1270

Drug-Resistant

Staphylococcus aureus Contamination in the Ward Environment

Yoshinori TANAKA,Akiko ADACHIand Atsushi ASHIMOTO Department ofBacteriology, FacultyofMedicine, TottoriUniversity Hideaki KISHIMOTO, Ryota TESHIMA and Kichizo YAMAMOTO Department ofOrthopedic Surgery,FacultyofMedicine, TottoriUniversity (Received: May24,1992) (Accepted: June28,1992) Key words:

Staphylococcus tamination,

aureus,

methicillin-resistance

coagulase-negative

, environmental

con-

Staphylococcus

Abstract A total April of

of 282

1991

strains

to January

S. epidermidis

and

(30%),

thirty-six

methicillin,

the

this

routine

of S.

aureus

(23%)

(48%)

DMPPC-resistant

testing

of

strains with

of

S.

Hospital . The

strains 65

of

of

were

anterior

environment

isolates

(20%)

nares

of the

from 84

One

were

strains hundred

methicillin

drug-resistant

erythromycin, than two

less

were

(21%).

S . aureus

multiple

, tetracycline, resistant to

of the

ward

main

S. haemolyticus

strains

aureus

were

testing

University performed

58

13

cephametazole

, along

transmission

from were

, and

and

strains

cephaloridine,

DMPPC-susceptible

nosocomial

isolated tests

staphylococci

ampicillin.

while that

to prevent

all

were

drug-susceptibility

strains

of The

antibiotics;

indicate

and

65

strains

(DMPPC)-resistant. seven

of Staphylococcus 1992

to

three

gentamicin, drugs

medical

. These

staff,

to and

results

is necessary

. Introduction

In

the

peared

in

with

1970s,

methicillin

hospitals

and

this

DMPPC-resistant In

and

April

1991,

resistant

increasingly

been

S. aureus

postsurgery

and

ward

of

bacteria

Staphylococcus,

, coagulase-positive

has

a new

environmental

(DMPPC)-resistant

to

in

the

the

Tottori

monitor

recognized in

Bacteria

were and

kept collected. on The

glass

to be tested open

for

the

was We

floor

plates

also

of

the

were

gram-staining.

Seiyaku

and Co.,

別 刷 請 求先:(〒683)米

the

Ltd.,

from

corner

bacteria These

incubated

Staphylococcus

of nosocomial

hosts

is

was

opened

contamination

well

infection

recognized1 , and

we

, especially

ap-

. Infection

,2,3). collected

that

due

air-borne to

DMPPC-

ward.

collected ward.

Hospital

Staphylococcus

collected at

for

Several

oxidation-fermentation (Nissui

were

placed

and -negative a cause

compromised

University

Materials

cover

as

and the

of

swabs 24 hr

colonies

University

the

from

put

at 37°C were

Hospital

corridor

sterilized

were

Methods

in swabs

straight

tested

were and

catalase

tests.

Species

of Staphylococcus

Tokyo),

with

which

staphylococci

ward

ward that

on

. Bacteria thus

the

for were

to the then

hour

rubbed

nutrient

were be

agar and

on

identified separated

were

with

of objects

田中

,

.

the

colony

further

to a slide selected

by

test•ESP

-18

with

the

ID

into

21

species

and

子市 西 町86

鳥取 大 学 医学 部 細 菌 学教 室

the

bacteria

surfaces

plate

from cocci

plate

air-borne

the

agar

transferred

gram-positive

can

. A nutrient one

吉紀

感染症学雑誌

第66巻 第9号

2

Drug-resistant subspecies.

