Sunday, July 24, 2011
Grand Ballroom, 5th fl (Sheraton New Orleans)
In recent years the awareness regarding healthy eating has increased. As a result of this, consumers are adding leafy greens and lettuce into their diets on a regular basis. This study aims to investigate the occurrence of multidrug resistant bacteria (MRB) on lettuce sold in the retail grocery market in Rochester, Michigan. The total heterotrophic bacteria (THB) count was done by bacterial growth on Tryptic Soy agar (TSA). Bacteria were identified by using API system. Antibiotic susceptibility was determined using antibiotic supplemented Mueller-Hinton II agar. The average THB colony count recorded on TSA was 9.33x107 CFU/g of lettuce. Antibiotic resistance among bacterial isolates was ampicillin (34.6%), ciprofloxacin (4.69 %), cefotaxime (11.7%), gentamicin (19.2%), imipenem (32.3%), and vancomycin (66.6%). Of the 93 bacterial colonies tested 2.15% were resistant to all six of the antibiotics and 87% were resistant to three or more antibiotics. MRB producing ESBL were also detected. Bacterial species contained in lettuce was Enterobacter, Klebsiella, Pseudomonas, Citrobacter, Acinetobacter, Escherichia, and Enterococcus. Pathogenic species of Salmonella, Shigella, Listeria, Yersinia and Campaylobacter were not identified in our samples. The lettuce used for human consumption and sold in retail grocery stores contains ESBL producing MAR bacteria. Through the plasmid-mediated transfer, MAR bacteria are capable of transferring their resistant genes to human bacterial flora, a phenomenon which could prove to increase MAR gene pool in human intestine and can effect modulation of mucosal innate immunity among children, elderly and immune-compromised persons.