Pulmonary Involvement in Leptospirosis

 The objective of this study was to assess the incidence of pulmonary involvement in a cohort of 26 patients in whom a diagnosis of leptospirosis had been made. Seventeen of the 26 patients had respiratory symptoms. Of these 17 patients, 13 had radiographs showing pulmonary abnormality. The most frequent finding was a bilateral patchy alveolar-acinar pattern in six patients. Three patients developed acute respiratory distress syndrome and died due to multiorgan failure. Only cigarette smoking was significantly associated with respiratory involvement (odds ratio, 19.2; 95% CI, 1.7–250;P<0.001). The results indicate that pulmonary manifestations are observed in a high percentage of patients with leptospirosis. Cigarette smoking is a risk factor for the development of pulmonary involvement in human leptospirosis.     

The Lung in Sickle Cell Disease: A Clinical Overview of Common Vascular, Infectious, and Other Problems

Acute pulmonary complications of sickle cell anemia are sickle cell lung disease and bacterial pneumonias. Chronic abnormalities in lung function include a restrictive ventilatory defect and perhaps increased venous admixture to the pulmonary circulation. Coexisting sarcoidosis may complicate sickle cell anemia and interact to potentiate sickling. Sickle cell lung disease, or acute “chest syndrome,” occurs with greatest frequency in adults, is due primarily to pulmonary infarction, and may lead to cor pulmonale. On the other hand, bacterial pneumonia due to Streptococcus pneumoniae occurs with greater frequency in infancy and childhood. Mycoplasma and other organisms may also cause pneumonia with protracted illness and slow resolution. Bacteremia and meningitis may be further complications, particularly in children. Precise diagnosis of the acute febrile pulmonary episode is often difficult. In adults the illness is commonly self-limited. However, a vigorous diagnostic approach is warranted in all severely ill patients.     

Morphometric differences in pulmonary lesions in primary and secondary ARDS. A preliminary study in autopsies

The present study was undertaken in order to describe the morphological differences between pulmonary lesions in acute respiratory distress syndrome originating from direct pulmonary injury (ARDSp) and those originating from extrapulmonary injury (ARDSexp).We investigated a total of 38 ARDS-patients (27 males) ranging in age from 19 to 75 years, classified according to underlying disease in pulmonary (ARDSp) and extrapulmonary disease (ARDSexp). The extent of acute diffuse alveolar damage was assessed morphometrically on histologic gross sections in the upper and lower lobes of one lung.The lesions showed quantitative differences in extent and distribution according to underlying disease (primary pulmonary or secondary involvement).In pulmonary ARDS, a predominance of alveolar collapse (16.6% ± 12.3% versus 10.3% ± 11.9%, p = 0,03), fibrinous exudate (1.7% ± 3.2% versus 0.4% ± 1.1%, p = 0.01) and alveolar wall edema (11.2% ± 7.4% versus 6.6% ± 4.4%, p = 0,05) were found compared to extrapulmonary ARDS.We conclude that the morphology of acute diffuse alveolar damage (DAD) is mainly determined by underlying disease (pulmonary ARDS or extrapulmonary ARDS) differing in quantitative terms within the lung. Physiological, radiographic and respiratory system mechanics differences described in ARDSp and ARDSexp may therefore be due to morphometric differences in pulmonary lesions.     

Factors associated with severity and mortality in patients with confirmed leptospirosis at a regional hospital in northern Taiwan

