Diagnostic imaging and therapeutic implications in lung infections in patients with HIV-1 infection

We studied retrospectively 132 episodes of infectious pneumonias in 89 patients examined from 1990 to 1995. Pneumocystis carinii was found to be the most common cause of pneumonia (33 patients). The other causes were: Streptococcus pneumoniae (15), Mycobacterium tuberculosis (14), Pseudomonas aeruginosa (8), Staphylococcus aureus (5), Cytomegalovirus (4), Haemophilus influentiae (4), Mycobacterium avium intracellulare (2), Klebsiella pneumoniae (2), E. coli (2), Serratia marcescens (1). No etiologic agent was found in 40 cases. We stress the need of a more frequent use of invasive diagnostic procedures in the study of focal lung consolidations because this radiologic sign is highly aspecific and may be caused by too many different pathogenic agents, needing different therapies-i.e., Streptococcus pneumoniae (15 cases), Pseudomonas aeruginosa (8), Staphylococcus aureus (5), Klebsiella pneumoniae (2), Escherichia coli (2), Pneumocystis carinii, Serratia marcescens and Haemophilus influentiae (1). Since there is an increase in mortality among patients treated with empiric antibiotic therapy, we stress the need of the routinary use of bronchoalveolar lavage in HIV+ patients with lung consolidation to perform specific therapy. Moreover, Pneumocystis carinii is by far the most frequent cause of diffuse interstitial infiltrates, and PCP has very suggestive clinical (dyspnea), radiologic (diffuse perihilar interstitial infiltrates; ground glass opacities; pneumatoceles) and laboratory (CD3+CD4 < 200/mcl; LDH > 600 UI/dl; PO2 < 70 mmHg) patterns, always related to the discovery of Pneumocystis carinii in escreatum. Thus, we decided to treat 15 patients with specific therapy for Pneumocystis carinii pneumonia with the above diagnostic algorithm, obtaining in all of them complete clinical and radiologic recovery. To conclude, in critical patients, invasive procedures should be performed only in the cases in which PCP is clinically improbable.     

Cavitary pulmonary lesions in patients infected with human immunodeficiency virus

The differential diagnosis of cavitary pulmonary lesions in individuals infected with human immunodeficiency virus (HIV) is broad, especially in patients with advanced disease. In patients with Pneumocystis carinii pneumonia, cavitation is an uncommon manifestation of a common disease. It is unusual in patients with pulmonary cryptococcosis, coccidioidomycosis, and histoplasmosis but occurs frequently in patients with invasive pulmonary aspergillosis. In patients with pulmonary tuberculosis, cavities are more common during earlier stages of HIV disease, when cellular immunity is relatively preserved. Mycobacterium avium complex is an uncommon cause of lung disease and infrequently produces cavities. However, Mycobacterium kansasii, is often associated with cavitation. Cavities can complicate any bacterial pneumonia and are especially common with pneumonia due to Pseudomonas aeruginosa, Nocardia asteroides, and Rhodococcus equi. Noninfectious causes of cavitary lesions are rare, but cavitary lesions caused by pulmonary Kaposi's sarcoma and non-Hodgkin's lymphoma have been reported. Because of the broad differential diagnosis and because most cavities are caused by treatable opportunistic infections, a definitive diagnosis is essential.     

Granulomatous Pneumocystis carinii pneumonia: DNA amplification studies on bronchoscopic alveolar lavage samples

Three HIV positive subjects presented with symptoms and radiographic changes suggestive of Pneumocystis carinii pneumonia. Methenamine silver staining of bronchoscopic alveolar lavage (BAL) fluid was negative (from one sample in one patient and two samples in the other two patients). Open lung biopsy was performed because of uncertain clinical progress and diagnosis; all three patients were found to have multiple pulmonary granulomata encasing numerous P carinii organisms. DNA amplification, using P carinii specific oligonucleotides, was performed on stored bronchoscopic BAL samples. P carinii specific amplification product was detected by ethidium bromide staining after electrophoretic separation on agarose gel in one case, and by the more sensitive technique of oligohybridisation in all three cases. In granulomatous P carinii pneumonia organisms are rarely identified in bronchoscopic alveolar lavage samples using histochemical staining, but are detectable by DNA amplification, although not at levels which can be readily distinguished from low, subclinical infection.     

