Antibiotic Resistance Patterns of Lactic Acid Bacteria Isolated From Different Fermented Milk Products of Turkish Origin

Aims: Lactic acid bacteria isolated from 48 Turkish fermented milk products obtained from local markets, dairies or bazaars were investigated for their resistance of antibiotics including ampicillin, erythromycin, gentamicin, chloramphenicol, lincomycin, meropenem, ciprofloxacin, teicoplanin, tetracycline and vancomycin.

Place and Duration of Study: Adnan Menderes University Biology Department, Microbiology laboratory, between 2012-2014

Methods: LAB strains, belonging to 14 species of Lactobacillus (n=68), 1 species of Lactococcus (n=16), 5 species of Enterococcus (n=14) and 2 species of Streptococcus (n=17) were isolated and identified at species level by their 16S rRNA gene sequencing. Minimal Inhibitory Concentrations (MIC) for 10 antibiotics were determined by agar dilution test using multipoint inoculator. Antibiotic resistance genes for erythromycin [erm(A), erm (B), erm (C)], gentamycin aac(6’) aph(2’’), chloramphenicol (cat), tetracycline [tet(K), tet(L), tet(M), tet(S), tet(Q)] and vancomycin [van(A), van(B), van(C), van(X)] were investigated in strains. Mating experiments were done with E. faecalis JH2-2 to detect the transferability of resistance genes.

Results: Among 115 strains antibiotic resistance was detected against lincomycin (27,8%), tetracycline (20%), ampicillin (13,9%), meropenem (11,3%), gentamycin (10,4%), erythromycin (7,8%), ciprofloxacin (6,1%), chloramphenicol (3,4%), vancomycin (0,87%). While all these strains were susceptible to teicoplanin, 29,5% of isolates were multiple resistant to various antibiotics. The resistance genes aac(6’) aph(2’’), erm(B), tet(L), tet(M) and van(C) were detected in strains of, Lb. delbrueckii subsp. bulgaricus, Lb. kefiri, Lc. lactis subsp. lactis, S. lutetiensis, S. macedonicus, E. faecalis, E. gallinarum isolated from some cheeses and one household kefir samples.

Conclusion: Antibiotic-resistant LAB carrying transeferable resistance genes in some Turkish dairy products, may act as a dangerous vehicle for transmission of these traits to the other bacteria by horizontal gene transfer.