Bacteriophage activity against antibiotic resistant avian pathogenic Escherichia coli from post-mortem cases presented at the veterinary pathology laboratory, Makerere University

Abstract

Escherichia coli are gram-negative non-spore forming bacilli that grow aerobically or anaerobically and may be variable in size and shape. Antimicrobial resistance is currently a very big global problem, initially reported in human patients but it has spread to the animal population, making it a very serious risk due to rampart difficult to treat microbial infections. This study aimed at determining the bacteriophage activity against antibiotic resistant avian pathogenic Escherichia coli from post-mortem cases presented at the veterinary pathology laboratory, Makerere University. A total of 52 Escherichia coli isolates, 20 from stock and 32 directly isolated from cases of avian colibacillosis. MacConkey agar was used for isolation and confirmation of E. coli isolates; in addition to standard biochemical tests. Antimicrobial sensitivity was established by disc diffusion method using 12 drugs; that is, Ciprofloxacin, Penicillin G, Cefixime, Trimethoprim, Chloramphenicol Amoxicillin Nitroflirantoin, Streptomycin, Nalidixic acid Ampicillin, Tetracycline and Gentamycin. The drugs that were most frequently resisted by Escherichia coli isolates were Penicillin G (100%), Sulphamethoxazole /Trimethoprim (88.5%), Ampicillin (86.5%) and Tetracycline (82.7%). The least resistance was towards Gentamicin (7.6%) and Nitrofurantoin (9.6%). All the 52 (100%) E. coli isolates were susceptible to Cefixime. Forty-six isolates (88.5%) were resistant to at least three classes of drugs (multi drug resistance) and these were tested for sensitivity to 20 stock bacteriophages. Only one bacterial isolate exhibited sensitivity to all the 20 test phages, which indicated low efficacy. Results showed that there is high drug resistance of E. coli causing colibacillosis cases in chicken. Bacteriophage activity on the resistant E. coli was found was low 1.9%. There is need to isolate more bacteriophages using the APEC as the host strain, in order to improve on their efficacy and their antibacterial spectrum. The latter will contribute to the fight against resistant APEC, whose only current management strategy is by use of antibiotics. In order to fully evaluate the potential use of bacteriophages as treatment of bacterial infections, all aspects of the phage biology must be fully understood; and this forms the next steps to follow up this study.