Moreover, the percentages OICR-9429 datasheet of strains

showing antibiotic resistance in the genera Weissella, Pediococcus and Lactobacillus were 60, 44 and 33%, respectively, while none of the leuconostocs and lactococci showed this phenotype. In this regard, our results indicate that the LAB High Content Screening susceptibility patterns of MIC values to clinically relevant antibiotics are species-dependent, similarly as previously described by other authors [39, 40]. Moreover, multiple antibiotic resistance was commonly found in strains within the genus Enterococcus (37%), mainly in E. faecalis, while being very infrequent in the non-enterococcal strains (5%). According to EFSA [29], the determination of MICs above the established breakpoint levels, for one or more antibiotic, requires further investigation to make the distinction between

added genes (genes acquired by the bacteria via gain of exogenous DNA) or to the mutation of indigenous genes. According to our results, acquired antibiotic resistance likely due to added genes is not a common feature amongst the non-enterococcal LAB of aquatic origin (7.5%). In this respect, this genotype was only found in the genera Pediococcus (12.5%) and Weissella (6.7%). Although P. pentosaceus LPV57 and LPM78 showed resistance to kanamycin (MIC of 128 mg/L), the respective resistance gene aac(6´ )-Ie-aph(2´ ´ )-Ia was not found in these strains. Similarly, P. pentosaceus TPP3 and SMF120 were phenotypically resistant to tetracycline (MIC of 16 mg/L), but

did not contain tet(K), tet(L) or tet(M). In this respect, Ammor et al.[41] reported Selleck Tipifarnib that pediococci are intrinsically Dimethyl sulfoxide resistant to the latter two antibiotics, as well as to glycopeptides (vancomycin and teicoplanin), streptomycin, ciprofloxacin and trimethoprim-sulphamethoxazole. Other authors proposed a MIC for tetracycline in pediococci ranging between 8 and 16 mg/L [42], or of 32 mg/L for oxytetracycline in P. pentosaceus[17]. The tetracycline breakpoints suggested for pediococci by EFSA are lower than the MICs observed in our work and others [17, 42]. On the other hand, the only antibiotic resistance detected in Leuconostoc strains was for vancomycin, which is an intrinsic property of this genus. It has been previously reported that Leuconostoc strains display poor, if any, resistance to antibiotics of clinical interest [38]. With regard to lactococci, the three L. cremoris strains evaluated were susceptible to all the antibiotics; however, relatively high MICs for rifampicin (16–32 mg/L) and trimethoprim (≥ 64 mg/L) were detected. In fact, most lactococcal species are resistant to trimethoprim [41]. As expected, all strains of heterofermentative Lactobacillus spp. were resistant to vancomycin but susceptible to the rest of the assayed antibiotics, except Lb. carnosus B43, which showed the highest MIC for ampicillin and penicillin (MICs of 8 and 4 mg/L, respectively).