Oral succession of gram-negative bacilli in myelosuppressed cancer patients.

Aerobic and facultative gram-negative bacilli (GNB) have been reported to increase on various body surfaces in the seriously ill and debilitated patient. This study examined quantitative aspects of GNB succession at five oral sites in cancer patients before and during myelosuppressive chemotherapy. GNB concentrations increased sharply during chemotherapy at 25 to 50% of the oral sites in both acute nonlymphocytic leukemia and small-cell lung carcinoma patients. Most sites did not exhibit shifts of GNB to levels higher than 0.1% of the cultivable flora. When shifts occurred, all sites sampled in the mouth were usually affected and GNB usually represented more than 10% of the cultivable flora. Low levels of indigenous microflora were observed in most sites exhibiting GNB shifts. None of the subjects harboring high levels of GNB developed the symptoms of acute infection which are commonly observed in myelosuppressed patients. Although Pseudomonas aeruginosa and Klebsiella pneumoniae were recovered from some sites, most GNB were nonpathogenic species of Pseudomonas; Pseudomonas pickettii was the most frequently recovered.