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

Severe exercise hypoxaemia with normal or near normal X-rays: a feature of Pneumocystis carinii infection

To find out whether Pneumocystis carinii pneumonia (PCP) can be detected while still in an early phase by the degree of exercise-induced oxygen desaturation, arterial oxygen saturation was measured by continuous pulse oximetry in patients positive for antibody to the human immunodeficiency virus and clinically suspected of having PCP, in patients with other chest diseases, and in controls. Among patients with proven PCP 94% of those with low arterial oxygen pressures (PaO2) showed desaturation on exercise oximetry, as did 80% of those with a normal oxygen pressure at rest, whereas only 10% of patients with other chest disorders and HIV disease showed significant desaturation.

Hematologic aspects of human immunodeficiency virus infection: laboratory and clinical considerations

Hematologic abnormalities are common in patients with HIV infection. This review will focus on HIV-associated cytopenias and coagulation abnormalities. Their occurrence, laboratory evaluation, and clinical significance and the mechanisms underlying their development are discussed. Therapeutic modalities are presented, with an emphasis on treatment strategies for HIV-associated thrombocytopenia.

Ribosomal RNA sequence shows Pneumocystis carinii to be a member of the fungi

Pneumocystis carinii pneumonia is the most common opportunistic infection in AIDS, and accounts for significant morbidity and mortality in these and other immunocompromised patients. P. carinii is a eukaryotic microorganism of uncertain taxonomy that can infect numerous mammalian hosts. Developing from a small, unicellular 'trophozoite' into a 'cyst' containing eight 'sporozoites', its life cycle superficially resembles those seen both in the Protozoa and Fungi. Morphological and ultrastructural observations have lead some investigators to conclude that the organism is a protozoan, while others have felt that it more closely resembles a fungus. Phylogenetic relationships can be inferred from comparisons of macromolecular sequences. Small subunit ribosomal RNAs (16S-like rRNAs) are well-suited for this purpose because they have the same function in all organisms and contain sufficient information to estimate both close and distant evolutionary relationships. Phylogenetic frameworks based upon such comparisons reveal that the plant, animal and fungal lineages are distinct from the diverse spectrum of protozoan lineages. In this letter, phylogenetic analysis of Pneumocystis 16S-like rRNA demonstrates it to be a member of the Fungi.

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.

Dapsone treatment of Pneumocystis carinii pneumonia in the acquired immunodeficiency syndrome

All patients with the acquired immunodeficiency syndrome treated for their first episode of Pneumocystis carinii pneumonia at San Francisco General Hospital between 1 April 1985 and 15 July 1985 were evaluated for their response to treatment with dapsone (100 mg/day) by mouth for 21 days. Of 44 patients evaluated, 18 were eligible for the study. Of these 18 patients, the conditions of 7 of them worsened or failed to improve during treatment with dapsone and they were considered treatment failures. These patients were changed to standard therapy after 4 to 8 days of dapsone therapy. The remaining 11 patients (61%) improved within 3 to 10 days after dapsone therapy was started. Side effects of dapsone therapy were noted in 6 of 11 patients (of these 11 patients, 5 had a rash, 1 had a rash and abnormal liver enzymes, and 1 had abnormal liver enzymes), but in none of the patients were these side effects severe enough to require the cessation of medication. Based on comparison with historical controls, oral dapsone therapy alone appeared to be less effective than standard therapy or the combination of dapsone plus trimethoprim for P. carinii pneumonia in patients with acquired immunodeficiency syndrome.

