Pneumocystis carinii pneumonia: a comparison between patients with the acquired immunodeficiency syndrome and patients with other immunodeficiencies

Clinical features of 49 episodes of Pneumocystis carinii pneumonia in patients with the acquired immunodeficiency syndrome were compared with those of 39 episodes in patients with other immunosuppressive diseases. At presentation patients with the syndrome were found to have a longer median duration of symptoms (28 days versus 5 days, p = 0.0001), lower mean respiratory rate (23.4 versus 30, p = 0.005), and higher median room air arterial oxygen tension (69 mm Hg versus 52 mm Hg, p = 0.0002). The survival rate from 1979 to 1983 was similar for the two groups (57% and 50% respectively). Patients with the syndrome had a higher incidence of adverse reactions to trimethoprim-sulfamethoxazole (22 of 34 versus 2 of 17, p = 0.0007). Survivors with the syndrome at initial presentation had a significantly lower respiratory rate, and higher room air arterial oxygen tension, lymphocyte count, and serum albumin level compared to nonsurvivors. Pneumocystis carinii pneumonia presents as a more insidious disease process in patients with the syndrome, and drug therapy in these patients is complicated by frequent adverse reactions.

Clinical spectrum of X-linked hyper-IgM syndrome

We report the clinical and immunologic features and outcome in 56 patients with X-linked hyper-IgM syndrome, a disorder caused by mutations in the CD40 ligand gene. Upper and lower respiratory tract infections (the latter frequently caused by Pneumocystis carinii), chronic diarrhea, and liver involvement (both often associated with Cryptosporidium infection) were common. Many patients had chronic neutropenia associated with oral and rectal ulcers. The marked prevalence of infections caused by intracellular pathogens suggests some degree of impairment of cell-mediated immunity. Although lymphocyte counts and in vitro proliferation to mitogens were normal, a defective in vitro proliferative response to antigens was observed in some patients, and additional defects of cell-mediated immunity may be presumed on the basis of current knowledge of CD40-ligand function. All patients received regular infusions of immunoglobulins. Four patients underwent liver transplantation because of sclerosing cholangitis, which relapsed in there. Three patients underwent bone marrow transplantation. Thirteen patients (23%) died of infection and/or liver disease. X-linked hyper-IgM syndrome, once considered a clinical variant of hypogammaglobulinemia, is a severe immunodeficiency with significant cellular involvement and a high mortality rate.

Trimethoprim-sulfamethoxazole or pentamidine for Pneumocystis carinii pneumonia in the acquired immunodeficiency syndrome. A prospective randomized trial

Forty patients with the acquired immunodeficiency syndrome (AIDS) and their first episodes of Pneumocystis carinii pneumonia were assigned at random to receive either trimethoprim-sulfamethoxazole or pentamidine isethionate. The two groups did not differ significantly in the severity of pulmonary or systemic processes at enrollment. Five patients treated initially with trimethoprim-sulfamethoxazole and one patient treated initially with pentamidine died during the 21-day treatment period (p = 0.09, Fisher's exact test). No significant differences were seen between groups in rates of improvement, pulmonary function tests, or 67Ga uptake by the lungs in the survivors at completion of therapy. Adverse reactions necessitated changing from the initial drug in 10 patients in the trimethoprim-sulfamethoxazole group and 11 in the pentamidine group. Minor reactions occurred in all patients. In patients with AIDS, trimethoprim-sulfamethoxazole and pentamidine do not have statistically significant differences in efficacy or frequency of adverse reactions.

Histoplasmosis in the acquired immune deficiency syndrome

This report describes the experience with disseminated histoplasmosis in seven of 15 patients with the acquired immune deficiency syndrome (AIDS) diagnosed in Indianapolis since 1981. Three were homosexual, two were intravenous drug addicts, one was the spouse of another patient with AIDS and disseminated histoplasmosis, and the seventh was a hemophiliac. Six had associated infections: candidiasis in three, Pneumocystis carinii pneumonia, recurrent mucocutaneous herpes simplex infection, and disseminated Mycobacterium avium infection in two each, and disseminated infection with an unidentified mycobacterium in one. Clinical diseases suggested sepsis in four. Histoplasma fungemia occurred in five, but the diagnosis was established first by visualization of organisms in blood or bone marrow in three. Results of Histoplasma serologic tests were positive in each. Three died before receiving 50 mg of amphotericin B, three had prompt improvement with amphotericin B, and one was treated with ketoconazole to prevent dissemination. However, two of the three patients treated with amphotericin B had relapses after a 35 mg/kg course, and the third died within a month following therapy. Disseminated histoplasmosis is a major opportunistic infection in patients with AIDS from endemic areas. AIDS should be strongly considered in otherwise healthy persons with disseminated histoplasmosis, especially if risk factors for AIDS are present. Amphotericin B is not curative in these patients.

