Characterization of escherichia coli from tilapia (Oreochromis niloticus) from wet markets in Metro Manila, Philippines for their resistance to carbapenems and extended spectrum β-lactams

Date of Publication

4-2017

Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Biology

Subject Categories

Biology

College

College of Science

Department/Unit

Biology

Thesis Adviser

Esperanza C. Cabrera

Abstract/Summary

Multiple drug resistant bacteria are now one of the serious health problems

worldwide, with carbapenem resistant Enterobacteriaceae and extended spectrum β- lactamase (ESBL)-producing Enterobacteriaceae being classified by the Centers for

Disease Control and Prevention under the categories of ―Serious Threats‖ and ―Urgent Threats‖ based on the three levels of concern, respectively. This study isolated Escherichia coli from 60 Oreochromis niloticus (tilapia) procured from Cartimar Market, Pasay City in January, 2016 and San Andres Market, Manila in September, 2016. The antimicrobial susceptibility patterns of the isolates were determined using the standard disc-agar diffusion method. The extended spectrum β-lactams antimicrobials tested were : ceftazidime, cefotaxime, ceftriaxone and aztreonam; and the carbapenems: meropenem, ertapenem and imipenem. Other antimicrobial agents tested were trimethoprim sulfamethoxazole, ciprofloxacin, tetracycline, gentamicin, chloramphenicol and ampicillin. Isolates found to be resistant to any of the cephalosporins and/or monobactam were further tested for the production of ESBL using the double disc synergy assay with clavulanate, while isolates resistant to any of the carbapenems are tested for the production of carbapenemase using the modified Hodge Test, and for production of metallo-β-lactamase using the double-disc synergy assay with EDTA. Of the 25 E. coli that were isolated, 24 (96%) showed resistance to at least one antimicrobial agent, with five (5) isolates (20%) being multiple drug resistant strains. The resistant strains were found to exhibit 20 different resistant phenotypes, suggesting that these are different strains, and are not clones of each other. Thirteen isolates tested resistant or intermediate to the extended spectrum β-lactams, wherein 11 isolates lost their resistance against cephalosporins and/or monobactam, suggesting the instability of the resistance genes in the host, a characteristic of plasmid-mediated ESBL production. The two ESBL suspects tested were confirmed to be positive for ESBL production. Noteworthy are the nearly half percent (48%) of isolates that were found to be resistant to carbapenems, with eight (8) of the 11 (73%) being positive for carbapenemase production. The sources of the E. coli in the study are the common tilapia that are popularly consumed by the general population. Studies have shown transmission of drug resistant bacteria from animals to man through the food chain. The result likewise is an alarming call to prohibit the use of antibiotics in aquaculture, as this selects for antimicrobial resistant microbial isolates in the animal flora and their surroundings to survive and be disseminated.

Abstract Format

html

Language

English

Format

Electronic

Accession Number

CDTU021772

Shelf Location

Archives, The Learning Commons, 12F, Henry Sy Sr. Hall

Keywords

Escherichia coli; Nile tilapia—Microbiology

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Embargo Period

5-26-2025

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