Staphylococcus

Staphylococcus

aureus

Antibiotic

zone

identified

(DMPPC)

disk,

susceptibility sizes

for

14mm;

pg

resistant,

18mm;

to gentamicin

(GM,

These October

testing

was

to

of•…23 for

48

to

30

resistant,

susceptible

to

19

species

and

by

at

disk

30•Ž

.

resistance

or

for

24

For

and

hr

subspecies4)

. The

.

methods5)

indicate

4

at

testing zone

37•Ž

with

the

diameters

. Antibiotic

30

of disk

pg

24mm

breakpoint

were:

susceptible

16mm;

into

1271

to be coagulase-positive

mm

hr

in the Ward

classified

performed

diameters

(CER,

be

confirmed

susceptibility

15mm;

disk),

finally

incubation

and

to cephaloridine 30

recognized

was

zone

after

resistance

resistant,

susceptible (CMZ,

now

susceptibility

methicillin indicate

is

Staphylococcus

pg

ampicillin

disk),

(AMPC

14mm;

17

mm;

erythromycin

, 30 jug

resistant

susceptible (EM,

,•†15mm; to

50 pg

disk),•…15mm; susceptible

tetracycline

disk),

resistant,

(TC,

15 mm;

mm;

to cephametazole

200

resistant

16

pg

disk),

17mm;

,•†16

mm;susceptible

, July

(3 months),

30 ,ug disk).

isolations

were

(6 months),

performed

1991,

and

in April

in January

(one

week

(9 months),

after

opening

the

new

ward)

species

were

and

1992.

Results In stains

total, were

January,

282

1992.

haemolyticus,

would

rate

only

increased that

mucous

membrane,

The

52%

isolation 2),

although

1991,

shows

number

of

56%

S.

S. aureus

epidermidis

were rate

for

of

isolated 1991,

and 102

species

14

strains

isolated;

strains

isolated

in July, were

if DMPPC-resistant of

were in July,

DMPPC-resistant

factors and

identified

in October

many

, 1991

strains

of

. Fifty-two

and S.

64 strains

in

epidermidis,

S.

88%

of

is 43%

shown

in

DMPPC-resistant, were S.

in

October the

transferred

haemolyticus,

Table 38%

rate

of

through the

2.

and

percent were

genus

flora

of

S . aureus

Staphylococcus the

of

DMPPC-

DMPPC-resistant

the

normal

Sixty-two

in January

human

. It is skin

and

DMPPC-resistant. S. aureus

relatively

in

few

Table

平 成4年9月20日

strains

found.

April, 20%

species 64

the

were for

in

Although be

Staphylococcus

S. aureus

isolated

notable

(Table

1

isolation

Staphylococcus resistant.

of

in April,

Table and

The

stains

separated

the

total

DMPPC-resistant

1

Isolation

isolates

for

each

strains

of Staphylococcus

term are

from

increased

being

isolated

the ward

gradually, at

present.

except

in April Coagulase-

1272

Yoshinori Table

2

Isolation

TANAKA

et al

of methicillin-resistant

strains

a) Number of methicillin-resistant strains/total number of strains b) CNS -1 is considered to be pathogenic for man ; this group contains S . epidermidis, S. capitis, S. saprophyticus, and S. xylosus.c ) CNS-2 is considered to be non -pathogenic for man ; this group contains S . warneri, S. haemolyticus, S. hominis, S. auricularis , S. cohnii, S. simulans, S. sciuri, S. caprae, S. equorum, and S. kloosi.

Table

3

Antibiotic

susceptibility

of 282 isolates

a) No . of strains tested was 52, 64, 102, and 64 in April (at the first week) , July (the third month), October, 1991 (the sixth month), and in January , 1992 (the 9th month), respectively.

negative Staphylococcus (CNS) species, such as S. epidermidis and S . xylosis, , S. captitis, S. saprophyticus, which are pathogenic for man (CNS-1), decreased in July, but there was a tendency to increase. The isolation

rate for DMPPC-resistant

strains

in all isolates in April was 37%, but that in the other terms was species of Staphylococcus(CNS-2), such as S. warneri

relatively low (all were 14%). Non-pathogenic haemolyticus,

S. hominis , S. auricularis,

, S.

