Microbiological analysis and safety evaluation of various canned foods in Addis Ababa

Abstract

The microbiological quality and safety of canned foods available to consumers on the market in Addis Ababa were evaluated and the fate of contaminating pathogens in the canned foods, when stored at ambient and refrigerator temperatures, was also assessed. A total of 100 samples of canned foods comprising 20 each of fish, meat, vegetables, milk and soups were collected from Addis Ababa super markets and grocer’s shops. The aerobic mesophilic bacteria were dominated by Bacillus spp., Micrococcus spp. and other Gram positive rods. Staphylococci were encountered in some fish and meat canned food products. Salmonella and Shigella spp. were not detected in any of the 100 samples. A total of 250 aerobic spore-forming bacilli were isolated from canned foods. B. cereus, B. firmus, and B. licheniformis were the most frequent isolates. Antibiotic susceptibility studies showed that over 88% of Bacillus isolates were sensitive to chloramphenicol, erythromycin, gentamycin and kanamycin. Most isolates exhibited resistance to amoxicillin and ampicillin. Multiple antibiotic resistance (resistance to two or more drugs) was seen in 139 (53%) isolates. The most widespread pattern was Amo, Amp, Cep, Met, PenG, Sxt, Tet. In a challenge study, both Shigella flexineri and Salmonella thyphimurium grew and multiplied luxuriously in canned meat, fish, vegetable and soup at refrigeration and ambient temperatures.

Keywords/phrases: Antimicrobial susceptibility, Bacillus spp., Canned foods, Microflora

Ethiop. J. Biol. Sci., 8(1): 53-69, 2009