Antimicrobial resistance in Gram-negative bacteria from food producing animals
Increase of bacteria resistant to antibiotics is a global public health concern with serious health and economic consequences. The control of this threat needs multidisciplinary joint efforts and strategies based on scientific evidences generated by surveillance systems or research. It is therefore crucial and recommended to generate updated data on antimicrobial resistance to increase the understanding of this problem for a better control. While research and monitoring of antimicrobial resistance are advanced in a lot of developed countries, there are limited information on this problem, specifically among animals, in most of developing countries. For example, in a country like Rwanda, there is a scarcity of information on the current status of antibiotic resistance particularly in food producing animals. The overall objective of this dissertation was to provide information, methods, and data that can be used when establishing a strategy to control antibiotic resistance in food animals in Rwanda. The first two studies presented herein were conducted with a focus of developing and optimizing methods to establish the status of antimicrobial resistance in food producing animals when laboratory resources are limited. The two study projects were conducted in food animals from farms located in Texas. Both studies showed that antibiotic resistant bacteria were present in food producing animals at variable levels according to the animal species and the antibiotic tested. In general, resistant bacteria were found to be at lower levels compared to susceptible bacteria. The methods used were optimized and appeared to be suitable to generate valuable information on antibiotic resistance in isolated bacteria. A third study was conducted in Rwanda to establish a baseline of data on antibiotic resistance in cattle, goats, pigs and poultry using methods developed in the first two studies conducted in Texas. The main observation of this study was that resistance to tetracycline was the most prevalent among indicator Escherichia coli isolated from food animals. And most of resistant Escherichia coli were from poultry fecal samples compared to other animal species. Escherichia coli resistant to third-generation cephalosporins were also detected, and they were all characterized as producers of extended spectrum beta-lactamases. Moreover, Escherichia coli resistant to quinolones was present among the studied food animals.