CULTURES OF SKIN BIOPSY-TISSUE FROM IMMUNOCOMPROMISED PATIENTS WITH CANCER AND RASHES

Background and Design: Microbiological cultures of skin biopsy tissue are often recommended in immunecompromised patients with cancer and ra shes, but in a previous study, they were usually sterile or grew clini cally insignificant organisms. To examine the use and bacteriological results of these cultures more comprehensively, we reviewed records fr om all immunocompromised adults with cancer and acute rash on which sk in biopsy was performed during 39 months on a bone marrow transplantat ion/acute leukemia unit of a university hospital (108 episodes of rash in 80 patients). Results: Of the 158 cultures that were performed, on e (1%; 95% confidence interval [CI], 0% to 4%]) was a true positive; 1 1 (7%; 95% CI, 3% to 13%) were false positive; 143 (91%; 95% CI, 87% t o 95%) were true negative; and three (2%; 95% CI, 1% to 6%) were false negative. Thus, the sensitivity of culture was 0.25, and the specific ity was 0.93. Coagulase-negative Staphylococcus was the single pathoge nic organism that grew, yet was judged to be a contaminant in three ep isodes. Among the 95 rashes in which fewer than four types of culture were performed, viral culture may have been helpful in one case (1%; 9 5% CI, 0% to 6%). Conclusions: Cultures of skin tissue from immunocomp romised cancer patients with rashes were often unable to diagnose infe ction or the absence of infection. Clinical judgment was crucial to th e interpretation of culture results.