Background/purposeThe clinical, epidemiological, and laboratory factors associated with disease severity and mortality from confirmed leptospirosis patients in Taiwan are not well known. This retrospective study examined patients with suspected leptospirosis admitted to En-Chu-Kong Hospital, a regional teaching hospital in northern Taiwan.MethodsFrom January 2002 to July 2014, 733 suspected cases were reported to the National Reference Laboratory, 57 of which were identified as laboratory and clinical confirmed. We analyzed the clinical, epidemiological, and laboratory factors associated with disease severity and mortality in 57 cases.ResultsThe mean age was 59.1 ± 18.2 years, 74% were male, and 49% had occupational contact with soil. The major complications were pulmonary involvement (54%), shock (44%), ventilator support (32%), jaundice (32%), hemorrhage (30%), acute kidney injury (30%), meningitis (11%) and myocarditis (2%). Leptospira santarosai serova Shermani was present in 42 (74%) patients and 37 (58%) patients had severe leptospirosis. Sixteen (28%) patients had concomitant infections, including nine patients with bloodstream infection. The only independent predictor for severe leptospirosis was shock (OR 14.8, 95% CI 2.97–73.59). Eleven patients died (19%). Acute respiratory distress syndrome with severe pulmonary hemorrhage syndrome (6 patients) was present in 55% of the fatal cases. The factors independently related to mortality were prior steroid use (OR 20.2, 95% CI 1.9–217.5) and hemorrhage (OR 71.2, 95% CI 4.9 – >999.9).ConclusionThese results indicate that shock is a predictor of severe leptospirosis, and prior steroid use and hemorrhage are predictors of death from leptospirosis.     

Haemorrhagic pneumonitis: A rare presentation of leptospirosis

Leptospirosis is an uncommon zoonosis. As a systemic disease, it presents itself by multisystem involvement. Pulmonary involvement with leptospirosis often is manifested by respiratory symptoms; but pneumonia commonly is not a prominent clinical manifestation of the illness. We report a case of leptospiral pneumonia in which pulmonary manifestations were primary clinical features of the illness. The prompt resolution of chest x-ray on institution of treatment is noteworthy.     

Immune receptors and adhesion molecules in human pulmonary leptospirosis

Pulmonary involvement in leptospirosis has been increasingly reported in the last 20 years, being related to the severity and mortality of the disease. The pathogenesis of pulmonary hemorrhage in leptospirosis is not understood. Lung endothelial cells have been proposed as targets in the pathogenesis of lung involvement in leptospirosis through the activation of Toll-like receptor 2 or the complement system, which stimulates the release of cytokines that lead to the activation of adhesion molecules. The aim of this study was to investigate the involvement of immune pathways and of the intercellular and vascular cell adhesion molecules (intercellular adhesion molecule and vascular cell adhesion molecule, respectively) in the lungs of patients with pulmonary involvement of leptospirosis. We studied the lungs of 18 patients who died of leptospirosis and compared them with 2 groups of controls: normal and noninfectious hemorrhagic lungs. Using immunohistochemistry and image analysis, we quantified the expression of the C3a anaphylatoxin receptor, intercellular adhesion molecule, vascular cell adhesion molecule, and Toll-like receptor 2 in small pulmonary vessels and in the alveolar septa. There was an increased expression of intercellular adhesion molecule (P < .03) and C3a anaphylatoxin receptor (P < .008) in alveolar septa in the leptospirosis group compared with the normal and hemorrhagic controls. In the vessels of the leptospirosis group, there was an increased expression of intercellular adhesion molecule (P = .004), vascular cell adhesion molecule (P = .030), and Toll-like receptor 2 (P = .042) compared with the normal group. Vascular cell adhesion molecule expression in vessels was higher in the leptospirosis group compared with the hemorrhagic group (P = .015). Our results indicate that immune receptors and adhesion molecules participate in the phenomena leading to pulmonary hemorrhage in leptospirosis.     

