Prevalence and antibiotic susceptibility of methicillin resistant Staphylococcus aureus (MRSA) isolated from bovine mastitis in settled Fulani herds in Kaduna State

Abstract

A study was conducted to determine the prevalence and antibiotic resistance of methicillin resistant Staphylococcus aureus (MRSA) from bovine mastitis in settled Fulani herds in Kaduna state. Three hundred and sixty milk samples randomly collected from selected herds in Kaduna South, Igabi, Lere, Sabon-Gari, Giwa and Zaria were examined. The prevalence of mastitis at cow level was 26.9%, out of which 3.1% and 23.9% were clinical and subclinical mastitis, respectively. The prevalence of both S. aureus and MRSA were 15.3% and 7.8 % respectively. Significant proportion (42.9%) of the MRSA were isolated from cases of mastitis (P<0.05). Very high percentages of MRSA were resistance to penicillin (100.0%), amoxicillin (89.3%), ampicillin (89.3%), tetracycline (85.7%) and erythromycin (71.1%). The multiple drug resistance indices of the MRSA strains revealed that all the MRSA strains were resistant to 5 or more antibiotics tested; 6 (21.4%) strains were resistant to 6 antibiotics, 6 (21.4%) were resistant to 7 antibiotics, 8 (28.6%) were resistant 8 antibiotics and 4 (14.3%) were resistant to 9 antibiotics, while 19 (67.9%) exhibited the extensive drug classification pattern. The MIC values of the antibiotics showed that all (100%) have values greater than 256 μg/mL against oxacillin while 15 (53.6%) have values greater than 256 μg/mL against vancomycin, respectively. Nineteen (67.9%) of the MRSA isolates tested for PBP2a gave strongly positive (3+ to 4+) reactions in the Latex Agglutination Test, 5 (1.9%) were weakly positive (1+) in the Latex Agglutination Test while 4 (14.3%) were negative. The occurrence of MRSA in bovine mastitis is of public health concern due to difficulty in treatment of staphylococcal diseases and possible transmission of resistant pathogens to humans. Therefore, continuous monitoring and surveillance of antibiotic resistance pathogens, good husbandry practices, culling of infected cows and pasteurization of milk to eliminate MRSA and other pathogens are recommended

Keywords: Prevalence, antibiotic susceptibility, MRSA, Bovine mastitis, cow milk, multi drug resistance, extensive drug resistance (XDR), minimum inhibitor concentration, Penicillin Binding Protein 2a