Isolation of gram-negative bacteria from cockroaches trapped from urban environment.

Three different areas--hospital, food-handling establishments and human dwellings, were surveyed for pathogenic gram-negative bacteria carried on the cuticles of cockroaches. Fifty species of bacteria were identified from all cockroaches. Escherichia coli, Klebsiella pneumoniae, Citrobacter freundii and Enterobacter cloacae were the most frequently found. Pathogenic and potentially pathogenic bacteria represented 58% of all bacteria identified. The numbers of pathogenic and potentially pathogenic bacteria were similar in hospital areas and food-handling establishments, while, human dwellings possessed a poorer bacterial flora. E. coli, K. pneumoniae and E. cloacae were dominant species in hospital areas, while in food-handling establishments and human dwellings, E. coli, K. pneumoniae and C. freundii predominated. Therefore, cockroaches can play a role in bacterial transmission, due to the bacteria carried on their cuticles.