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

Laboratory and Epidemiology Communications

An Electronic System Combining MIC2000TM and Antibiogram ClusterAnalysis f♭r SuⅣeillance of Methicillin‑Resistant

Staphylococcus aureus in Hospitals
Junichi Yoshida*, Toshiyuki Ishimaru, Shoji Kawano and Motoichi Akao
Infection Control Committee, Shimonoseki CiO, Hospital,
Koyo‑cho 1‑13‑1, Shimonoseki 750‑8520, Japan
Communicated by Hiroshi Yoshikura(Accepted May 10, 2000)

Pulsed‑field gel electrophoresis (PFGE) is the method ofchoice for typing Staphylococcus aureus (1). However itwards, and specimens･ For computation, the default settings ofrequlreS a PrOCeSSlng time of more than several days, trained

SPSSTM was used, except for the output, as a dendrogram･ Anyisolates for which the HRescaled Distance Cluster Combinen

specialists, special equipment, and reagents such as restriction(see the scaleinFigure) was 2 0r less were considered to form

enzymes (2)･ We previously reported that cluster analysis

a cluster group･ The computing time to obtain dendrograms

based on antibiotic susceptibilities gave resu)ts that agreed

was 2‑3 min.

with PFGE in 79% ofall cases (3). Tb expedite data process‑ing of methicillin‑resistant Staphylococcus aweus (MRSA),

Figure, exceptlng Six, all of the isolates were grouped into

We obtained 76 isolates from 48 patients.Asshown in

we here introduce an electronic system that combines

MIC2000TM (Nagase Enterprise, Tokyo) and c)uster analysis.

the five groups A‑E: A consisted of 27 isolates, B of 10isolates, C or 18 isolates, D or 10 isolates, and E or5 isolates.

MIC2000TM provides electronic data onminimum inhibitory

The excepted six isolates, 5, 74, 1 1, 9, 42 and 71, respectivelyconcentration (MIC) in a tabulated form, such as in the filederived kom patients 03, 46, 08, 07, 26and 43, did not belong

type of a comma separated value (.csv), which are used

to any of the above groups. Some patients harbored MRSAs

directly for computerized analyses.

from different groups; for example, patient 12 had group A

MRSA isolates, obtained from October to December 1999,
were used for the analysis. The MIC values ( LL g/ml) for 17(isolates 17 and 18) and group C (isolate 16) in different sites,and patient 4 1 had group A (isolates 68, 66, and 69) and groupdrugs (see Table for the drugs used) were converted into log2

B (isolate 65) in the same infection site.

scale; ifMIC exceeded 2n but the inhibitory effect at a higher
concentration was not detemined, the converted value wasIsolates from the same ward demonstrated a tendency toprovisionally set to n+1. The transfbrmlng program Can be
downloaded from the web site (http://www.yoshidaj.com).

belong to the same group; for example, isolates from Ward
4E were from groups A and C, isolates from Ward 3E werefrom groups A and B, isolates from Ward PED were from

The transformed data were directly processed by the statisticalgroup E, etc･ Isolates obtained on the day of admission fromsoftware SPSSTM version 10.0 (SPSS Inc., Chicago, Ill., USA)four pediatric (Ward PED) patients 19, 23, 25, and 44, whofor hierarchical cluster analysts On the operatlng Systemwere referred from three different practitioners, were all in

WindowsTM (Microsoft Corp" Redmond, Wash., USA). The

group E･ This finding may suggest the extramuralspread of

one MRSA strain.

variables were log2 tranSfbmed data orMIC f♭r 1 7 dmgs andthe labels were code numbers corresponding to the patients,

Table･ MIC ( jig/ml) and susceptibilityof representative strains from MIC2000TM
MpIPC
FM0X

AaPC

CTM

CEZ

CLDM

CFDN

CMz

IPM

S‑A

MIN0

LVFX

CAM

AaK

VCM

F0M

GMG NunABCDE

上U 5 1 1 tJ 0 つJ ′LU 5 tJ>>>>>44444

R氏R良R>>>>>44444

R礼氏良R> > > > tJ tJ つJ つJ 2 2 2 2 2

R良氏R氏> > > > つJ つJ つJ つJ 2 2 2 2 2R氏良RR

つJ つJ tJ つJ

22220 R氏RRR

つJ つJ つJ 12 2 2 /ら.〇〇

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氏良R氏良′b ′b 5 5 5R氏礼氏礼> > > >44444

R良RRR

12211 2 4 4 2 2

R氏良氏氏

刈7亡 < <｢ 二.≡.