Leptospirosis mimicking acute cholecystitis among athletes participating in a triathlon

Leptospirosis, a disease acquired by exposure to contaminated water, is characterized by fever accompanied by various symptoms, including abdominal pain. An acute febrile illness occurred in athletes who participated in an Illinois triathlon in which the swimming event took place in a freshwater lake. Of 876 athletes, 120 sought medical care and 22 were hospitalized. Two of the athletes had their gallbladders removed because of abdominal pain and clinical suspicion of acute cholecystitis. We applied an immunohistochemical test for leptospirosis to these gallbladders and demonstrated bacterial antigens staining (granular and filamentous patterns) around blood vessels of the serosa and muscle layer. Rare intact bacteria were seen in 1 case. These results show that leptospirosis can mimic the clinical symptoms of acute cholecystitis. If a cholecystectomy is performed in febrile patients with suspicious environmental or animal exposure, pathologic studies for leptospirosis on formalin-fixed, paraffin-embedded tissues may be of great value.     

Accuracy of AccessBio Immunoglobulin M and Total Antibody Rapid Immunochromatographic Assays for the Diagnosis of Acute Scrub Typhus Infection

Using archived samples, we assessed the diagnostic capacity of a rapid immunochromatographic test (ICT) for the detection of Orientia tsutsugamushi IgM and total antibodies to aid with the diagnosis of acute scrub typhus infection in febrile patients in Laos. The sensitivity and the specificity of the ICT for the detection of IgM were 96.8% (121/125 samples; 95% confidence interval [CI], 92.1 to 99.1%) and 93.3% (98/105 samples; 95% CI, 86.7 to 97.3%), respectively. For the detection of total antibodies, the sensitivity was 97.6% (122/125 samples; 95% CI, 93.1 to 99.5%), but the specificity was much lower, at 71.4% (75/105 samples; 95% CI, 61.8 to 79.8%).Scrub typhus, caused by Orientia tsutsugamushi, is an important acute febrile illness in the Asia-Pacific region. As very few health facilities have accessible accurate diagnostic tests, the diagnosis of scrub fever must be based on clinical features. However, this is difficult because the clinical symptoms and signs are similar to those of many other febrile diseases, such as murine typhus, leptospirosis, and dengue virus infection. The diagnosis of scrub typhus infection has relied on the detection of O. tsutsugamushi antibodies during the acute phase of the disease, and the “gold standard” assay is the indirect immunofluorescence antibody assay (IFA) (9). The development of rapid, diagnostic tests by the use of immunochromatographic test (ICT) technologies has provided a mechanism for point-of-care serological testing. The objective of the study described here was to assess the diagnostic capacities of two commercial rapid ICTs for the detection of O. tsutsugamushi IgM and whole antibodies to aid with the diagnosis of acute scrub typhus infection by the use of stored, characterized sera collected from febrile patients in the tropical environment of the Lao People''s Democratic Republic (Laos) and Thailand where scrub typhus is endemic.     

Serological and molecular study of Leptospira in pediatric patients at a tertiary care centre of northern India

Leptospirosis is considered as one of the most neglected zoonotic tropical diseases. Animals and humans acquire this infection through direct contact with contaminated urine or body fluids of infected animals. This prospective study was undertaken to know the proportion of leptospirosis in pediatric patients presented with acute febrile illness at the Post Graduate Department of Microbiology, King George's Medical University, Lucknow, Uttar Pradesh. Blood samples were collected over a period of one year from January to December 2018 from 70 pediatric patients aged up to 0–12 years presented with febrile illness for 3–14 days. Out of the 70 samples, 7 (10%) samples were found positive by IgM ELISA, 4 (5.7%) samples were positive by MAT and 3(4.3%) were found positive by PCR. Risk factors such as contact with infected animals and contaminated environment were highly associated with seropositivity of leptospirosis. Clinical symptoms such as fever, chills, myalgia, headache, abdominal pain and cough were significantly associated (p < 0.05) with the seropositivity of leptospirosis.     

Unusual clinical manifestations of leptospirosis

Leptospirosis has protean clinical manifestations. The classical presentation of the disease is an acute biphasic febrile illness with or without jaundice. Unusual clinical manifestations may result from involvement of pulmonary, cardiovascular, neural, gastrointestinal, ocular and other systems. Immunological phenomena secondary to antigenic mimicry may also be an important component of many clinical features and may be responsible for reactive arthritis. Leptospirosis in early pregnancy may lead to fetal loss. There are a few reports of leptospirosis in HIV-infected individuals but no generalisation can be made due to paucity of data. It is important to bear in mind that leptospiral illness may be a significant component in cases of dual infections or in simultaneous infections with more than two pathogens.     

