A study of the microbial content of the domestic kitchen

A total of 46 houses were sampled, 13 of these being sampled over a wide range of sites (76 sites in total), and the remaining 33 being sampled at potential ‘key’ sites for cross contamination. Highest counts (i.e. > 450 cfu’s per area sampled) were associated with two main types of site, viz. wet areas around the sink (surface, plughole, draining board, washing up bowl) and cloths used for wiping surfaces and/or drying equipment (dish washing cloths and sponges, tea towels). Gram-negative rods were predominant in the sink area whereas Gram-positive cocci were predominant in cloths. Results of the study showed Enterobacter cloacae to be isolated from 52.2% of the 46 kitchens examined, with other Enterobacter spp. at 26.1%. Other enterobacteria isolated included Klebsiella pneumoniae (23.9%) and Escherichia coli (19.6%). The most common pseudomonad was Pseudomonas aeruginosa at 15.2%. Bacillus subtilis was isolated from 56.5% of the domestic kitchens sampled, and all of the kitchens were found to have Staphylococcus spp. (100%) and Micrococcus spp. (100%) present in several of the sites sampled. Food poisoning bacteria were seldom detected in the kitchens examined, although individual isolates of Listeria monocytogenes, Yersinia entero-colitica and Bacillus cereus were recorded.