S. cohnii,

S. simulans, S. sciuri, S. caprae, S. equorum and S. kloosi were isolated at the highest rate in July , and the isolation rate for DMPPC-resistant strains of CNS-2 was high (41%) in July. In total, ten strains of S . sciuri, S. caprae, S. equorum and S. kloosi, which are usually

found in soil, were isolated in July. It is considered that the ward was contaminated

as that time. of DMPPC-resistant and susceptible Staphylococcus against six other antibiotics, ABPC, CER, CMZ, TC, EM, and GM , was investigated (Fig. 1 and Table 3). Although most of the DMPPC-susceptible strains were also susceptible to other antibiotics or resistant to only one or two drugs , DMPPC-resistant strains were resistant to three to six antibiotics. There were two strains which showed The cross-resistance

resistance

to all the seven drugs.

The numbers of DMPPC-susceptible and - resistant strains of S. aureus , in Fig . 1. The DMPPC-resistant strains of S. aureus had a high frequency of cross-resistance to other drugs and the DMPPC-susceptible strains also had cross-resistance to other drugs. The DMPPC-resistant strains of CNS-1 had multiple drug resistance , on an average to four drugs, and the DMPPC-susceptible strains of CNS-1 were resistant to 0 to 3 drugs. It is notable that 88% of S . CNS-1 and CNS-2 are shown

感 染 症 学雑 誌

第66巻

第9号

Drug-resistant

Staphylococcus

1273

in the Ward

Fig. 1 Multiple drug resistance of S. aureus and coagulase-negative Staphylococcus (a) Cross-resistance of MRSA (upper) and MSSA (lower) to ABPC, CER. CMZ, TC, EM, and GM. (b) Cross-resistance of DMPPC-resistant (upper) and —susceptible (lower) CNS-1 to seven drugs. The CNS-1group contains S. epidermidis, S. capitis, and S. saprophyticus.(c) Cross-resistance of DMPPC-resistant (upper) and —susceptible (lower) CNS-2 to seven drugs. The CNS-2group contains S. warneri, S. haemolyticus, S. hominis, S. auricularis, S. cohnii, S. simulans, S. sciuri, S. caprae, S. equorum, and S. kloosi. (a)

(c)

(b)

haemolyticus, which constituted 50%of CNS-2, were resistant to DMPPC, and that the DMPPC-resistant strains of S. haemolyticus were resistant to 5 drugs on the average. The antibiotics susceptibility of 282 strains to 7 drugs is shown in Table 3. More than half of the isolates were resistant to ABPC in each term, and the average rate of resistance to ABPC was 57%.The average rate of resistance to DMPPC and EM was 48% and 38%,respectively. In contrast, the rates of resistance to TC (14%)and CER (18%)were relatively low. Discussion Staphylococcus Test• SP• 18 identify are

certified

Many the

in

37.8%

in

1980

in

were

tested

total

S.

which (MIC

S.

air

Manual

in

1989, in

a surgical

for

aureus

ward

and the from

methicillin-resistance. isolates,

and

classified

of

but

can

Systematic

that

these

1983 The

highly

species 21

identify

and

S. arlettae,

another

to

1988, frequency

methicilin-resistant

the

4 subspecies4). and

2

The

Nissui

subspecies.

S. equorum

62

and

also

strains

of isolation aureus

the

ID

It

cannot

S. kloosi,

which

medical

staff,

isolated of S.

patient, frequency

Hospital

were

airborne

from

that

University

214

S.

isolated

reported

strains study,

and

(MRSA)

Nakasone6) in

epidemic

In

and species

Bacteriology4).

specimens

wards.

19 into

S. aureus

Kusano clinical

into

Staphylococcus

DMPPC-resistant

from

samples

being

genus

caseolyticus,

described

isolated

to 63.2%

from

specimens

the

environment6,7,8'9'10,11,12).

S. aureus

and

and

have

as

separate

in Bergey's

studies hospital

MRSA

staff

recognized

can

S. saccharolyticus

not

and

is now

system

increased from

aureus,

the

isolated

in

of MRSA

(>12.5

pg/ml)

(H-MRSA;

of

steadily, noses

isolated

strains

strains

of isolation

the

from

of medical from

clinical

operating was

MIC

room,

55%-80%

in

>100ƒÊg/ml),

by 1987, accounting for about 60% of MRSA were not detected in 1983, had increased in frequency staff has been reported by several authors 8,9,10). The isolation of S. aureus from medical z12.5 ƒÊg/ml)7).

