Cockroaches (Blatta and Periplaneta species) as reservoirs of drug-resistant salmonellas.

A total of 221 cockroaches (Blatta and Periplaneta spp.), collected in hospitals, houses, animal sheds, grocery stores and restaurants, in various parts of South Kanara District, a south-west coastal region of India, were studied bacteriologically for the presence of various salmonellas. Salmonellas were isolated from 4.1% of these cockroaches. Nine strains of salmonellas were recovered, belonging to five serotypes--Salmonella bovismorbificans, S. oslo, S. typhimurium, S. mbandaka and S. braenderup, the former two being the commonest serotypes. All salmonellas were resistant to one or other of 11 antibacterial drugs used in the susceptibility test. Isolation of salmonellas from cockroaches collected from the livestock premises and human dwellings suggested that they may act as significant reservoirs of salmonella in nature. Recovery of serotypes, phage types and R-types that were commonly isolated from humans and animals of this locality, suggested a transmission role for cockroaches. By harbouring potentially pathogenic, drug-resistant salmonellas, these wandering arthropods may pose dangerous infective hazards to humans and animals.