Antimicrobial Resistance of Staphylococci at Animal Human Interface in Smallholders and Dairy Farms in Central Oromia, Ethiopia.

Purpose: Staphylococcus species come from a variety of sources and can contaminate milk during milking, cause mastitis and other diseases in animals and humans. The enterotoxins they produce cause food poisoning. Our objectives were to isolate, biochemically characterize, and determine antimicrobial susceptibility profiles of Staphylococcus species from dairy farms in central Oromia, Ethiopia. Methods: A total of 339 samples (n = 135 [raw milk], n = 135 [udders' swabs], n = 25 [milkers' hands swabs], n = 44 [pooled milking utensils' swabs]) were collected from smallholders and dairy farms. Bacteriological culture and biochemical tests were performed to isolate and identify Staphylococcus species, and the Kirby Bauer disk diffusion method was used for antimicrobial susceptibility testing. Results: Across all sample types and dairy farms, 247 (72.9%) Staphylococcus isolates were obtained which comprised of 101 (74.8%) isolates from raw milk, 98 (72.6%) from udder swabs, 30 (68.2%) from pooled utensil swabs, and 18 (72%) from milkers' hand swabs. Fifty coagulase-positive Staphylococcus isolates (20 S. aureus, 20 S. hyicus and 10 S. intermedius) subjected to antimicrobial susceptibility tests have shown various degrees of resistance. All S. aureus isolates were 100% resistant to ampicillin and penicillin. Out of 20 S. hyicus isolates, 90% were resistant to ampicillin and 85% to penicillin. S. intermedius isolates (n=10) were 70% resistant to nalidixic acid and penicillin whilst remaining 100% resistant to ampicillin. Five S. aureus, three S. intermedius and two S. hyicus isolates from raw milk, milk utensil swabs and milkers' hand swabs were multidrug-resistant (resistance to at least three classes of antimicrobials). Conclusion: This study revealed a high prevalence of staphylococci in the dairy cattle, milkers and milking utensils with multidrug-resistant coagulase-positive Staphylococcus species suggesting the significance of pasteurization. Further research is encouraged on the factors leading to antibiotic resistance in Staphylococcus species.

Antimicrobial Resistance of Staphylococcus aureus Isolates from Dairy Cows and Genetic Diversity of Resistant Isolates.

Staphylococcus aureus is a frequent and major contagious mastitis bacterial pathogen. The antibiotic treatment cure rates vary considerably from 4% to 92%. Staphylococcus aureus readily becomes resistant to antibiotics, resulting in persistent noncurable intramammary infection that usually results in culling of infected animals. Because of its notorious ability to acquire resistance to the commonly used as well as last resort antimicrobials such as methicillin and vancomycin and the development of multidrug-resistant strains, antimicrobial resistance (AMR) in S. aureus is of paramount importance in human medicine. The objective of this study was to evaluate the prevalence of AMR and genetic diversity of S. aureus isolates from milk of dairy cattle. Staphylococcus aureus isolates (n = 239) from 33 dairy farms in Tennessee were tested against 10 antimicrobials by broth microdilution method using the Sensititer system. Genetic diversity of resistant isolates was evaluated by pulsed-field gel electrophoresis (PFGE). Overall, AMR of the S. aureus isolates varied from as low as 1.3% for ceftiofur to as high as 25% for sulfadimethoxine. Out of 239 S. aureus isolates, 82 (34.3%) of them were resistant to at least 1 of the 10 antimicrobials. The AMR isolates belonged to two major PFGE types, indicating the presence of dominant clonal patterns among the resistant isolates. In general, there was a variation of prevalence of AMR within and among farms over time, with an increasing trend in tetracycline resistance. Judicious use of antimicrobials in dairy cattle farms can reduce the development of antimicrobial-resistant S. aureus.

First-time detection of mycobacterium species from goats in Ethiopia.

Tuberculosis (TB) is an important zoonosis affecting a wide range of hosts. An abattoir study was conducted on 1,536 randomly selected male goats slaughtered at Modjo Modern Export Abattoir to determine the prevalence of tuberculosis in slaughtered goats. Carcasses and organs of all the study animals were first examined by routine meat inspection followed by detailed meat inspection. Samples from tuberculous lesions were cultured for mycobacterial isolation and identification. Histopathology was done on 31 samples with tuberculous lesions. Detailed meat inspection detected 65 (4.2%; 95% confidence interval (CI) = 3.3-5.4%) tuberculous lesions. From these, 20 (30.8%) samples were confirmed mycobacterium positive on culture, out of which 18 were Mycobacterium bovis and two were Mycobacterium tuberculosis. Routine meat inspection failed to detect tuberculous lesions in 23% of carcasses with TB lesions detected by detailed examination. However, no statistically significant difference was observed between both methods in detecting tuberculous lesions (Kappa = 0.87). Origin and age of the goats did not statistically affect the disease prevalence (P > 0.05). Histopathologic lesions were observed in 21 samples (68%; 95% CI = 50.1-81.4%) out of the 31 carcasses with gross tuberculous lesions examined by histopathology. Eighteen (58%) tuberculous samples positive for histopathology were also culture positive. The sensitivity and specificity of histopathology were 90% (95% CI = 76.9-100%) and 72.7% (95% CI = 46.4-99%), respectively, using culture as a reference test. To the best of our knowledge, this is the first report of caprine tuberculosis from Ethiopia. Further studies are required at the farm level to determine the prevalence of tuberculosis in the general goat population.