1 こ.

<良良SSSl1555

くくくSSSSS>>>>>O O (XU O O

氏良氏氏氏>>>>>44444

RR氏良R

1 1 こ こ. 6 6一つ 4 5

良RSSS

く く く < < 二 二 二 二 二 11111

SSSSS‑.=判別朋瑚瑚V瑚V R 良 S 氏 St｢ 二.≡.
くくくこG, cluster grouping (see Figure); Num･. number of strains (see Figure); MPIPC, oxacillin; ABPC, ampicillin; CEZ, cefazolin; CTM, cefotiam; CMZ,cehetazole; FMOX, numoxef; IPM, imlPenam; CFDN, cefdinir; S/A, sulbactam andampicillin; GM, gentamycin; ABM, arbekacin; CAM, clarithromycln;
CLDM, clindamycin; MINO, minocycline; VCM, VanComycin; FOM, fosfomycln; LVFX, levonoxacin; R, resistant; I, intermediate; S, sensitive.

*Co汀eSpOnding author: Fax: +8ト832‑24‑3838, E‑mail: infb@yoshidaj. com79

Jpn. J. Infect. Dis., 53, 2000Hierarchical Cluster AnalysLS
Dendrogram using Average Linkage (Between Groups)
Rescaled Distance Cluster Combine
C A S EONum1 ･<l l BbE)8 OC CD uJlUヒL

40321 4 23014 2301 3142 01 24 1796852 10836542ー70一34895126ー0Y34345‑6▲｢453 64 ▲｢635 465 46‑3 P6hr

UJEL.CWEt.Ju EJuLAEWuJ L.JWEu L,JWuE Ju ELJu WEuJL,E.JuECU仙cuECU DE印w DE D印

510152025+I一l‑‑‑‑‑‑+一一‑I‑I‑‑+一一一一一‑一一一+一一‑一一一一一‑+‑‑I‑‑‑‑‑‑+671542 6345 127536 132465 27146 2 347 85296437 126547893062451 3809 217.

‖)UFigure･ Computer output of the cluster analysis superimposed withcluster grouping (G) and patient codes (Pt) in the left
columns･ W, ward from which MRSA strains were Isolated; ICU, intensive careumit; FED, pediatric ward; Num, number ofisolates.

80

Jpn. J. Infect. Dis., 53, 2000
The content of this communication was presented at theTyping of Staphylococcus aureus colonlSlng human nasal

74th Congress of Japanese Societyof Infectious Diseases at

1. Ichiyama, S., Ohta, M., Shimokata, K., Kato, N. andcarriers by pulsed‑field gel electrophoresis. J. Med.
Microbio1., 42, 127‑132.
3. Yoshida, J., Umeda, A., Ikeda, S., Matsuo, K., Ishimaru,
T. and Akao, M. (1999): MRSA fingerprinting amenable
at communityhospitals with cluster analysis on suscepti‑
bilityas evidenced by molecular epidemiology. Nippon‑Takeuchi, J. (1991): Genomic DNA fingerprinting byGeka‑Gakkai‑Zasshi (∫. Jpn. Surg. Soc.), 100, 624 (inpulsed‑field gel electrophoresis as an epidemiOloglCalmarker for study of nosocomial infections caused by

4. Yoshida, J., Nagata, T., Nishioka, Y., Nose, Y. and Tanaka,methicillin‑resistant Staphylococcus aureus. J. Clin.

M. ( 1 996): Outbreak of multi‑drug resistant Staphylo‑Fukuoka, in April or 2000.

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