Pneumocystis carinii pneumonitis

A genetic approach for analyzing the co-operative function of the tRNA mimicry complex, eRF1/eRF3, in translation termination on the ribosome

During termination of translation in eukaryotes, a GTP-binding protein, eRF3, functions within a complex with the tRNA-mimicking protein, eRF1, to decode stop codons. It remains unclear how the tRNA-mimicking protein co-operates with the GTPase and with the functional sites on the ribosome. In order to elucidate the molecular characteristics of tRNA-mimicking proteins involved in stop codon decoding, we have devised a heterologous genetic system in Saccharomyces cerevisiae. We found that eRF3 from Pneumocystis carinii (Pc-eRF3) did not complement depletion of S. cerevisiae eRF3. The strength of Pc-eRF3 binding to Sc-eRF1 depends on the GTP-binding domain, suggesting that defects of the GTPase switch in the heterologous complex causes the observed lethality. We isolated mutants of Pc-eRF3 and Sc-eRF1 that restore cell growth in the presence of Pc-eRF3 as the sole source of eRF3. Mapping of these mutations onto the latest 3D-complex structure revealed that they were located in the binding-interface region between eRF1 and eRF3, as well as in the ribosomal functional sites. Intriguingly, a novel functional site was revealed adjacent to the decoding site of eRF1, on the tip domain that mimics the tRNA anticodon loop. This novel domain likely participates in codon recognition, coupled with the GTPase function.

Pneumocystis jiroveci Pneumonia

Pneumocystis pneumonia (PCP) is one of the most common pulmonary infections in persons with impaired cell-mediated immunity, and particularly those infected with human immunodeficiency virus (HIV).1–7 Pneumocystis was first described in the lungs of guinea pigs, during experiments on American trypanosomiasis by Carlos Chagas8 in 1909 and by Antonio Carinii9 in 1910. Both considered the cysts of Pneumocystis as part of the trypanosome’s life cycle. Shortly afterward the Delanoes10 found identical forms in the lungs of rats that had not been infected with trypanosomes and recognized the organism as a separate species. The name Pneumocystis carinii, was given to this organism as a generic name (Greek:pneumon, “lung”; kystis, “cyst”), honoring Carinii.11

Collagenases and the serine proteinases elastase and cathepsin G in steroid-induced Pneumocystis carinii pneumonia

Pneumocystis carinii pneumonia (PCP) is characterized by the formation of leaky alveoli and a foamy alveolar exudate. To induce PCP, male Wistar rats were immunosuppressed by oral dexamethasone treatment for 12 weeks, during which time all rats developed PCP. Bronchoalveolar lavage fluid (BALF) was analyzed at that time and at 1, 2, and 4 weeks after the cessation of dexamethasone treatment, during which time the rats were recovering from PCP and immunosuppression (and was compared with the BALF obtained from healthy control rats), for type IV collagenase, elastase, cathepsin G, and collagenase activities. Scores for 72-kDa (matrix metalloproteinase type [MMP-2]) and 92-kDa (MMP-9) type IV collagenase-gelatinase activities correlated with those for BALF macrophages (r = 0.58; P < 0.001) and neutrophils (r = 0.66; P < 0.001), respectively, suggesting that they may, in part, be derived from these cells. However, MMP-2 was constitutively expressed and may play a role in normal tissue remodeling. MMP-9 activity was highest in the group with PCP (1.8 +/- 0.37; P > 0.05), with a gradual decline (1.0 +/- 0.48 by week 4; P > 0.05) toward normal (0.67 +/- 0.42) during recovery, which suggests a role for it in tissue-destructive inflammatory events. In rats with PCP the endogenously active collagenase was present at high levels compared with those in healthy controls (2.6 +/- 0.69 versus 0.17 +/- 0.17, respectively; P < 0.01), but they returned to normal by week 4 of recovery (0.42 +/- 0.30; P > 0.05). Collagenase activity showed a correlation with cyst number (r = 0.57; P < 0.001). The BALF of rats with PCP also contained the serine proteinases, which may act as pro-MMP activators. Ultramorphology disclosed increased pinocytotic activities, subepithelial bleb formation, and degeneration and denudation of the basal lamina. These findings suggest that the increased activities of collagenases in BALF caused by the host response against P. carinii might contribute to leaky alveoli.

Pneumocystis carinii pneumonia in patients without predisposing illnesses. Acute episode and follow-up of five cases

Pneumocystis carinii pneumonia (PCP) is described almost exclusively in immunocompromised hosts. This report describes our experience with acute episodes and the follow-up of five patients with PCP who had no known predisposing conditions. The average follow-up period was 3.6 years (range, 2.6 to 4 years). Lymphocyte subpopulations (CD4, CD8, and CD4:CD8), serum immunoglobulins (IgG, IgM, and IgA), and serologic studies for human immunodeficiency virus were carried out on all patients at least twice, both at the beginning and the end of the follow-up. None of the patients presented compatible data with AIDS or any other identifiable risk factors. We conclude that PCP can occur in patients who apparently do not have immunosuppression.