Salmonella lung involvement in patients with HIV infection

STUDY OBJECTIVE: To determine the frequency, clinical features, and outcome of lung involvement in HIV-infected patients having nontyphoid strains of Salmonella bacteremia. DESIGN: A retrospective clinical study. PATIENTS AND SETTING: We studied the records of all HIV-infected patients with Salmonella bacteremia diagnosed at a university tertiary hospital from January 1987 to December 1995. RESULTS: Lung involvement was found in 18 (35.3%) of 51 HIV-infected individuals with Salmonella bacteremia. Six of 18 (33.3%) were diagnosed as having definite Salmonella pulmonary infection by isolation of Salmonella from respiratory specimens, while probable Salmonella lung disease was considered in two patients who developed lung abscesses without the identification of any pathogen. Predisposing factors for focal disease, such as prior lung disease or Salmonella serotype, were equally prevalent regardless of the presence of Salmonella pulmonary involvement. Cavitary infiltrates or abscess formation were seen in five of the eight patients. With the exception of one patient coinfected with Nocardia asteroides who died 1 month later, all patients were cured with antibiotic treatment. Superinfection with other pulmonary pathogens (10 cases, 56%) was more frequent than Salmonella pneumonia; the most frequent alternative diagnosis was Pneumocystis carinii pneumonia (5 cases, 28%), pyogenic bacterial infection (17%), and tuberculosis (11%). CONCLUSIONS: In HIV-infected patients with Salmonella bacteremia, lung involvement is frequent, although there were no significant factors to explain this association. Cavitary disease was the most common radiologic pattern, and focal lung disease due to Salmonella does not seem to be associated with a worse prognosis. Coinfection and superinfection with other respiratory pathogens are more common than isolated Salmonella lung disease, and therefore, additional diagnostic procedures must be considered in the evaluation of these patients.     

Pneumocystis carinii pneumonia: an opportunistic infectious risk associated with systemic diseases and their treatment

Pneumocystis carinii, an opportunistic pathogen, often causes pneumonia in persons with human immunodeficiency virus (HIV) infection. In patients free of HIV infection, the risk is clearly associated with certain diseases and immunosuppressive therapy. Pneumocystis carinii pneumonia can complicate solid or hematologic malignancies, organ transplantation and connective tissue diseases. Recent therapeutic strategies based on aggressive immunosuppression have increased the risk of opportunistic infection with Pneumocystis carinii, particularly in patients with Wegener's syndrome and systemic lupus erythematosus. The risk of interhuman nosocomial transmission of Pneumocystis carinii in units caring for HIV-infected patients and patients with immunosuppressive diseases should also be considered. The undeniable progress in therapeutic immunosuppression has increased the risk of opportunistic infections. The gravity of Pneumocystis carinii pneumonia demonstrates the importance of optimizing treatment choice in order to strike the right balance between beneficial effect and risk of opportunistic infection.     

Extrapulmonary and disseminated pneumocystosis in HIV infection

Three cases of extrapulmonary disseminated Pneumocystis carinii infection are reported. All 3 patients had HIV infection with less than 50 CD4 lymphocytes per cubic millimeter and were having aerosols of pentamidine as prophylactic treatment of pneumocystosis. P. carinii may invade numerous organs and in particular the liver, spleen and bone marrow. Extrapulmonary lesions, often pan-symptomatic, are to be feared in deeply immunodepressed patients receiving prophylactic aerosols of pentamidine. Infection of the choroid can be detected by systematic ophthalmoscopy. An early diagnosis raises hopes of a good, if temporary, response to treatment.     

