Molecular and conventional studies on staphylococcus aureus isolated from milk of subclinical bovine mastitis cases and associated dairy workers

ABSTRACT

Staphylococcus aureus [S.aureus] is the world over pathogen that causes a variety of infections in man and animals. Detection of S. aureus in collected milk samples from apparently normal animals and comparing their genotypic traits with those isolated from hands of dairy workers. A total of 160 apparently normal quarter foremilk samples, collected from 40 machine milking Friesian lactating cows from Aswan governorate, were cultivated on Baird Parker media. 40 swabs collected from dairy workers' hands or faces were streaked on mannitol salt egg yolk agar [MSEY agar]. Isolated Staphylococcus aureus strains were examined for coagulase slide test, Catalase and DNAase test. Staphylococcus aureus isolated were tested by a two multiplex PCR assays one of them was to detect 16SrRNA gene and coagulase [coa] gene. The second multiplex PCR was to clarify presence of Staphylococcus aureus entertoxins type A [SEA] and B [SEB] in positive coagulase S.aureus. For bovine milk, A prevalence rate of 40.6% and 45.0% of California mastitis test [CMT] and Somatic cell count [SCC] was detected respectively. Whereas, coagulase test was positive in 54.4% and 61.1% of bovine milk and dairy workers in the same sequence. 16Sr-RNA gene was positive in 100% of both bovine milk and dairy workers. But coagulase [Coa] gene was positive in 63.4% and 72.2% of milk and dairy workers respectively. SEA was positive in 21.8% and 38.8% of milk and dairy workers respectively, while SEB was positive in 30.1% and 50% in the same sequence. Testing milk [by CMT, SCC microbial isolation] for detection of subclinical mastitis is an essential part of daily evaluation record of each dairy farm. Detection of Staphylococcus aureus by PCR as well as entertoxins identification was found to be rapid, sensitive and accurate. Special concern should be directed to elucidate the kinetic transfer of Staphylococcus aureus between animals and human. Detection of Staphylococcus aureus entertoxin A and B was found to be easy and rapid by using PCR