Pneumocystis carinii pneumonia in patients with systemic lupus erythematosus

At the University Hospital, Kuala Lumpur, Malaysia, nine patients with systemic lupus erythematosus (SLE) were treated for Pneumocystis carinii pneumonia (PCP) between January 1987 and December 1988. When they developed PCP all the patients' SLE disease course was active and eight of them were on prednisolone. Four of these eight patients were also receiving cyclophosphamide. Patients who were on more intensive immunosuppressive therapy were found to develop more severe PCP. All the patients except one were treated with high-dose cotrimoxazole. Four patients responded to antipneumocystis treatment and survived, while PCP was responsible for the death of the five non-survivors.

Pneumocystis carinii pneumonia after 40 years

Forty years ago, Pneumocystis carinii was identified by Czech researchers J. Vanĕk and O. Jírovec as the causative agent of interstitial plasma cell pneumonia in infants. At present, it is the commonest pulmonary pathogen in AIDS patients. This review summarizes the experience and latest data on the etiopathogenesis, pathology, clinical presentation, diagnosis and therapy of P. carinii pneumonia.

Pneumothorax with Pneumocystis carinii pneumonia in AIDS. Incidence and clinical characteristics

A retrospective review of the charts of patients with the acquired immunodeficiency syndrome (AIDS) was performed at three university-affiliated teaching hospitals in Denver between May 1982 and April 1987. Patients were evaluated for the presence or absence of Pneumocystis carinii pneumonia (PCP) and for the occurrence of pneumothorax at any time during their clinical course. The incidence of pneumothorax in AIDS patients with PCP was 9.0 percent (8/89), compared with 0 percent (0/45) in AIDS patients without PCP (p less than 0.03). All of the pneumothoraces resolved, most without chest tube placement. This study suggests that in patients with AIDS, PCP is associated with an increased incidence of pneumothorax, while AIDS patients without PCP are not at increased risk for the development of pneumothorax.

Pneumocystis carinii pneumonia complicating multiple myeloma

Pneumocystis carinii pneumonia complicated the course of two patients with multiple myeloma. The diagnosis was established in both cases by bronchoalveolar lavage, which demonstrated the typical pneumocysts. Clinical and roentgenographic improvement in both patients was observed following a course of trimethoprim-sulfamethoxazole. One patient had lymphocyte subsets performed with a CD4/CD8 ratio of 0.8; both patients were HIV antibody-negative by ELISA. Both patients tolerated prophylactic TMP-SMX given concurrently with the subsequent chemotherapy for myeloma. We suggest that the immune defect seen in multiple myeloma may have placed these patients at risk for opportunistic infections such as P carinii pneumonia; however, as opposed to patients with AIDS, our patients tolerated therapy with TMP-SMZ quite well.

[Purpura fulminans and C7 deficiency complicated by Pneumocystis carinii pneumonia]

A case of meningococcal purpura fulminans is reported in a 22-year-old woman who also suffered from a congenital deficiency in the seventh component of the complement system. This was her third episode of recurrent meningitis. In the course of her treatment in intensive care, the septic shock was cured, but she developed Pneumocystis carinii pneumonia. Histological investigations revealed abnormalities in her T-cell population, with a very low T-helper (CD4) to T-suppressor (CD8) ratio. Laboratory data showed that she did not have any antibodies to HIV.

Pneumocystis carinii pneumonia. Differences in lung parasite number and inflammation in patients with and without AIDS

Pneumocystis carinii pneumonia has emerged as a significant cause of morbidity and mortality in immunocompromised patients with and without AIDS. To determine differences in P. carinii pneumonia in patients with and without AIDS, the P. carinii parasite numbers, lung inflammatory cell populations, gas exchange, and survival were assessed in a series of 75 consecutive patients with P. carinii pneumonia. Bronchoalveolar lavage was used to quantify the parasite and inflammatory cell numbers in these patients. The data from this study indicate: (1) patients with P. carinii pneumonia and AIDS have significantly greater numbers of P. carinii per ml of lavage compared to other immunocompromised patients with P. carinii pneumonia (p less than 0.0001); (2) patients with P. carinii pneumonia and AIDS also have significantly fewer neutrophils recovered in the lavage compared to other immunocompromised patients with P. carinii pneumonia (p = 0.0001); (3) patients with AIDS and P. carinii pneumonia have higher arterial oxygen tensions than those patients with P. carinii pneumonia in conditions other than AIDS (p = 0.008); and (4) increased lavage neutrophils (rather than parasite number) correlate with poorer oxygenation and poorer patient survival (p = 0.01). This investigation demonstrates substantial differences in lung inflammation and parasite number during P. carinii pneumonia in patients with and without AIDS. The data further suggest that lung inflammation contributes substantially to respiratory impairment in patients with P. carinii pneumonia.

