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A Medium for the Rapid Recognition of Penicillin-resistant Coagulase-positive Staphylococci

1957; BMJ; Volume: 10; Issue: 1 Linguagem: Inglês

10.1136/jcp.10.1.96

1472-4146

R. M. M. Klemperer, Geoffrey Haughton,

Bacterial Identification and Susceptibility Testing

Because ofthegrowing importance ofstaphylococcalcross-infection in hospitals, a simple, reliable, and rapidmethodfortheprimary isolation of theseorganisms from wounds, carriers, clothing, bedding, anddustisneeded. Thatmostwidely usedisgrowth onplain orblood agarplates, fromwhichsuspect colonies are pickedandtested by either thetubeorslide coagulase test.Theaddition ofsalttonutrient agartoafinal concentration of70,%' suppresses the growth ofother bacteria, andisofgreat valuein recovering staphylococci fromfaeces, butithas thedisadvantage that colonies maynotappear for 48hours, anddonotalways givea positive slide coagulase test unless subcultured onnutrient agar. A great improvement istheuseofnutrient agar containing phenolphthalein phosphate asemployed byBarber andBurston (1955) intheir studies of hospital infections. Afterincubation theplates wereexposed toammoniavapour, whenphosphatase-producing colonies, mainly coagulase-positive staphylococci, gavea reddish colour, andwere later tested forcoagulase production bythetube test. Duthie andLorenz(1952) addedsterile human fibrinogen witha little humanplasma tomolten agarat50°C.,after whichplates wererapidly poured.Suchplates gaveopaquerings offibrin aroundcoagulase-positive