Anema Michael IKHAGUEBOR

Allium fistulosum (Spring onions) also known as scallions or green onions are vegetables derived from various species of the genus Allium. The leaves and bulbs which are used as vegetables can either be eaten raw or cooked, chopped into other dishes and used as garnishes. These onions which require cultivation temperature ranging from 10o C to 22o C and irrigation during dry periods can be contaminated by various types of bacteria. This study therefore investigated the antibiotic resistance profile of some food-borne bacteria isolates from spring onions.Twenty-four (24) samples of spring onions were obtained from vendors across eight markets in Benin metropolis. Ten grams (10g) of spring onions was blended with a high speed homogenizer and the homogenate was serially diluted using peptone water. Standard microbiological methods were used to evaluate the bacteria load present in the samples. The bacteria were identified using both phenotypic and molecular techniques with the aid of polymerase chain reaction (PCR). Antibiotic sensitivity test was carried out using Kirby￾Bauer disk diffusion method on Mueller Hinton agar. The results were interpreted by measuring the zones of inhibition around each antibiotic disc in millimeters. Isolates that resisted one or more antibiotics from three or more distinct antibiotics classes were classified as multidrug resistant (MDR) isolates. The multidrug resistant (MDR) food-borne bacterial isolates were then subjected to plasmid profiling.The heterotrophic bacterial count showed that spring onions from Oba market had the highest
count (8.71 ±1.80× 106cfu/g) while Oluku had the lowest (5.71±1.50× 106cfu/g). The bacteria isolates were Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Bacillus cereus, Proteus vulgaris and Serratia marcescens. The percentage occurrence of isolates ranged from 25% to 100% with Bacillus cereus having the highest and Enterobacter aerogenes the lowest. Serratia marcescens was resistant to all antibiotics used while Enterobacter aerogenes was the least resistant. The multiple antibiotic resistance index (MAR I) ranged from 0.25 to 1.0 for all bacteria isolated. Two of the isolates (Klebsiella pneumoniae and Proteus vulgaris) had plasmids of size 1000 base pair (1.0 Kb). The presence of these food-borne bacterial isolates could be due to use of contaminated irrigation water, improper handling during harvesting and point of sales. The bacteria isolates which were multi-drug resistant and plasmid mediated pose a grave threat to publichealth. Spring onions should therefore be properly cooked prior to consumption