COMPARISON OF DIFFERENT PHENOTYPIC METHODS FOR THE DETECTION OF EXTENDED SPECTRUM BETA LACTAMASES IN ESCHERICHIA COLI AND IN AMP C CO-PRODUCING PHENOTYPES THROUGH SINGLE PLATE DETECTION TECHNIQUE

Qanita Fahim, Fatima Hameed, Ayesha Khalid, Muhammad Saeed Anwar

Abstract


Objectives: The study was done to determine the prevalence of Extended spectrum beta lactamases (ESBL) in urinary isolates of Escherichia coli (E. coli) and to evaluate and compare different phenotypic methods for its detection through single plate detection technique, even in AmpC co-producing ESBL phenotypes of E.coli.

Study design: Cross sectional comparative.

Place and duration of study: The study was done in the Department of Microbiology, Combined Military Hospital, Lahore, Pakistan from January 2016 to June 2016.

Materials & Methods: Out of 945 samples for urine culture, received from various units of CMH Lahore, 70 specimens yielded growth of E. coli. In single plate screening technique, E.coli isolates were tested by Double disk synergy test (DDST) and Modified double disk synergy test (MDDST) using Cefepime (FEP) & Piperacillin-tazobactam (TZP) on a single plate for the detection of ESBL to save time and money. Phenotypic confirmatory disk diffusion method (PCDDT) was taken as “Gold Standard”.

Results: From 70 E coli isolates, 34 were positive for ESBL production. DDST detected ESBL in 12/34 isolates. MDDST detected ESBL in 33/34 isolates including 14 isolates that were co-producers. Therefore, MDDST proved to be very effective in detecting ESBL in AmpC co-producing E.coli.

Conclusion: The prevalence of ESBL producing E coli in our hospital was 48.75%. Single plate screening technique seems to be convenient and time saving (within 24 hrs) and increases the probability of detecting ESBL through different methods even in Amp C co-producing E.coli.

Key words: ESBL, Amp C, DDST, MDDST.


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