Antibiotic resistance of Escherichia coli and Salmonella spp. isolated from leafy vegetables sold in Pasay City market

Abstract

Vegetables are known to carry microorganisms such as bacteria. The presence of pathogenic bacteria such as Escherichia coli and Salmonella spp. in vegetables that are eaten raw can pose a serious threat to human health. A great concern affecting the whole world now is the occurrence of antibiotic resistant foodborne bacteria that are causing illnesses that are becoming difficult to cure. This study was undertaken to assess the microbial quality and the presence of antibiotic resistant E. coli and Salmonella spp. in 3 different kinds of leafy vegetables that are usually eaten raw (i.e., cabbage, Napa cabbage and pechay). A total of 45 vegetable samples were purchased from five randomly-selected openair stalls in a Pasay City Public Market. The total bacterial counts (TBC) were determined using plate count method. The isolation and identification of E. coli and Salmonella spp. were done using differential media and biochemical tests. The confirmed isolates were then subjected to antibiotic susceptibility/resistance screening using the Kirby-Bauer method. The TBC values of the three vegetables ranged between 7.34-10.5 log CFU/g, which exceed the safe value for consumption. Two pechay samples were contaminated with E coli while one pechay and one cabbage were contaminated with Salmonella spp. All E. coli isolates (n=2) were resistant to ampicillin while Salmonella spp. isolates (n=2) were resistant to ampicillin, as well as to amoxicillin-clavulanate. The exceedingly high TBC values and the presence of antibiotic resistant foodborne bacteria can be used as a warning to the public. The presence of antibiotic resistant bacteria in vegetables can be alarming, but consumers are not prevented from buying them in public markets. Vigilance in proper washing of these vegetables before being eaten is highly recommended so that the risk of getting these antibiotic resistant pathogens can be reduced.