Antibiotic quality and use practices amongst dairy farmers and drug retailers in central Kenyan highlands

Abstract

Understanding antibiotic use in dairy systems is critical to guide antimicrobial stewardship programs. We investigated antibiotic use practices in small-holder dairy farms, antibiotic quality, and antimicrobial resistance (AMR) awareness among veterinary drug retailers in a mixed farming community in the central Kenyan highlands. Data were collected from 248 dairy farms and 72 veterinary drug stores between February 2020 and October 2021. A scale was developed to measure knowledge about AMR and antibiotic use using item response theory, and regression models were used to evaluate factors associated with antibiotic use and AMR knowledge. The active pharmaceutical ingredient (API) content of 27 antibiotic samples was determined using high-performance liquid chromatography (HPLC). The presence and levels of 11 antibiotic residues in 108 milk samples collected from the study farms were also investigated using liquid chromatography tandem mass spectrometry (LC-MS/MS). Almost all farms (98.8%, n = 244) reported using antibiotics at least once in the last year, mostly for therapeutic reasons (35.5%). The most used antibiotics were tetracycline (30.6%), penicillin (16.7%), and sulfonamide (9.4%), either individually or in combination, and predominantly in the injectable form. Larger farm size (OR = 1.02, p < 0.001) and history of vaccination use (OR = 1.17, p < 0.001) were significantly associated with a higher frequency of antibiotic use. Drug retailers who advised on animal treatments had a significantly higher mean knowledge scores than those who only sold drugs. We found that 44.4% (12/27) of the tested antibiotics did not meet the United States Pharmacopeial test specifications (percentage of label claim). We detected nine antibiotics in milk, including oxytetracycline, sulfamethoxazole, and trimethoprim. However, only three samples exceeded the maximum residue limits set by the Codex Alimentarius Commission. Our findings indicate that antibiotics of poor quality are accessible and used in small-holder dairy systems, which can be found in milk. These results will aid future investigations on how to promote sustainable antibiotic use practices in dairy systems.

Figure 1

Fit of the Poisson generalized linear model relating the number of dairy cattle on study farms, vaccination history, and number of antibiotics used. The 95% confidence interval is represented by the colored bands.

Figure 2

Fit of the generalized linear model relating the knowledge scale and demographic attributes. The 95% confidence interval is represented by the error bars.

Figure 3

Content of the active pharmaceutical ingredient (API) determined for each antibiotic purchased. Each sample is represented by a dot, with red color indicating extreme deviation, amber indicating moderate deviation, and green indicating compliance within the quality range. EFT, ceftiofur; OXY, oxytetracycline; DSTR, dihydrostreptomycin; PEN, penicillin; SXT, sulfamethoxazole; TMP, trimethoprim; TET, tetracycline; SUL, sulfadiazine; STR, streptomycin.