Antibiotic Sensitivity of Pathogenic Bacteria Associated with Subclinical Mastitis of Dairy Cows in the Poro Region of the Ivory Cost

Subclinical mastitis is the most considered pathology in dairy farming and is responsible for economic losses in cows. The condition remains asymptomatic in dairy cows and treatment is mainly done without laboratory analysis. The objective of this work is to research bacterial causes of subclinical mastitis in dairy cows and to study their sensitivity to certain antibiotics. Thus, this study was carried out in four departments (Korhogo, Sinématiali, Dikodougou and M'bengué) in the Poro region (Ivory Coast) from May to August 2022 in traditional farms on 288 neighborhood milk samples taken from dairy cows with subclinical mastitis. The milk samples were analyzed using standard bacteriological isolation and identification techniques. Staphylococcus aureus were isolated on Baird-Parker potassium tellurite agar and mixed with egg yolk, Klebsiella spp isolated on MacConkey agar, Escherichia coli isolated on MacConkey, Pseudomonas aeruginosa isolated on TSA and King A agar, Micrococcus spp isolated on Chapman agar; then incubated at 37°C for 24 to 48 hours. The identification of bacteria was carried out by standard methods (appearance of colonies, Gram staining, catalase test, coagula-associated oxidase test, etc.). The biochemical characteristics were studied using the API Bio Mérieux galleries (API Staph and API20E etc.) The sensitivity of the main germs isolated was tested against ten (10) antimicrobials including those used in the treatment of mastitis by veterinary clinicians in the region. from Poro.The bacteriological analysis were identified 43% of Gram-positive cocci in minority, with particulary 18% of Staphylococcus aureus. In majority, Gram-negative bacilli were detected at 57% with particulary 38% of Enterobacteria (Klebsiella spp and Escherichia coli). The antibiogram showed excellent sensitivity to Staphylococcus aureus to Gentamycin 100%, good sensitivity to chloramphenicol and neomycin at 90% then acceptable sensitivity to the Trimethoprim-Sulfamethoxazole combination, to cefalexin of 80%. The coagulase negative staphylococcus (SCN) group revealed good sensitivity to Cefalexin and Gentamicin of (87.5%) and acceptable sensitivity to Chloramphenicol, Neomycin of (75%) each. On the other hand, Enterobacteria showed excellent resistance to Ampicillin, Spiramycin and Penicillin 100% and acceptable resistance to Gentamycin (95.84%). Remarkable resistance has been observed on the following antibiotics : Ampicillin, Penicillin and Colistin. This remarkable resistance was noted in Staphylococci (100% for Staphylococcus aureus and 87.5% for SCN) and Enterobacteria. Given these results, suggestions were made for the treatment and prevention of subclinical mastitis on farms in the Poro region (northern Ivory Coast).