The antibiotic resistance genetic elements in lactobacillus strains

Abstract

Antibiotics were a major tool utilized by the health care industry to fight bacterial infection; however, bacteria were highly adaptable creature and were capable of developing resistance to antibiotic. Consequently, decades of antibiotic use, or rather misuse, have resulted resistance to many modern antibiotics. This antibiotic resistance could cause significant danger and suffering for many people with common bacterial infection, those once easily treated with antibiotics. For several decades, studies on selection and dissemination of antibiotic resistance have focused mainly on clinically relevant species. However, recently, many investigators have speculated that commercial bacteria including lactic acid bacteria (LAB) might act as reservoirs of antibiotic resistance genes similar to those found in human pathogens. The main threat associated with these bacteria was that they could transfer resistance genes to pathogenic bacteria. Gene conferring resistance to Erythromycin, Tetracycline, Vancomycin have been detected in Lactobacillus species isolated food products. A number of initiatives have been recently launched by various organizations across the globe to address the biosafety concerns of starter microorganism in horizontal transfer of antibiotic resistance genes to intestinal microorganism and food associated pathogenic bacteria. The aim of this study was to examine the transfer of Tetracycline, Kanamycin, Ampicillin and Erythromycin resistance determinants from Lactobacillus acidophilus isolated from market drug products and Lactobacillus helveticus isolated from fermented food. The transfer was performed by using an in vitro mating method (conjugation). The conjugation experiments were carried out with the donors and recipients using the filter mating method. The recipients were Methicillin - sensitive- Staphylococcus aureus (MSSA) and Bacillus subtilis. Using disc diffusion test, all the donors and recipients were tested the sensitivity to Tetracycline, Kanamycin, Ampicillin and Erythromycin before mating. Antibiotic susceptibility profiles were determined for Lactobacillus acidophilus and Lactobacillus helveticus. Lactobacillus acidophilus was resistant to Kanamycin, Erythromycin, Ampicilllin, Tetracycline at high concentrations (> 512µg/ml). In other hand, the MICs (Minimum inhibitory concentration) of Lactobacillus helveticus to Tetracycline, Ampicillin, Erythromycin were 16µg/ml, 32µg/ml, 32µg/ml respectively. Lactobacillus helveticus was resistant to Kanamycin at concentration higher than 512µg/ml. The MIC (Minimum inhibitory concentration) of Methicillin - sensitive- Staphylococcus aureus (MSSA) and Bacillus subtilis to Ampicilin were at 2µg/ml. The MICs of Staphylococcus aureus and Bacillus subtillis to Tetracycline were at 2µg/ml and 1µg/ml respectively. The MICs of Staphylococcus aureus and Bacillus subtillis to Erythromycin were at 64µg/ml and 32µg/ml respectively and to Kanamycin were at 128µg/ml. All transconjugated Staphylococcus aureus and Bacillus subtillis were confirmed by disc diffusion test and agarose gel electrophoresis. Impacts of these transfers were examined in the light of food or drug safety and potential effects on public health application.