Jpn. J. Infect. Dis., 53, 2000

Laboratory and Epidemiology Communications

EpidemiologlCal Analysis Of a Methicillin‑Resistant Staphylococcus aureus
Outbreak in a Surgery Ward by Genomic DNA
Fingerprlntlng Using Pulsed‑Field Gel Electrophoresis
Aki Kaneko, Sosuke Kimura, Fumiko Kirikae, Kiminori Toyooka, Masahito Hashimoto,
MitsuharuHasegawa, Kazuhisa Mezaki, Tadatoshi Kuratsuji, Morito Sumlya,
Oichirou Kobori, Yoshio Yazaki and Teruo Kirikae*International Medical Center ofJapan,Toyama 1‑21‑1, Shinjuku, Tob70 162‑8655
Communicated by Hiroshi Yoshikura(Accepted May 26, 2000)

Nosocomial infection, especially postoperative infection,

M1 12345678M2

caused by methicillin‑resistant Staphylococcus aureus(MRSA), is a major problem in surgical wards (1)･ Genomic
DNA fingerprinting uslng Pulsed‑field gel electrophoresIS(PFGE) is a powerful tool to investigate the source, trans‑mission, and spread ofMRSA infection (2).
In a surgery ward in a hospital in Tokyo, three patients

successively contracted severe sepsis. MRSA was isolated fromthe patients'blood. The isolatesand isolates &om carriersinthe
same ward duringthe same period were tested for chromosomal
DNA type (Contour‑clamped homogeneous electric rleldsystem, CHEF MapperTM: BioIRad Laboratories, Hercules,Calif., USA), antibiotic resistance (WalkAway'M, DadeBehring, Deer field, Ill., USA), enterotoxin serotype (SETI
RPLA: Denka Seiken Co., Tokyo), toxic shock syndrome
toxin‑ 1 (TSSTl 1) production (TST‑RPLA: Denka Seiken), andcoagulase serotype (Denka Seiken).
PFGE profile ofSmaI DNA digests (Fig. 1) and antibioticresistance patterns (Tables 1, 2) differed among the threesepsis isolates (No. 57, 63,and 66). Thisindicates that, though
the sepsIS occurred apparently in a form of butbreak, theseincidences were due to infection by different MRSA strains

Fig. 1. Pulsed一点eld electrophoresis of SmaI‑digested genomic DNA

resulting solely from contamination of the ward by multiple

舟om MRSA isolates.

MRSA strains. However, band‑based cluster analyses ofPFGE profiles (Molecular AnalystTM: Bio‑Rad) indicated a

Lane 1: isolate No.57 (patternD), lane 2: No. 63 (B), lane 3: No. 66(G), lane4: No. 67 (H), lane 5: No. 69 (C), lane 6: No. 70 (E), lane 7:

No. 73 (F), lane 8: No. 74 (A), Ml: low range PFG Marker, M2:
1amda ladder PFG Marker.

*Corresponding author: Fax: +8 1 ‑3‑3202‑7364, E‑mail: tkirikae@ri.imcj.go.jp
84Jpn. J. Infect. Dis., 53, 2000
Table I. Antibiotic pattem classified by MIC pattem of I 6 antibiotics against MRSA
AntibioticMIC(LLg/ml)of:Pattem PCG MPIPC ABPC PIPC CEZ CMZ CTM IPM EM GM OFLX MINO VCM CLDM
abCde良良R良良氏R氏氏氏

RR良R氏

氏R良良良

R氏良臥臥

R氏氏良氏

氏良良良氏

氏良氏R氏

良氏良良R

l▲ S T▲ l S

R良良氏氏

良氏臥s氏

SSSSS

ST

SSSSS

R氏氏R良T▲0M氏RIISPCG: benzyl‑penicillin, MPIPC: oxacillin, ABPC: ampicillin, PIPC: piperacillin, CEZ: cefazolin, CMZ: cehetazole, CTM: cefotiam,
IPM: imipenem/cilastatin, EM: erythromycin, GM: gentamicin, OFLX: onoxacin, MINO: minocycline, VCM: vancomysin, CLDM: clindamycin,
ST: streptomycin, FOM: fosfomycin, R: resistant, S: susceptible, I: intemlediate

Table 2. Phenotypic and genotypic characterization of the S. azLYeuS isolates
I sol ation

ward,TE悪占alttUe品

r芯㌫

Nov.

TSST‑1 CoagulaseA(1 999)
cardiacEnterotox inIsolation PFGE Antibiotic

Symptom I.ULb.I:U▲▲

sep

sis

5 ′0 ′○7 つJ ′0DaG

abC

HCEFA

deaaa

B

Ctype

D+ + +一一一+++++I E I L+ + +ⅡⅡⅡ

+++++

ⅡⅡⅡⅡⅡ

surgery Nov.
Nov.
D D N D N∝ ec ov ∝ ocolonization

上U AV 7 7 7

7 9 0 つJ 4一 一 l 一 一

1LIF 一110 0 %REFERENCES

A B C D E lil G H

1. Nichols, R. L. (1998): Postoperative infections in the age

ofdrug‑resistant gram‑positive bacteria. Am.J.Med., 1 04,11S‑16S.

2. Ichiyama, S., Ohta, M., Shimokata, K., Kato, N. andTakeuchi, J. (1991): Genomic DNA fingerprintings bypulsed‑field gel electrophoresis as an epidemiologlCalmarker for study of nosocomial infections caused bymethicillin‑resistant Staphylococcus aureus. J. Clin.

Microbio1., 29, 2690‑2695.
3. Kaneko, A., Miyazawa, H., Kirikae, F., Toyooka, K.,
Hashimoto, M., Yamasaki, S., Hasegawa, M., Takeuchi,C., Kuratsuji, T., Sumlya, M., Kobori, 0., Yazaki, Y.

Fig. 2. cluster analysis of MRSA isolates based on PFGE pattems.

and Kirikae, T. (2000): Epidemiological analysis of

more than 98% similarity among all the strains tested (Fig.
2)･ This may indicate that MRSA of the same.origin may
have persisted inthe ward with continuous mutat10nS. All themethicillin‑resistant Staphylococcus aureus outbreaks inisolates produced enterotoxin type C, TSST‑1 and coagulase

printing uslng Pulsed‑field gel electrophoresis. Jpn. J.

Type II (Table 2).

Infect. Dis., 53, 82‑84.

a neonatal intensive care unit by genomic DNA finger‑85