Diagnosis of Toxoplasma parasitemia in patients with AIDS by gene detection after amplification with polymerase chain reaction.

We sought evidence of toxoplasma parasitemia among 37 people with active or dormant Toxoplasma gondii infection or no evidence of infection. DNA was extracted from erythrocyte-free portions of blood samples, and the T. gondii B1 gene was amplified by the polymerase chain reaction. Evidence of T. gondii parasitemia was found in six patients with severe immunosuppression from AIDS and clinical evidence suggestive of or compatible with toxoplasmosis. Results were negative for patients unlikely to have active toxoplasmosis. Gene detection after amplification with the polymerase chain reaction is a promising test for detection of parasitemia, and parasitemia should be tested for in patients with AIDS and unexplained fever or central nervous system abnormalities.

Detection of Toxoplasma gondii parasitemia by gene amplification, cell culture, and mouse inoculation.

Diagnosis of Toxoplasma gondii infection is difficult, especially in immunosuppressed people. The AIDS epidemic has increased the number of people at risk and increased the need for better diagnostic methods. We have compared three methods for detection of T. gondii parasitemia. Rabbits were infected subcutaneously with 10(4) T. gondii tachyzoites. Blood samples were obtained, and buffy coat or leukocyte fractions were prepared. We sought the T. gondii B1 gene by gene amplification by the polymerase chain reaction, and we sought viable T. gondii cells by inoculating fibroblast cell cultures and by mouse inoculation. Thirty-two blood samples were obtained from seven infected rabbits, and 18 were obtained from four control, uninfected rabbits. Parasitemia was detected in 20 of 32 samples (62%) from infected samples by mouse inoculation, 12 of 32 samples (37%) by gene amplification and detection, and 8 of 32 samples (25%) by cell culture. Mouse inoculation requires use of live animals and has a long turnaround time. Currently, cell culture is the least sensitive but most practical and widely available method for the detection of T. gondii parasitemia. Gene amplification and detection was more sensitive than cell culture and may become available in clinical laboratories as techniques are developed further and automated.

Cytomegalovirus-induced reactivation of Toxoplasma gondii pneumonia in mice: lung lymphocyte phenotypes and suppressor function.

Active cytomegalovirus (CMV) infection is associated with immunosuppression and predisposes to the development of life-threatening superinfections in immunocompromised patients. In a mouse model of virus-induced immunosuppression, acute murine CMV (MCMV) infection induced reactivation of dormant Toxoplasma gondii infection, producing Toxoplasma pneumonia. Changes in lung lymphocyte numbers and phenotypes appeared to be integral to the pathogenesis of MCMV-induced reactivation of T. gondii pneumonia. Numbers of lung CD4+ cells decreased during acute MCMV infection in mice with dormant T. gondii infection as well as in previously uninfected mice. Dually infected mice subsequently developed reactivation of Toxoplasma pneumonia. The pneumonia was characterized by a large influx of T lymphocytes, predominantly CD8+ cells, into the lungs. These lung lymphocytes markedly suppressed the ability of immune splenocytes to proliferate in response to T. gondii antigens and concanavalin A in vitro. These results suggested that the initial fall in the numbers of lung CD4+ cells observed after MCMV infection may have induced reactivation of T. gondii infection in the lungs. The subsequent pneumonia appeared to be a manifestation of a massive influx of T lymphocytes, especially CD8+ cells, into the lungs.

Sputum antimicrobial levels and clinical outcome in bronchitis.

The role of antimicrobials in the treatment of bronchitis remains controversial. Antimicrobials are rarely indicated in acute bronchitis. Antimicrobials are indicated in a subset of patients with acute exacerbations of chronic bronchitis. The efficacy of an antimicrobial agent in bronchitis can be estimated by the ratio of the sputum concentration of the antimicrobial to its in vitro activity against common respiratory pathogens (S/M90). These S/M90 rates are presented in tabular form. However, given the lack of solid data to support antimicrobial treatment for most episodes of bronchitis, use of the S/M90 to select antimicrobial therapy remains theoretical rather than of proven clinical benefit.

Tissue penetration of the new quinolones in humans.

Data on the penetration of new quinolones into selected extravascular sites in humans, i.e., blister fluid, sputum, prostatic secretions, cerebrospinal fluid, aqueous humor, bone, prostate tissue, and cells, are reviewed and the data presented in tabular form. Published reports indicate that penetration into all sites, including intracellular sites, is high and exceeds that achievable for other commonly used antimicrobial agents, including penicillins, cephalosporins, and aminoglycosides. Available clinical treatment data support the expected favorable outcome predicted by the high extravascular concentrations achieved with quinolones.