Jpn. J. Infect. Dis., 53 (2), 84-85, 2000
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Laboratory and Epidemiology Communications
Epidemiological Analysis of a Methicillin-Resistant Staphylococcus aureus Outbreak in a Surgery Ward by Genomic DNA Fingerprinting Using Pulsed-Field Gel Electrophoresis
Aki Kaneko, Sosuke Kimura, Fumiko Kirikae, Kiminori Toyooka, Masahito Hashimoto, Mitsuharu Hasegawa, Kazuhisa Mezaki, Tadatoshi Kuratsuji, Morito Sumiya, Oichirou Kobori, Yoshio Yazaki and Teruo Kirikae*
International Medical Center of Japan,
Toyama 1-21-1, Shinjuku, Tokyo 162-8655
Communicated by Hiroshi Yoshikura
(Accepted May 26, 2000)
Nosocomial infection, especially postoperative infection, caused by methicillin-resistant Staphylococcus aureus (MRSA), is a major problem in surgical wards (1). Genomic DNA fingerprinting using pulsed-field gel electrophoresis (PFGE) is a powerful tool to investigate the source, transmission, and spread of MRSA infection (2).
In a surgery ward in a hospital in Tokyo, three patients successively contracted severe sepsis. MRSA was isolated from the patients' blood. The isolates and isolates from carriers in the same ward during the same period were tested for chromosomal DNA type (contour-clamped homogeneous electric field system, CHEF MapperTM: Bio-Rad Laboratories, Hercules, Calif., USA), antibiotic resistance (WalkAwayTM, Dade Behring, Deerfield, Ill., USA), enterotoxin serotype (SET-RPLA: Denka Seiken Co., Tokyo), toxic shock syndrome toxin-1 (TSST-1) production (TST-RPLA: Denka Seiken), and coagulase serotype (Denka Seiken).
PFGE profile of SmaI DNA digests (Fig. 1) and antibiotic resistance patterns (Tables 1, 2) differed among the three sepsis isolates (No. 57, 63, and 66). This indicates that, though the sepsis occurred apparently in a form of outbreak, these incidences were due to infection by different MRSA strains resulting solely from contamination of the ward by multiple MRSA strains. However, band-based cluster analyses of PFGE profiles (Molecular AnalystTM: Bio-Rad) indicated a more than 98% similarity among all the strains tested (Fig. 2). This may indicate that MRSA of the same origin may have persisted in the ward with continuous mutations. All the isolates produced enterotoxin type C, TSST-1 and coagulase Type II (Table 2).
REFERENCES
*Corresponding author: Fax: 81-3-3202-7364, E-mail: tkirikae@ri.imcj.go.jp
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