Michael N. Dohn

Sequence Polymorphisms in the Pneumocystis carinii Cytochrome b Gene and Their Association with Atovaquone Prophylaxis Failure

Atovaquone (Mepron, 566c80) is an effective agent against Pneumocystis carinii, which probably acts by binding to cytochrome b and inhibiting electron transport. To assess the possibility that atovaquone resistance might be developing, the genes for the cytochrome b from P. carinii sp. f. carinii and P. carinii sp. f. hominis were partially sequenced. Eight of 10 patient isolates had cytochrome b genes with the same amino acid sequence. The P. carinii cytochrome b genes from 2 of 4 patients who had atovaquone prophylaxis failure contained mutations resulting in amino acid changes in one of the ubiquinone (coenzyme Q) binding sites (Qo). These mutations are homologous to mutations in other microorganisms that confer resistance to similar inhibitors. Variations in the sequence of the P. carinii cytochrome b gene suggest but do not prove the development of drug resistance.

The continuing utility of bronchoalveolar lavage to diagnose opportunistic infection in AIDS patients

PURPOSE To determine whether bronchoalveolar lavage (BAL) remains a useful technique in assessing human immunodeficiency virus (HIV)-infected patients with pulmonary symptoms. PATIENTS AND METHODS All HIV-infected patients with pulmonary symptoms referred to a university hospital-based pulmonary service underwent bronchoscopy and BAL within 24 hours of referral. All samples were handled in a standardized fashion. The results of the lavage were compared with chest roentgenograms and clinical results. RESULTS A total of 894 lavages were performed on HIV-infected patients over a 7-year period. The overall diagnostic yield was 60%, with 420 patients having Pneumocystis carinii. Infections other than P carinii were found in 185 cases, including 75 lavages with P carinii and another infection. The other infections included Mycobacterium tuberculosis (17 patients), Mycobacterium kansasii (15 patients), Histoplasma capsulatum (24 patients), Cryptococcus neoformans (17 patients), and bacterial infection (103 patients). For 364 lavages, no diagnosis was made. Chest roentgenograms were not useful in predicting what infection would be diagnosed. There was no difference in the yield of BAL over the 7-year period, despite the introduction of aerosol pentamidine prophylaxis and antiretroviral therapy. CONCLUSION Bronchoscopy with BAL continues to have a role in the evaluation of HIV-infected patients with pulmonary symptoms.

A Preliminary Evaluation of 566C80 for the Treatment of Pneumocystis Pneumonia in Patients with the Acquired Immunodeficiency Syndrome

BACKGROUND The drug 566C80 is an investigational hydroxynaphthoquinone that is active against Pneumocystis carinii in vitro and in animal models. Initial studies in humans indicate that 566C80 is safe and has adequate bioavailability after oral administration. METHODS We conducted an open-label trial of 566C80 in 34 adults with the acquired immunodeficiency syndrome (AIDS) and untreated pneumocystis pneumonia. All the patients had a partial pressure of arterial oxygen of at least 60 mm Hg while breathing room air. They were enrolled sequentially in three cohorts taking 566C80 at different dosages, all administered orally: 750 mg three times daily for 5 days, then twice daily for 16 days; 750 mg three times daily for 21 days; and 750 mg four times daily for 21 days. RESULTS All 34 patients survived, and 27 (79 percent) were successfully treated with 566C80 alone. The mean partial pressure of oxygen in 33 patients was 78 mm Hg at entry and 93 mm Hg after the course of 566C80 (P less than 0.001). In five patients (15 percent) the drug was discontinued because of lack of response. In four patients (12 percent), the drug was discontinued because of toxicity (fever and rash in two patients each). In two of these, treatment was considered to have succeeded because 566C80 was not discontinued because of toxicity until after day 14. Five of the successfully treated patients had rashes that resolved despite continued therapy. In nine patients, serum alanine aminotransferase levels rose above 100 U per liter. During the first three months after the completion of therapy, pneumocystis pneumonia recurred in 4 of the 27 successfully treated patients, and another 3 patients had recurrences between month 3 and month 6 of follow-up. The mean (+/- SEM) steady-state plasma levels of 566C80 were similar in the three cohorts: 16.3 +/- 2.10, 20.4 +/- 2.48, and 18.9 +/- 3.08 micrograms per milliliter in the patients taking the drug twice daily, three times daily, and four times daily, respectively. CONCLUSIONS From these preliminary data, the investigational compound 566C80 appears to be a safe, effective, and well-tolerated therapy for P. carinii pneumonia of mild-to-moderate severity in patients with AIDS.