Patient-ventilator asynchrony during noninvasive ventilation: the role of expiratory trigger

OBJECTIVE

Air leaks around the mask are very likely to occur during noninvasive ventilation, in particular when prolonged ventilatory treatment is required. It has been suggested that leaks from the mask may impair the expiratory trigger cycling mechanism when inspiratory pressure support ventilation (PSV) is used. The aim of this study was to compare the short-term effect of two different expiratory cycling mechanisms (time-cycled vs flow-cycled) during noninvasive inspiratory pressure support ventilation (NIPSV) on patient-ventilator synchronisation in severe hypoxemic respiratory failure.

STUDY POPULATION

Six patients with acute lung injury (ALI) due to acquired immunodeficiency syndrome (AIDS)-related opportunistic pneumonia were enrolled in the protocol.

INTERVENTION

Each subject was first studied during spontaneous breathing with a Venturi oxygen mask (SB) and successively submitted to a randomly assigned 20' conventional flow-cycling (NIPSVfc) or time-cycling inspiratory pressure support ventilation (NIPSVtc). The pre-set parameters were: inspiratory pressure of 10 cm H2O, PEEP of 5 cm H2O for the same inspired oxygen fraction as during SB. A tight fit of the mask was avoided in order to facilitate air leaks around the mask. The esophageal pressure time product (PTPes) and tidal swings (delta Pes) were measured to evaluate the patient's respiratory effort. A subjective "comfort score" and the difference between patient and machine respiratory rate [delta RR(p-v)], calculated on esophageal and airway pressure curves, were used as indices of patient-machine interaction.

RESULTS

Air leaks through the mask occurred in five out of six patients. The values of PEEPi (< 1.9 cm H2O) excluded significant expiratory muscle activity. NIPSVtc significantly reduced PTPes, delta Pes, and delta RR(p-v) when compared to NIPS-Vfc [230 +/- 41 (SE) vs 376 +/- 72 cm H2O.s.min-1; 8 +/- 2 vs 13 +/- 2 cm H2O; 1 +/- 1 vs 9 +/- 2 br.min-1; respectively] with a concomitant significant improvement of the "comfort score".

CONCLUSIONS

In the presence of air leaks a time-cycled expiratory trigger provides a better patient-machine interaction than a flow-cycled expiratory trigger during NIPSV.

Corticosteroids prevent early deterioration in patients with moderately severe Pneumocystis carinii pneumonia and the acquired immunodeficiency syndrome (AIDS)

OBJECTIVE

To determine whether oral corticosteroids can prevent early deterioration in patients with acquired immunodeficiency syndrome (AIDS)-related Pneumocystis carinii pneumonia.

DESIGN

Prospective, double-blind, placebo-controlled, randomized trial.

METHODS

Included patients were having their first P. carinii pneumonia episode, had no other known active pulmonary pathology, had no contraindications for corticosteroids, received no anti-P. carinii pneumonia medications for more than 48 hours, and had oxygen saturation by pulse oximetry of 85% or more and less than 90% at rest or a 5-percentage-point decrease in oxygen saturation with exercise while breathing room air. Consenting subjects were randomly assigned to prednisone, 60 mg/d for 7 days, followed by a progressive tapering over 14 days or to an identical placebo. Early deterioration, the endpoint of the trial, was defined as a 10% decrease in baseline oxygen saturation on day 3 or thereafter. The cases of patients developing early deterioration were considered to be failures of treatment; the code was then broken, and the patient's treatment was left to the judgment of the treating physician. Sequential analysis was done with the primary variable being development of early deterioration.

