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

Laboratory and Epidemiology Communications

EpidemiologlCal Analysts Of Nosocomial Outbreaks of Methicillin‑Resistant

Staphylococcus aureus in a Surgery Ward
Namiko Mori, Tomoko Fujino, Toshitaka Kashima, Jyoji Tomioka, Akihiko Kawana,Hisashi Kawahata, Yoshie Takahashi, Fumiko Yamanishi, Sosuke Kimura,
Tadatoshi Kuratsuji, 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 Yoshikura(Accepted September 17, 2001)

Nosocomial infection, especially postoperative infectionand P6) developed sepsis, one (P5) had surgical site infec‑

Paused by methicillin‑resistant Staphylococcus aureus (MRSA),

lS.a Serious problem ln Surgical wards (1)･ Genome typingtion. MRSA was isolated from the patients'blood and thesurglCal sites. MRSA was also isolated from the sputum ofuslng Pulsed‑field gel electrophoresis (PFGE) is a powerful

three other patients (Pl, P3, and P4) who did not manifest

tool for investlgatlng the source, transmission, and spread ofany clinical symptoms due to infections. A total of six isolates

MRSA.

were obtained and co°ed as 2001 outbreak isolates. ln theIn July 2001, an MRSA outbreak occu汀ed in a 42‑bedsame ward, two MRSA outbreaks had occu汀ed in November

surgical ward of a hospital with 925 beds. Two patients (P2to December 1999 (2), and in June toAugust 2000 (3). Eightdifferent PFGE pattems (MRSA.lMCJ.A3, A5, A6, A7, AIO,Al 1, A12, and B) were found in the former case (2) and five*Co汀eSpOnding author: Fax: +8 1‑3‑3202‑7364, E‑mail: tkirikae@ri.imcj.go.jp

pattems (MRSA.IMCJ.Al, A2, A4, A8, and A9) in the latter159

Jpn. J. Infect. Dis., 54, 2001
outbreak isolates, three isolates, Nos. 893, 896, and 897 (lanes
2, 5, and 6 in Fig. la), shared the same PFGE pattem. Twoisolates, Nos. 894 and 895 (lanes 3 and 4), shared the samecase (3).

Chromosomal DNAtyping was performed using a contour‑
clamped homogene?us electric field system (CHEF MapperT" :Bio‑Rad LaboratorleS, Hercules, Calif., USA). The isolates

pattem but the pattem was different from that of the above
three. Isolates of No. 892 had a pattem different from any ofthe others (Fig. la). Three MRSA clones appeared to havewere also tested fわr antibiotic resistance (WalkAwayTM: DadeBehring, Deerfield, Ill･, USA), enterotoxin serotyping (SET‑RPLA: Denka Seiken Co., Tbkyo), toxIC Shock syndrome
toxin‑ 1 (TSSTll ) production (TST‑RPLA: Denka Seiken), andcoagulase serotyping (Denka Seiken).
PFGE pattems ofSmal DNA digests of six isolates fromparticlpated in the 2001 outbreak.

Nos. 893, 896, and 897 had PFGE pattems identical withthat of2000 Outbreak isolate A4 (lane 12 in Fig. lb), Nos.
894 and 895 pattems identical with the 1 999 Outbreak isolate

A7 (lane 6 in Fig･ lb), and No. 892 a pattem identical withthe 1999 Outbreak isolate AIO (lane 5 in Fig. lb). The isola‑the 2001 Outbreak and 13 isolates from the 1999 and 2000

Outbreaks are shown in Figs. la and b. Among the 2001

tion dates ofMRSA with each PFGE pattern are shown inFig･ 2･ PFGE pattems in the 2001 Outbreak are already fわundaM

123456in the 1 999 and 2000 outbreaks. Band‑based cluster analysts

Mof PFGE (Molecular AnalystTM: Bio‑Rad) indicated a morethan 70% similarityamong the isolates in 1 999‑2001 except forpattem 良 (Fig. 2). This may indicate that MRSA orthe sameorlgln persisted in the ward, experienclng Small mutations.

Sensitivityto antibiotics is shown in Tables 1, 2, and 3. All
the 2001 Outbreak isolates had the same pattern (pattem e,70菅o To

ミooN慧cIJ霊‑･ J2蕊1AIOA20A30A40A50A60A70A A A A A B 0 0ノ l 1 1b M1 2345678M910111213M0○○0120 00 0

Fig. 2. Band‑based cluster analysts Ofthe PFGE patterns of these outbreakisolates and the isolation dates orMRSA with each PFGE pattcm.

