at 0.2-0.4 mg/l, which is generally required for public baths in Japan.

Survey of methicillin-resistant Staphylococcus aureus from neonates and the environment in the NICU.

Methicillin-resistant Staphylococcus aureus (MRSA) is a risk factor of nosocomial infection with compromised hosts including neonates. Currently, the prevalence of MRSA carriers among children is increasing in Japan. There are some reports of nosocomial infection caused by MRSA in a pediatric ward or neonatal intensive care unit (NICU). During 6 months (from January 2001 to June 2001), 37 MRSA strains were isolated from 37 neonates who were admitted in the NICU and 52 MRSA were strains isolated from NICU environments. We performed DNA typing of MRSA using an arbitrary primed-PCR method on these isolates. Thirty-seven clinical isolates were classified into four types (A type, 14; B type, 4; C type, 4; D type, 3; and others, 12). The A-type strains of MRSA continued to be isolated for more than 6 months. In the NICU environment, the detection rate of the A-type MRSA was 23.1% (12/52). The A-type strains were frequently isolated from environments around patients. The A-type strains of MRSA were prevalent in the NICU, probably due to nosocomial infection. Although none of the neonatal patients developed severe MRSA infection, the same genotype strains were persistently isolated during a period of more than 6 months from patients and the NICU environment around patients. Environmental control around neonatal patients is important to prevent nosocomial infection in the NICU.