The Isolation of Staph Aureus from Cow's Milk

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The goal of this study was to isolate staphylococcus aureus from samples of cow’s milk obtained from different farm settings and to determine their antibiotic susceptibility patterns. “Cow’s milk samples were collected from commercial farms in Rooigrond and Molelwane and communal farms in Lokaleng and Mogosane” in the North West province of South Africa. Gram staining, DNase, oxidase, catalase haemolysis and the MASTASTAPHTM rapid agglutination tests were used for bacteria identification. Staphylococci are normal inhabitants of the skin and mucous membranes of animals and humans. The disease causing staphylococci are “usually coagulase-positive1 and have been found to cause disease in their hosts throughout the world”. For the study, a total of 28 milk samples were collected and screened for the presence of S. aureus. Milk is an xceptional growth medium for the growth of many bacteria including S. aureus. A total of 240 s aureus isolates were obtained. “Diseases in cattle caused by Staphylococcus aureus range from simple abscesses and mastitis to the more severe toxic shock syndrome”. Cow’s milk samples were collected and isolated from different areas in north western Africa. For the isolation,”ten fold serial dilutions were performed using 2% peptone water and aliquots of 100 ul from each were plated onto mannitol salt agar” and then incubated at 37 C for 18 to 24 hr. the identification was done using Gram staining technique after which the organisms were microscopically observed. A total of 240 S. aureus were obtained . “All 240 S. aureus isolates were subjected to antibiotic susceptibility tests. Nine antimicrobial agents, from different antibiotic classes were used”. After pressing the antibiotic disc onto the inoculated Mueller Hinton agar the plates were incubated at 37 C for 18 to 24h, the zone of inhibition diameters are measured and results obtained. S aureus are then classified as resistant, intermediated resistant or susceptible to a particular...
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