Increased translocation of bacteria from the gastrointestinal tracts of tumor-bearing mice

Publisher Website
Google Scholar
Abstract
Aerobic gram-negative bacilli and other indigenous gastrointestinal (GI) bacterial are important opportunistic pathogens in immunosuppressed cancer patients. These same bacteria frequently translocate from the GI tracts of mice immunosuppressed by single injections of certain anticancer drugs or by T-lymphocyte impairments. Since similar cellular and humoral immune deficiencies may be present in the tumor-bearing host, it was determined if progressive growth of a tumor alone would be sufficient to enhance the translocation of indigenous bacteria from the murine GI tract. Pathogen-free DBA/2 mice were injected i.p. with 106 viable sarcoma 180 (S-180) cells or 0.5 ml of sterile buffer. Mesenteric lymph nodes, livers, spleens and kidneys were tested for the presence of translocated aerobic GI baceteria on various days after tumor injection. Immunity was assessed by measuring footpad delayed-type hypersensitivity and serum hemagglutinins to sheep erythrocytes. Overall, translocated aerobic GI bacteria infected 33 of 92 S-180-bearing mice (36%) and only 9 of 99 control mice (9%) (P < 10-6). Cumulatively, 50 of 460 sites (10.9%) in S-180-bearing mice were infected with translocated GI bacteria as opposed to only 9 of 485 sites (1.9%) in control animals (P < 10-7). GI bacteria often translocated to infect > 1 site in tumor-bearing mice, but not in controls. Aerobic gram-negative bacilli translocated 11 times in tumor-bearing mice, but only once in controls, even though the mean cecal population levels of these bacteria were relatively low (range, 4.33 to 5.28 log10 bacteria per g). The population levels of cecal aerobic bacteria were similar in S-180 and control mice throughout the period of observation. S-180 mice had significantly suppressed (P < 0.04) delayed-type hypersensitivity and serum hemagglutinin responses when sensitized 4 or 8 days after S-180 injection. S-180 growth was associated with neutrophilic leukocytosis and a slight drop in platelet counts; no bleeding was detected. Thus, the translocation of gram-negative bacilli and other indigenous aerobic bacteria from the GI tract to the mesenteric lymph nodes and other organs was increased in immunosuppressed S-180 bearing mice, and this increase was not caused by bacterial overgrowth in the intestines or by neutropenia.