Infectious aetiologies of subclinical bovine mastitis and antimicrobial susceptibility on northwest of Algeria

Abstract

Subclinical mastitis is one of the most common and expensive diseases in dairy cattle farming, the financial losses caused by mastitis can have a serious effect on economy of dairy industry. Inflammation of mammary gland is a multifactorial and complex disease; the infection can be caused by a large range of pathogenic germs. The objective of this study was to carry out a screening of subclinical mastitis by California mastitis test and to determine the infectious aetiology. A score ≥ 1 was considered positive. 135 milk samples were examined by California mastitis test for mastitis detection, from which 42 samples were found positive and were subjected to bacteriological analysis by standard biochemical tests, in addition an antibiotic sensitivity test was done on bacterial isolate. The prevalence of subclinical mastitis was 31.1% in quarters level and 62.8% in dairy cows, hindquarters were the most infected 35% compared to forequarters 27%. the frequency of infected quarters according to California mastitis test scores 1, 2 and 3 was 7.4%, 14.8% and 8.8% respectively, the most isolated germs from the samples were coagulase negative staphylococci (39%), Enterococcus faecium (10%), Klebsiella pneumoniae (7%) and Enterobacter cloacae (7%), and Enterococcus faecalis (7%). Staphylococcus spp showed a high sensitivity 100% to erythromycin, trimethoprim and neomycin, and lower sensitivity of 33% to amoxicillin. The Enterobacteriaceae exhibited a medium sensitivity of 50% to only trimethoprim and were resistant to other antibiotics.