Jpn. J. Infect. Dis., 54, 2001

Laboratory and Epidemiology Communications

Molecular Epidemiology of Methicillin‑Resistant Staphylococcus aureus
in a Hospital in Chiang Mai
Prasit Tharavichitkul, Tomoko FujinoI , Namiko MoriI, Aki Kaneko. ,Fumiko Kirikael , Thira Sirisanthana2 and TeruO Kirikael *Department of Microbiology, Faculo) ofMedicine, and 2ResearlCh Institute for Health Sciences,

Chiang Mai UniversioJ, Chiang Mat 50200, mailand andJInternational Medical Center ofJapan,

IToyama 1‑21‑1, Shinjuku‑ku, To砂0 162‑8655

Communicated by Hiroshi Yoshikura(Accepted May 21, 2001)

Methicillin‑resistant Staphylococcus aureus (MRSA) is aTable I. The two dominant isolates, belonglng tO Al and CI

major posocomial pathogen in Thailand ( 1 )I Epidemiologicalclusters, spread over most wards in the hospital and wereanalysts Ofthe MRSA isolates in a hospital, uslng restriction
kagment length polymorphisms of genomic DNA in pulsed‑
field gel electrophoresis (PFGE), is essential for assessment

M 1 23456789101112Mof hospital infection control (2).

Eighty‑two slngle‑patient MRSA isolates were collectedduring January‑February 200 1 in a hospital with about 2000

beds in Chiang Mai. These isolates were analyzed for chromo‑
somal DNAtyping by using a contour‑clamped homogenePus
electric field system (CHEF MapperTM, Bio‑Rad Laboratones,Hercules, Calif., USA). In the present study, the isolates show‑
lng the same PFGE pattems were considered to onglnate丘om

the same MRSA strain.
Twelve different PFGE pattems ofSmaI DNA digests weredetected (Fig. 1). When PFGE pattems with more than 70%
similarity in the band‑based cluster analysis (Molecular
AnalystTM, Bio‑Rad) were grouped into the same cluster, fourclusters, A to D (Fig. 2A), were identifled. Clusters B and C
were similar to cluster Aゎy more than 59 and 55 %, respec‑tively. Cluster D shared less similarity with other clusters (Fig.
2A). Figure 2B shows that clusters Al and CI were dominant,each occupying 61% and 2 1 % oftotal isolates. A geographic
distribution of MRSA isolates in the hospital is shown in

Fig. 1. Pulsed‑field gel electrophoresis ofSmaI‑digested genomic DNA

from MRSA isolates. Lane 1: PFGE pattern Al, lane 2: Cl,*Corresponding author: Fax: +8 113‑3202‑7364, E‑mail: tkirikae

lane 3: A2, lane 4:A3, lane 5:A4, lane 6:A5, lane 7: A6, lane 8:A7,lane 9: A8, lane 10: C2, lane ll: B, lane 12: D, M: lowrange PFGMarker.

@ri.imcj.go.jp
82Jpn. J. Infect. Dis., 54, 2001
4050607090801 0 0%

Table 1. Distribution ofMRSA isolates in a hospitalA l舶 鵬が舶 MBc lmD

PFGE pattemWardA
123456B7C81D2a b C d 〜‑ gh･1jk 1 m ∩ 0 p q r S I u > W x y Z 組め 弧.SFig･ 2A･ Cluster analysis ofMRSA isolates based on PFGE patterns ofSmaI‑digested gcnomic DNA.

2(.ON)SelelOSH
11111

30 20

11‑ 5111

I●ll1 1AI CI A2A3A4A5A6A7

AB C2

B D

Fig. 2B. Histogram ofMRSA isolates based on PFGE pattems.

example, wards c, d, k, 1, m, r, t, u, and x f♭r clusterAl, andJpn. Phamacol. Ther., 29 (in press)･2. Tharavichitkul, P., Kirikae, F., Kaneko, A., Hashimoto,wards d, i, and o f♭r cluster Cl. These data indicate that there

M., Toyooka, K., Hasegawa, M., lwata, K･, KuratsuJl,

isolated on more than one occasion in the same wards; forT., Yazaki, Y., Sirisanthana, T. and Kirikae, T. (2000):
CompariSon of genomic DNA fhgerprlntlng uSlng

were dominant MRSA strains, which intemittently caused
the outbreaks during the study period, in the hospital･

pulsed‑field gel electrophoresis and antibiotics suscep‑tibility of clinical isolates of methicillin‑resistant Staphy‑

REFERENCES

lococcus aureus between Chiang Mai and Tokyo. Jpn. J.
Infect. Dis., 53, 86‑87.

I. Sirisanthana, T. (2001): Hospital infection in Thailand.

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