DefinePK

Abstract

The disease mastitis caused by different microorganisms can lead to significant yield losses of milk and its quality. The detection of disease at subclinical stage is much more effective to prevent the occurrence of the disease than the detection of the disease at later stages. For determining the prevalence of Staphylococcus sp. causing Subclinical Mastitis SCM in dairy cows in Chittagong, a Southern district of Bangladesh, milk samples were collected from 4 different dairy farms under Chittagong City Corporation. After initial screening by California mastitis test to identify milk samples infected with SCM pathogens, Staphylococcus sp. were isolated and identified by culturing CMT-positive milk samples on selective Mannitol Salt Agar MSA medium which was followed by biochemical characterization. PCR was employed to detect S. aureus from Staphylococcus isolates using species-specific primers. Culture Sensitivity CS test was done to determine the antibiotic sensitivity pattern of Staphylococcus isolates against 8 commercially available antibiotic discs ampicillin, amoxycillin, cephalexin, ciprofloxacin, erythromycin, gentamycin, doxycycline hydrochloride and oxytetracycline. To develop plasmid profiles, further extraction of plasmids from Staphylococcus isolates were performed. The results of this research showed that the prevalence of SCM was 74.49. The 26.71 of milk samples were infected with Staphylococcus sp., 11.64 were contaminated with coagulase positive Staphylococcus and 15.07 with coagulase negative Staphylococcus. Molecular study using PCR revealed that the prevalence of S. aureus causing SCM was 5.48. CS test of Staphylococcus isolates showed that a high percentage 88.89 of Staphylococcus isolates were resistant to oxytetracycline while most 94.44 of the Staphylococcus isolates were susceptible to ciprofloxacin. Plasmid profile analysis revealed that 72.22 of Staphylococcus isolates carried 1 or more plasmids, while further analyses indicate that the multi drug resistance properties may or may not be associated with their presence.