A prevalence of 28% of Salmonella sp. in poultry feeds recorded was similar to a prevalence of 29% reported in Tanzania [26] and Bangladesh [27]. Nevertheless, studies in Africa have continued to show varying results. A prevalence of 38% and 31% was reported in Nigeria [16, 28] and a prevalence of 71%, 55% and 29% in Bangladesh [15, 20, and 27]. The prevalence of Salmonella sp. from different poultry feeds was 38%, 37%, 19% and 17% in layer mash, grower mash, starter mash and finisher mash, respectively, contrary to a previous study that recorded a prevalence of 20%, 0%, 40% and 25% in layer mash, grower mash, starter mash and finisher mash, respectively [14] and prevalence of 21%, 38%, 31% and 33% in layer mash, grower mash, starter mash and finisher mash respectively in Tanzania [26].
The disparity of Salmonella prevalence could be due to differences in sampling, testing methods and difficulties in Salmonella detection methods [26].
The prevalence of 58% of Escherichia coli obtained was similar to a related study carried out in Bangladesh with a prevalence of 57% [27]. Other related studies reported different prevalence of 16% in Iraq [1] and in Nigeria 10.6% and 11% respectively [29, 16]. The prevalence of bacteria varies considerably depending on nature of production, country and detection methods applied [30]. Microbial contamination of poultry feeds of plant and animal origin has also been associated with harvesting, manufacturing and climatic conditions encountered [12].
Therefore, it is important to reinforce hygienic handling of feeds and preventive control measures to minimize the danger of potential animal and human health hazards.
Varying results in this study could be attributed to methods of harvesting raw materials, different climatic conditions, food formulation, and storage and transportation technologies [16, 12]. The high bacteria count in layer mash could be due to use of fish wastes as animal proteins which harbors heavier bacterial growth [14]. The differences in bacterial load in different types of poultry feed could be as a result of mixed infections with other microbes, different environmental conditions and management [31]. Findings in this study indicates that contaminated poultry feed could be dangerous, cause infections and thus not fit for animal consumption [32, 33].
Different resistant patterns of Salmonella sp. and E. coli were similar to other related studies. Both isolates of Salmonella and E. coli registered the highest resistance for Ampicillin 41% and 71% respectively, and highest susceptibility to Ciprofloxacin, 83% and 100% respectively. The isolates of E. coli indicated highest resistance to ampicillin 71%, followed by tetracycline 10%, co-trimozaxole and ceftriazone 7% and 0% ciprofloxacin similar to a previous study in Bangladesh that recorded ciprofloxacin as most effective antibiotic against E. coli isolates from poultry feeds [34]. Salmonella sp showed highest resistance to ampicillin 41%, tetracycline and ceftriaxone 5%, co-trimoxazole 2% and ciprofloxacin 0% contrary to a previous related study in Bangladesh that reported resistance of 30% to ciprofloxacin, 20% to gentamicin, 60% to nalidixic acid and 0% to ceftriaxone [35]. In Kenya, a study on antimicrobial resistance in Salmonella and E. coli isolates from poultry wastes reported high resistance to amoxicillin which is a beta-lactam, followed by tetracycline and co-trimoxazole [36]. High resistance to co-trimoxazole, beta-lactamst and etracycline among bacterial isolates from chicken in Kenya was also reported [37, 38]. This suggests possible transmission of antibiotic resistant bacteria through poultry feed to poultry.
The resistant isolates of Salmonella sp and Escherichia coli isolates carried TEM and SHV genes, contrary to a previous study that reported absence of major extended spectrum beta-lactamases in Salmonella isolates from poultry feeds in India [39].
The resistant isolates of Salmonella sp and Escherichia coli also carried (Dfr and (strB) genes. However, other related studies on poultry feeds did not look at resistance genes [27, 40, and 35].
Therefore, poultry feeds are potential source of antimicrobial resistant gene transfer to poultry and humans posing a health threat to the society.