RESULTS

The trial was terminated 5 April 1989 on the basis of the sequential analysis when a total of nine episodes of early deterioration had occurred in the first 37 patients at an overall significance level of P = 0.0136. A total of 8 of 19 placebo-treated patients (42.1%) developed early deterioration compared with only 1 of 18 patients (5.6%) treated with corticosteroids. Baseline characteristics were not statistically different between the two treatment groups. The adjusted odds ratio for the treatment effect was 5.87 (95% CI, 1.27 to 27.4). The adjusted point estimates for the probability of early deterioration in the placebo and corticosteroid groups were 43% and 12%, respectively. All 8 patients in the placebo group developing early deterioration recovered rapidly with addition of corticosteroid treatment. The single patient with early deterioration in the corticosteroid group died on day 6 from overwhelming P. carinii pneumonia, as documented at autopsy. The corticosteroid group had an increased exercise tolerance on day 7 that persisted at day 30.

CONCLUSION

Oral corticosteroids prevent early deterioration and increase exercise tolerance in patients with moderately severe AIDS-related P. carinii pneumonia.

Analysis of underlying diseases and prognosis factors associated with Pneumocystis carinii pneumonia in immunocompromised HIV-negative patients

The aim of this retrospective study was to determine the underlying diseases associated with Pneumocystis carinii pneumonia (PCP) in immunocompromised HIV-negative patients and to identify prognosis factors in this population. One hundred three cases of PCP were diagnosed over a 5-year period. Diagnosis was established on the basis of clinical features and by detection of Pneumocystis carinii cysts in bronchoalveolar lavage fluid. Underlying diseases comprised hematologic malignancies (n=60; 58%), inflammatory diseases (n=27; 26%), and solid tumors (n=18; 17.5%); 9 (8%) patients were solid organ transplant recipients. Seventy-one (69%) patients received cytotoxic drugs, 57 (55%) were treated with long-term corticotherapy, and 15 (14.7%) underwent bone marrow transplantation. Fifty-eight (56%) patients were admitted to the intensive care unit, and 52 (41%) required mechanical ventilation. Thirty-nine (38%) patients died of PCP; data from these patients were compared with those from surviving patients. The following factors were associated with a poor prognosis: high respiratory rate (P=0.005), high pulse rate (P=0.0003), elevated C-reactive protein (P=0.01), elevated serum lactate dehydrogenase level (P=0.02), and mechanical ventilation (OR, 14.4; 95%CI, 5-50). The results suggest that PCP can occur during the course of many immunosuppressive diseases, particularly various hematologic malignancies. The diagnosis of PCP should be considered more frequently and advocated earlier in immunocompromised HIV-negative patients, since prompt diagnosis may improve the prognosis of these patients.

Permanent declines in pulmonary function following pneumonia in human immunodeficiency virus-infected persons. The Pulmonary Complications of HIV Infection Study Group

Human immunodeficiency virus (HIV)-associated respiratory infections, most notably Pneumocystis carinii pneumonia (PCP), but also bacterial pneumonia (BP), result in reductions in lung function that have been studied mainly during the course of acute infection. Whether HIV-associated pneumonias also cause permanent changes in pulmonary function is unknown. In this study we investigated the long-term effects of PCP and BP on pulmonary function in a cohort of HIV-infected persons. One thousand, one hundred forty-nine HIV-infected persons were followed in a prospective, observational cohort study at six centers in the United States. Study participants had pulmonary function testing performed at regular preset intervals. PCP and BP diagnoses were verified with defined criteria. Longitudinal multivariate analysis was used to model pulmonary function in terms of demographic data and occurrence of PCP or BP. We found that PCP or BP was associated with permanent decreases in FEV(1), FVC, FEV(1)/FVC, and the diffusing capacity of carbon monoxide. Neither infection resulted in statistically significant changes in TLC. We conclude that PCP and BP result in expiratory airflow reductions that persist after the acute infection resolves. The clinical implications of these changes are unknown, but they may contribute to prolonged respiratory complaints in HIV-infected patients who have had pneumonia.

Pneumocystis carinii pneumonia in patients in the developing world who have acquired immunodeficiency syndrome

We review Pneumocystis carinii pneumonia (PCP) in patients in the developing world (i.e., Africa, Asia, the Philippines, and Central and South America) who have acquired immunodeficiency disease (AIDS). During the first decade of the AIDS pandemic, PCP rarely occurred in African adults. More recent reports have noted that PCP comprises a significantly greater percentage of cases of pneumonia than it did in the past. This trend dramatically contrasts with that observed in industrialized nations, where a reduction in the number of cases of PCP has occurred as a result of the widespread use of primary P. carinii prophylaxis and highly active antiretroviral therapy. Throughout the developing world, the rate of coinfection with Mycobacterium tuberculosis and PCP is high, ranging from 25% to 80%. Initiation of treatment when PCP is in an advanced stage may account for the high mortality rates (20%-80%) associated with pediatric PCP in the developing world.