Respiratory complications of cardiac transplantation

The authors evaluated all respiratory complications of cardiac transplantation in a 10-year study of 94 consecutive recipients. Mean follow-up time was 20 +/- 17 months. The initial 20 patients were treated with azathioprine and prednisone, while the subsequent 74 patients received cyclosporine and prednisone. In the azathioprine group, respiratory infections accounted for 24 of 60 (40%) infections. Two-thirds of the respiratory infections occurred in the first 3 postoperative months and were generally localized processes (focal pneumonitis, nodule(s), abscess, or empyema). Gram-positive and gram-negative bacteria (8/30) and aspergillus (8/30) were the predominant pathogens. Respiratory failure occurred in 29% of infectious episodes. In the cyclosporine group, there were significantly fewer respiratory infections. There was also a reduction in the number of nonrespiratory infections; hence, the percentage of total infections due to respiratory causes, 26 of 50 (52%), was not significantly different. In contrast, however, nearly two-thirds of the respiratory infections in cyclosporine-treated patients occurred after the first 3 postoperative months, and were usually diffuse processes. Despite diffuse disease, respiratory failure was observed with similar frequency (19%). Pneumocystis carinii (9/31) and cytomegalovirus (CMV) (7/31) were the predominant pathogens. CMV pneumonitis tended to occur earlier than that due to P. carinii (2.9 +/- 1.9 mo vs. 9.8 +/- 11.2 mo, respectively), but there was considerable overlap. In comparison with infectious processes, there were 50% fewer noninfectious respiratory complications in both groups. These were primarily pleural (46%) or thromboembolic (18%) disorders. Four of five pulmonary emboli occurred in patients with intercurrent cardiorespiratory illness, and were detected only at autopsy. The authors conclude that respiratory infections account for one-half of all infections observed in cardiac transplant recipients, despite the reduced infection rate associated with the use of cyclosporine. Furthermore, respiratory infections in cyclosporine-treated patients exhibit different clinical and etiologic features than those seen in azathioprine-treated patients. Finally, occult thromboemboli may be difficult to recognize in cardiac transplant recipients because of the high incidence of coexisting cardiorespiratory disease.

Pneumocystis carinii antigenemia in acquired immunodeficiency syndrome

The present study was conducted to determine the prevalence and significance of Pneumocystis carinii antigenemia in patients with acquired immunodeficiency syndrome (AIDS) and clinically or invasively diagnosed P. carinii pneumonitis. Single serum specimens from 20 AIDS patients invasively examined for P. carinii organisms and 106 AIDS patients with a clinical diagnosis only of P. carinii pneumonitis were blindly tested for P. carinii antigenemia by a counterimmunoelectrophoresis assay. In the 20 specimen-documented cases, the antigen test demonstrated a sensitivity of 75% and a specificity of 90%. The positive predictive value of the test was 90%, while the negative predictive value was 70%. In AIDS patients with specimen-documented P. carinii pneumonitis, the prevalence of P. carinii antigenemia coincided almost exactly with the prevalence of positive invasively obtained specimens (60 and 59%, respectively). In patients with a clinical diagnosis only of P. carinii pneumonitis, half as many (30%) were found to exhibit antigenemia. Sequential P. carinii antigen titers determined by a new latex agglutination technique on three AIDS patients with specimen-documented P. carinii pneumonitis demonstrated the influence of specific therapy upon P. carinii antigenemia and its potential prognostic application.

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.

Cationic antitrypanosomal and other antimicrobial agents in the therapy of experimental Pneumocystis carinii pneumonia

Cationic compounds used in the treatment of veterinary African trypanosomiasis have structural properties similar to those of pentamidine, which has been used in the therapy of human trypanosomiasis and infection with Pneumocystis carinii. We have compared the activities of these drugs and other antimicrobial agents in an immunosuppressed rat model of P. carinii pneumonia. Diminazene, imidocarb, amicarbalide, quinapyramine, and isometamidium showed efficacy greater than or equal to that of pentamidine in the therapy of P. carinii infection, whereas ethidium and methylglyoxal bis(guanylhydrazone) were only slightly active against the organism. Diminazene and pentamidine also exhibited comparable efficacy in P. carinii prophylaxis, alpha-Difluoromethylornithine (DFMO), a polyamine inhibitor, was ineffective therapy when used alone and did not improve the effectiveness of pentamidine or diminazene. Quinine, quinidine, quinacrine, chlorpromazine, spiramycin, Pentostam, Astiban, dehydroemetine, ampicillin, gentamicin, chloramphenicol, and spectinomycin also showed little or no activity against the organism. Thus, in this model anti-P. carinii activity appears to be a common property of veterinary cationic trypanocidal compounds. This should be important in studying structure-activity relationships and in developing new drugs for the treatment of P. carinii infection in humans.

