PHENOTYPIC IDENTIFICATION OF AMPC BETA-LACTAMASE PRODUCING GRAM NEGATIVE RODS AND THEIR ANTIBIOTIC SUSCEPTIBILITY PATTERN AMONG CLINICAL SAMPLES OF INTENSIVE CARE UNIT PATIENTS

Abstract

Objective: To determine the frequency of AmpC β-lactamase producing GNRs and their antibiotic susceptibility pattern, isolated from clinical samples of Intensive Care Unit (ICU) patients from a tertiary care hospital of Rawalpindi.

Material & Methods: The current study was conducted in Department of Microbiology, AFIP; Rawalpindi from April to October 2018. Gram Negative Rods (GNRs) were isolated and identified by standard microbiological methods (Colony Morphology, Gram’s stain, Catalase Test, Oxidase Test, Motility Test and API 20 E). Screening of isolates for AmpC β-lactamases was done by cefoxitin disc (30 µg). The double disc synergy test was duplicated with ceftazidime disc (30 µg) and cefotaxime disc (30 µg) using cloxacillin disc (250 µg) as an inhibitor.

Results: Out of 196 total isolates, 100 (51.02 %) were screened positive AmpC producers then out of screened positive AmpC producing isolates 21 isolates were confirmed as AmpC producers (10.7 %). Among AmpC producers 100% resistance was observed for ampillicin and co-amoxiclave, 40 % for ceftriaxone and imipenim, 15 % cefepime, 20 % doxycycline, 30 % ciprofloxacin, 40 % amikacin and gentamicin, 20 % tazobactam-pipracillin and 50 % for co- trimoxazole. However, no resistance was seen with meropenem.

Conclusion: The present study highlights low burden of AmpC β Lactimase producing GNRs in our setup.  Double Disc Synergy test is suggested to be used for detection in areas with high AmpC burden, as Cefoxitin disc screening alone is not reliable method.

Key Words: AmpC β-lactamase, GNR, Antibiotic susceptibility.