Fever among outpatients with advanced human immunodeficiency virus infection

BACKGROUND: Fever is common among persons with human immunodeficiency virus (HIV) infection. However, the clinical implications of fever in this population have not been evaluated. We therefore undertook a prospective study of fever in persons with advanced HIV infection to determine the incidence and etiology of fever in this patient group. METHODS: Prospective natural history study of 176 patients with advanced HIV infection followed up at Memorial Sloan-Kettering Cancer Center, New York, NY, from April 1, 1990, through December 31, 1990. RESULTS: Fever occurred in 46% of patients. A diagnosis was made in 83% of episodes, with acquired immunodeficiency virus-defining illnesses accounting for half of the diagnosed cases. Patients whose conditions required more than 2 weeks to diagnose most often had lymphoma, Mycobacterium avium-intracellulare bacteremia, or Pneumocystis carinii pneumonia. Four patients had persistent unexplained fever without a clear source. Only one patient had fever that clearly responded to antiretroviral therapy. CONCLUSIONS: Fever is common among outpatients with advanced HIV infection. Human immunodeficiency virus itself is rarely the cause of fever in such patients; the cause of the fever should be thoroughly evaluated.     

Pneumocystis carinii meningoradiculitis in a patient with AIDS

Pneumocystis carinii is a common opportunistic pathogen in patients infected with the human immunodeficiency virus (HIV). Pneumocystis carinii pneumonia is common, while extrapulmonary infections with Pneumocystis carinii have been reported sparingly. The clinical features are frequently nonspecific. The detection of Pneumocystis carinii in cerebrospinal fluid (CSF) has not been reported thus far. In this report, an unusual case of Pneumocystis carinii meningoradiculitis in an HIV-infected patient who had previously received primary prophylaxis with trimethoprim-sulfamethoxazole is presented.     

The diagnosis of Pneumocystis carinii pneumonia by cytologic evaluation of Papanicolaou and Leishman-stained bronchoalveolar specimens in patients with the acquired immunodeficiency syndrome

The presence of foamy alveolar casts or flocculent material in Papanicolaou and Leishman-stained smears of bronchoalveolar lavage (BAL) fluid is said to be indicative of infection with Pneumocystis carinii. We have investigated the sensitivity and specificity of this method of diagnosing pneumocystis pneumonia in patients with the acquired immunodeficiency syndrome (AIDS). Patients (n = 114) with diffuse lung infiltrates were submitted to fibreoptic bronchoscopy and BAL. Seventy of them were patients with AIDS. The other 44 individuals were not infected by the human immunodeficiency virus (HIV). Pneumocystis carinii organisms were identified on Grocott's methenamine silver (GMS)-stained BAL smears in 30 patients with AIDS. Flocculent material was present in the Papanicolaou and Leishman-stained smears from all of these cases. Conversely, P. carinii were not seen on GMS-stained smears in the remaining 84 individuals with or without AIDS. No flocculent material was observed in Papanicolaou or Leishman-stained smears in these 84 patients. We concluded that the presence of flocculent material in Papanicolaou or Leishman-stained smears of BAL fluid is indicative of P. carinii pneumonia in patients with AIDS.     

