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

Laboratory and Epidemiology Communications

Molecular Epidemiology of Methicillin‑Resistant Staphylococcus aureus
in a Tokyo Hospital in 2000
Tomoko Fujino, Namiko Mori, Akihiko Kawana, Hisashi Kawabata, Tadatoshi KuratsuJl,
Koichiro Kudo, Oichirou Kobori, Yoshio Yazaki and Teruo Kirikae*International Medical Center ofJapan,
Toyama 1‑21‑1, Shinjuku‑ku, Too)0 162‑8655
Communicated by Hiroshi Ⅵ)shikura(Accepted June 4, 2001)

10% of the total isolates, respectively. The most frequentcluster ofpattems (Al to All) made up 56% of the total
isolates. A geographic distribution of MRSA isolates in theMethicillin‑resistant Staphylococcus aureus (MRSA) is amajor nosoeomial pathogen in healthcare facilities (I)･

EpidemiologlCal analysis ofwhole MRSA isolates present in a

hospital is shown in Table 1. The isolates with PFGE pattem
A was spread over most of wards in the hospital and twoisolates with the same PFGE pattem A existed in wards suchhospital, including restriction kagment length polymorphismsof genomic DNA using pulsed‑丘eld gel electrophoresis (PFGE),is essential for assessment of hospital infection controls (2).

as 7N and 7S･ All isolates with patty B were from 4N (n =Two‑hundred‑forty‑six MRSA isolates were obtained from74 inpatients in December 2000 in a Tbkyo hospital with 27wards and 925 beds. Among these isolates, 50 isolates, each1) and 4S (〟 ‑ 3) which are a pediatnc ward and an obstetrics

derived from a slngle patient, Were analyzed for chromosomal

DNA typlng by uslng a COntOur‑Clamped homogeneouselectriCfield system (CHEF MapperTM, Bio‑Rad Laboratories,A A BCDElmF M円G l別mHI 史U40ノ'Jl‑5‑ 'l7占VHercules, Calif. , USA), for antibiotic resistance (WalkAwayTM,Dade Behring, Deerfield, Ill･, USA), enterotoxin serotyping(SET‑RPLA, Denka Seiken Co., Tokyo), toxIC Shocksyndrome toxin‑1 (TSSTl 1) production (TST‑RPLA: DenkaSeiken), and coagulase serotyp.ing (Denka Seiken)･ In theO l'一

present study, the isolates showlng the same PFGE pattems

were considered to have the same strain of MRSA.
Twenty‑nine different PFGE pattems ofSmaI DNA digests
were detected (Fig. 1 ). A band‑based cluster analysis of thesepattems (Molecular AnalystTM, Bio‑Rad) revealed that there
existed eight clusters of pattems A to I when defined as one
cluster ofpattems with more than a 70% similarity (Fig. 2A).
Pattems B to H showed more than a 50 % similarityto pattem
A, and pattem I showed less similarity with others (Fig. 2A).

The frequency distribution of MRSA isolates based on PFGE
pattems is shown in Fig. 2B. The most fTrequent pattem (Al)and the second‑most frequent one (A2) represented 1 6% andM l2 3456789 1011121314151617181920212223242526272$29M∴∴∴せ由Pq 98 7 6 5 4 3 2 1 0

ここ｢̲̲̲二二筆書表臣雲霞監岳===芸i(.oN)S3)t!tOSIー≡≡=【:;コFig. I. Pulsed‑field gel electrophoresis ofSmaI‑digested genomic DNA

from MRSA isolates. M: low range PFG Marker. Lanes 1 to 29:
MRSA isolates with different PFGE pattems Al to I shownin Fig. 2.

言寄等中音等滞号音等軍曹u qポ仰C,"8滞､*Corresponding author: Fax: 8 1‑3‑3202‑7364, E‑mail: tkirikae@ri.imcj.go.jp

Fig. 2. Cluster analysis or MRSA isolates based on PFGE pattems.

91

Jpn. J. Infect. Dis., 54, 2001
Table I. Distribution ofMRSA in a hospital
PFGE pattem
a24 5 ′LU エ 7 0 0ノ 1 1 ‑ 1 ‑1 1つJ45エリ

78910ll

C12D
12E

12F

345G123H

1421〟

Ns Ns Ns oN sm1S乃珊娼456

2 2111211111●■ll#Number ofpatientswith MRSA

Table 2. Antibiotic pattern classfield by antibiotic pattem of 1 7 antibiotics against MRSA
Antibipattern
abCde∫gh ‑･ーk1m∩0pq‑ 〜otiEM
良R氏 良 良 良氏良 良R 良 sc

LV
氏I良 I良1S良氏良1 良R良 R良Antibiotic

FXC

LDM

礼良R良 氏良 s氏R良 良 良sRS

F
良氏良氏良1R良 良 良 s ISRs

OMsGM良 良氏良 良 良s s s s良s良ABK
良 sssssssss

MIN

0l ST▲ STlS S,1 I1 S1 S ltS

VCM
SSSSSSSSSSSSSS#Allthe isolates were resistant to PCG, MPIPC, ABPC, CEZ, CTM, CFDN, FMOX, IPM.
PCG: benzyl‑Penicillin, MPIPC: oxacillin, ABPC: ampicillin, CEZ: cefazolin, CTM: ccfotiam, CFDN: ccfdinir,
FMOX: nomoxcf, lPM : hnipenem/Cilastatin, EM: erythromycin, LVFX: Icvofloxacin, CLDM: clindamycin,

FOM: fosfomycin, GM: gentamicin, ABK: arbekacin, MINO:minocycline, VCM: vancomycln,
ST:streptomycin, R: resistant, S: susceptible, I: intermediate.

different pattems. Those isolates were resistant to 10‑15 ofand gynecology ward, respectively. Isolates with pattem F

were from lON, 1 lN, 13N, and 15, and isolates with pattem

17 tested drugs. No isolate was resistant either to vancomycln

Gwerefrom9S, llN, 13N, and 16.
Sensitivlty tO antibiotics is shown in Table 2. The MRSA

or streptomycin. No isolate with a specific antibiotic pattem
spread in a specific ward. No correlation was found between
the antibiotic pattems and PFGE pattems (data not shown).

isolates had a wide spectmm of dmg‑resistance showlng 1992

93