An Official ATS Workshop Summary: Recent advances and future directions in pneumocystis pneumonia (PCP)

Pneumocystis pneumonia (PCP) is a major cause of morbidity and mortality among immunocompromised persons, and it remains a leading acquired immune deficiency syndrome (AIDS)-defining opportunistic infection in human immunodeficiency virus (HIV)-infected individuals throughout the world. Pneumocystis has proven difficult to study, in part due to the lack of a reliable culture system for the organism. With the development of molecular techniques, significant advances in our understanding of the organism and the disease have been made over the past several years. These advances include an improved understanding of host-organism interactions and host defense, the development of noninvasive polymerase chain reaction (PCR)-based diagnostic assays, and the emerging data regarding the possible development of trimethoprim-sulfamethoxazole-resistant Pneumocystis. In addition, the recognition that patients without PCP may nevertheless be carriers of or colonized with Pneumocystis, and observations that suggest a role for Pneumocystis in the progression of pulmonary disease, combine to signal the need for a comprehensive and accessible review. In May 2005, the American Thoracic Society sponsored a one-day workshop, "Recent Advances and Future Directions in Pneumocystis Pneumonia (PCP)," which brought together 45 Pneumocystis researchers. The workshop included 21 presentations on diverse topics, which are summarized in this report. The workshop participants identified priorities for future research, which are summarized in this document.

Lung function abnormalities in patients infected with the human immunodeficiency virus with and without overt pneumonitis

Pulmonary function was measured in 169 male patients seropositive for the human immunodeficiency virus (HIV). The transfer factor for carbon monoxide (TLCO) in symptom free patients and patients with persistent generalised lymphadenopathy was normal (greater than 83% of predicted values). Patients with the AIDS related complex, non-pulmonary Kaposi sarcoma, and non-pulmonary non-Kaposi sarcoma AIDS (that is, opportunist infections affecting other organs) had lower mean values for TLCO (77%, 70%, and 70% of predicted respectively). These values were significantly lower than values for symptom free patients. Lower mean values of 50% and 63% predicted TLCO were observed in patients during the acute and recovery phases of Pneumocystis carinii pneumonia. TLCO was also low in patients with lung mycobacterial infection and in a patient with lung Kaposi sarcoma. Forced expiratory volume in one second, peak expiratory flow, and maximal expiratory flow at 50% of vital capacity were significantly reduced only in patients with acute pneumocystis pneumonia. This study shows that abnormalities in the results of pulmonary function tests, particularly TLCO, although greatest in patients with pulmonary complications of AIDS, are also present in patients with AIDS but without other evidence of pulmonary disease, and in patients with the AIDS related complex. The predictive and prognostic implications of these findings require further investigation.

Continuous axenic cultivation of Pneumocystis carinii

Continuous axenic culture of Pneumocystis carinii has been achieved. A culture vessel is used that allows for frequent medium exchange without disturbance of organisms that grow attached to a collagen-coated porous membrane. The growth medium is based on Minimal Essential Medium with Earle's salt supplemented with S-adenosyl-L-methionine, putrescine, ferric pyrophosphate, N-acetyl glucosamine, putrescine, p-aminobenzoic acid, L-cysteine and L-glutamine, and horse serum. Incubation is in room air at 31 degrees C. The pH of the medium begins at 8.8 and rises to approximately 9 as the cells grow. Doubling times calculated from growth curves obtained from cultures inoculated at moderate densities ranged from 35 to 65 hours. With a low-density inoculum, the doubling time is reduced to 19 hours. The morphology of cultured organisms in stained smears and in transmission electron micrographs is that of P. carinii, and P. carinii-specific mAbs label the cultured material. Cultured organisms are infective for immunosuppressed rats and can be stored frozen and used to reinitiate culture.