Respiratory infections in patients with HIV

Pneumocystis carinii pneumonia has long been considered the predominant pulmonary disease in patients with HIV, but several factors are changing this perception. The population infected with HIV is increasingly composed of injection drug users, and racial and ethnic minorities, which represent groups that have a high incidence of bacterial pneumonia and tuberculosis. The increased longevity attributed to antiretroviral therapy and P. carinii pneumonia prophylaxis is accompanied by more profound immunosuppression, rendering patients susceptible to Pseudomonas, Aspergillus, and other opportunistic pneumonias. Trimetrexate and atovaquone are now available for the treatment of P. carinii pneumonia. Both are less effective than standard regimens of trimethoprim-sulfamethoxazole, but have fewer adverse effects. The diagnosis of respiratory infections complicating HIV usually depends on isolation of the pathogen. The routine use of transbronchial biopsy during bronchoscopy is controversial because the prevalence of P. carinii pneumonia is high in most centers caring for patients with AIDS, and bronchoalveolar lavage is usually diagnostic in this disease. However, biopsy enhances the yield of bronchoscopy, especially in the diagnosis of noninfectious pulmonary disorders and infections other than P. carinii pneumonia.     

Community-acquired bacteremia in HIV-positive patients: protective benefit of co-trimoxazole

OBJECTIVE: To evaluate the effect of the type of Pneumocystis carinii pneumonia (PCP) prophylaxis on the development of community-acquired bacteremia. DESIGN: Case-control study using all cases of community-acquired bacteremia identified prospectively during a longitudinal study of all infections in a cohort of HIV-infected persons. SETTING: University-affiliated Department of Veterans Affairs Medical Center HIV program. PATIENTS: All patients with community-acquired bacteremia seen at the facility between January 1990 and December 1995 were included. Controls, seen at the same facility and matched by date and CD4 count, were used to assess risk factors. A total of 57 cases and 114 controls were analysed. MAIN OUTCOME MEASURES: Risk of development of bacteremia, distribution of organisms, and effect of specific prophylactic regimens for PCP. RESULTS: Bacteremia was caused by Staphylococcus aureus (23%), Pseudomonas aeruginosa (18%), Escherichia coli (16%), Streptococcus pneumoniae (14%) and others (31%). Groups were similar by age, race, HIV risk factors and CD4 count. The presence of an intravenous catheter was mildly predictive of the development of bacteremia [odds ratio (OR), 2.67; P = 0.024]. Type of PCP prophylaxis in cases and controls with CD4 < 200 x 10(6)/l included co-trimoxazole (trimethoprim-sulfamethoxazole, TMP-SMX; 31 and 60%, respectively), dapsone (33 and 24%, respectively) and aerosolized pentamidine (27 and 13%, respectively). Use of TMP-SMX (but not dapsone or aerosolized pentamidine) was associated with the absence of bacteremia (OR, 0.28; P = 0.001). A similar protective effect was found when controlling for the presence of an intravenous catheter. CONCLUSION: PCP prophylaxis with TMP-SMX apparently protects against community-acquired bacteremia in HIV-infected persons.     

AIDS: infections of the retina and choroid

Various viral, bacterial, parasitic and fungal agents have been found to cause infections of retina and choroidea in HIV-infected patients. Usually these infections are opportunistic infections caused by the profound immunodeficiency, which is a result of the decay of lymphocytes by HIV. Before the HIV epidemic only rare cases of cytomegalovirus (CMV) retinitis were known in the literature. Now CMV retinitis has become the most common infection of the eye in AIDS patients. Ocular toxoplasmosis in HIV-infected patients can have a severe clinical appearance without treatment. Spontaneous recovery, as it usually occurs in otherwise healthy patients, does not take place in HIV-infected patients, so that a lifelong maintenance therapy is mandatory. Pneumocystis carinii chorioiditis was unknown before the HIV epidemic. In 1987 Pneumocystis carinii were found in the choroidea and two years later the clinical appearance could be described. Infections of choroidea and retina associated with AIDS may not be seen as isolated diseases. Commonly other organs are infected by the same or another organism. In case of AIDS-associated eye infections other organs should be checked for opportunistic disease. Diagnosis can be difficult. Because most of all intraocular infections associated with AIDS are CMV retinitis, an effective therapy can be initiated in most cases and in the follow-up a diagnosis can finally be made. Serological testing may be inconclusive because of occasional false-negative findings. Treatment often only suppresses the infections and so ongoing maintenance therapy may be necessary, as in the cases of CMV retinitis and Toxoplasma retinochorioiditis. A variety of different diseases, which can be treated by a multitude of different substances with a lot of adverse effects and contraindications, can complicate the therapeutic modalities used for the management of each individual disorder. Additionally HIV-infected patients suffer from at least two or three different diseases and must be treated lifelong with plenty of substances, which often are given with higher doses than usual. Only by cooperation of HIV-experienced doctors of different specialities in hospitals and offices the complex subject of HIV infection can be managed.     

