Microbiol. Immunol. Vol. 36 (11), 1195-1200, 1992

The

Patterns

and

among

Transmissibility

Clinical

Strains

of Antibiotic

of Pseudomonas

Resistance

aeruginosa

Eleanor S. PALILLO, and Mohd Azib SALLEH* Department of Genetics,Faculty of Life Sciences, National Universityof Malaysia, 43600 Bangi, Selangor, Malaysia (Accepted for publication, July 31, 1992)

Abstract Four hundred and ninety-eight predominantly pyocin-type 10 clinical strains of Pseudomonasaeruginosawere analyzed for resistance to carbenicillin, cefoperazone, cefotaxime, ceftazidime, gentamicin, amikacin and netilmicin. Based on NCCLS-recommended MIC breakpoints, 245 strains were found to be resistant, of which 41.6% were resistant to carbenicillin, 38% to gentamicin, 37.8% to netilmicin, 26.3% to cefoperazone, 17.9% to cefotaxime, 0.6% to amikacin and none to ceftazidime. Quadruple resistance to carbenicillin, cefoperazone, gentamicin and netilmicin was the most frequent pattern observed. Resistance to older antibiotics (kanamycin, streptomycin and tetracycline) and to mercuric chloride were also common. Conjugation experiments suggested that self-transmissible and non-transmissible plasmids occurred in at least 66 strains.

P.

aeruginosa

infections of

carbenicillin-

of

antibiotic

of

continuous

of

resistance

to

strains

determining

the

by

Research, (7).

of

Dr.

Kuala Minimal technique

Y.

M.

Lumpur) inhibitory on

Lumpur

Yong,

and by

inhibition

trypticase

concentrations Mueller-Hinton

newer

early

the

present

Such

agar

(MHA,

the

eight

was

be in

to

useful

Malaysia.

morphological was

carried

strains

Medical

by via

supplemented

out (kindly

of

described

determined Oxoid)

aim

Institute as

of

various

cefotaxime,

of

Malaysian

were

from

main

indicator

(Difco)

the

isolates

would

basis

subject

study,

organism

Pyocin-typing of

incidence

incidence

1986

data

this

fatal

the

Malaysian

The

(MICs)

11 9 5

In

especially

Division,

agar

growing

Hospital.

on

the

the

during

among

often appearance

been

antibiotics

growth

soy

(9),

on

isolated

(11).

on

and the

has

among

identified

Phillips

70s

bacterium

netilmicin. resistance

Bacteriology on

Since

focused

General

and

isolated

of

5)

were

to

antibiotic

described

patterns

4,

strains

amikacin

as

severe

(2). the

this

resistance

resistance

on

causes

aminoglycosides.

The

were

traits

(1,

and

in

of

antibiotic

Kuala

studies

biochemical

dilution

the

incidence

strains

studies

of

cefoperazone,

Bacterial

strains

investigated.

epidemiological

provided

Recent

at

the

which patients

clinical

newer ƒÀ-lactams

specimens

ceftazidime,

by

among

transmissibility were

determine

pathogen

immunocompromised

gentamicin-resistant

interest.

aeruginosa

and

opportunistic in

and

and

clinical

for

an

resistance

patterns P.

is

particularly

Govan the

agar with

11 9 6

E.S. PALILLO

two-fold

dilutions

being

1,024

gated

on

each

of

and blood

agar

enriched

with

60;

12;

netilmicin

200. Vogel supplemented

was

added.

Lab.,

Chemicals,

square

for

size

cells

at

NB,

(Km),

mercuric

in for

Inc

Diagnostics

obtained

(ƒÊg/ml)

:-

(Hg),

tetracycline

experiments which 2 ƒÊg/m1

obtained

from

Bristol

U.S.A.

(Cp),

Hoest-

.,

using

was

chloride

, U.K. other

(all

2),

BAB

cefotaxime

150;

conjugation Hg for

were

Pfizer

U.S.A.

were

No.

120;

(Sm),

agents

Sigma,

Oxoid

(Cp),

used except

propa-

purposes

concentrations

350;

(Nm),

were

(NB,

streptomycin

Glaxo

and

by

C for

(ceftazidime, antibiotics)

the

2 hr.

leu-8, as

filter

Cz), .

statistical

Chi-

software

discs

selective

chl-3,

riflin

the

plates.

