Elucidation of resistance acquisition between various genera of gram-negative bacteria

Abstract

The antimicrobial agents have the potential to maintain the selective pressure on bacteria. Bacteria can alter various mechanisms for survival under selective pressure. Thus, the bacteria acquire resistance through conjugation from co-existing bacteria during antimicrobial stress. The study was designed experimentally to investigate the acquired resistance on the basis of time against different genera of gram-negative bacteria. The study was conducted at the Department of Pathology, King Edward Medical University, Mayo Hospital, Lahore, Pakistan. E coli strain was sensitive to Ciprofloxacin and Pseudomonas aeruginosa strain was resistant to Ciprofloxacin. The macro broth dilution technique was used to verify the susceptibility of E. coli and P. aeruginosa. 0.5 MacFarland standard solution of E. coli and P. aeruginosa were mixed and kept at the sub-minimal inhibitory concentration (0.781 µg/ml) of Ciprofloxacin for 28 days. MIC of Ciprofloxacin was measured against E. coli at weekly basis. It was observed that the Ciprofloxacin MIC against E. coli after 7, 14, 21 and 28 days were <01 µg/ml, <01 µg/ml, <04 µg/ml and <25 µg/ml respectively. In conclusion, E. coli acquires resistance from P. aeruginosa under selective pressure of sub-minimal concentration of antibiotic Ciprofloxacin in 28 days.