Prevalence and plasmid curing of antibiotic resistant gram negative bacteria isolated from the environment

This study was designed to determine the prevalence of antibiotic resistant Gram-negative bacteria in the environment and their ability to transfer resistance genes to other bacteria strains. A total of 138 isolates were identified from urban and rural sewage, water and soil samples collected in Nsukka, Nigeria using standard microbiological identification methods. Out of these 138 isolates, 70 were Escherichia coli while 68 were Pseudomonas aeruginosa. Twenty one (70%), 12 (40%), 5 (16.7%) Escherichia coli isolates and 18 (60%), 3 (10%) and 15 (50%) Pseudomonas aeruginosa were obtained from urban environmental samples of sewage, water and soil respectively while 16 (53.3%), 9 (30%), 7(23.3%) Escherichia coli and 12 (40%), 1 (3.3%), 19 (63.3%) Pseudomonas aeruginosa isolates were isolated from rural environmental samples of sewage, water and soil respectively. The isolates from urban sewage recorded the highest antibiotic resistance frequency when Septrin was used with percentage resistance of 61.9% and 77.8% for E. coli and P. aeruginosa respectively. Isolates of E. coli from urban water showed the least resistance when Ciprofloxacin and Gentamycin were used and highest resistance frequency when Septrin was used. P. aeruginosa recorded the highest antibiotic resistance frequency when Augumentin, Streptomycin, Septrin and Amoxicillin were used with each having percentage resistance of 33.3%. E. coli isolates from urban soil samples were completely resistant to Ofloxacin and Ciprofloxacin while resistance to Augumentin and Amoxicillin was observed with percentage resistance frequency of 40% while P. aeruginosa showed different degrees of resistance to all the antibiotics used. E. coli and P. aeruginosa isolates from rural sewage recorded the least resistance when ciprofloxacin was used with percentage resistance of 12.5% and 16.7%, respectively. Both isolates recorded the highest antibiotic resistance frequency when Amoxicillin was used. E. coli was susceptible to Ofloxacin and Ciprofloxacin while it was highly resistant to Augumentin with percentage resistance frequency of 33.3%. P. aeruginosa in water from rural environment was susceptible to all the antibiotics used. The E. coli and P. aeruginosa isolates from soil samples obtained from rural environment showed low resistance to the antibiotics. Five isolates (Two E. coli and three P. aeruginosa isolates) that were resistant to at least two different classes of antibiotics were subjected to plasmid curing. Result showed that some of the bacterial isolates haboured transferable resistance plasmids which can promote the transfer of resistance genes to other bacteria strains. This study reveals that antibiotic resistant E. coli and P. aeruginosa is present in the environment and also have the ability to transfer their resistance genes to other bacteria strains. Therefore, adequate treatment of sewage and proper disposal of waste in the environment is vital so as to reduce the risk of infection and antibiotic resistance in the environment.