平成4年9月20日

1274

Yoshinori

TANAKA

et al

Another study has shown that mattresses and other environmental objects played an important part in MRSA infection11). Our results showed that the frequency of isolation of DMPPC-resistant staphylococci and MRSA in the total isolates of 282 strains was 48% and 20%, respectively. The frequency of isolation of MRSA was far lower than that reported by Takesue et al7). However, preventive measures against nosocomial infection should be taken as soon as possible , since consideration of these reports indicates that the frequency of isolation of MRSA will increase . The Staphylococcus antibiogram showed that multiple drug-resistance was observed against many antibiotics and that DMPPC-resistant Staphylococcus cross-resistance was more frequent than that of DMPPC-sensitive Staphylococcus . According to the reports of Dandalides et al.13)and Hamilton-Miller and Iliffe14), although community-acquired isolates are frequently susceptible to a wide variety of agents , strains isolated from hospitalized patients have been noted to be resistant to an increasing number of antibiotics. In a review of a large number of studies, including that of Archer et al .15>and others16), it was suggested that CNS, particularly S. epidermidis , may be a reservoir for antibiotic-resistant genes in the hospital environment. Furthermore, Chambers17> demonstrated that methicillin-resistance in CNS and therapeutic failure with beta-lactam antibiotics in vivo were associated with the production of an altered pencillin binding protein (PBP), identical to PBP 2a (PBP2') found in MRSA . With this in mind, it can be seen that periodic trials should be carried out to isolate DMPPC-resistant staphylococci from the hospital environment and from the anterior nares of medical staff , since once MRSA has become endemic, extraordinary efforts may be required to halt nosocomial transmission . References

1) Karchmer, A.W., Archer, G.L. & Dismukes, W .E.: Staphylococcus epidermidis causing prosthetic valve endocarditis: microbiologic and clinical observation as guides to therapy . Ann. Intern. Med. 98: 447-455, 1983. 2) Sorrell, T.C., Packham, D.R., Shanker , S., Foldes, M. and Munroe, R.: Vancomycin therapy for methicillin-resistant Stahylococcus aureus. Ann. Intern . Med. 97: 344-350, 1982. 3) Watanakunakorn, C.: Treatment of infections due to methicillin-resistant Staphylococcus aures . Ann. Intern. Med. 97: 376-378, 1982.

4) Schleifer, K.H. & Kloos, W. E.: Staphylococcus. Mair, N.S., Sharpe, M. E. and Holt, J.G. ed.) p.

In Bergey's

Manual

of Systematic

Bacteriology. (Sneath, P. H.A.,

1013-1035, Williams & Wilkins, Baltimore, 1986. 5) Barry, A. L. & Thornsberry, C.: Susceptibility tests: Diffusion test procedures. In Manual of Clinical Microbiology . (Balows, A., Hausler, W. J. Jr., Herrmann, K.L., Isenberg, H. D. and Shadomy, HJ. ed.) p.1117-1125, American Society for Microbiology, Washington, D.C., 1991 . 6) Kusano, N. & Nakasone, I.: Nosocomial infection with methicilline-resistant Staphylococcus aureus. Japn. J. Clin. Pathol. (Rinsho Byori) 38: 990-997, 1990. (in Japanese with English abstract)

7) Takesue, Y., Yokoyama, Tsumura, operating

T., Kodama, T., Fujimoto, M., Okita , M., Sewake, H., Murakami,

H.: Methicillin-resistant room.

Staphylococcus

aureus

Hiroshima J. Med. Sci. 38: 183-186,1989

in nosocomial

infections

in the

Y., Imamura, surgical

Y. &

ward

and

.

8) Ashiq, B.: The carrier state: methicillin-resistant Staphylococcusaureus . A hospital study "screening of hospital personel" for nasal carriage of Staphylococcusaureus. J. Pak. Med. Assoc 39: 35-38 . 1989.

