Detection of thermotolerant Escherichia coli in street-vended beverages around a university in the City of Manila

Abstract

Presence of thermotolerant Escherichia coli has been detected in different food sources including street foods indicating fecal contamination. Even though not all strains are pathogenic, E. coli has been known to acquire antibiotic resistance and has the capability to transfer it to other bacteria through horizontal gene transfer. This study was performed to assess the of street-vended beverages sold around a university in the city of Manila. A total of 20 street-vended beverage samples were acquired and these were subjected to the presumptive test (Lactose Broth), the confirmatory test (BGLB), and the completed test (EMBA) to test for the presence of coliforms. The positive samples from the presumptive and confirmatory tests were then incubated at 44.5 °C onto a single strength lactose broth for the isolation of thermotolerant E. coli. Presumptive MPN/ml of 0.28 to greater than 11 and 4.6 to greater than 11 were recorded for buko juice and buko pandan respectively. Gulaman, melon juice, chocolate drink, and halo-halo have MPN/ml values of greater than 11. Three out of seven of the buko juice samples, two out of three of the buko pandan samples, one melon juice sample, one out of three of the chocolate drink samples contained thermotolerant E. coli. No thermotolerant E. coli was isolated from both the gulaman and halo-halo. The possible presence of thermotolerant E. coli indicates fecal contamination in the sampled beverages. Incidentally, the isolates were subjected to antibiotic sensitivity testing using the Kirby-Bauer method. One of the thermotolerant isolates from the buko juice samples were found to be resistant to ceftriaxone and ciprofloxacin. Additionally, resistance to trimethoprim-sulfamethoxazole was also observed in another thermotolerant E. coli isolate from the buko juice and chocolate drink samples. One isolate from melon juice exhibited resistance to ciprofloxacin. Thus, a more-focused study on the antibiotic resistance profile from these beverages must be conducted to confirm the incidental data obtained.