Antibiotic resistance has become one of the major issues pertaining to public health safety. For a long time the phenomenon of bacterial resistance to antibiotics has been associated exclusively with selective pressure in the hospital environment. It was only the increasing knowledge of the genetic basis of resistance and the mechanisms accompanying its transmission that shifted the focus of researchers to comprehensively approach its epidemiology. Lactic acid bacteria (LAB) have been recognised as safe with the GRAS (Generally Recognized as Safe) and QPS (Qualified Presumption of Safety) status granted by FDA and EFSA. However, the recently conducted studies have shown that among the strains of the starter cultures and probiotic strains, there are also those resistant to antibiotics, which can transmit their antibiotic resistance to other microorganisms. If the resistance is innate, associated with information encoded in the chromosome, it is not a cause for concern. Unfortunately, increasingly often, there are reported strains with the so-called acquired resistance resulting from the spot mutations or gene transfer. As a consequence those two phenomena lead to permanent resistance inheritance and to its propagation by horizontal gene transfer (HGT). Owing to that gene transfer, in cells appear new resistance genes, which are transferred on mobile genetic elements, such as plasmids, transposons and insertion sequences. More and more worrying reports appear, which indicate that LAB including probiotic strains exhibit the acquired resistance to a growing number of antibiotic groups, especially to tetracyclines, macrolides, glycopeptides and amphenicols. A number of those strains have been found to contain determinants of resistance on mobile genetic elements and their ability has been confirmed to transfer genes by HGT to other bacteria including pathogens.
antibiotic resistance, LAB, probiotics, horizontal gene transfer