Enumeration of Staphylococcus aureus in foods with special reference to egg-yolk reaction and mannitol negative mutants

Selective isolation and enumeration of low numbers of Staphylococcus aureus by a procedure that relies on elevated-temperature culturing

A procedure for the selective detection of Staphylococcus aureus was elaborated, consisting of three parts: (i) enrichment in liquid Baird-Parker medium; (ii) isolation on Baird-Parker agar incubated at 43 degrees C, and (iii) confirmation by means of the test for thermostable nuclease. Elevated-temperature incubation of Baird-Parker medium did not make it inhibitory to cells stressed by heat treatment or osmotic shock.

Liquid modification of Baird-Parker's medium for selective enrichment of Staphylococcus aureus

A liquid modification of Baird-Parker's medium is suggested for the detection of low (less than 20/g) numbers of Staphylococcus aureus. Model experiments showed that the medium had an acceptable level of selectivity and that it was non-inhibitory to injured cells. Practical evaluation demonstrated the advantage of selective enrichment procedures over both non-selective enrichment technique and direct plating methods.