Pneumocystis carinii pneumonia in patients without HIV infection

Pneumocystis carinii is an important, but sporadic, opportunistic pulmonary pathogen in immunosuppressed HIV seronegative persons. Historically, patients at highest risk for P. carinii pneumonia are included infants with severe malnutrition, children with primary immunodeficiencies, patients with hematological malignancies, and recipients of solid organ or bone marrow transplants. Recently, solid tumor patients, in particular those receiving high-dose corticosteroids for brain neoplasms, and patients with inflammatory or collagen-vascular disorders, especially patients with Wegener granulomatosis receiving immunosuppressive therapy, have been identified as subgroups at increased risk for P. carinii pneumonia. Other factors associated with P. carinii pneumonia include the intensity of the immunosuppressive regimen and tapering doses of corticosteroids. Because P. carinii pneumonia is associated with significant morbidity and mortality, it is important to identify high-risk patient populations to administer effective chemoprophylactic agents, such as trimethoprim-sulfamethoxazole.

Characterization of transmission of Pneumocystis carinii f. sp. muris through immunocompetent BALB/c mice

By using mouse models, it has been shown that Pneumocystis carinii f. sp. muris can be transmitted to immunocompetent mice that are exposed to immunosuppressed mice with active P. carinii pneumonia. We sought to determine whether P. carinii f. sp. muris could be transmitted between normal mice. The rationale for these experiments was to demonstrate whether the normal host could serve as the reservoir of organisms that produce Pcp when the organism is acquired by the immunosuppressed host. Under the conditions of these experiments, normal mice are able to be infected by brief cohousing with P. carinii-infected SCID mice. There was active replication of organisms in the normal host such that the organism could be transmitted to other normal mice, again with active replication. Mice that had seroconverted after exposure to P. carinii-infected SCID mice were more resistant to infection when reexposed. Infection in normal mice was well tolerated with minimal effects on dynamic lung compliance. We speculate, based on these results, that transmission from normal host to normal host, as an asymptomatic or minimally symptomatic infection, could be a way to maintain this opportunistic pathogen in the environment.

Lymphocytic interstitial pneumonia in patients at risk for the acquired immune deficiency syndrome

Three patients with the acquired immune deficiency syndrome (AIDS) or AIDS-related complex and lymphocytic interstitial pneumonia are reported. All patients presented with progressive dyspnea, nonproductive cough, fever, anorexia, weight loss, and arterial hypoxemia. Chest roentgenograms exhibited bilateral diffuse reticular-nodular densities. The diagnosis of lymphocytic interstitial pneumonia was made by fiberoptic bronchoscopy or open lung biopsy. Two patients were treated with corticosteroids, with significant improvement. The third patient died of pneumonia due to Pneumocystis carinii six months after the diagnosis of lymphocytic interstitial pneumonia was established. Serum antibodies to human immunodeficiency virus (HIV) were demonstrable in the two patients in whom the test was performed. Lymphocytic interstitial pneumonia is probably another pulmonary manifestation of AIDS or AIDS-related complex. Although the clinical presentation may be identical to the more common opportunistic infections, the treatment differs, and the prognosis may be better.

Impact of management guidelines on the outcome of severe community acquired pneumonia

BACKGROUND

Ten years ago we published a study of 50 adults with severe community acquired pneumonia admitted to our intensive care unit and subsequently introduced guidelines for the management of severe community acquired pneumonia which are largely in accordance with those of the British Thoracic Society. The results of a follow up study are now reported in order to assess their impact on the outcome of this disease.

METHODS

Fifty seven cases of severe community acquired pneumonia admitted to our ICU between 1984 and 1993 were studied. Causal pathogens, clinical and laboratory features of severity, antibiotic therapy and mortality were studied and, where possible, compared with results from the previous study.

RESULTS

Streptococcus pneumoniae, Legionella pneumophila and Staphylococcus aureus were the most frequent causes of severe community acquired pneumonia, as in the previous study. The intensity of microbial investigation has increased, particularly with regard to pneumococcal and Legionella antigen testing, the latter allowing earlier diagnosis of Legionella infection than previously. In spite of this, no pathogen was identified in 33% of cases compared with 18% previously. Indices of severity of illness were widely recognised, and a decrease in unplanned transfers to the ICU following "unexpected" cardiorespiratory arrest from 25% to 7% (p < 0.02) was found. Antibiotic therapy largely reflected guideline recommendations with 98% receiving a beta-lactam agent and 91% erythromycin. The overall mortality was 58% compared with 54% previously.

CONCLUSIONS

Management guidelines for severe community acquired pneumonia have been widely adopted but without a reduction in mortality in our hospital. Factors other than early diagnosis, appropriate antibiotics, or prompt ICU transfer may influence the outcome in severe community acquired pneumonia.