(13)]

the

of

,

cells

BAB

were

,

plates,

resuspended of P . aeruginosa

PA09505 and

and

(Millipore

on

Sub-lines

and

initial

donor

filters

(placed

incubation,

on

recipients

volumes

membrane

paper

Following plated

equal

cellulose

the

and

used

filtering

through

incubating

[pur-136,

(12)]-were

(CO,

broth selective

following

limits

strains

cefoperazone

150;

performed

diluted

PAO—PA09501 rif-4

37

serially

the

250;

U.S.A.

cultures

and

uppermost) fresh

phase

0.45 ƒÊm)

nutrient

antibacterial

analysis

were

log

at

concentration

U.S.A.).

matings late

pore

in

statistical Inc.,

Bacterial recipient

of

(Hg)

lower bacterial

For

(Rp),

U.S.A.

(Minitab

in

kanamycin

Corp.,

Australia

values

Minitab

and

minimal medium same concentrations

Schering

Pharmaceuticals,

Ajax

30;

powders

(Ak),

or

(Cb),

rifampicin

& Bonner with the

Standard

U.S.A.

Roussel

30;

upper

Otherwise,

agents

(Gm),

(Nm),

SALLEH

extract(Oxoid).

carbenicillin

gentamicin

; the

Oxoid)

yeast

antibacterial 60;

(Tc), was

(BAB,

0.5%

(AK),

(Ct),

antibiotics respectively.

base

with

supplemented amikacin

various

0.5 ƒÊg/ml,

AND M.A.

[argB18

, chl-2, experiments

retransfer

,

respectively. A from

total

of

pus,

55

samples.

The found

into

of

be

for

73.52

245

(49.1

%)

biotics.

Figure

The Gm

five

was

was

498

to

three

patterns and

not

the

of

breakpoints

were distribution

Cp

(26.3%),

Ct

of

and

one

antibiotics, were (13.5%).

as

Cp,

6.96 ƒÊg/m1;

resistant

Cz Ct

and

by

antibiotics sensitive

CbrCprGMrNMr Simultaneous

to

all Am

to

followed

(12.7%)

by

strains of

resistance

being

values

follows:

resistant

(41.6%

(17.9%)

strains),

MIC50

only (34

,

one for

each

resistance

, the

more

to

was two

. by the the

(17

.6%),

A

single

three

most

CbrCprCtrGmrNmr to

Gm

and

,

anti-

antibiotic

antibiotics

,

effi-

pg/m1;

, followed None of

, respectively. to Cz . The .7%)

were

1.52

or

(0.6%).

resistance

,

could

, 12.13 ƒÊg/ml; NCCLS (10)

strains)

four

, 54 . isolated

strains

recommended

Cb

Simultaneous

of

group

strains

untypable

the

are

as

were blood

predominant

were

terms

419 (84.1%) (0 .8%) from

61

against

classified

for

resistance

CbrGmrNmr

4.29 ƒÊg/ml;

most

strains Ak

lowest

which and 4

remaining

In

MIC

of resistant

six

to

the

the

and

shown).

highest

Cz.

was

seven

Nm

, of

sputum

Of

was

(15.5%) to

10

Nm,

the

(36.7%

resistant

Gm,

strains

(37.8%),

resistant

(17.1%),

common (16.7%)

Nm

predominant

strain

on

frequency

(38%),

most

the

type

while

Cz,

3.03 ƒÊg/ml;

isolated

from

strains.

highest

1 summarizes

resistance

strains

Ct,

ranked

of

(4%)

groups

Cp,

Based

out

the

(data

Gm,

jig/mi.

were

20 that

of

different

Cb,

antibiotics

2.83 ƒÊg/m1;

Cb,

aeruginosa

revealed

heterogeneous

the

P. urine,

(87.8%) 24

MICs

to

cacy

437

of

from

tests

for

classified

Ak,

strains %)

Pyocin

accounting be

498 (11.1

Nm

11 9 7

NOTES

Fig. 1. The frequencies of resistance of P. aeruginosa isolates to seven antibiotics. Resistance was determined on the basis of MI C breakpoints recommended by the NCCLS (10). MICs were determined by the agar dilution method.

occurred

in

strains,

187

utilize

the

two

analysis

resistance

significant pyocin has a

were

among

highly the

and

urine

from

tively,

with

findings

trations appear

9)

to Two

antibiotic

be

and

to

also

that tract

strains

sub-line

antibiotics, mercuric

to

the

high-level

conjugal

the

urine 1

P