Cyclophosphamide in pulmonary alveolar hemorrhage due to leptospirosis

Background and Aims:

Severe pulmonary involvement in leptospirosis carries high mortality rates. It is the most common cause of death due to leptospirosis in many parts of India and the world. Exacerbated immune response of the host plays an important role in its pathogenesis. Hence, immunosuppressive drugs could be useful in its treatment. Glucocorticosteroids have been found to be useful in several studies. Cyclophosphamide, an immunosuppressive agent, has been found to be useful in a majority of pulmonary alveolar hemorrhages due to non leptospiral causes. This study was carried out to study the effects of cyclophosphamide in patients with leptospiral pulmonary alveolar hemorrhage.

Method:

A total of 65 patients with confirmed leptospirosis with severe pulmonary involvement admitted to a tertiary care center in south Gujarat were included in the study. All of the patients were treated with injection crystalline penicillin, methyl prednisolone pulse therapy, and non invasive mechanical ventilation. A total of 33 patients were given parenteral cyclophosphamide 60 mg/kg body weight stat on diagnosis. Their outcomes were compared with the remaining 32 patients who had not been given this drug. Survival was considered the main outcome indicator.

Results:

Out of the 33 patients treated with cyclophosphamide, 22 (66.7%) survived, while in the control group out of 32 patients, three (9.4%) survived. On statistical analysis, the odds ratio was 19.33 (4.22–102.13) and the P-value was <0.001. Leucopenia (78.78%) and alopecia (18.75%) were the main side effects noted. No mortality was noted due to these side effects.

Conclusion:

Cyclophosphamide improves survival in cases of severe pulmonary alveolar hemorrhage due to leptospirosis. Statistically, the improvement is highly significant.     

Acute respiratory distress syndrome: Pulmonary and extrapulmonary not so similar

Acute respiratory distress syndrome (ARDS) is characterized by acute onset respiratory failure with bilateral pulmonary infiltrates and hypoxemia. Current evidence suggests different respiratory mechanics in pulmonary ARDS (ARDSp) and extrapulmonary ARDS (ARDSexp) with disproportionate decrease in lung compliance in the former and chest wall compliance in the latter. Herein, we report two patients of ARDS, one each with ARDSp and ARDSexp that were managed using real-time esophageal pressure monitoring using the AVEA ventilator to tailor the ventilatory strategy.     

Demographic, etiological, and histological pulmonary analysis of patients with acute respiratory failure: a study of 19 years of autopsies

INTRODUCTION:

Acute respiratory failure has been one of the most important causes of death in intensive care units, and certain aspects of its pulmonary pathology are currently unknown.

OBJECTIVES:

The objective was to describe the demographic data, etiology, and pulmonary histopathological findings of different diseases in the autopsies of patients with acute respiratory failure.

METHOD:

Autopsies of 4,710 patients with acute respiratory failure from 1990 to 2008 were reviewed, and the following data were obtained: age, sex, and major associated diseases. The pulmonary histopathology was categorized as diffuse alveolar damage, pulmonary edema, alveolar hemorrhage, and lymphoplasmacytic interstitial pneumonia. The odds ratio of the concordance between the major associated diseases and specific autopsy findings was calculated using logistic regression.

RESULTS:

Bacterial bronchopneumonia was present in 33.9% of the cases and cancer in 28.1%. The pulmonary histopathology showed diffuse alveolar damage in 40.7% (1,917) of the cases. A multivariate analysis showed a significant and powerful association between diffuse alveolar damage and bronchopneumonia, HIV/AIDS, sepsis, and septic shock, between liver cirrhosis and pulmonary embolism, between pulmonary edema and acute myocardial infarction, between dilated cardiomyopathy and cancer, between alveolar hemorrhage and bronchopneumonia and pulmonary embolism, and between lymphoplasmacytic interstitial pneumonia and HIV/AIDS and liver cirrhosis.