Diagnosis of pulmonary infections in immunocompromised patients

In an immunocompromised patient with fever and pulmonary infiltrates, it frequently is difficult to decide which invasive procedure, if any, to use to obtain a definitive diagnosis. Because most lung infiltrates in immunosuppressed patients are caused by bacteria and sputum usually is readily available for examination, empiric therapy with potent, safe, broad spectrum, antibacterial drugs often is successful. Invasive procedures that prove a diagnosis may result in substantive changes in therapy in perhaps as few as 10 to 20 per cent of patients, and the procedure itself may harm the patient. In a unique study in which patients with acute pneumonitis without neutropenia were randomized to either empiric antibiotic treatment or treatment based on results of open lung biopsy, patients with open lung biopsy had a worse outcome, possibly related to morbidity of open lung biopsy. Furthermore, no diagnoses were provided by open lung biopsy that were not treated by the empiric regimen. A missed treatable disease may be tragic, however. A thoughtful clinician must evaluate each patient with careful consideration of the history in light of the underlying disease and its treatment, rapidity of clinical course, physical examination, and laboratory data, particularly the chest radiograph, sputum examination, and bleeding parameters. Fiberoptic bronchoscopy with washings and brushings is very safe; the addition of transbronchial biopsy adds diagnostic power at the price of some complications. Bronchoalveolar lavage is a very promising technique that probably will find widespread use. However, none of the foregoing techniques is completely sensitive. When no diagnosis is established and bronchoscopy studies are negative, open lung biopsy must be considered, especially when the chest radiograph or computed tomography scan suggests focal disease or lymphadenopathy. Needle aspiration can be used, particularly if local experience is favorable and lung disease is peripheral. When evaluating a procedure, local experience must be considered rather than reliance on published diagnostic yields and complication rates. New diagnostic and therapeutic developments may change decision analysis in the near future. At present, cultures for viruses and fungi and serologic techniques have little application at most medical centers, and decisions on data from invasive procedures pivot on interpretation of histology and smears. Development of assays for antigen (for example, Aspergillus) and rapid culture techniques (for example, cytomegalovirus and the shell vial method), coupled with new, effective antimicrobials, may demand maximum effort for a definitive diagnosis in every patient.

Management of Pneumocystis carinii pneumonia in patients with AIDS and other conditions: experience in a Philadelphia University Teaching Hospital

We reviewed the records of 49 patients who had 55 episodes of Pneumocystis carinii pneumonia (PCP) from January 1984 to January 1987. Thirty-three patients had acquired immunodeficiency syndrome (AIDS), with the risk groups being homosexual/bisexual practices (26), hemophilia (6), and blood transfusion (1). Fourteen patients had a history of malignancy or chemotherapy and two underwent organ transplantation. Overall response to therapy of PCP was 75% (77% of patients with AIDS, 68% of those with other conditions). All six relapses occurred in patients with AIDS. Both trimethoprim-sulfamethoxazole (TMP-SMX) and pentamidine were associated with a higher rate of toxicity in those patients than in patients with other conditions. A 30% rate of failure due to side effects occurred when TMP-SMX was used as initial therapy, but the combination is considered effective and should be given an adequate therapeutic trial. Pentamidine was an effective alternative for patients who failed with TMP-SMX and for those who failed therapy due to side effects, but was associated with serious toxicities. Our experience was similar in some respects to previous published results from New York and California.

Diagnosis of Pneumocystis carinii pneumonia by cytologic evaluation of Papanicolaou-stained bronchial specimens

To evaluate the sensitivity and specificity of diagnosing Pneumocystis carinii pneumonia (PCP) by Papanicolaou-stained bronchial brushing and wash/lavage specimens obtained by fiberoptic bronchoscopy, the cytologic preparations and clinical records from 58 immunocompromised patients were reviewed. Bronchial brushings and wash/lavage specimens were examined using methenamine silver (Grocott) and Papanicolaou stains. Pneumocystis carinii pneumonia was recognized with Papanicolaou stain by identifying distinctive alveolar casts, which frequently contained collections of encysted sporozoites. Thirty cases of PCP were identified, and Grocott-stained bronchial wash/lavage specimens were positive in 29 instances (97%). Grocott staining of the transbronchial biopsy was positive for PCP in 18 of 22 specimens (82%). Bronchial brushings were insensitive, yielding a positive specimen in only 30% of cases of PCP. Alveolar casts of PCP were identified by Papanicolaou-stained slides of wash/lavage specimens in 83% of cases of Pneumocystis pneumonia. These proteinaceous alveolar casts were not seen in other pulmonary disorders. Encysted sporozoites were found in 56% of cases in which Papanicolaou-stained alveolar casts were identified. We conclude that the diagnosis of PCP can be made rapidly and reliably on the Papanicolaou-stained bronchial wash/lavage or bronchial brush specimens by detecting the characteristic alveolar casts, which contain P. carinii-encysted sporozoites. The presence of encysted sporozoites within alveolar casts is pathognomonic for PCP, and methenamine silver stains can be eliminated in those cases in which encysted sporozoites are identified.

