Pneumococcal bacteremia in patients with neoplastic diseases

Pathogenesis of pneumococcal pneumonia in cyclophosphamide-induced leukopenia in mice

Streptococcus pneumoniae pneumonia frequently occurs in leukopenic hosts, and most patients subsequently develop lung injury and septicemia. However, few correlations have been made so far between microbial growth, inflammation, and histopathology of pneumonia in specific leukopenic states. In the present study, the pathogenesis of pneumococcal pneumonia was investigated in mice rendered leukopenic by the immunosuppressor antineoplastic drug cyclophosphamide. Compared to the immunocompetent state, cyclophosphamide-induced leukopenia did not hamper interleukin-1 (IL-1), IL-6, macrophage inflammatory protein-1 (MIP-1), MIP-2, and monocyte chemotactic protein-1 secretion in infected lungs. Leukopenia did not facilitate bacterial dissemination into the bloodstream despite enhanced bacterial proliferation into lung tissues. Pulmonary capillary permeability and edema as well as lung injury were enhanced in leukopenic mice despite the absence of neutrophilic and monocytic infiltration into their lungs, suggesting an important role for bacterial virulence factors and making obvious the fact that neutrophils are ultimately not required for lung injury in this model. Scanning and transmission electron microscopy revealed extensive disruption of alveolar epithelium and a defect in surfactant production, which were associated with alveolar collapse, hemorrhage, and fibrin deposits in alveoli. These results contrast with those observed in immunocompetent animals and indicate that leukopenic hosts suffering from pneumococcal pneumonia are at a higher risk of developing diffuse alveolar damage.

Pulmonary and systemic host response to Streptococcus pneumoniae and Klebsiella pneumoniae bacteremia in normal and immunosuppressed mice

Mortality related to bacteremic pneumonia remains high, and the role of sepsis in inflammation, pulmonary injury, and death remains unclear, mostly in leukopenic states. In the present study, the microbiology, histopathology, and host response to Streptococcus pneumoniae and Klebsiella pneumoniae infection were determined in an experimental model of bacteremia in immunocompetent and leukopenic mice. Leukocyte depletion by cyclophosphamide did not impair the early clearance of pneumococci from blood but facilitated growth in lungs. By contrast, klebsiellae rapidly grew in blood of leukopenic mice. These observations suggest that tissue-based phagocytes and circulating leukocytes, respectively, play prominent roles in S. pneumoniae and K. pneumoniae eradication. The kinetics of leukocyte recruitment in lungs during S. pneumoniae bacteremia suggested early strong inflammation in immunocompetent mice that is associated with tumor necrosis factor alpha release and histological disorders, including cell debris and surfactant in alveolar spaces. Leukocyte depletion further stimulated pulmonary capillary leakage both in S. pneumoniae and K. pneumoniae bacteremia, which seemed attributable to bacterial virulence factors. Nitric oxide production did not differ significantly among groups. Leukopenia and low platelet counts characterized the late stage of bacteremia for both strains, but only K. pneumoniae altered renal function. Understanding the pathogenesis of bacteremia will help establish beneficial therapies for both sepsis and pneumonia.

Infection and immunity in chronic lymphocytic leukemia

Patients having chronic lymphocytic leukemia (CLL) are at increased risk for infectious morbidity and mortality. The predisposition to infections in CLL patients has many components, including both immunodeficiency related to the leukemia itself (humoral and cellular immune dysfunction) and the results of cumulative immunosuppression related to CLL treatment. The risk of infectious complications increases with the duration of CLL, reflecting the natural history of the disease and the cumulative immunosuppression related to its treatment. Hence, in early, untreated CLL, the infectious risk is mainly related to hypogammaglobulinemia, and infections by encapsulated bacteria are common. However, in patients having advanced CLL, particularly those who receive the newer purine analogues, neutropenia and defects in cell-mediated immunity appear to be the major predisposing factors. An expanded spectrum of pathogens, including opportunistic fungi, Pneumocystis carinii, Listeria monocytogenes, mycobacteria, and herpesviruses, are seen in that setting. The changing spectrum of infections in this latter group of patients mandates a newer approach to prophylaxis and therapy.

Pneumococcal bacteremia in cancer patients

Twenty-eight episodes of Streptococcus pneumoniae bacteremia occurring in 27 cancer patients hospitalized in the Institut Jules Bordet between July 1979 and April 1985 were reviewed. Ten patients had hematological malignancies and 17 had solid tumors (in 7 cases, of the lung). Forty-four per cent of the patients were neutropenic (less than 1000/microliters) and 36% of the patients were in septic shock. In 36% of the patients no clinical source of S. pneumoniae bacteremia could be found. Seventy-nine (21% patients) received empirical antibiotic treatment containing a beta-lactam. Two patients who did not receive any empirical treatment died within 12 hours. Overall, 11/27 patients died within the first week, and 8/27 died within the first three days. Mortality in neutropenic patients was not different from that in non-neutropenic patients. In comparison with a similar study performed previously in our institution, there was no difference in incidence, type of patient, source of bacteremia, or mortality.

Placebo controlled pneumococcal immunization in patients with bronchogenic carcinoma

Pneumococcal vaccine [heptadecavalent types 1, 2, 3, 4, 6A, 7F, 8, 9N, 11A, 12F, 14, 15F, 17F, 18C, 19F, 23F and 25 pneumococcal capsular polysaccharide vaccine (Moniarix)] or placebo were evaluated in 26 and 21 patients with bronchogenic carcinoma, most of whom did not receive prior radiotherapy or chemotherapy. No difference was detected as far as clinical outcome is concerned: 3 vaccinated patients out of 26 (11.5%) developed pneumococcal infections (1 fatal bacteremia) and 4/21 (19%) of those who received a placebo presented such an infection (1 fatal bacteremia). The antibody response was significantly increased in the vaccines for types 1, 2, 7F, 8, 9N, 12F, 14, 17F, 18C, 23F and 25.

Comparison of latex agglutination and counterimmunoelectrophoresis in the diagnosis of acute Streptococcus pneumoniae infections

The ability of latex agglutination (Slidex Pneumokit) and counterimmunoelectrophoresis to detect Streptococcus pneumoniae antigen in body fluids was evaluated. The patients were classified as having proven Streptococcus pneumoniae infection, suspected Streptococcus pneumoniae infection, acute superinfection of chronic bronchitis or non-pneumococcal respiratory infection. Sixty-two non-pneumococcal meningitis patients were also included in the study. Latex agglutination and counterimmunoelectrophoresis tests were performed on serum, urine and cerebrospinal fluid specimens when indicated and repeated each week until the patient was discharged. Latex agglutination was done on samples boiled for 10 min. In vitro sensitivity of counterimmuno-electrophoresis and latex agglutination were 10 and 1 ng/ml respectively for type three antigen. In pulmonary disease (proven and suspected Streptococcus pneumoniae infection) counterimmunoelectrophoresis and latex agglutination had a clinical sensitivity of 72.9 and 87.5% respectively, a specificity of 96.3 and 92.6%, a predictive value for a positive test of 97.2 and 95.4% and for a negative test of 66.6 and 80.6%. Latex agglutination may offer an alternative to counterimmunoelectrophoresis in the rapid diagnosis of Streptococcus pneumoniae infections since it is easier to perform and gives a reliable result within 15 min.