Utility of airway endoscopy in the diagnosis of respiratory complications of cardiac transplantation

We evaluated 39 episodes (in 32 patients) of pulmonary parenchymal infiltrates following cardiac transplantation with fiberoptic bronchoscopy (FOB) in a prospective study of 94 consecutive recipients. Initial FOB established the diagnosis in 24/39 (62 percent) instances. Subsequent examinations included repeat FOB (five), open lung biopsy (five), needle aspiration (two), and autopsy (nine), establishing 49 diagnoses. Specific pathogens were identified in 45 instances, neoplasm in two, and idiopathic interstitial pneumonitis in two. Bronchoalveolar lavage alone yielded diagnoses in 63 percent and transbronchial biopsy and bronchial washings/brushings in 46 and 43 percent, respectively. Transbronchial biopsy suggested idiopathic interstitial pneumonitis in 17 instances, but four had spontaneous clearing, and open lung biopsy or autopsy showed alternative diagnoses (particularly CMV and Aspergillus) in 11. The main complication of FOB was moderate (25 to 100 ml) hemorrhage after transbronchial biopsy (10 percent); no severe episodes occurred despite elevated pulmonary vascular pressures. In this population of immunocompromised hosts: (1) bronchoalveolar lavage is the most sensitive bronchoscopic technique for detecting infection; (2) transbronchial biopsy is not useful in detecting CMV or Aspergillus infection; (3) pulmonary hypertension is associated with some risk of moderate but not severe hemorrhage after transbronchial biopsy.

Histoplasmosis in patients at risk for the acquired immunodeficiency syndrome in a nonendemic setting

We reviewed 18 cases of histoplasmosis in patients at risk for the acquired immunodeficiency syndrome seen at two New York City hospitals in the past 3 1/2 years. Seventeen patients were Hispanic, including 13 born in Puerto Rico and three in South America. Clinical presentation was subacute, with high fever, weight loss, and mild respiratory symptoms with well-maintained gas exchange. Five patients had normal chest roentgenograms. The most common chest roentgenographic abnormality was diffuse small nodules. A rapid diagnosis was established histologically in 72 percent of patients, most commonly by transbronchial lung biopsy; cultures were positive in 94 percent of patients while serology was positive in five of six patients. Mycobacterium tuberculosis was a concurrent, often unrecognized, pathogen in six cases. Most patients responded to amphotericin therapy. Histoplasmosis may represent an early sign of altered host immunity in the acquired immunodeficiency syndrome.

Potent antipneumocystis and antitoxoplasma activities of piritrexim, a lipid-soluble antifolate

Piritrexim, a lipid-soluble antifolate, was evaluated for its activity against Pneumocystis carinii and Toxoplasma gondii. The concentration of piritrexim needed to inhibit 50% of the catalytic activity of P. carinii dihydrofolate reductase (DHFR) was 19.3 nM, and that for T. gondii DHFR was 17.0 nM, concentrations that were 40- to over 1,000-fold less than those needed for the inhibition of activity by trimethoprim and pyrimethamine, the antifolates conventionally used in treating these organisms. Piritrexim was able to inhibit replication of T. gondii in a mouse peritoneal macrophage model at concentrations of 0.1 to 1.0 microM. Leucovorin, a reduced folate that can bypass the inhibition of DHFR by antifols in mammalian cells but not in protozoa, did not affect the ability of piritrexim to inhibit T. gondii replication. The addition of sulfadiazine, which alone was ineffective, to piritrexim allowed inhibition of T. gondii replication at lower concentrations of piritrexim than when piritrexim was used alone. These results suggest that piritrexim, alone or combined with a sulfonamide, may be a highly potent antitoxoplasma and antipneumocystis agent that could provide major pharmacologic and clinical advantages over available agents.