Clinical features of tuberculosis associated with HIV infection in Taiwan

To understand the clinical characteristics and outcome of tuberculosis (TB) in patients with acquired immunodeficiency syndrome (AIDS) in Taiwan, we reviewed the medical records of 118 adult AIDS patients who were hospitalized at National Taiwan University Hospital between January 1988 and September 1995. Among them, 29 (24.6%) had TB. The mean age of the AIDS patients with TB was 37 years (range, 25-66 yr). Most patients were in the advanced stages of AIDS when human immunodeficiency virus (HIV) infection and/or TB were first diagnosed. The mean CD4+ lymphocyte count was 0.037 x 10(9)/L (range, 0-0.152 x 10(9)/L) at the time TB was diagnosed. There was no statistically significant difference in the mean CD4+ lymphocyte count between patients with isolated pulmonary TB and those with extrapulmonary involvement. Twenty-two patients (75.8%) had extrapulmonary TB with the most common site being the lymph nodes (72.7%). Clinical symptoms were nonspecific, and the chest physical examination was not helpful in the diagnosis. Acid-fast bacilli were detected in sputum smears from eight patients (36.4%). A primary tuberculosis pattern (hilar adenopathy, pleural effusion, middle or lower lobe infiltrates) in the chest radiographs was the most common radiologic finding (36.4%) in patients with pulmonary TB. The reactivation pattern (predominant upper-lobe infiltrates with or without cavitation) could only be found in cases of pulmonary TB without extrapulmonary involvement. Atypical patterns (diffuse interstitial infiltrates mimicking Pneumocystis carinii pneumonia or other patterns) and normal chest radiographs were noted in nearly one-third of the patients with pulmonary TB. A good response to antituberculosis drugs and a favorable outcome were demonstrated in the patients, except for two with drug-resistant Mycobacterium tuberculosis infection. Early identification of TB in HIV-infected patients requires clinical awareness of the unusual clinical presentations, especially among patients in the advanced stages of AIDS.     

Rapid shift in peak melatonin secretion associated with improved performance in short shift work schedule

OBJECTIVE: To describe the changes in the characteristics of human immunodeficiency virus (HIV)-related deaths in children with perinatally acquired infection. METHODS: A retrospective review of all deaths that occurred in HIV-infected children managed at The New York Hospital-Program for Children with AIDS during a 7-year period from January, 1990, to December, 1996. Differences in the characteristics at death between 15 children who died in 1990 and 10 children who died in 1996 were analyzed. RESULTS: Fifty-eight deaths in our cohort of HIV-infected children were identified during the 7-year period. The mean age at death was 4.43 years. Sixty-nine percent of children were black, 55% were male and 94% were receiving Medicaid. The mean weight/age Z score was -3.9 and the mean CD4 index was 0.067 with 65% having <50 CD4 cells/microl at the time of death (TOD). The most common organ/organ systems to be involved at the TOD were lung (78%) and central nervous system (61%). Mycobacterium avium complex (MAC) was the most common isolate at the TOD (26%) followed by Pneumocystis carinii (20%) and Pseudomonas aeruginosa (17%). The leading non-infectious cause of death was cardiac failure (9%). Comparison of the characteristics at the TOD between 1990 and 1996 revealed significant differences in mean age (2.1 vs. 9.2 years, P < 0.0001), mean CD4 count index (0.18 vs. 0.02, P < 0.03), mean number of organ/organ system involvement (3.9 vs. 5.9, P < 0.05), percent receiving antiretroviral therapy (33% vs. 70%, P < 0.02), mean number of years receiving antiretroviral therapy (0.88 vs. 3.86 years, P < 0.01), percent receiving P. carinii pneumonia prophylaxis (27% vs. 100%, P < 0.001), percent receiving MAC prophylaxis/therapy (0% vs. 100%, P < 0.0001), and cause of death from P. carinii pneumonia (53% vs. 0%, P < 0.01). CONCLUSIONS: Compared with children who died in 1990, HIV-infected children who died in 1996 were significantly older, more lymphopenic and more likely to have a greater number of organ system involvements and to have received antiviral therapy and antimicrobial prophylaxis. In 1996 no child died of P. carinii pneumonia. In 1996 MAC and P. aeruginosa were the two most important opportunistic infections causing death. These changes in the characteristics at death will warrant review of resources used in treating these children and may be critical in advising parents and care givers about the prognosis of this chronic infection.     