TNF Receptor Signaling Contributes to Chemokine Secretion, Inflammation, and Respiratory Deficits duringPneumocystisPneumonia

CD8(+) T cells contribute to the pathophysiology of Pneumocystis pneumonia (PcP) in a murine model of AIDS-related disease. The present studies were undertaken to more precisely define the mechanisms by which these immune cells mediate the inflammatory response that leads to lung injury. Experimental mice were depleted of either CD4(+) T cells or both CD4(+) and CD8(+) T cells and then infected with Pneumocystis: The CD4(+)-depleted mice had significantly greater pulmonary TNF-alpha levels than mice depleted of both CD4(+) and CD8(+) T cells. Elevated TNF-alpha levels were associated with increased lung concentrations of the chemokines RANTES, monocyte chemoattractant protein 1, macrophage-inflammatory protein 2, and cytokine-induced neutrophil chemoattractant. To determine whether TNFR signaling was involved in the CD8(+) T cell-dependent chemokine response, TNFRI- and II-deficient mice were CD4(+) depleted and infected with Pneumocystis: TNFR-deficient mice had significantly reduced pulmonary RANTES, monocyte chemoattractant protein 1, macrophage-inflammatory protein 2, and cytokine-induced neutrophil chemoattractant responses, reduced inflammatory cell recruitment to the alveoli, and reduced histological evidence of PcP-related alveolitis as compared with infected wild-type mice. Diminished pulmonary inflammation correlated with improved surfactant activity and improved pulmonary function in the TNFR-deficient mice. These data indicate that TNFR signaling is required for maximal CD8(+) T cell-dependent pulmonary inflammation and lung injury during PcP and also demonstrate that CD8(+) T cells can use TNFR signaling pathways to respond to an extracellular fungal pathogen.

Intravenous or inhaled pentamidine for treating Pneumocystis carinii pneumonia in AIDS. A randomized trial

OBJECTIVE

To evaluate the efficacy and toxicity of aerosolized pentamidine and of reduced-dose intravenous pentamidine for the treatment of mild to moderate Pneumocystis carinii pneumonia in patients with the acquired immunodeficiency syndrome (AIDS).

DESIGN

Randomized open study with serial pulmonary function testing and measurement of pentamidine concentrations in plasma and bronchoalveolar lavage fluid.

PATIENTS

Of 44 men and 1 woman with a mild to moderate first episode of P. carinii pneumonia (Pao2 greater than or equal to 7.3 kPa [55 mm Hg]), 23 received aerosolized pentamidine and 22, intravenous pentamidine.

INTERVENTIONS

Pentamidine isethionate, 600 mg by inhalation using a Respirgard II nebulizer (Marquest Medical Products, Inc., Englewood, Colorado) or 3 mg/kg body weight intravenously, administered once daily for 2 to 3 weeks.

MEASUREMENTS AND MAIN RESULTS

The planned 60-patient study was stopped after 45 patients had been enrolled. The rates (aerosolized compared with intravenous pentamidine) of initial failure, early recrudescence of symptoms, and relapse were 12% and 19% (difference, 7%; 99% confidence interval [CI], - 23% to 37%; P = 0.67), 35% and 0% (difference, 35%; CI, 13% to 58%; P = 0.02), and 24% and 0% (difference, 24%; CI, 4% to 49%; P = 0.03). The rates (aerosolized compared with intravenous pentamidine) of major toxicity were 0% (0 of 17 patients) and 10% (2 of 21 patients) (difference 10%; CI, -1% to 29%; P = 0.24). The mean (+/- SD) pentamidine concentration in bronchoalveolar lavage fluid for patients receiving aerosolized pentamidine was 96.6 +/- 65.1 ng/mL compared with 14.4 +/- 17.7 ng/mL for patients receiving intravenous treatment. Trough concentrations of pentamidine in plasma increased from 0 to 25.4 +/- 16.4, 56.5 +/- 26.1, and 61.1 +/- 56.0 ng/mL at the end of weeks 1, 2, and 3 of intravenous therapy, respectively.

CONCLUSIONS

The data suggest that reduced-dose intravenous pentamidine was more effective than aerosolized pentamidine for treating mild to moderate P. carinii pneumonia. Systemic absorption during aerosolized therapy was minimal; daily doses of intravenous pentamidine resulted in increased accumulation of pentamidine in plasma.

