Korhonen Antibiotic Resistance of Lactic Acid Bacteria

Lactic acid bacteria (LAB) are a heterogeneous group of bacteria found widely in nature . They colonize the gastrointestinal and urogenital tracts of humans and animals, and are present in foods such as dairy products, fermented meats, fruits and vegetables. LAB are also intentionally added to several probiotic products because of their potential health benefits. Many LAB species are generally recognized as safe (GRAS), and several LAB species have received a Qualified Presumption of Safety (QPS) status given by European Food Safety Authority (EFSA). Resistance to antimicrobial d rugs (antibiotics) is a common character istic in the world of bacteria. In the interaction between bacteria, genetic material is transferred from one bacterium to another, and also genes coding for resistance to a certain antibiotic may be passed on to other bacterial species. Since LAB are natural and profitable inhabitants in many environments (gastrointestinal tract, several foods), strains with resistance to antibiotics would not be detrimental to the wellbeing of humans or animals. However, there is some concern that antibiotic resistance in LAB could then be transferred to possibly pathogenic bacterial species, complicating the treatment of a d isease or infection and lead to the spread of antibiotic-resistant bacteria. Hitherto, only little attention has been paid to the antimicrobial susceptibilities of LAB (European Commission. 2005, European Commission 2008). In order to illustrate the current situation of antibiotic resistance patterns in beneficial LAB, stud ies were first conducted to isolate and identify lactic acid bacteria of animal and human origins, and secondly to evaluate their antimicrobial resistance patterns. Moreover, tentative cutoff values d ivid ing the populations into susceptible and resistant were also proposed based on minimum inhibitory concentrations (MIC) for a total of fourteen Lactobacillus species. Most of the LAB strains were found to be suscep tible to all antimicrobial agents used in the stud ies. The most frequently found resistance was against tetracycline, followed by resistance against aminoglycosides. The horizontal transferability of antibiotic resistance between LAB (Lactococcus garvieae species) and pathogenic Listeria monocytogenes was also achieved , demonstrating that a gene coding for tetracycline resistance tet(S) can be transferred from a fish pathogen to a human pathogen by conjugation in vitro. Universal Decimal Classification:579.864, 615.015.8, 615.33, 577.18 National Library of Medicine Classification: QW 142.5.A8, QW 45 CAB Thesaurus: lactic acid bacteria; Lactobacillus; drug resistance; antibiotics; tetracycline; aminoglycoside antibiotics; horizontal transmission; Lactococcus garvieae, Listeria monocytogenes