Source of Pneumocystis carinii in recurrent episodes of pneumonia in AIDS patients.

OBJECTIVE To investigate the hypothesis that P.carinii special form hominis (P.c. hominis) reinfections occur in AIDS patients. DESIGN Polymerase chain reaction (PCR) was used to identify patients who had different P.c. hominis mitochondrial DNA (mtrRNA) genotypes in the two disease episodes (genotype switching). P.c. hominis from these patients were analysed with an allele-specific PCR (ASP) assay to determine whether the genotype found in a second disease episode were present in the first disease episode. To assess the possible contributions of other factors to genotype switching, data on the sampling method and drugs used to treat each patient were compiled. METHODS Bronchoalveolar lavage fluid (BALF) was subjected to PCR using primers that amplified a 346 base-pair region of the mtrRNA locus known to be polymorphic at site 85 of the amplicon. Samples from patients in whom the P.c. hominis mtrRNA sequence had changed at site 85 in the two disease episodes were studied by ASP in which primers designed to prime synthesis from the allele of the mtrRNA sequence found in second episodes of disease were used in PCR of P.c. hominis DNA from first episodes of P. carinii pneumonia. RESULTS In four of five patients who produced P.c. hominis with different mtrRNA genotypes during first and second episodes, ASP did not detect the second-episode genotype in first-episode BALF. There was no evidence that either sampling methods or drug-resistance contributed to genotype switching. CONCLUSIONS P.c. hominis reinfections occur in AIDS patients.

Utility of bronchoalveolar lavage in assessing pneumonia in immunosuppressed renal transplant recipients

PURPOSE To determine if initial results obtained from diagnostic bronchoalveolar lavage (BAL) in immunosuppressed renal transplant patients with pulmonary infiltrates, fever, or hypoxemia can affect therapeutic decisions, morbidity, and mortality. DESIGN A retrospective study of all BAL specimens obtained from renal transplant patients from January 1985 through June 1991. Initial results of Gram stain, cytology, cell differential count, and semi-quantitative bacterial cultures, all available within 24 hours of bronchoscopy, were compared with clinical outcomes and final diagnoses. SETTING University hospital nephrology-transplant/pulmonary service. PATIENTS Seventy renal transplant patients with a suspected pneumonia were stratified into 3 groups. A total of 48 patients underwent 58 bronchoscopies. Group 1 was comprised of 32 BALs that yielded 1 or more infectious organisms and was considered diagnostic. Group 2 (n = 26) were those BALs in which no organism was isolated and were thus nondiagnostic. Twenty-two additional immunosuppressed renal transplant recipients with pneumonia were considered by the admitting transplant nephrologist to have an uncomplicated community-acquired lung infection and thus were empirically treated and did not undergo BAL (Group 3). METHODS BAL fluid analysis included cell differential count, cytopathologic examination, and culture for mycobacteria, legionella, fungi, viruses, and bacteria using a semi-quantitative technique. Etiologic diagnosis and the time of onset of the infectious processes were recorded. Therapeutic outcome and mortality were determined for each group. RESULTS Thirty-nine etiologic organisms were found in 32 patients, with 6 patients having more than 1 infection. Twenty-two patients had 26 negative BALs, and 8 of these patients were clinically believed to have a volume overload state. Eight of 13 (61%) patients with bacterial pneumonia had BAL neutrophil counts greater than 20%, whereas 11 of 13 (84%) patients without bacterial pneumonia had neutrophil counts less than 20% (p < 0.05). Those patients with an infectious etiology remained in the hospital longer than patients without a specific etiologic organism identified (p < 0.02). Therapeutic decisions leading to the institution of specific antibiotics were more frequently made in patients with a diagnostic BAL (p < 0.0001). An overall 3-month mortality (16%) was low compared with the historical rate (30%). CONCLUSION BAL is a useful procedure in the diagnosis of an infectious process in immunosuppressed renal transplant patients where initial results can alter therapy in more than 70% of cases.

Atovaquone suspension for treatment of Pneumocystis carinii pneumonia in HIV-infected patients.

