Vol. 6, Issue 1 (2017)

Author(s):
Shah Md Wasif Faisal, Amer Khorshed Alam, Md Nilavrow Sajed and Nur-E-Hasnat

Abstract:
The aim of this study was to isolate and identify different kinds of gram negative bacteria from street vended sauce and brand sauce in the city of Dhaka to evaluate their safety margin. Nine different sauce samples were collected from different areas of Dhaka city. Four of those samples were brand sauce and five were street sauce. Four types of selective media were used to isolate gram negative bacteria: Mac-Conkey Agar (MAC), Thiosulfate-Citrate-Bile Salts-Sucrose Agar (TCBS agar), Salmonella- Shigella Agar (SS agar) and Eosin-Methylene Blue (EMB). Serial dilution of each sauce sample was performed then samples were cultured on selective media plates by spread plate technique and colony forming units were observed to determine whether their number was below or above the minimum infective dose to evaluate their safety margin. Biochemical tests were performed to identify the isolated colony forming units. Bacteria isolated in different selective media from all the brand sauce samples were far below the minimum infective dose for humans. Bacteria isolated from all Street Sauce samples in the MAC agar and EMB media were found to be more than minimum infective dose. Three of the five Street sauce samples displayed more colony forming units in the SS agar media than the minimum infective dose. In TCBS agar media two of the five Street sauce samples displayed colonies near the minimum infection dose and another one was above. Biochemical tests displayed presence of Escherichia coli, Salmonella typhi, Shigella dysenteriae, Vibrio cholera and Vibrio parahaemolyticus.