CONCLUSIONS:

Bronchopneumonia was the most common diagnosis in these cases. The most prevalent pulmonary histopathological pattern was diffuse alveolar damage, which was associated with different inflammatory conditions. Further studies are necessary to elucidate the complete pathophysiological mechanisms involved with each disease and the development of acute respiratory failure.     

Leukotoxin-diol: a putative toxic mediator involved in acute respiratory distress syndrome.

Leukotoxin is clinically associated with acute respiratory distress syndrome (ARDS). Recently, we found that leukotoxin-diol, the hydrated product of leukotoxin, is more toxic than the parent leukotoxin in vitro (Moghaddam and colleagues, Nature Med. 1997;3:562-566). To test if this difference in the toxicity of leukotoxin and leukotoxin-diol exists in vivo, Swiss Webster mice were administered leukotoxin or leukotoxin-diol. All mice treated with leukotoxin-diol died of ARDS-like respiratory distress, whereas the animals exposed to leukotoxin at the same dose survived. Histopathologic evaluation of the lungs revealed massive alveolar edema and hemorrhage with interstitial edema around blood vessels in the lungs of mice treated with leukotoxin-diol, whereas the lungs of mice treated with identical doses of leukotoxin had perivascular edema only and little change in alveolar spaces. Immunohistochemistry showed that the soluble epoxide hydrolase responsible for the hydrolysis of leukotoxin to its diol is concentrated in the vascular smooth muscle of small and medium-sized pulmonary vessels. In addition, 4-phenylchalcone oxide, an inhibitor of soluble epoxide hydrolase, was found to decrease the mortality induced by leukotoxin but had no effect on mortality induced by leukotoxin-diol. These studies provide strong in vivo evidence that leukotoxin may act as a protoxicant and that the corresponding diol is a putative toxic mediator involved in the development of ARDS.     

Early diagnosis of leptospirosis by immunoglobulin M immunoblot testing

There is an urgent need for the development of serodiagnostic approaches with improved sensitivity for patients with acute leptospirosis. Immunoblots were performed on 188 sera collected from 74 patients with laboratory-confirmed early leptospiral infection to detect immunoglobulin M (IgM) antibodies to antigens pooled from 10 leptospiral strains prevalent in Thailand. Sera from patients with other febrile diseases served as controls. IgM reactivity to seven distinct antigens, with apparent molecular masses of 14 to 18, 19 to 23, 24 to 30, 32, 35/36, 37, and 41/42 kDa, was observed. The low-molecular-mass 14- to 18-kDa band was the most frequently detected antigen, being recognized in sera from 82.4% of patients during the first 3 days after the onset of symptoms. We evaluated the accuracy of the IgM immunoblot (IgM-IB) test by using reactivity to the 14- to 18-kDa band and/or at least two bands among the 19- to 23-, 24- to 30-, 32-, 35/36-, 37-, and 41/42-kDa antigens as the diagnostic criterion. The sensitivities of the IgM-IB test and the microscopic agglutination test (MAT) were 88.2% and 2.0%, respectively, with sera from patients 1 to 3 days after the onset of symptoms. In contrast, the IgM-IB test was positive with only 2/48 (4.2%) sera from patients with other febrile illnesses. The high sensitivity and specificity of the IgM-IB test for acute leptospirosis would provide greatly improved diagnostic accuracy for identification of patients who would benefit from early antibiotic intervention. In addition, the antigens identified by the IgM-IB test may serve as components of a rapid, accurate, point-of-care diagnostic test for early leptospirosis.     

