This study was conducted to investigate the presence of antimicrobials in animal derived foods in Nakuru city. A total of forty-nine samples were analyzed for antimicrobial residue determination using an immunoassay designed to test for presence of quinolones, ceftiofur, thiamphenicol, streptomycin, tylosin and tetracyclines. Samples were randomly collected from slaughter houses, shops, supermarkets and a milk quality analysis laboratory. Results of analysis showed that streptomycin and tetracycline had the highest mean residue levels (13.40 ppb (parts per billion) and 5.13 ppb respectively). One milk sample contained streptomycin at levels above the Codex Alimentarius maximum residue limits (MRL).Comparison of antimicrobial residue levels using Mann-Whitney U test showed statistically significant difference(U = 78.00, Z = -3.535, p<0.001)in levels of tetracycline residues detected from meat and milk samples, the amounts being higher in meat samples compared to milk. A critically important antibiotic, quinolone, was detected at 14.5 ppb in one bovine muscle sample. This is an important finding since the consequences of antimicrobial resistance that may result from food chains have greatest impact when pathogens are resistant to critically important antimicrobials in humans. This mini-survey suggests that antimicrobial residues are present in animal derived-foods in Nakuru county, Kenya, and recommends for a more detailed study to investigate the findings in greater depth.

Keywords: Antimicrobial residue, immunoassay, tetracycline, streptomycin, quinolones, parts per billion, Mann-Whitney, Maximum residue limits