Pseudomonas aeruginosa cellulitis and ecthyma gangrenosum in immunocompromised children.

Pseudomonas aeruginosa skin infections are generally considered to be secondary manifestations of disseminated disease. A retrospective analysis of all cases of P. aeruginosa skin infections seen at St. Jude Children's Research Hospital since 1962 revealed 16 episodes of the infection (ecthyma gangrenosum, 8 episodes, 7 patients; cellulitis, 8 episodes, 7 patients) in which blood cultures were uniformly negative for P. aeruginosa. All cases were identified while the patients were receiving ambulatory care. Five episodes developed while the patients' neutrophil counts were greater than 1 x 10(9) cells/liter. Eight patients had acute lymphoblastic leukemia, 2 had acute myeloid leukemia, 2 had aplastic anemia, 1 had transient agranulocytosis and 1 had cyclic neutropenia. There were no solid tumor patients. Although patients received different antibiotic combinations, all had resolutions of their lesions without fatal complications. Patients diagnosed as having cellulitis required a mean of 9.2 days of treatment with intravenous antibiotics, as compared with 17.8 days for those with ecthyma gangrenosum (P less than 0.05 by the Wilcoxon test). These observations show that P. aeruginosa skin infections can develop in the absence of bacteremia in immunocompromised children.