Food Commensals as a Potential Major Avenue in Transmitting Antibiotic Resistance Genes

The rapid emergence of antibiotic resistant (ART) pathogens is a major threat to public health. While the surfacing of ART foodborne pathogens is alarming, the magnitude of the antibiotic resistance (AR) gene pool in foodborne commensals is yet to be revealed. Incidence of ART commensals in dairy, meat, seafood and produce products was examined in this study. Twelve of the 15 retail cheese samples tested were found to contain Tet microbes ranging from 10(squared) to 10(to the seventh power) CFU per gram of food. All 15 retail produce samples examined contained Em microbes up to 10(to the seventh power) CFU per gram of product. The presence of large populations of ART bacteria in these foods, particularly in many ready-to-eat health food items, indicates that the ART bacteria are abundant in the food chain. AR-encoding genes were detected in ART isolates and the main hosts for these genes in several types of foods were further identified. Particularly, Streptococcus thermophilus, a commonly used dairy starter culture, was found to be a major carrier of organism for AR genes in cheeses, arguing that it might no longer be suitable for cheese production.