ObjectiveTo describe clinical experience with atovaquone suspension for the treatment of Pneumocystis carinii pneumonia (PCP) in HIV-infected patients. DesignA retrospective chart review. MethodsThe medical records of 54 HIV-infected patients with PCP treated with atovaquone were examined. The outcomes of 34 patients treated with atovaquone suspension (750 mg twice a day) were compared with those of 20 patients treated with atovaquone tablets (750 mg three times a day). ResultsThe proportion of patients successfully treated was similar with the suspension (74%) and tablet (70%) formulations of atovaquone. The proportion of patients with an inadequate response to therapy was lower for patients treated with atovaquone suspension (15%) than tablets (30%). Both formulations were well tolerated. ConclusionAtovaquone suspension is effective and well tolerated for the treatment of PCP.

Decreased phosphatidylcholine in the lung fluid of patients with sarcoidosis

Surfactant decreases the immune response of lymphocytes. Pulmonary sarcoidosis is a disease characterized by an increased number and activity of lymphocytes in the lung. We measured the lipids and lymphocytes retrieved from the lung by bronchoalveolar lavage. Thirteen patients with active pulmonary sarcoidosis had a significantly higher percentage of lymphocytes (18±21%, mean ± standard error of the mean) than 10 control subjects (4±1.9%, p<0.01). Using an external marker, we found the absolute amount of disaturated phosphatidylcholine to be higher in the control group (174±17.4 μg/ml lung fluid) than in the sarcoid group (91±1.9 μg/ml of lung fluid, p<0.002).

Analysis of Pneumocystis carinii organism burden, viability and antigens in bronchoalveolar lavage fluid in AIDS patients with pneumocystosis: correlation with disease severity.

ObjectivesWe examined 96 bronchoalveolar lavage fluid (BALF) specimens from AIDS patients with proven Pneumocystis carinii pneumonia (PCP) in order to compare the relationship of organism burden, viability and antigen expression with disease severity at the time of clinical presentation. MethodsTinctorial analysis of BALF specimens with proven PCP using Diff-Quik, cresyl echt violet and erythrosin B stains to evaluate organism burden and viability. P. carinii antigen examination was performed by Western blot analysis. ResultsP. carinii cluster ratios were more sensitive than cyst counts as an indicator of organism burden, and correlated well with the alveolar-arterial oxygen gradient as a measure of disease severity. Erythrosin B, the vital stain used to measure P. carinii viability, displayed a wide range of values and provided little useful information. Antigens of 35–45 and 95 kD, which were specific for P. carinii, were found by immunoblot analysis in BALF cellular fraction of most patients with pneumocystosis. By contrast, antigens of 52 and 66 kD, which were found in both BALF supernatant and cellular fractions of P. carinii patients and controls, most likely represented albumin and immunoglobulin G heavy chain, respectively, of host origin. The 35–45 kD antigen was found in 88% of the BALF specimens and appeared to represent an important marker of P. carinii infection. The 95 kD antigen was detected in 49% of the specimens. ConclusionsWe conclude that analysis of P. carinii characteristics in BALF specimens of patients with pneumocystis may provide additional information. These data will also be helpful in developing more sensitive assays and in targeting specific P. carinii factors for future investigation.

Estimating the Cost Effectiveness of Atovaquone versus Intravenous Pentamidine in the Treatment of Mild-to-Moderate Pneumocystis carinii Pneumonia

SummaryPneumocystis carinii pneumonia (PCP) is the most common severe opportunistic infection, and one of the most costly, among people with AIDS. Over 50% of patients experience toxic effects of the major anti-PCP medications — cotrimoxazole (trimethoprim-sulfamethoxazole) and pentamidine. Recently, the US Food and Drug Administration approved a new oral drug therapy, atovaquone, as an alternative to pentamidine for the treatment of people with mild-to-moderate PCP who are intolerant of cotrimoxazole.We developed a decision tree model to estimate the costs and cost effectiveness of atovaquone therapy compared with intravenous pentamidine therapy for cotrimoxazole-intolerant patients with mild-to-moderate PCP. Clinical outcomes were based on data from a phase III trial comparing the 2 medications. Our economic outcomes were based on treatment algorithms derived from discharge data, published reports and the clinical judgement of the co-authors.We estimate the total expected cost of treating a patient for an episode of PCP with atovaquone to be SUS3990 compared with

Quality of Care on Short-Term Medical Missions: Experience with a Standardized Patient Record and Related Issues:

US6545 for pentamidine under our baseline scenario (1995 dollars). Our decision model also provides insight into the large cost-savings benefits of treating mild-to-moderate PCP on an outpatient basis.