Resistance profile of contaminating organisms isolated from ready -to-eat vegetable salad from selected eateries in a university setting

In recent years, salad has become a very popular component of menu served at birthdays, wedding parties and at home; they are also sold in fast food centers in most major cities in Nigeria. Reports of unverified rampant cases of gastroenteritis following consumption of meals served with fresh vegetable salads have become serious public health concern which necessitate the need for this investigation. Ready to eat salad samples were investigated for pathogenic bacteria and the strains isolated were subjected to biochemical and morphological test for identification. The isolates were subjected to antibiotic susceptibility test using standard antibiotics disks following the Clinical and Laboratory Standards Institute guidelines. The Multiple antibiotic resistance index was determined. The isolates were also subjected to investigation to determine the resistance factors using the QIAGEN plasmid purificationmini kit. A total of nine bacteria were isolated from the three samples of salad isolated and identified namely Staphylococcus aureus, Salmonella typhi, Shigella dysenteriae, Escherichia coli, Proteus mirabilis, Enterobacter cloacae, Micrococcus luteus, Streptococcus can is and Pseudomonas aeruginosa, The total viable count of to the isolates ranged from 2.6X105cfu/mlto 8.1x105cfu/ml. The total coliform count ranged from 1.23 X105cfu/ml to 7.4X105 cfu/ml. Percentage resistance was 86% for S. aureus; 93% for S.typhi; 50% for Shigella dysenteriae; 57% for E.coli; 71% for Proteus mirabilis; 57% for Enterobacter spp; 43% for Micrococcus spp; 71% for Streptococcus pygenes and 64% for Pseudomonas aeruginosa.The MAR index ranged between 0.43 for Micrococcus spp and 0.93 for Salmonellatyphi showing a high degree of multiple drug resistance (MDR). The plasmid profile of the resistant bacteria showed Salmonella typhi, Shigella dysenteriae and Escherichia coli had plasmid borne resistant factors while Staphylococcus aureus had chromosomal borne resistance factor. The result of this work emphasized danger of multidrug resistant pathogens in ready to eat unprocessed food.