Prevalent myocarditis at necropsy in the acquired immunodeficiency syndrome

The prevalence of myocarditis was retrospectively evaluated in 71 consecutive necropsy patients who died from acquired immunodeficiency syndrome (AIDS) between 1982 and 1986. Myocarditis was found in 37 cases (52%). Biventricular dilation at necropsy was present in seven cases (10%) and was accompanied by myocarditis in each case; fatal congestive heart failure occurred in four of these seven cases. Although viral, protozoan, bacterial, fungal and mycobacterial opportunistic pathogens were present in myocardial sections of 7 of 37 myocarditis cases, the etiology of myocarditis in the majority of these patients with AIDS remained idiopathic. Thus, myocarditis is a frequent finding at necropsy in patients with AIDS and may contribute to the development of biventricular dilation.

Diagnosis of Pneumocystis carinii pneumonia: improved detection in sputum with use of monoclonal antibodies

With the dramatic increase in the frequency of Pneumocystis carinii pneumonia associated with human immunodeficiency virus infection, there has been a need for more rapid and less invasive diagnostic techniques. Recent studies have shown that examination of induced sputum can establish the diagnosis of P. carinii pneumonia in about 55 percent of cases. To assess whether a recently developed indirect immunofluorescent stain using monoclonal antibodies was more sensitive than Giemsa or toluidine blue O stains in detecting P. carinii in sputum, we undertook two prospective studies. Of 63 patients at one institution from whom sputum specimens were obtained, 49 were ultimately given a diagnosis of P. carinii pneumonia, 46 of them by staining of sputum. The sensitivity of the three stains in detecting P. carinii was 45 of 49 (92 percent) for immunofluorescence; 37 of 49 (76 percent) for Diff-Quik (a Giemsa-type stain); and 39 of 49 (80 percent) for toluidine blue O. There were no false positive immunofluorescent stains. In a similar study of a series of 25 patients at another institution, a diagnosis of P. carinii pneumonia was made in 23 of 25 patients by staining of induced sputum. We conclude that examination of induced sputum is a rapid, sensitive, and inexpensive method for diagnosing P. carinii pneumonia and that indirect immunofluorescence is a practical and highly sensitive staining technique for establishing this diagnosis.

Bioavailability of oral trimetrexate in patients with acquired immunodeficiency syndrome

The combination of the lipophilic antifolate trimetrexate and the rescue agent leucovorin has shown promise in the treatment of Pneumocystis carinii pneumonia in patients with acquired immunodeficiency syndrome. The pharmacokinetic behavior of trimetrexate administered either by intravenous bolus or orally was studied in six patients with acquired immunodeficiency syndrome with a reversed-phase high-pressure liquid chromatography assay. The mean clearance following bolus injection was 38 ml/min per m2, with a range of 15 to 55 ml/min per m2. The postdistributive half-life ranged from 6 to 16 h. With oral administration, the mean bioavailability was 44% (range, 19 to 67%). An oral dose of 60 mg/m2 (162 mumol/m2) resulted in concentrations in plasma that approximated those achieved with a 30-mg/m2 (81-mumol/m2) intravenous dose. The toxicity of this combination regimen was minimal. It appears that the oral route is a practical route of administration for trimetrexate in patients with acquired immunodeficiency syndrome requiring long-term outpatient treatment or prophylaxis for P. carinii pneumonia.

Adverse reactions to trimethoprim-sulfamethoxazole in hemophiliacs

Adverse reactions to trimethoprim-sulfamethoxazole are very prevalent in patients with acquired immunodeficiency syndrome (AIDS). Recently we have observed severe toxicities associated with trimethoprim-sulfamethoxazole in three hemophiliacs, a group known to be at risk for developing AIDS. At the time of these reactions to the antibiotic, none of the patients had yet manifested any stigmata of AIDS per se. We advise caution in the use of trimethoprim-sulfamethoxazole in hemophiliacs and other patients at high risk for the development of AIDS.