Neuropeptides in pulmonary edema fluid of adult respiratory distress syndrome

A role for peptidergic nerves in the adult respiratory distress syndrome (ARDS) was examined by radioimmunochemically quantifying neuropeptides in pulmonary edema (PE) fluids from seven patients with ARDS and six patients with PE from congestive heart failure (CHF). The PE fluid mean concentrations of substance P (SP) and gastrin-releasing peptide (GRP) were significantly higher in ARDS (0.59 ±0.29SD and 0.10=0.03 nM, respectively,P < 0.001 for both) than in CHF (0.19±0.08 and 0.04±0.01), whereas no difference was detected between the mean levels of vasoacti ve intestinal peptide (VIP) and calcitonin gene-related peptide (CGRP) in the two forms of PE. Mean alveolar fluid concentration of SP was 8.7 nM (range 2.1–20.5 nM,N=4) in sheep with acute lung injury from intravenousPseudomonas aeruginosa, but was undetectable in sheep with balloon-induced high left atrial pressure simulating CHF (N=2) or control sheep (N=2). Pulmonary lymphatic clearance of SP, which reflected the rate of generation of SP in the lungs, attained a maximum of 25–95 pmol/h in sheep givenP. aeruginosa intravenously, but was detected in only one of four control sheep at a lower level. Some pulmonary neuropeptides thus are released locally by acute lung injury and may contribute to endothelial and/or epithelial abnormalities underlying the altered capillary-alveolar permeability in ARDS.     

Fas and fas ligand are up-regulated in pulmonary edema fluid and lung tissue of patients with acute lung injury and the acute respiratory distress syndrome

Apoptosis mediated by Fas/Fas ligand (FasL) interaction has been implicated in human disease processes, including pulmonary disorders. However, the role of the Fas/FasL system in acute lung injury (ALI) and in the acute respiratory distress syndrome (ARDS) is poorly defined. Accordingly, we investigated both the soluble and cellular expression of the Fas/FasL system in patients with ALI or ARDS. The major findings are summarized as follows. First, the soluble expression of the Fas/FasL system was assessed in undiluted pulmonary edema fluid and simultaneous plasma. Pulmonary edema fluid obtained from patients with ALI or ARDS (n = 51) had significantly higher concentrations of both soluble Fas (27 ng/ml; median; P < 0.05) and soluble FasL (0.125 ng/ml; P < 0.05) compared to control patients with hydrostatic pulmonary edema (n = 40; soluble Fas, 12 ng/ml; soluble FasL, 0.080 ng/ml). In addition, the concentrations of both soluble Fas and soluble FasL were significantly higher in the pulmonary edema fluid of the patients with ALI or ARDS compared to simultaneous plasma samples (soluble Fas, 16 ng/ml; soluble FasL, 0.058 ng/ml; P < 0.05), indicating local release in the lung. Higher soluble Fas concentrations were associated with worse clinical outcomes. Second, cellular expression of the Fas/FasL system was assessed by semiquantitative immunofluorescence microscopy in lung tissue obtained at autopsy from a different set of patients. Both Fas and FasL were immunolocalized to a greater extent in the patients who died with ALI or ARDS (n = 10) than in the patients who died without pulmonary disease (n = 10). Both proteins were co-expressed by epithelial cells that lined the alveolar walls, as well as by inflammatory cells and sloughed epithelial cells that were located in the air spaces. Semiquantitative immunohistochemistry showed that markers of apoptosis (terminal dUTP nick-end labeling, caspase-3, Bax, and p53) were more prevalent in alveolar wall cells from the patients who died with ALI or ARDS compared to the patients who died without pulmonary disease. These findings indicate that alveolar epithelial injury in humans with ALI or ARDS is in part associated with local up-regulation of the Fas/FasL system and activation of the apoptotic cascade in the epithelial cells that line the alveolar air spaces.     