Table 1. Antibiotic patternclassificd by antibiotic pattcm of 12 antibiotics

agalnSt MRSA
Antibiotics

Antibiotic
pattema b C d C r･ g.G

GM氏RR良ssss

FOM
RR1S氏ISSMINO
l▲ S T▲ S,1 ‑ ‑1 SSSSSSSSS

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

from MRSA isolates.
a: PFGE analysis of the 2001 Outbreak isolates ofNos. 892 (lane 1),

b: PFGE analysis or the isolates orthe 1999 and 2000 Outbreaks ofAll isolates wcrc resistant to PCG, ABPC, CEZ, CTM, IPM, EM,CLDM.
PCG: benzyl‑Penicillin, ABPC: ampICillin, CEZ: cefazolin, CTM:cefotiam, lPM: imlPenem/cilastatin, EM: erythromycin, CLDM:

MRSA.IMCJ.Al 1 (lane I), B (lane 2), A12 (lane 3), A3 (lane 4),

clindamycin, GM: gentamicin, FOM: fosfomycin, MINO.I minocycline,

AIO (lane 5), A7 (lane 6), A5 (lane 7), A6 (lane 8), Al (lan° 9), A

ST: streptomycin, VCM: Vancomycin. R: resistant, S: susceptible, I:2 (lane 10), A8 (lane H),A4 (lane 12), andA9 (lane 13).

in tらmed iate.

893 (lane 2), 894 (lane 3), 895 (lane 4), 896 (lane 5), and 897 (lane6). M: low range PFG Marker.

160

Jpn. J. Infect. Dis., 54, 2001
Table 2. Phenotypic and genotypic characterization of S. aureus isolatespatient(P) IsolateNoI Specimen ,Pap.TeEm ,Aanuttbiotic Enterotoxin TSST‑1 Coagulase
nr nr nr nr nr nr

892

1 2 tJ 4 5 ′んU

sputum

A1blood

A4894

sputum

A7895

sputum

A7896

surglCal897

site

A4bloodA4pattern+一十+++l▲ l 1 l▲ l 1
1 1‑ ■l ▲ l‑ ▼‑▲CeCee

enterotoxin type C and type II coagulase, but not TSST‑1

Table 3. Antibiotic and PFGE patterns ofMRSA isolates(Table 2).

Antibiotic pattem

PFGE

CCCCCC0893

Patients P2, P5, and P6 infected with MRSAwith the same
PFGE pattem were in different rooms but were treated by aNo.vi/,D,ec･ Juni.‑.Aoug･ ,J.ud･1

team or doctors. This may indicate the spread of MRSA by

A A A A A A B 12345∠U70 ノl1

medical staff members.
a c rl a

REFERENCES
I. Nichols, R. L. (1998): Postoperative infections in the ageof dmg‑resistant gram‑positive bacteria. Am. ∫. Med.,

104, llS‑16S.

012

2･ Kaneko, A., Kimura, S., Kirikae, F., Toyooka, K.,Hashimoto, M., Hasegawa, M., Mezaki, K., KuratsuJl,T., Sumlya, M., Kobori, 0., Yazaki, Y. and Kirikae, T.

aadb(2000) : Epidemiological analysis of a methicillin‑resistant
Staphylococcus aureus outbreak in a surgery ward bygenomic DNAfingerpnntinguslng Pulsed‑field gel electro‑phoresis. Jpn. J. Infect. Dis., 53, 84185.

3. Kaneko, A., Fujino, T.,Kimura, S., Kuroki, H., Suzuki, T.,
Table 2). The pattem was different from those of the same
PFGE pattem isolated at different dates (A4, A7, or A10)

Hasegawa, M., KLmtSuji, T., Sumlya, M., Kudo, K., Kobori,0., Yazaki, Y and Kirikae, T. (2000): Epidemiological(Table 3). This may indicate that antibiotic sensitivity marker

analysIS Of a methicillin‑resistant Staphylococcus aureus

isunsuitablefor assesslng the phylogeny ofMRSA. All the 200 1

outbreak in surgery wards by genomic DNA polymor‑Outbreak isolates except Not 893 produced enterotoxin typephisms. Jpn. J. Infect. Dis., 53, 207‑209.

C, TSST‑1 andtype II coagulase (Table 2). No. 893 produced

161