Pentamidine isethionate. A review of its antiprotozoal activity, pharmacokinetic properties and therapeutic use in Pneumocystis carinii pneumonia

Pentamidine isethionate, an aromatic diamidine, is an antiprotozoal agent proven to decrease mortality from Pneumocystis carinii pneumonia in debilitated infants and immunodeficient adults and children. Like the combination antimicrobial agent co-trimoxazole, pentamidine has been shown in retrospective studies to resolve episodes of pneumonia in approximately 41 to 87% of patients, including those with the acquired immunodeficiency syndrome (AIDS), when used alone or as sequential therapy. Although about 45% of all patients given pentamidine experience side effects--which may include nephrotoxicity, hypotension, hypoglycaemia or local reactions--in patients with AIDS the incidence of side effects is less with pentamidine than with co-trimoxazole. Thus, despite its profile of potentially severe side effects, pentamidine isethionate is a proven antimicrobial agent with a distinct place in the treatment of Pneumocystis carinii pneumonia in the growing population of AIDS patients.

Pneumocystis carinii pneumonia. Review of 53 cases

Between 1976 and 1983, 53 cases of Pneumocystis carinii pneumonia were documented at the Mayo Clinic. Underlying diseases included leukemia in 15 patients, lymphoma in nine, nonhematologic malignancies in five, acquired immune deficiency syndrome in two, an various inflammatory diseases treated by corticosteroids in 16 patients. Cytotoxic drugs with corticosteroids were used in 68 percent of patients, whereas 23 percent received corticosteroids alone. Clinical features consisted of progressive dyspnea (74 percent), cough (55 percent), and fever (62 percent), with normal findings on examination (43 percent), or crackles (53 percent). Arterial oxygen tension and oxygen saturation were 48.6 +/- 12.8 mm Hg and 81.2 +/- 6.5 percent, respectively. Chest roentgenographs exhibited diffuse alveolar and interstitial infiltrates with predominantly perihilar distribution. The diagnostic rates for open lung biopsy and bronchoscopy were 97 percent and 62 percent, respectively. Clinical improvement and survival following appropriate therapy were noted in 22 patients (41.5 percent), whereas the remaining 31 patients died within four weeks of hospitalization. When survivors were compared with nonsurvivors, there was no difference in mean age, leukocyte counts, arterial oxygen tension, or duration of symptoms before treatment. A coexisting pulmonary infection was identified more frequently in nonsurvivors (51.6 percent) than in survivors (22.7 percent, p = 0.01). The mortality from P. carinii pneumonia alone was 47 percent, whereas 76 percent of those with coexisting infection died. Despite antibiotic therapy and potentially effective chemoprophylaxis, P. carinii pneumonia remains a significant and life-threatening complication of diseases or treatments associated with immune suppression.

Bronchoalveolar lavage as the exclusive diagnostic modality for Pneumocystis carinii pneumonia. A prospective study among patients with acquired immunodeficiency syndrome

Pneumocystis carinii pneumonia (PCP) is the most common life-threatening opportunistic infection among patients with the acquired immunodeficiency syndrome (AIDS). Because retrospective studies suggested that bronchoalveolar lavage (BAL) compared favorably to lung biopsy in the diagnosis of PCP, we prospectively evaluated the utility of BAL in 40 consecutive patients with AIDS or risk of AIDS who presented with respiratory complaints. The BAL revealed P carinii in 36 of 42 episodes of pneumonia (86 percent) among 40 patients. Clinical follow-up of the six patients whose BAL was negative for PCP suggested only one possible false negative BAL for PCP. Therefore, BAL detected PCP in 36 of 37 patients for a sensitivity of 97 percent. BAL detected cytomegalovirus in 15 of 38 patients, as well as Mycobacterium avium-intracellulare and Cryptococcus (each in one patient). By virtue of accuracy and lack of morbidity demonstrated in our study, BAL should supplant lung biopsy techniques in the evaluation of AIDS patients with pulmonary symptoms.