Transfer of Antibiotic Resistance Genes from Gram-positive Bacterium to Gram-negative Bacterium

The emergence of antibiotic resistance due to uncontrolled use of antibiotics in non-humans, poses a major threat for treating bacterial infections in humans. Added to this is the possibility of transfer of resistance from Gram-positive bacteria to Gram-negative bacteria. Therefore, the possibility of resistance gene transfer from a non-human originated pathogenic bacterium to a pathogenic bacterium infecting humans needs evaluation. In this study, poultry litter samples collected from Tamil Nadu, India were screened for the presence of meropenem- and cefotaxime-resistant Staphylococcus sciuri. Standard microbiological techniques and 16S rRNA analysis were used to confirm S. sciuri. In the resistant isolates, resistance genes such as blaNDM-1, blaOXA-48-like, blaKPC, blaVIM, blaIMP and blaCTX-M were screened. Transconjugation studies were performed using donor, S. sciuri and recipient, E. coli AB1157 (Strr). A total of 26 meropenem-resistant and 24 cefotaxime resistant S. sciuri were isolated from poultry litter samples. The presence of blaNDM-1 (n=2), blaIMP (n=8), blaCTX-M-9 (n=5) and blaCTX-M-2 (n=1) was detected. Transconjugation results confirmed that S. sciuri carrying plasmid-borne resistance gene blaNDM-1 conjugated to E. coli AB1157. The transferability of resistance genes from S. sciuri to E. coli could be another possible reason for spread of antibiotic-resistant bacteria in humans.