Clinical predictors of Pneumocystis carinii pneumonia, bacterial pneumonia and tuberculosis in HIV-infected patients

BACKGROUND

Clinicians are frequently faced with the differential diagnosis between Pneumocystis carinii pneumonia (PCP), bacterial pneumonia, and pulmonary tuberculosis in HIV-infected patients.

OBJECTIVES

To identify features that could help differentiate these three pneumonia types at presentation by evaluating the clinical characteristics of the three diagnoses among patients at two urban teaching hospitals.

DESIGN

Retrospective chart review.

METHODS

Cases were HIV-infected patients with a verified hospital discharge diagnosis of PCP (n = 99), bacterial pneumonia (n = 94), or tuberculosis (n = 36). Admitting notes were reviewed in a standardized manner; univariate and multivariate analyses were used to determine clinical predictors of each diagnosis.

RESULTS

Combinations of variables with the highest sensitivity, specificity, and odds ratios (OR) were as follows: for PCP, exertional dyspnea plus interstitial infiltrate (sensitivity 58%, specificity 92%; OR, 16.3); for bacterial pneumonia, lobar infiltrate plus fever < or = 7 days duration (sensitivity 48%, specificity 94%; OR, 14.6); and for tuberculosis, cough > 7 days plus night sweats (sensitivity 33%, specificity 86%; OR, 3.1). On regression analysis, independent predictors included interstitial infiltrate (OR, 10.2), exertional dyspnea (OR, 4.9), and oral thrush (OR, 2.9) for PCP; rhonchi on examination (OR, 12.4), a chart mention of 'toxic' appearance (OR, 9.1), fever < or = 7 days (OR, 6.6), and lobar infiltrate (OR, 5.8) for bacterial pneumonia; and cavitary infiltrate (OR, 21.1), fever > 7 days (OR, 3.9), and weight loss (OR, 3.6) for tuberculosis.

CONCLUSIONS

Simple clinical variables, all readily available at the time of hospital admission, can help to differentiate these common pneumonia syndromes in HIV-infected patients. These findings can help to inform clinical decision-making regarding choice of therapy, use of invasive diagnostic procedures, and need for respiratory isolation.

Sequences of Pneumocystis carinii f. sp. hominis strains associated with recurrent pneumonia vary at multiple loci

The sequences of the internal transcribed spacer (ITS) of Pneumocystis carinii f. sp. hominis strains from 7 of 15 AIDS patients were found to vary during discrete episodes of P. carinii pneumonia. Changes in the ITS sequence correlated with changes in the mitochondrial large-subunit rRNA sequence. The coincidence of changes in the sequences of the ITS, which is located in the nucleus, with changes in a mitochondrial gene excludes mutation as the cause of the genetic differences between P. carinii f. sp. hominis strains isolated during different episodes of P. carinii pneumonia and supports the hypothesis that recurrent P. carinii pneumonia is caused by reinfection rather than by reactivation of latent organisms. Thus, limiting the exposure of immunocompromised patients to P. carinii f. sp. hominis should help prevent P. carinii pneumonia.

IL-10 modulates host responses and lung damage induced by Pneumocystis carinii infection

Host responses to Pneumocystis carinii infection mediate impairment of pulmonary function and contribute to the pathogenesis of pneumonia. IL-10 is known to inhibit inflammation and reduce the severity of pathology caused by a number of infectious organisms. In the present studies, IL-10-deficient (IL-10 knockout (KO)) mice were infected with P. carinii to determine whether the severity of pathogenesis and the efficiency of clearance of the organisms could be altered in the absence of IL-10. The clearance kinetics of P. carinii from IL-10 KO mice was significantly enhanced compared with that of wild-type (WT) mice. This corresponded to a more intense CD4(+) and CD8(+) T cell response as well as an earlier neutrophil response in the lungs of IL-10 KO mice. Furthermore, IL-12, IL-18, and IFN-gamma were found in the bronchoalveolar lavage fluids at earlier time points in IL-10 KO mice suggesting that alveolar macrophages were activated earlier than in WT mice. However, when CD4(+) cells were depleted from P. carinii-infected IL-10 KO mice, the ability to enhance clearance was lost. Furthermore, CD4-depleted IL-10 KO mice had significantly more lung injury than CD4-depleted WT mice even though the intensity of the inflammatory responses was similar. This was characterized by increased vascular leakage, decreased oxygenation, and decreased arterial pH. These data indicate that IL-10 down-regulates the immune response to P. carinii in WT mice; however, in the absence of CD4(+) T cells, IL-10 plays a critical role in controlling lung damage independent of modulating the inflammatory response.

