Jpn. J. Infect. Dis., 54, 191-193, 2001
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Laboratory and Epidemiology Communications
Epidemiological Analysis of Methicillin-Resistant Staphylococcus aureus in a Community Hospital in Hiroshima
Rie Sasaki, Tomoko Fujino1, Junko Kawasaki, Tsutomu Furukawa, Namiko Mori1, Norikazu Shigeto and Teruo Kirikae1*
National Hataka Hospital, Hataka 2-14-1, Aki, Hiroshima 736-0088 and 1International Medical Center of Japan, Toyama 1-23-1, Shinjuku-ku, Tokyo 162-8655
Communicated by Hiroshi Yoshikura
(Accepted October 30, 2001)
Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen in hospitals, including community hospitals with relatively small numbers of beds (1). Molecular analysis of MRSA isolates in a hospital, using restriction fragment length polymorphisms of genomic DNA using pulsed-field gel electrophoresis (PFGE), is essential for assessment of hospital infection controls (2).
The present study was conducted in a hospital in Hiroshima with two wards and 100 beds. In September 2001, MRSA was isolated from two patients' sputa and one patient's urine in ward I and four patients' sputa, one patient's bile, and one patient's nasal swab in ward II. MRSA was isolated from the sputum of five patients and the pus of one in ward I, and the sputum of three patients in ward II in December 2000. The isolates were tested for chromosomal DNA typing by using a contour-clamped homogeneous electric field system (CHEF MapperTM: Bio-Rad Laboratories, Hercules, Calif., USA), enterotoxin serotyping (SET-RPLA: Denka Seiken Co., Tokyo), toxic shock syndrome toxin-1 (TSST-1) production (TST-RPLA: Denka Seiken), and coagulase serotyping (Denka Seiken).
From nine MRSA isolates, seven different PFGE patterns of SmaI DNA digests were detected (Fig. 1). Isolate No. 898 from ward I and No. 903 from ward II, and isolates Nos. 901 and 905 from ward II had the same PFGE pattern, respectively. All isolates except Nos. 899 and 900 produced enterotoxin type C, TSST-1, and coagulase type II (Table 1). Isolate No. 899 produced TSST-1 and coagulase type II, but not enterotoxin. Isolate No. 900 produced enterotoxin types A and C, TSST-1, and coagulase type II.
The PFGE patterns of these MRSA isolates were compared with those of MRSA isolates obtained in the same hospital in August and December 2000 (2). From a total of 31 isolates, 20 different PFGE patterns were detected (Fig. 2A). Band-based cluster analysis of these patterns (Molecular AnalystTM: Bio-Rad) revealed six clusters A to F (Fig. 2B) (patterns sharing a similarity of 70% or higher were grouped into a cluster). The PFGE pattern and the isolation term of all MRSA isolates were summarized in Table 2. Six of nine MRSA isolates in August 2000, nine of 13 isolates in December 2000, and eight of nine isolates in September 2001 were of cluster type A. Three isolates from ward I in August, five from the same ward in December, and one from ward I (No. 898) and one from ward II (No. 903) in September were of the same PFGE pattern (A1). One isolate from ward II in August and two isolates from ward II (Nos. 901 and 905) in September were of the same PFGE pattern. Other MRSA isolates were of different PFGE patterns from those with patterns A1 and A2, and from each other (A3 to A12, B, C1 to C3, and E1 and E2, and F). Collectively, the above observation indicates that the spread of a single MRSA strain (pattern A1) occurred in ward I in August and December 2000. The MRSA outbreak of a single strain was being stamped out in ward I in September 2001. Meanwhile, most other MRSA infections in this hospital appeared to occur sporadically, indicating that these MRSA were mainly come from other healthcare facilities in the same community.
REFERENCES
*Corresponding author: Fax: +81-3-3202-7364, E-mail: tkirikae@ri.imcj.go.jp
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