New systems of cardiac mapping or life to the electrophysiologist may become complicated

We report the case of an infant with progressive human immunodeficiency virus (HIV) infection and persistent seronegativity. The child had Pneumocystis carinii pneumonia at 4 months of age and was documented to be HIV-infected by HIV-1 deoxyribonucleic acid (DNA) polymerase chain reaction (PCR), but enzyme-linked immunosorbent assay (ELISA) and Western blot tests for HIV-1 and HIV-2 specific antibodies remained negative until the infant was 10 months old. This case should increase awareness about the possibility of seronegative HIV infection in infants and stress the fact that in questionable cases, even if the screening serology is negative, additional methods of diagnosis (ie, PCR, viral culture, and p24 antigen) should be considered.     

Breast abscess with lethal septicemia due to Pseudomonas aeruginosa in a patient with AIDS

OBJECTIVE: The incidence of Pseudomonas aeruginosa in HIV-infected patients has increased over the last years. We describe a case of pseudomonal breast abscess complicated with fatal septicemia in an AIDS patient. CASE REPORT: A 21-year-old woman was admitted for fever, chills, nausea, vomiting and pain in the breast. She had a swelling in the right breast of 3 days duration. HIV infection had been confirmed 6 years earlier. CD4 count was 2/mm3. Surgical drainage produced a blue-green purulent discharge which grew Pseudomonas aeruginosa on culture. Despite cloxacilin, then ceftazidime and amikacin, initial improvement was followed 2 weeks later by nodular pulmonary infiltration with cavitation. P. aeruginosa was recovered from sputum and blood cultures, but stepwise resistance developed and the patient died 3 months after admission. DISCUSSION: Breast abscesses are infrequent in nonlactating women. P. aeruginosa is rarely involved, even in HIV patients. Due to the risk of resistance, prompt administration of appropriate antibiotics is required.     

Pneumocystis carinii pneumonia in preterm infants: report of two cases successfully diagnosed by non-bronchoscopic bronchoalveolar lavage

We present two cases of Pneumocystis carinii pneumonia in apparently immunocompetent preterm infants presenting with unexplained respiratory distress associated with a predominantly interstitial process on the chest radiograph. Definite diagnosis was promptly established on the detection of cyst forms in the lung fluid obtained by non-bronchoscopic bronchoalveolar lavage, and a favourable outcome was achieved.     

