Mastitis on selected farms in Wakiso district, Uganda: Burden, pathogens and predictors of infectivity of antimicrobial resistant bacteria in dairy herds.

BACKGROUND: Mastitis and associated antimicrobial resistance (AMR) are major challenges to the dairy industry worldwide. OBJECTIVE: This study aimed to expose the mastitis burden, causative bacteria and drivers for mastitis-causing multi-drug-resistant (MDR) Staphylococci infectivity in cows on dairy farms in Wakiso district, Uganda. METHODS: On 22 farms, practices were documented using questionnaires, and 175 cows were screened by the California mastitis test. Composite milk samples from the positive reactors were submitted to the laboratory for bacterial culture testing. Antimicrobial sensitivity testing by the Kirby Bauer disc diffusion method was done only on Staphylococci with a panel of 10 antimicrobials of clinical relevance. RESULTS: Mastitis was detected in 80.6% (n = 141) of the 175 sampled cows, of which sub-clinical mastitis (76.0%: n = 133) was predominant. The Chi-squared analysis hypothesized that cow age (p = 0.017), sub-county (p = 0.013), parity (p < 0.0001), sex of farm owner (p = 0.003), farm duration in dairy production (p = 0.048) and the use of milking salve (p = 0.006) were associated with mastitis. Coagulase-negative Staphylococci were the most prevalent (71.4%; n = 95), followed by Staphylococcus aureus (30.1%, n = 40). Staphylococci (76.3%; n = 135) were majorly resistant to penicillin and tetracycline. Only one isolate was phenotyped as a methicillin-resistant Staphylococcus specie (MRSS). The prevalences of MDR strains at cow and isolate level were 6.3% and 8.3%. The major MDR phenotype identified was penicillin-tetracycline-trimethoprim-sulphamethoxazole. The isolate detected as an MRSS exhibited the broadest MDR pattern. Cow parity was identified as a predictor of infectivity of mastitis-causing MDR Staphylococci in dairy herds. CONCLUSION: The high prevalence of mastitis and associated pathogen AMR found exposes possibilities of economic losses for the dairy sector warranting the need for farmer sensitization on the institution of proper mastitis prevention and control programs, with emphasis on milking hygiene practices and routine disease monitoring.

Epidemiological Dynamics of Extended-Spectrum ß-Lactamase- or AmpC ß-Lactamase-Producing Escherichia coli Screened in Apparently Healthy Chickens in Uganda.

The dynamics of extended-spectrum ß-lactamase- (ESBL-) and AmpC ß-lactamase-producing bacteria (which are deadly groups of antimicrobial-resistant bacteria) have not been well understood in developing countries. This raises major concerns to antimicrobial resistance (AMR) control. We investigated the prevalence and factors linked to the fecal carriage of ESBL- or AmpC-producing Escherichia coli (ESBL-/AmpC-EC) in commercial chickens. Cloacal swabs from 400 birds were sampled and submitted to the Central Diagnostic Laboratory for ESBL-/AmpC-EC screening by culture methods using MacConkey agar supplemented with cefotaxime. Epidemiological data were collected using a structured questionnaire and plausible risk factor analyses prepared by R software using X 2 test and logistic regression modeling. Results showed that the prevalence of ESBL-/AmpC-EC was 17.5%. Univariable screening hypothesized that carriage was probably influenced by a type of commercial chicken, geographical location, age group, flock size, and housing system (p < 0.05). Modeling exposed that broiler birds were at a higher risk of being ESBL-/AmpC-EC carriers (COR = 9.82, CI = 3.85-25.07). Birds from Wakiso Town Council (COR = 4.89, CI = 2.04-11.72) and flocks of 700-1200 birds were also at a higher risk of harboring ESBL-/AmpC-EC (COR = 2.41, CI = 1.11-5.23). Birds aged 4 months and below were more susceptible to ESBL-/AmpC-EC carriage compared with those aged 1 month and below being 6.33 times (CI = 1.65-24.35) likely to be carriers. The occurrence of ESBL-/AmpC-EC in flocks suggests possible treatment failures while managing colibacillosis. Consequently, injudicious antimicrobial use should be replaced with an accurate diagnosis by bacterial culture and sensitivity testing so as to circumvent AMR emergence, spread, and associated losses.

Prevalence of Mycobacterium bovis skin positivity and associated risk factors in cattle from western Uganda.

PURPOSE: A cross-sectional study was undertaken to determine the prevalence of Mycobacterium bovis skin positivity and associated risk factors in cattle in western Uganda. METHODS: Herds were selected using multi-stage cluster sampling. The comparative cervical intradermal tuberculin test (CCT) was used to determine cattle tuberculosis status using US Department of Agriculture protocols. Risk factor data were collected from cattle owners through questionnaires collected by in-person interviews. Multivariable logistic regression models were used to measure the association between risk factors and herd CCT reactor prevalence. RESULTS: A total of 525 cattle from 63 herds were screened for M. bovis infection. Of the 525 cattle tested, 2.1 % were CCT reactors and 15.43 % were CCT suspects. Of herds tested, 14.28 % had at least 1 CCT reactor. Using a private water source for cattle and not introducing new cattle into the farm were associated with lower prevalence of M. bovis skin positivity. The herd-level prevalence of M. bovis reactors in Kashaari County of Mbarara District was 14.5 %, and the individual cattle prevalence was low (2.1 %). CONCLUSIONS: Using communal sources of drinking water for cattle and introducing new cattle on the farm were farm management practices associated with increased risk of M. bovis exposure in cattle. Despite the low prevalence of bovine tuberculosis (TB), there is a need to educate the populace on the possibility of human infection with zoonotic TB and for educating farmers on practices to reduce the risk of acquiring M. bovis in the Mbarara District.