English abstract
Background: extended spectrum β-lactamase (ESBL) producing
gram negative bacilli are becoming a growing problem worldwide
with difficulties in designing a national formulary for empirical
treatment of gram negative sepsis.
Objectives: In this study, we investigated the in vitro activity of
Carbapenems, Pipracillin-Tazobactam, Ciprofloxacin alone or
in combination with aminoglycosides against ESBL-producing
strains isolated from clinical samples.
Methods: Three hundred and one ESBL-producing Escherichia
coli and K. pneumoniae strains isolated from clinical samples were
investigated. Isolates were screened initially for ESBL production
using an automated system. All ESBL isolates were further
confirmed using the double-disk diffusion method.
Results: The overall Piperacillin-Tazobactam susceptibility was
57.9 (64.4% E. coli and 43.6% Klebsiella pneumoniae). Only 29.6
% of ESBLs (24.9% E. coli and 39.6% Klebsiella pneumoniae) were
ciprofloxacin susceptible. 98.1% E. coli and 93.1% of Klebsiella
pneumoniae were susceptible to Piperacillin-Tazobactam plus
Amikacin combination. 73.7% E. coli and 61.4% of Klebsiella
pneumoniae were susceptible to Piperacillin-Tazobactam plus
Gentamicin combination. 96.7% E. coli and 91.1% of Klebsiella
pneumoniae were susceptible to Ciprofloxacin plus Amikacin
combination. 41.2% E. coli and 51.5% of Klebsiella pneumoniae
were susceptible to Ciprofloxacin plus Gentamicin combination.
Conclusion: ESBLs have high resistance profile against
Piperacillin/Tazobactam and Ciprofloxacin. The ESBLs from
Oman have similar resistantce pattern as those reported from
UK and USA. This resistance decreases when these drugs
are combined with Amikacin. All ESBLs are susceptible to
Carbapenems. However, carbepenam overuse can lead to
emergence of carbapenems resistant gram negative bacilli and
ESBLs. Combination of Amikacin plus Piperacillin/Tazobactam
is a feasible empirical therapy for ESBLs.
