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

Laboratory and Epidemiology Communications

An Outbreak of Methicillin‑Resistant Staphylococcus aureus (MRSA)
in a Tuberculosis Ward
Namiko Mori, Hiroshi Kawata, Toshio Hama, Tomoko Fujino, Hisashi Kawahata,Akihiko Kawana, Tamiko Suzuki, Fumiko Yamanishi, Tadatoshi KuratsuJl,

Koichiro Kudo, Oichirou Kobori, Yoshio Yazaki and Teruo Kirikae*
In ternational Medical Center ofJapan,
Toyama 1‑21‑1, Shinjuku‑ku, TobJo 162‑8655
Communicated by Hiroshi Ybshikura(Accepted September 1 2, 2001 )Methicillin‑resistant Staphylococcus aweus (MRSA) is one

and a doctor. A total of 15 isolates were obtained and co°ed

as isolates TBWO701.
The isolates TBWO70l were tested for chromosomal DNAof the most important nosocomial pathogens, which are spreadprimarily by direct or indirect person‑to‑person contact (1 ).

Genometypingusing pulsed‑field gel electrophoresis (PFGE)
is a powerful tool for investlgatlng the source, transmission,and spread orMRSA.
In June 2001, an MRSA outbreak occurred in one of twotyping by using a contour‑clamped homogeneou.s electric fleldsystem (CHEF MapperTM: Bio‑Rad LaboratorleS, Hercules,Calif., USA), antibiotic susceptibility (WalkAwayTM: DadeBehring, Deerfield, Ill., USA), enterotoxin serotyping (SET‑RPLA: Denka Seiken Co., Tokyo), toxic shock syndrome
toxin‑ 1 (TSST‑ 1 ) production (TST‑RPLA: Denka Seiken), andcoagulase serotyping (Denka Seiken).
PFGE patterns ofSmal DNA digests of the 15 isolates

tuberculosis wards of a 925‑bed hospital･ The tuberculosis
ward has 42 beds and 32 medical staff members, including
doctors, nurses and assistant nurses, routinely working in theward･ Two patients (Pl and P3) developed severe sepsis･TBWO701 are shown in Fig. 1. Figure 2 shows cluster band‑
based analysis of PFGE pattems (Molecular AnalystTM: Bio‑Rad) or TBWO701 together with all the MRSA isolates

MRSA was isolated from the patients'blood and sputum,respectively. Sputum or nasal swabs from other 32 patientsand nasal swabs from 32 medical staff members were examinedfor MRSA isolation. MRSA was isolated from 12 patientsobtained from the same hospital in December 2000 (isolatesHOSP1200). Ten clusters, from pattem A to J, are observed*Corresponding author: Fax: +8 1 ‑3‑3202‑7364, E‑mail: tkirikae

ifpattems with more than a 70% similarity are postulated toform a cluster (Fig. 2). Isolates HOSP1200 consisted of nine@ri.imcj.gojp
157

Jpn. J. Infect. Dis., 54, 2001
M l2

3456

78509101112131415M

60

AAAAAAAA 84931151

0 1A12972十一.鶏6BCDEIFig. 1. Pulsed‑field gel electrophoresis ofSmaI‑digested genomic DNA

E2FIfrom MRSA isolates. Lane I: isolate No. 876 (pattern Jl), lane 2:

F2

No. 877 (A2), lane 3: No. 878 (Jl), lan° 4: No. 879 (F4), lan° 5: No･品⊂=

880(Jl), lanc6: No. 881 (F6), lan° 7: No. 882 (Jl),lan° 8: No･ 883(Jl), lanc9: No. 884(Jl), lane )0: No. 885 (Jl), lane ll: No. 886

F5(Jl), lane 12: No. 887 (J2), lane 13: No. 888 (Jl), lane 14: No. 889

L G G H .tJ JV(Jl), lan° 15: No. 890 (A2), M: low range PFG Marker.

P 23 1 421 12i〜clusters, pattems A to Hsolates TBW070l consisted of threeclusters, A (A2), F (F4 and F6), and J (Jl and J2). The J cluster
was a newcomer which was not fわund in December 2000.