Protozoal infections in the acquired immunodeficiency syndrome

Several protozoa have emerged as the major opportunistic infections and cause of death in patients with acquired immunodeficiency syndrome (AIDS). Pneumocystis carinii pneumonia is the leading cause of death in AIDS patients. Electron microscopy (EM) usually shows numerous trophozoites and cysts of Pneumocystis filling up the entire alveolar space, while only cysts are seen under the light microscope. The focal thickening of cyst wall of Pneumocystis, as demonstrated by EM and manifested as a "parentheses" shaped structure with silver stain, serves as a diagnostic marker for Pneumocystis. Freeze-fracture EM has demonstrated the intimate contact between Pneumocystis trophozoites and the type I pneumocytes, which may contribute to the alveolar-capillary block, leading to severe respiratory distress. However, EM is seldom needed for the diagnosis of this infection. Toxoplasma encephalitis, which is an unusual clinical manifestation in cases of toxoplasmosis reported previously, has become a common complication and one of the major causes of death in patients with AIDS. Because subclinical infection by Toxoplasma is common, serologic tests usually offer no definite answers as to whether the infection is acute or chronic, active or past. The small size and its non-specificity in both morphology and tissue affinity make light microscopic diagnosis of toxoplasmosis difficult. Only immunologic staining, such as immunoperoxidase and immunofluorescence, can help to achieve a definite positive identification of the organism. When special antibodies or facility for such staining is not available, EM is the final resort for identifying Toxoplasma by showing the apical complex with the characteristic sausage-shaped rhoptries. Cryptosporidiosis, practically unknown before the AIDS outbreak, has become one of the most common intestinal protozoa in both immunocompromised and immunocompetent patients. The protracted and sometimes fatal course of cryptosporidiosis in immunocompromised patients can be explained by the presence of autoinfective oocysts (thin-walled oocysts), as detected by EM, and by recycling of first-generation schizonts observed experimentally. While diagnosis of cryptosporidiosis can be made by detection of oocysts in stools in most cases, EM is still the last resort for a definitive identification of Cryptosporidium species. While the incidence of isosporiasis is still low, it has been found more frequently in patients with AIDS than in the general population. The parasite, Isospora belli, being a coccidian as is the Cryptosporidium species, is similar to the latter in its life cycle and clinical manifestations.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibitors of folic acid synthesis in the treatment of experimental Pneumocystis carinii pneumonia

Inhibitors of folic acid synthesis were compared alone and in different combinations in the therapy of pneumocystosis in immunosuppressed rats. Sulfonamides (sulfamethoxazole, sulfadiazine, and sulfadoxine) and sulfones (dapsone) used alone were very active against Pneumocystis carinii, as judged by histologic examination of the lungs and by organism quantitation. Improved efficacy could not be demonstrated by the addition of an inhibitor of dihydrofolate reductase to the regimen. Dihydrofolate reductase inhibitors (trimethoprim, diaveridine, and pyrimethamine) used alone were ineffective against P. carinii. All drugs were well tolerated except pyrimethamine, which caused bone marrow depression; folinic acid ameliorated this adverse reaction but did not interfere with P. carinii treatment. These data have potential clinical implications but need to be interpreted with caution and in light of other systems of P. carinii drug evaluation.

Severe hypersensitivity reaction upon rechallenge with trimethoprim-sulfamethoxazole in a patient with AIDS

A patient with acquired immunodeficiency syndrome (AIDS) developed rash, fever, neutropenia, and elevated liver function tests during an initial course of trimethoprim-sulfamethoxazole (TMP-SMX) therapy. Upon reexposure to the drug, the patient experienced a severe anaphylactoid reaction associated with pulmonary edema and rhabdomyolysis. Reactions associated with TMP-SMX rechallenge in this patient population have been previously reported but have not been associated with this degree of severity. TMP-SMX therapy should be instituted with extreme caution in patients with AIDS who have demonstrated a prior hypersensitivity reaction to the drug.

