Antibacterial effect of silver nanoparticles and capsaicin against MDR-ESBL producing Escherichia coli: An in vitro study

Abstract

To evaluate the antibacterial property of silver nanoparticles (AgNPs) and capsaicin against multidrug resistant (MDR) and extended spectrum beta-lactamase (ESBL) producing Escherichia coli of bovine and poultry origin. Antibacterial efficacy of AgNPs and capsaicin was measured using broth dilution method. Five MDR-ESBL producing E. coli isolates of poultry (PEC4, PEC6, PEC15 and PEC16) and cattle mastitis origin (MEC2) were taken to evaluate the antibacterial effect of AgNPs and capsaicin. At 50 mmol/L AgNPs, the viability of MDR of bacterial pathogens was reduced to almost 80%–90% and at 1000 mmol/L, the viability went down to 0%–3%. The minimum inhibitory concentration (MIC50) of AgNPs against these MDR-ESBL producing isolates was found to vary between 172–218 mmol/L whereas the MIC80 varied between 450–640 mmol/L. Capsaicin showed more prominent bactericidal effect and only at 2.5 mmol/L concentration, the viability was shown to be reduced by 20%–35% whereas at 7.5 mmol/L concentration, there was approximately 60% reduction in viability. Further at 25 mmol/L concentration, the viability was reduced to 0%–8%. The MIC50 and MIC80 of capsaicin against these MDR-ESBL producing isolates were found to vary between 4.6–7.5 mmol/L and 10.9–16.9 mmol/L, respectively. The results point out that capsaicin and AgNPs could be of use in treating ESBL infection.