Antimicrobial resistance and pathogenicity of Escherichia coli isolated from common dairy products in the Lebanon.

In a recent study, bacteria have been isolated from popular Lebanese dairy products, which had been collected in the Beqaa Valley, in north-eastern Lebanon. The foods investigated were two cheeses (shankleesh and baladi) and a dried fermented mixture of yogurt and wheat grains (kishk). Bacterial colonies on McConkey and sorbitol-McConkey agar that showed the morphology of Escherichia coli were biochemically tested and then classified, using PCR-based assays, into the various strains of pathogenic and non-pathogenic E. coli. Some of the confirmed E. coli isolates were proven to be pathogenic, including two identified as E. coli O157:H7. When the pathogenic isolates were tested for their susceptibility to 10 different antibiotics (all commonly used, by clinicians and veterinarians, for the treatment of infections with Gram-negative bacteria), each tested isolate was found to be highly resistant to at least one antibiotic. It therefore appears that, in Lebanon, some popular dairy products pose a public-health hazard, acting as vehicles for the transmission of drug-resistant pathogens.