Five different antibiotic sensitivitypattems, C, j, k, t, and u,
were seen among.isolates TBWO701 (Tables 1 and 2)･ Amo.ng
them, eleven stralnS produced enterotoxin type B, two stralnS(Nos. 877 and 890) ofenterotoxintype C, and one strain (Not879) ofenterotoxin types B and C (Table 2). Isolate No･ 88 1
did not produce any type or enterotoxin. Three strains (Nos･877, 879, and 890) produced TSST‑1. All isolates except NorFig. 2. Cluster analysis ofMRSA isolates based on PFGE pattems･
TBWO70 1 isolates are represented by bold letters, lines and arrows･

881, which produced coagulase type Ill, produced type II

In general, the main mode of transmission orMRSA is via

coagulase (Table 2).

It was remarkable that ten TBWO701 isolates (Nos. 876,hands, which may become contaminated by contact with878, 880, 8821886, 888, and 889) had the same charactercolonized or infected persons, or environmental surfaces(Table 2). They all produced enterotoxin type B, produced

contaminated with MRSA (2)･ Most patients inthe tuberculosis

coagulase type II, did not produce TSSTJl , and had the samewards have a higher level ofdaily actlVlty aS COmpared toPFGE pattems ofSmaI DNA digests and the same spectrum

other patients, and, as a consequence, share more direct oror antibiotic susceptibility｡ They were unlque relative to theindirect contact with each other than do patients in other acuteprevious isolates in the fbllowlng aspects: the isolates had ahealth care facilities. However, environmental surfaces in thenew PFGE pattem Jl (Table 2 and Fig. 2), produced entero‑wards, such as cards, shogi‑ and go‑pleCeS, a dumbbell, an

toxfn type B (98% of all hospital isolates produced entero‑toxlnS Other thantype B) (1), and were TSST‑ 1 negative (96%instrument of foof excise (aotake), a remote TV controller, aof hospital isolates were TSST‑1 positive) (1)･ These resultsa public telephone, re鮎gerator gnp, a stethoscope, a keyboard

indicate that clonal expansion of a new‑type MRSA occurredof a personal computer, and a clinical chart, were negativein the tuberculosis ward.

f♭r MRSA culture.

catalog fb∫ shopplng, a tap, a Washing machine, a receiver orTable 1. Antibiotic patternclassified by antibiotic pattem of I 6 antibiotics agalnSt MRSA
Antibiotics

Antibiotic
pattem
C･lJ k ▲L u

CLDM
良良良ss

FOM
氏良氏sIGMABKMINOsss氏s‑ ‑▲ S S S良ssss

STSSSSSVCMSSSSS

All isolates were resistant to PCG, MPIPC, ABPC, CEZ, CTM, FMOX, IPM, LVFX, EM.
PCG: benzyl‑penicillin, MPIPC: oxacillin, ABPC: ampicillin, CEZ: cefazolin, CTM: cefotiam, FMOX:nomoxef, IPM: imlpenem/cilastatin, LVFX: levonoxacin, EM: erythromycin, CLDM: clindamycln,
FOM: fosfomycin, GM: gentamicin, ABK: arbekacin, MINO: minocycline, ST: streptomycin, VCM:vancomycin, R: resistant, S: susceptible, I: intermediate.

158

Jpn. J. Infect. Dis., 54, 2001
Table 2･ Phenotypic and genotypic characterization of S. aweus isolatesPatien t(P)/Infection/

Isolate No.

PFGE AntibioticTS S
p"e慧anlel(M) Specimen colonization patte‑ ;LaL;;tVXL▲ー′0 7 0 ノ 0 1 2 つJ 4 5 /LU 7 0 ノO O 0 O nXUnXU 8 0 0 0 0 0 0

7 7 8 交じ RUO O0 0O 8 cnrp. nr nr D▲ nr nr nrp.

blood

1 2 つJ 4 5 6 7 0 ノ l▲ 1I

Infection

BCB即B

1舶J HmEe∫l 〟∫Iーl氾1J

sputum ColonizationtL1

C 0agu aSeIEnterotoxin
一 + 一 + 一一

H H mH H H

C u k u･‑一u u u t u

sputum In fee ti on

sputum Colonizatioll

sputum Colonization
sputum Colonization

一口U a B 良 B B a B

sputum Colonization
sputum Colonization
sputum Colon ization
0 1 2 つJ 4

sputum Colonization

I I I I

sputum ColoIlization
nasal cavlty Colonization
nasal cavlty Colonization
sputum Colonization

nasal cavity Colonization

J. Infect. Dis., 54, 91‑93.
2･ Gamer, J･ S. (1996): Guideline for isolation precauti.ons
in hospitals. The Hospital Infection Control PractlCeS
Advisory Committee. Infect. Control. Hosp. Epidemio1.,

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(200 1 ) : Molecular epidemiology of methicillin‑resistant
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