Investigation of Radish and Parsley Vegetables Contamination to Antibiotic Resistant Bacteria - A Case Study, Guilan Province

Manure application and irrigation practice with wastewaters in olericulture may introduce antibiotics and antibiotic resistant bacteria to soil which may contaminate edible vegatables. The aim of this study was to investigate the antibiotic resistant bacteria isolated from radish (Raphanus sativu) and parsley (Petroselinum crispum L.) and their cultivated soils. Three vegetable farms were selected in Pirbazar, Chaboksar and Fouman areas in Guilan province. Samples were taken from vegetables and soils at three replications. After making serial dilution, their heterotrophic and coliform bacteria number were determined on NA and EMB agar media respectively, containing 100 µg/mL antibiotic. Four antibiotics including cephalexin, ciprofloxacin, gentamicin and trimethoprim were tested. Antibiotic resistant index (ARI) was calculated by dividing bacteria colony numbers on each antibiotic contained medium to control (medium without antibiotic). Data were analyzed as split-split plot design with three locations as main plot sector, two olericulture fields as sub-plot and four antibiotics as sub-sub plot factor. The effect of antibiotic was significant on the vegetable and soil bacteria ARI (p<0.05). But the effect of sampling area and farm (radish and parsley farms) were significant only on the heterotrophic and coliform bacteria ARI, respectively (p <0.01). In Chaboksar area, 29% of vegetable's heterotrophic bacteria and 42% of soil coliforms were resistant to gentamicin. The highest coliform ARI (38%) was obtained in radish and was to gentamicin. Overall, culturable bacteria from vegetables of Chaboksar area had higher antibiotic resistance index and eating fresh vegetables cultivated in this area is not recommended.