High incidence of Klebsiella pneumoniae clinical isolates to
extended-spectrum B-lactam drugs in intensive care units
Asem A. Shehabi
*, Azmi Mahafzah
, Izdiad Baadran
, Fouad A. Qadar
, Naheel Dajani
Department of Pathology-Microbiology, Faculty of Medicine, Jordan University Hospital, Amman, Jordan
Department of Surgery and Anaesthesia, Faculty of Medicine, Jordan University Hospital, Amman, Jordan
Received 15 June 1999; revised and accepted 15 September 1999.
A prospective study conducted among Jordanian ICU patients in 1997 using Etest identiﬁed resistance rates among isolates of E. coli
(25%–44%), Enterobacter spp. (54%–62%), and klebsiella spp. (30%–80%) to extended-spectrum B-lactams (ESBLs): ceftazidime,
cefotaxime, ceftriaxone, and aztreonam. All these isolates were susceptible to imipenem and showed low resistance rate to ciproﬂoxacin
(5%–19%) and amikacin (13%–18%). Higher and signiﬁcant resistance rates of Klebsiella isolates to ceftazidime (80%) and aztreonam
(65%) were observed in 1997 compared with a previous study performed in 1994. The majority of Klebsiella pneumoniae (70%) express
different ESBL phenotypes that were almost resistant to aztreonam and ceftazidime but susceptible or resistant to cefotaxime and/or
ceftriaxone. This prospective study strongly suggests that ESBL production of Klebsiella pneumoniae isolates have been highly dissemi-
nated among ICU patients during 1997. © 2000 Elsevier Science Inc. All rights reserved.
Many studies worldwide reported the emergence of ex-
tended-spectrum B-lactamases (ESBLs) among members of
the family Enterobacteriaceae, particularly Klebsiella spp.
and E. coli, in association with extensive use of expanded-
spectrum cephalosporins, nosocomial infection, and nursing
homes (Hanberger et al., 1999; Wiener et al., 1999; Shan-
non et al., 1998; Olivier et al., 1998; Dominique et al., 1997;
Moosdeen, 1997; Jacoby et al., 1996; Rice et al., 1996).
ESBL-producing bacteria confer resistance usually to cefta-
zidime, cefotaxime, ceftriaxone, and aztreonam. Also, this
resistance is mostly encoded by genes on plasmids that
easily can be transmissible among certain entericbacteria
species, and contribute to increased spread of antibiotic
resistance in hospitalized patients (Hyunjoo et al., 1999; Liu
et al., 1998; Livermore and Yuan, 1996).
In 1994, a prospective study on the prevalence of multi-
resistant gram-negative clinical isolates indicated that 25%–
43% of Klebsiella species, Enterobacter species, and E. coli
isolated from intensive care patients at the Jordan Univer-
sity Hospital were resistant to more than one extended
spectrum B-lactam drug (Shehabi et al., 1996).
A second prospective study was undertaken in 1997 to
detect resistance trends and to investigate the prevalence of
ESBL-producing of Klebsiella spp. and E. coli isolated from
ICU patients at the same hospital.
2. Patients and methods
All included Gram-negative bacteria isolates were con-
secutively recovered from clinical specimens of hospital-
ized patients admitted to three intensive care units (ICUs) in
the Jordan University Hospital (JUH) in Amman, over a
1-year period of 1994 and 1997. The clinical signiﬁcance of
these isolates associated with infection or colonization was
not investigated. All clinical isolates of Enterobacteriaceae
were identiﬁed at the species level with API 20E, and the
nonfermenting isolates identiﬁed by API 20NE (Bio-
Merieux Systems, France), or to genus level by a set of
standard biochemical tests, including triple sugar iron
slants, citrate, urease, indole, motility, H
s, oxidase, and
Antimicrobial susceptibility testing was ﬁrst performed
for all isolates by a disk diffusion method on Mueller-
* Corresponding author. Tel.: ϩ962-6-535-5000; fax: ϩ962-6-593-2744.
E-mail address: Toxico@ju.edu.jo (A.A. Shehabi)
Diagnostic Microbiology and Infectious Disease 36 (2000) 53–56
0732-8893/00/$ – see front matter © 2000 Elsevier Science Inc. All rights reserved.