Phenotypic expression, molecular characterization and transferability of erythromycin resistance genes in Enterococcus spp. isolated from naturally fermented food

Abstract

Aims: To evaluate phenotypic resistance to macrolides-lincosamides and streptogramin B (MLS B ) antibiotics and to determine their localization as well as transferability of erythromycin resistance genes in enterococcal isolates of naturally fermented food-Idli batter. Methods and Results: Diverse MLS B phenotypes observed among the enterococcal spp. (n = 32) were analysed through double disc and triple disc test. Standard minimum inhibitory concentration tests along with induction studies displayed synergistic or cross-resistance among MLS B antibiotics. Plasmid profiling and Southern hybridization revealed that erm(B) and msr(C) genes were localized either on chromosome or on high molecular weight plasmids and showed co-localization of these genes with lnu(B), tet(L) and tet (W) in one of the isolate. In vitro conjugation experiments demonstrated plasmid-mediated transfer of erm(B) gene from three Enterococcus durans strains to Enterococcus faecalis JH2-2. Conclusions: The study illustrated diverse MLS B phenotypes, multiple resistance genes and transferable plasmids among enterococci isolated from naturally fermented foods. Significance and Impact of the Study: From a public health point of view, the study identified that naturally fermented foods could represent a source of antibiotic resistance enterococci that can spread through foods. These results also suggest that vigilance may be exercised with the use of combination or novel MLS B antibiotics in treating enterococcal infections.

Screening, Characterization and In Vitro Evaluation of Probiotic Properties Among Lactic Acid Bacteria Through Comparative Analysis

“…It is essential for a probiotic strain to be sensitive to most of Fig. 1 Comparison of phylogenetic dendrogram constructed by using the scores of (GTG) 5 (a), RAPD (b) and concatenated scores of (GTG) 5 and RAPD (c) the antibiotics, as they may otherwise serve as agents in transfer of antibiotic resistance genes through conjugation [20,31]. Many reports have been published in support for the production of bacteriocins among different species of LAB and are found to be effective against several foodborne pathogens present in the GIT of humans [4].…”

Heterogeneity of macrolide-lincosamide-streptogramin phenotype & conjugal transfer of erm(B) in Pediococcus pentosaceus

“…The plates were incubated at 37°C in ambient air. MICs of CLD were also defined in the presence of sub-inhibitory concentrations of ERY12. A double disc diffusion test with CLD (2 μg) and ERY (15 μg) discs was performed on MRS agar as described earlier12.…”

“…MICs of CLD were also defined in the presence of sub-inhibitory concentrations of ERY12. A double disc diffusion test with CLD (2 μg) and ERY (15 μg) discs was performed on MRS agar as described earlier12. The CLD resistant (CLD R ) isolates were subjected to modified Hodge test for detection of lincosamide nucleotidyltransferase ( Lnu ) activity12.…”

“…Hence, the development of resistance to these antibiotics is a cause of concern810. In addition, various novel resistance phenotypes being observed in pathogenic11 and food-borne12 bacterial species have complicated the treatment of human infections.…”

“…Acquired resistance to erythromycin (ERY) among LAB species such as Lactobacillus and Enterococcus along with human pathogens8 has been described. Further, the treatment of MLS B -resistant human pathogens are difficult to treat due to the emergence of novel mechanisms evident through unusual phenotypes1112. Although ERY resistance (ER r ) is commonly observed among food LAB8, but Pediococcus species has shown no resistance to ERY among P. pentosaceus isolates1131415.…”