Antimicrobial Resistance in Escherichia Coli, Klebsiella pneumoniae and Pseudomonas Aeruginosa Isolated from Milk of Dairy Cows in Three Nigerian Cities

Bovine mastitis is usually associated with bacterial pathogens isolated from the milk or mammary glands of dairy cows. A total of 205 isolates comprising of 110 (53.66%) Escherichia coli, 67 (32.68%) Klebsiella pneumoniae, and 28 (13.66%) Pseudomonas aeruginosa obtained from cases of bovine mastitis from southwest and Northern Nigeria during a period of one year were tested for susceptibility to ampicillin, tetracycline, neomycin, streptomycin, sulphadimidine and nalidixic acid using minimum inhibitory concentration (MIC) method. The results demonstrated wide variation of in the susceptibility patterns for the various organisms from different regions of Nigeria. The three organisms displayed highest resistance to sulphadimidine 200 (97.5%) followed by ampicillin 153 (74.63%), tetracycline 103 (50.24%), neomycin 90 (43.90%), streptomycin 68 (33.17%) and nalidixic acid 29 (14.15%) respectively. The resistance patterns of the strains revealed 27 distinct resistance groups. In conclusion these data confirmed that majority of the Gram negative organisms that are causative agents of mastitis in Nigeria were resistant to several antibiotics. This could be a result of indiscriminate use of drugs by dairy farmers for treatment of mastitis in their herd