9) Cookson, B., Peters, B., Webster, M., Phillips, I., Rahman , M. & Noble, W.: Staff carriage of epidemic methicillineresistant Staphylococcus aureus. J. Clin. Microbiol. 27: 1471-1476, 1989. 10) Aoki, Y. & Kashiwagi, H.: Significance of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) by medical staff in nosocomial infection. J. Japn. Assoc. Infect. Dis. 64: 549-556, 1990. (in Japanese with English abstract) 11) Ndawula, E.M. & Brown , L.: Mattresses as reservoirs epidemic methicillin-resistant Staphylococcus aureus . Lancet33 7: 488, 1991. 12) Yomoda, S., Takahashi, A., Tsunoda, S., Kobayashi , I., Ohkubo, T. & Inoue, M.: Isolation of methicillin-resistant

Staphylococcusaureus (MRSA)at Gunma University

Hospital.

Chemotherapy

39: 813-821,1991.

English abstract) 感 染 症 学 雑誌

(in Japanese with 第66巻

第9号

Drug-resistant

Staphylococcus

in the Ward

1275

13) Dandalides, P.C., Rutala, W.A., Thomann , C.A. & Sarubbi, F.A.: Serious postoperative infections caused by coagulase-negative

staphylococci:

an epidemiological and clinical study. J. Hosp. Infect. 8: 233-241,

14) Hamilton-Miller,J.M.T. & Iliffe, A.: Antimicrobial 19:217-226,

resistance

in coagulase-negative

1986. staphylococci. J. Med. Microbiol.

1985.

15) Archer, G.L., Dietrick, D.R. & Johnson, J.L.: Molecular epidemiology of trans missible gentamicin resistance coagulase-negative staphylococci in a cardiac surgery unit. J. Infect. Dis. 151: 243-251, 1985. 16) Pfaller, M.A. & Herwaldt, L.A.: Laboratory , clinical, and epidemiological aspectes of coagulase-negative lococci. Clin. Microbiol.

Rev. 1: 281-299,

among staphy-

1988 .

17) Chambers, H.F.: Coagulase-negative staphylococci resistant to /3-lactam antibiotics binding protein 2a. Antimicrob. Agents Chemother. 31: 1919-1924 , 1987.

病 棟 に お け るStaphylococcus

aureusの

in vivo produce penicillin-

汚染

鳥取大学医学部細菌学教室 田中

吉 紀,足 立

昭 子,足

本

敦

鳥取大学医学部整形外科学教室 岸本

要 1991年4月

英 彰,豊

受 付)

(平成4年6月28日

受理)

汚染 状 況 の

推 移 を 調 べ た.1991年4月,7月,10月,1992年

し,計282株 S.epidermidis (23%),

84株(30%),

Skaemo砂ticus58株(21%)で

メ チ シ リ ン(DMPPC)耐

平成4年9月20日

得 た.主 S.

ら れ た.ま GMに て3剤

廊 下 お よ び 病 室 の 床 か ら菌 を 採 集 のStaphylococcusを

吉蔵

株(48%),65株

に 開 設 され た 鳥 取 大 学 医学 部 附 属 病

の4回

良 太,山 本

(平成4年4月24日

旨

院 新 病 棟 に お け るStaphylococcUSの

の1月

島

な菌 種 は

aureus65株 あ っ た.

性 株 は 全 菌 株282株

中136

DMPPC感

のSaum鋸 た,ABPC,

中13株(20%)に CER,

CMZ,

対 す る 感 受 性 を 調 べ る と,DMPPCを か ら7剤

Staphylococcusの

EM, 含 め

に 耐 性 で あ っ た の に 対 し て,

受 性 株 は 高 々2剤

す ぎ な か っ た.こ

TC,

み

に 耐 性 で あ った に

れ ら の こ と か ら環 境 中 か らの 検 索 は,医

療 ス タ ッ フの 鼻 前 庭

か ら の 検 索 と と も にStaphylococcusに 感 染 の 防 止 に 有 益 で あ る と 考 え ら れ る.

よ る院 内