Abstract
Antimicrobial agents are supposed to be the most important means for treating bacterial infections. The use of steroidal and non-steroidal drugs is leading the disturbance of the normal microflora of gastrointestinal tract. This interference may result in abnormality of natural defence mechanism which is due to the colonic microbial ecosystem, making the host resistant to infections caused by commensal microorganisms and nosocomial pathogens. The agar well diffusion assay method was performed to observe the zones of inhibition caused by antimicrobial agents. Up to 25 antimicrobial drugs were used and out of 25 drugs, five antimicrobial drugs gave huge zones of inhibition.