Irene R. Billones, Raff Metho R. Palma, Anne Jinky B. Villacastin (February 2006)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
Urban population growth has stimulated a rise in the number of street food vendors in many cities throughout the world; demand for relatively inexpensive, ready-to-eat food has increased as people have less time to prepare meals. Thus, food safety has become an ever-present concern, and microbial contamination in food has been given attention.
This study aims to establish the presence of four of the most common bacterial food borne pathogens –Salmonella spp., Shigella spp., Escherichia coli, Staphylococus aureus – in selected food samples from stalls within the vicinity of three chosen elementary schools in Iloilo City.
Available food sauces, fruits and juices sold in the schools were gathered for a pure culture of bacteria present. After two days of incubation in 37°C, colonies from the pure cultures were isolated and again incubated for two days. Colonial morphology of isolates were observed. The IMViC (Indole, Methyl Red, Voges Proskauer, Citrate Utilization) Biochemical tests were used in identifying the isolates. These biochemical tests are used to differentiate genus of the family Enterobacteriaceae by detecting differences in their metabolism. The morphological and tested characteristics of isolates taken from food samples were then determined and checked against known characteristics of the four pathogens being tested.
The study shows that Escherichia coli has the most number of colonies in all the food samples, followed by Shigella then by Staphylococus aureus. No colony with the properties of Salmonella bacteria was identified in any food sample tested.