Locoregional anesthesia for injuries of the lower limbs

OBJECTIVE: To determine whether quantification of specific antifungal antibody responses in serum can provide supplemental information for the diagnosis of Aspergillus fumigatus infections and the monitoring of antifungal treatment in patients after lung transplantation. DESIGN: Retrospective study. SETTING: Center for lung transplantation, University Hospital Groningen, the Netherlands. PATIENTS: 4 patients with proven A. fumigatus infections after lung transplantation and fatal outcome. MEASUREMENTS: The IgG antibody response specific for A. fumigatus antigens was measured by enzyme-linked immunosorbent assay and was compared with radiographic features, cytologic findings, microbiological cultures, and clinical diagnosis. RESULTS: Increasing IgG antibody responses specific for A. fumigatus antigens closely paralleled cytologic or microbiological identification of A. fumigatus from bronchoalveolar lavage fluid and decrease of lung function. Increasing specific IgG antibody responses were found to precede radiographic identification of lung cavitation by 1 to 2 weeks, precede the diagnosis of aspergillosis by 2 to 20 weeks, and detect fungal reinfection. In most cases, successful antifungal treatment decreased specific IgG antibody response. A decrease in specific IgG antibody response correlated with the inability to culture or identify A. fumigatus in bronchoalveolar lavage fluid and with radiographic and clinical improvement. CONCLUSIONS: Specific IgG antibody responses in serum correlate with radiographic, cytologic, and microbiological findings and with the clinical diagnosis of A. fumigatus infections in patients who have had lung transplantation. Increased IgG antibody responses in serum may provide important information that is helpful in the diagnosis and early treatment of pulmonary fungal infections and in monitoring antifungal treatment.     

Pneumocystis carinii pneumonia masquerading as tuberculosis

Recent laboratory studies indicate that genetic diversity exists in human strains of Pneumocystis carinii. Structural and functional variability in infecting strains could result in differences in host-parasite interactions and the natural history of P carinii pneumonia. We report 5 unusual cases in which the clinical presentation mimicked tuberculosis. All patients were cared for at a university-based public hospital clinic in Los Angeles, Calif, during a 2-year period. These patients were chronically ill, had lost weight, and each had cavities or cystic spaces as the primary radiographic findings. None were receiving aerosol pentamidine and only one had a history of smoking. Four patients were initially treated for tuberculosis and the fifth for disseminated Mycobacterium avium complex. Pneumocystis carinii was the only pathogen identified in each case. The unusual clinical presentations delayed the diagnosis of P carinii in all 5 cases. Practitioners must be aware of the variable presentations of P carinii pneumonia.     

Reduced binding and phagocytosis of Pneumocystis carinii by alveolar macrophages from persons infected with HIV-1 correlates with mannose receptor downregulation

The macrophage mannose receptor, a pattern recognition molecule and component of innate immunity, mediates binding and phagocytosis of Pneumocystis carinii and likely represents an important clearance mechanism in the lungs of immunocompetent hosts. The purpose of this study was to examine the ability of alveolar macrophages from HIV-infected individuals to bind and phagocytose P. carinii, and to investigate the role of the macrophage mannose receptor in mediating this interaction. Compared with healthy individuals, alveolar macrophage phagocytosis of P. carinii from HIV+ persons was reduced up to 74% (P = 0.02), primarily reflecting a reduction in the number of organisms associated with each macrophage (P = 0.019). Furthermore, macrophages from HIV+ individuals demonstrated up to an 80% (P < 0.05) reduction in mannose receptor surface expression and endocytosis. Mannose receptor affinity was unaltered, and mRNA levels were modestly reduced (P < 0.05). Cells from HIV+ individuals with CD4(+) counts < 200 cells/mm3 (representing individuals at high clinical risk for P. carinii pneumonia) demonstrated the lowest levels of P. carinii phagocytosis and mannose receptor endocytosis. In vitro HIV infection of alveolar macrophages from healthy individuals reduced mannose receptor endocytosis to 53.2% (P < 0.05) and P. carinii binding and phagocytosis to 67.4% (P < 0.05) of control. Our studies suggest that HIV infection may alter innate immunity in the lungs, and that impaired alveolar macrophage mannose receptor-mediated binding and phagocytosis of P. carinii may contribute to the susceptibility of HIV-infected individuals to this opportunistic pulmonary pathogen.