Cockroach-Associated Food-Borne Bacterial Pathogens from Some Hospitals and Food Handling Establishment in Addis Ababa

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Addis Ababa University


A study was carried out to determine the role of cockroaches as reservoirs and vectors of food-borne bacterial pathogens in some hospitals and food handling establishments in Addis Ababa. A total of 1600 adult cockroaches were captured aseptically from eight study sites between December 2002 and June 2003, and all were identified as Blattella germanica. Ten cockroaches were pulled as one sample from each of the eight study areas and killed with chloroform. Using selective media, their external surface wash and internal (gut) homogenates, after adequate decontamination of the extemal surface, were culturally examined for the presence of Salmonella, Shigella, Escherichia coli 0157:H7, Staphylococcus aureus and Bacillus cereus. We have also initiated challenge studies to evaluate survival and excretion of Salmonella B, Shigella B, and Staphylococcus aureus in B. germanica following ingestion of 10 6 CFU/g of contaminated food. In the process of isolation and identification of the test pathogens, 12 Salmonella spp., 2 Shigella B, 2 E. coli 0157, 17 S. aureus and 25 B. cereus isolates were made. Furthermore, most of the isolates were resistant to two or more antimicrobial drugs in a susceptibility test. In the challenge experiment, cultural examination of fecal pellets showed that Salmonella and S. aureus could be excreted for 35 and 14 days post infection, respectively. However, culture examination of fecal pellets of Shigella B infected cockroaches failed to yield the bacterium for 30 days post infection. These results indicate that cockroaches (B. germanica) are the possible reservoirs and vectors of multi-drug resistant food-borne pathogens in hospitals and food-catering areas that may be responsible for nosocomial and community acquired infections. Hence, there is a need to implement effective cockroach controlling programs focusing on hygiene. Continuous surveillance and rational use of antimicrobial drugs are also required in order to minimize the emergence and spread of drug resistant pathogenic bacteria by cockroaches. Further work is essential to establish the natural transmission of human food-bome diseases by cockroaches