Pulmonary function in human immunodeficiency virus infection. A prospective 18-month study of serial lung function in 474 patients

To investigate the development of a reduced DLCO in patients with HIV-related disease, we studied 474 HIV-seropositive patients and performed serial lung function measurements over 18 months. The mean values of DLCO at presentation were lower in patients with more advanced HIV disease compared with asymptomatic HIV-seropositive patients (DLCO 88% of predicted). When compared with the DLCO in asymptomatic HIV-seropositive patients, the DLCO had reduced values in patients with persistent generalized lymphadenopathy (PGL) (82% of predicted, p less than 0.05), acquired deficiency syndrome-related complex (ARC) (73% predicted, p less than 0.001), nonpulmonary Kaposi's sarcoma (KS) (72% of predicted, p less than 0.001), nonpulmonary complications of AIDS excluding KS (73% of predicted, p less than 0.001), pulmonary KS (63% of predicted, p less than 0.001), pulmonary mycobacterial infection (68% of predicted, p less than 0.05), pyogenic infection (70%, p less than 0.05), acute Pneumocystis carinii pneumonia (PCP; 49%, p less than 0.001), and following recovery from PCP (71%, p less than 0.001). Serial lung function measurements over 18 months revealed no change in DLCO within any patient group, and in particular there was no tendency for a gradual decline. Clinical deterioration due to the development of PCP was associated with a reduction in DLCO. Conversely, in patients recovering from PCP, there was a partial improvement in DLCO over 3 months. Zidovudine (AZT) use did not affect DLCO within any diagnostic group or the recovery in DLCO following PCP. However, cigarette smoking was associated with further reductions in DLCO in all patient groups and with an impaired recovery of DLCO following acute PCP.(ABSTRACT TRUNCATED AT 250 WORDS)

Case report: hypercalcemia in a patient with AIDS and Pneumocystis carinii pneumonia

Pneumocystis carinii infection is commonly seen in patients infected with HIV, and there is evidence of macrophage involvement in the disease process. Macrophage dysfunction can result in abnormal vitamin D metabolism as is often seen in a granulomatous disease such as sarcoidosis. This article describes a patient with AIDS who had P. carinii pneumonia and hypercalcemia and had elevated 1,25-dihydroxyvitamin D levels, the first such reported case in the literature. There was no other evidence of a granulomatous disease such as sarcoidosis or tuberculosis to account for this. It is suggested that the increase in 1,25-dihydroxyvitamin D level was secondary to P. carinii induced macrophage dysfunction. As the patient's P. carinii pneumonia resolved, his 1,25 dihydroxyvitamin D level normalized along with the resolution of hypercalcemia.

Neither neutrophils nor reactive oxygen species contribute to tissue damage during Pneumocystis pneumonia in mice

Neutrophils are implicated in the damage of lung tissue in many disease states, including infectious diseases and environmental insults. These effects may be due to oxidative or nonoxidative functions of the neutrophil or both. We examined the role of neutrophils in pulmonary damage during infection with the opportunistic fungal pathogen Pneumocystis sp. in four mouse models of neutrophil dysfunction. These were (i) a knockout of the gp91(phox) component of NADPH oxidase, in which reactive oxygen species (ROS) production is greatly reduced; (ii) a double knockout of gp91(phox) and inducible nitric oxide synthase, in which ROS and nitric oxide production is greatly decreased; (iii) a knockout of the chemokine receptor CXCR2, in which accumulation of intra-alveolar neutrophils is severely diminished; and (iv) antibody depletion of circulating neutrophils in wild-type mice with the monoclonal antibody RB6. Surprisingly, in each case, indicators of pulmonary damage (respiratory rates, arterial oxygen partial pressures, and intra-alveolar albumin concentrations) were the same in knockout mice and comparable wild-type mice. Therefore, whereas neutrophils are a valid correlative marker of lung damage during Pneumocystis infection, neither neutrophils nor ROS appear to be the causative agent of tissue damage. We also show that there is no difference in Pneumocystis burdens between wild-type and knockout mice, which supports the idea that neutrophils do not have a major role in the clearance of this organism.