Coliform Bacteria Profile of the Surface of Raw Salad Vegetables Sold in Open Markets in Owerri Metropolis, South Eastern Nigeria

Abstract

The consumption of fresh vegetables has great health benefits. However, this has been linked to several food borne infections and disease outbreaks in the past because some of these vegetables have been identified as agents in the transmission of human food pathogens. This study examined the coliform bacteria profile of raw salad vegetables sold in open markets in Owerri metropolis, South Eastern Nigeria. The samples of different raw salad vegetables (cabbage, cucumber, carrot and tomatoes) bought from different vendors in open markets were examined for the presence of coliform bacteria. Surface wash water of samples were used for the enumeration of total and fecal coliforms. The results from the study showed that all the samples harboured coliform bacteria with the cabbage recording the highest coliform count (CA3= 2.8 x 107cfu/g on MacConkey agar) while the highest E. coli count occurred in tomato (TO3=2.7 x 106cfu/g on EMB agar); carrot (CB3= 2.6 x 104cfu/g on MacConkey agar)and cucumber (CU2= 3.9 x 102cfu/g on EMB agar) recorded the lowest coliform and E. coli counts respectively. The percentage prevalence of the isolates on the samples were Enterobacter species (83.3%), Escherichia coli (66.6%) and Klebsiella species (33.3%).The counts were obviously above the coliform acceptable limit (<100cfu/g) for salad vegetables. This suggests that salad vegetables used in this study are of public health concern because, they harbour microorganisms that could be hazardous to human health. Positive detection of coliforms (especially, E. coli) is an effective confirmation of fecal contamination, hence good hygiene measures should be observed throughout the processing chain and consumers should also practice appropriate hygiene during the preparation of salad vegetables for consumption. This will eventually help in reducing the microbial contents of the vegetables before consumption.