suMMARY An alternative method for detecting the production of slime by coagulase negative staphylococci was compared with the routinely used Christensen method on 124 isolates ofcoagulase negative staphylococci from carriage sites, blood cultures, and infected peritoneal dialysis fluids. The alternative method requires the use ofa specially prepared solid medium-brain heart infusion broth, supplemented with 5% sucrose, and Congo red stain. Of the 124 tests, there was complete agreement between methods in 107 and only one strain was clearly negative by Christensen's method while positive on Congo red agar.The Congo red method is rapid, sensitive, and reproducible and has the advantage that colonies remain viable on the medium. It is also not subject to interbatch variation ofmedia which sometimes affects the reproducibility of the Christensen method.

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The susceptibility to vancomycin of nine staphylococcal strains responsible for nine episodes of peritonitis in patients on continuous ambulatory peritoneal dialysis was correlated with outcome of therapy. All strains examined had MIC values indicating sensitivity (MIC.:; 4 μg/ml). Tolerance was observed in one strain of Staphylococcus aureus (MIC = 1 μg/ml., MBC = 64 μg/ml). Time-kill studies using three different media demonstrated this organism's reduced susceptibility to vancomycin and suggested that testmedium composition may also affect the result. The patient with the tolerant strain, required an extended period of treatment.