Total ginsenosides synergize with ulinastatin against septic acute lung injury and acute respir atory distress syndrome

Total ginsenosides synergize with ulinastatin (UTI) against septic acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). We randomly divided 80 cases of severe sepsis-induced ALI and ARDS into a UTI group and a ginsenosides (GS)+UTI group. Continuous electrocardiac monitoring of pulse, respiratory rate, blood pressure, and heart rate; invasive hemodynamic monitoring; ventilator-assisted breathing and circulation support; and anti-infection as well as UTI treatment were given in the UTI group with GS treatment added for 7 consecutive days in the GS+UTI group. The indicators of pulmonary vascular permeability, pulmonary circulation, blood gases, and hemodynamics as well as APACHE II and ALI scores were detected on days 1, 3, and 7. The ALI score in the GS+UTI group was significantly decreased (P < 0.05) compared with that of the UTI group, and the indicators of pulmonary capillary permeability such as pulmonary vascular permeability index, extravascular lung water index, and oxygenation index, in the GS+UTI group improved significantly more than that of the UTI group. The indicators of hemodynamics and pulmonary circulation such as cardiac index, intrathoracic blood volume index, and central venous pressure improved significantly (P < 0.05), and the APACHE II score in the GS+UTI group was lower than that of the UTI group. GS can effectively collaborate with UTI against ALI and/or ARDS.     

The novel coronavirus disease (COVID-19) complicated by pulmonary embolism and acute respiratory distress syndrome

Acute respiratory distress syndrome and coagulopathy played an important role in morbidity and mortality of severe COVID-19 patients. A higher frequency of pulmonary embolism (PE) than expected in COVID-19 patients was recently reported. The presenting symptoms for PE were untypical including dyspnea, which is one of the major symptoms in severe COVID-19, especially in those patients with acute respiratory distress syndrome (ARDS). We reported two COVID-19 cases with coexisting complications of PE and ARDS, aiming to consolidate the emerging knowledge of this global health emergency and raise the awareness that the hypoxemia or severe dyspnea in COVID-19 may be related to PE and not necessarily always due to the parenchymal disease.     

Post-mortem histological pulmonary analysis in patients with HIV/AIDS

OBJECTIVES: Certain aspects of pulmonary pathology observed in autopsies of HIV/AIDS patients are still unknown. This study considers 250 autopsies of HIV/AIDS patients who died of acute respiratory failure and describes the demographic data, etiology, and histological pulmonary findings of the various pathologies. METHODS: The following data were obtained: age, sex, and major associated diseases (found at the autopsy). Pulmonary histopathology was categorized as: diffuse alveolar damage; pulmonary edema; alveolar hemorrhage; and acute interstitial pneumonia. Odds ratio of the HIV/AIDS-associated diseases developing a specific histopathological pattern was determined by logistic regression. RESULTS: A total of 197 men and 53 women were studied. The mean age was 36 years. Bacterial bronchopneumonia was present in 36% (91 cases) and Pneumocystis jiroveci pneumonia in 27% (68) of patients. Pulmonary histopathology showed acute interstitial pneumonia in 40% (99), diffuse alveolar damage in 36% (89), pulmonary edema in 13% (33), and alveolar hemorrhage in 12% (29) of patients. Multivariate analysis showed a significant and positive association between Pneumocystis jiroveci pneumonia and acute interstitial pneumonia (Odds ratio, 4.51; 95% CI, 2.46-8.24; p<0.001), severe sepsis and/or septic shock and diffuse alveolar damage (Odds ratio, 3.60; 95% CI, 1.78-7.27; p<0.001), and cytomegalovirus and acute interstitial pneumonia (Odds ratio, 2.22; 95% CI, 1.01-4.93; p=0.05). CONCLUSIONS: This report is the first autopsy study to include demographic data, etiologic diagnosis, and respective histopathological findings in patients with HIV/AIDS and acute respiratory failure. Further studies are necessary to elucidate the complete pulmonary physiopathological mechanism involved with each HIV/AIDS-associated disease.