PREVALENCE OF BACTERIAL CONTAMINATION IN MIXED VEGETABLE SALAD IN DHAKA CITY

Abstract

ABSTRACT The research work was undertaken with a view to isolate and identify bacteria from mixed vegetable salad sold within Dhaka city with special emphasis on E. coli, Salmonella. and Staphylococcus .The samples were analysed to isolate and identify the bacterial species by continual cultural, morphological, staining and biochemical tests, the microbial load such as Total viable count (TVC) & Total coliform count (TCC) and the prevalence of bacteria and antimicrobial-resistant pattern of isolates was investigated by the disc diffusion method. A total number of 120 mixed vegetable salad samples were collected from different restaurants, food corners and street vendors of different locations of Dhaka City. Escherichia coli showed metallic sheen on EMB agar and produced rose pink colonies on MacConkey agar, positive to Indole, MR and catalase test but negative to VP test. It was revealed as gram negative, small rod shaped, arranged in single or pair shaped under microscope. Salmonella spp. were identified by observing black smooth colony on SS agar and pinkish red smooth colony on BGA agar. They showed positive to MR, catalase test and negative to Indole and VP test and revealed gram negative, short rod shaped in gram staining. Staphylococcus species showed β haemolysis, fermented mannitol salt agar and produced yellowish colonies. The catalase, MR, VP and indole test was positive and these cocci arranged in grapes like clusters. The prevalence was 10%, 5% and 4.1% for E. coli, Salmonella and Staphylococcus respectively. The antimicrobial sensitivity test indicated that all bacterial species were resistant to Ampicillin, Amoxicillin, Cefixime and Tetracycline.