Antimicrobial resistance surveillance: a case study of escherichia coli isolates from selected chicken farms in Masaka City, Uganda

Abstract

The increasing field reports of apparent antimicrobial resistance and resulting treatment failures in poultry farms, that were not supported by scientific evidence was the impetus for this study on chicken farms in Masaka City. The study recruited 50 chicken farms from which 280 samples were collected to investigate the antibiograms, genetic drivers and risk factors associated with development of antimicrobial resistance among E. coli. The E. coli isolates were subjected to a panel of six antibiotics including ampicillin (10μg), neomycin (30μg), Gentamycin (30μg); tetracycline (30μg), ciprofloxacin (30μg); and potentiated Sulphonamides [trimethoprim/sulfamethoxazole (1.25/ 23.75μg)]. The highest level of resistance was recorded against Tetracycline and Sulphonamides at 76% and 74%, respectively. The E. coli isolates demonstrated the highest susceptibility (96%) to gentamycin (CN). Conventional and multiplex PCRs were run on the E. coli isolates to screen for genes that code for Tetracycline (Tet M, O, & K) and Sulphonamide (Sul-1 & Sul-2) resistances respectively. All isolates were negative for the tetracycline resistance at genotypic level. Only three (3) and four (4) isolates were positive for the Sul 1 & 2 genes respectively. The prophylactic use of antibiotics as an intervention against disease occurrence was 2.02 times responsible for causation of AMR on chicken farms. To the contrary, farms where antibiotics were only prudently used during disease outbreaks had less chances of AMR occurrence. This association was significant at odds of 0.21 and a p-value of 0.002. Therefore, when used appropriately amidst outbreaks, antibiotics are protective against development of AMR on farms as opposed to other concoctions such as herbs. Furthermore, farms that kept < 500 chickens were 3.63 times more at risk of experiencing E. coli resistance compared to farms that had flocks of over 1000 chickens. At adjusted odds ratio of 3.63 and 95% confidence interval of 1.16 to 11.31, this association was statistically significant at p-value 0.027. In conclusion, the findings are indicative of a likely bigger challenge in Masaka city. Therefore, there is a need for regular AMU on-farm monitoring, use of available laboratory diagnostics in addition to further in-depth studies as regards AMR on chicken farms.