Association of Pseudomonas maltophilia with malignant lesions.

Infections caused by nonfermentative, gram-negative, rod-shaped bacteria (NFGNR) in 564 patients were reviewed. For comparison, 227 patients with Serratia marcescens infections were also studied. Among the patients with NFGNR infections, 24% had some form of malignant solid tumor, and 9% had leukemia and lymphoma. Among the patients with S. marcescens infections, 22% had some type of malignant solid tumor, and 8% had leukemia and lymphoma. The frequency of various species of NFGNR (except Pseudomonas maltophilia and S. marcescens) in patients with a malignancy at the site from which the specimens had been obtained was 5 to 24%. However, 39 of 82 patients (48%) with P. maltophilia infections had a malignancy at the site from which P. maltophilia had been isolated. There were significantly more P. maltophilia infections at the sites of malignant lesions than there were other NFGNR or S. marcescens infections (P less than 0.05).