Study of resistance mechanism in Enterobacter spp. with special reference to antimicrobials ceftazidime, moxifloxacin and nalidixic acid

Microbial resistance to antimicrobials is spreading all over the world making it difficult to treat diseases effectively. This study aims to understand the mechanism of resistance towards the antimicrobials Ceftazidime, Moxifloxacin and Nalidixic acid, by using resistant Enterobacter spp. and sensitive Enterobacter spp. While there was complete inhibition of growth of sensitive Enterobacter spp. at 8 µg/ml Ceftazidime, 0.125 µg/ml of Moxifloxacin and 16 µg/ml of Nalidixic acid, resistant Enterobacter spp. even tolerated 256, 32 and 1536 µg/ml Ceftazidime, Moxifloxacin and Nalidixic acid respectively. Browthdilution method was used to determine the growth of organisms at different concentrations of antibacterial agents. Mechanism of resistance was found to be present in plasmid. Absence of Beta lactamase enzyme seems to be an important finding in this sudy. B. lactamase enzyme was checked with help of the acidometric and idometric method. Plasmid isolation and analysis was done by agarose gel electrophoresis. Successful curing of plasmid was carried out with 10% sodium dodecyl sulfate (SDS). When colonies after SDS treatment were tested, resistant strains were found which were later converted to sensitive ones. In this study, the resistant Enterobacter spp. executed resistance to three different classes of antimicrobials due to the resistance plasmid. The results obtained in this study support most of the previous study findings who contributed in this field. Therefore, it might be useful to recognize the resistance mechanism, and to determine the correct practicing of drug usage.