Trimetrexate for the treatment of Pneumocystis carinii pneumonia in patients with the acquired immunodeficiency syndrome

Preclinical studies have demonstrated that trimetrexate is a potent inhibitor of dihydrofolate reductase from Pneumocystis carinii. On the basis of this evidence, this lipid-soluble antifolate was used as an antipneumocystis agent in 49 patients with the acquired immunodeficiency syndrome (AIDS) and pneumocystis pneumonia. Simultaneous treatment with the reduced folate leucovorin was used as a specific antidote to protect host tissues from the toxic effects of the antifolate without affecting the antipneumocystis action of trimetrexate. Patients were assigned to three groups and treated for 21 days: in Group I, trimetrexate with leucovorin was used as salvage therapy in patients in whom standard treatments (both pentamidine isethionate and trimethoprim-sulfamethoxazole) could not be tolerated or had failed (16 patients); in Group II, trimetrexate with leucovorin was used as initial therapy in patients with a history of sulfonamide inefficacy or intolerance (16 patients); and in Group III, trimetrexate with leucovorin plus sulfadiazine was used as initial therapy (17 patients). The response and survival rates were, respectively, 69 percent and 69 percent in Group I; 63 percent and 88 percent in Group II; and 71 percent and 77 percent in Group III. Trimetrexate therapy had minimal toxicity; transient neutropenia or thrombocytopenia occurred in 12 patients and mild elevation of serum aminotransferases in 4. We conclude that the combination of trimetrexate and leucovorin is safe and effective for the initial treatment of pneumocystis pneumonia in patients with AIDS and for the treatment of patients with intolerance or lack of response to standard therapies.

Hematological side effects of co-trimoxazole

Decrease of blood cells may be induced by either components of co-trimoxazole. Side effects of the trimethoprim component are much more frequent, particularly in risk groups. They are dose dependent, usually not severe, only rarely of clinical significance and easily treated or prevented by folate supplementation. In contrast, side effects of the sulfamethoxazole component seem to be extremely rare. They are similar to the hematological side effects of other sulfonamide drugs. They are idiosyncratic, nonpredictable and mostly mediated by the immune-system. They may be of life-threatening severity and no therapy is known except termination of exposure and supportive measures such as substitution of blood cells and antiinfectious therapy by non-related antibiotics.

The role of open lung biopsy in patients with the acquired immunodeficiency syndrome

To assess the role of open lung biopsy in patients with the acquired immunodeficiency syndrome (AIDS), we retrospectively reviewed the cases of 42 patients with AIDS who underwent this procedure for the diagnosis of pulmonary infiltrates. Four patients had no preceding bronchoscopy because the severity of the respiratory failure or abnormalities of coagulation precluded the safe performance of this procedure. Twenty-nine cases had a preceding nondiagnostic bronchoscopic procedure, and nine others underwent open lung biopsy because of progressive deterioration despite treatment for diseases diagnosed bronchoscopically. We found that open lung biopsy was likely to be useful diagnostically when bronchoscopy could not be safely performed or when a preceding bronchoscopic procedure was not diagnostic. Open lung biopsies done on patients whose condition continued to deteriorate despite treatment for disorders established bronchoscopically were not likely to yield information therapeutically useful. In only one of nine such cases was a new treatable diagnosis obtained (Legionella). The others showed either severe pulmonary fibrosis or persistence of the initial disease process diagnosed at the time of bronchoscopy.

Acquired immunodeficiency syndrome (AIDS)

The Acquired Immunodeficiency Syndrome (AIDS), caused by the human immunodeficiency virus (HIV), also called the human T-lymphotropic virus type III/lymphadenopathy-associated virus [HTLV-III/LAV], has affected over 23,000 people; more than half of those with the disease have died. The actual case fatality rate approaches 100%. AIDS affects all groups and classes of people, although some are at special risk. Distribution of the disease is worldwide. The illness' effects on the body are widespread; of special interest are the ophthalmologic manifestations. The eye may be infected by various viruses (cytomegalovirus, varicella-zoster virus, herpes simplex virus or HIV itself), toxoplasma gondii, candida sp, cryptococcus neoformans, M. tuberculosis, or M. avium-intracellulare. Kaposi's sarcoma may affect the eye as well. Retinal vascular abnormalities (e.g., cotton-wool spots, vasculitis) are not uncommon in AIDS. The syndrome may present with neuro-ophthalmologic manifestations. No effective treatment for the illness is currently available, although several hold promise and there is hope for an AIDS vaccine. Prevention of infection through reduction of risks appears to be the only defense against AIDS at this time.

Pulmonary Kaposi's sarcoma in patients with acquired immune deficiency syndrome: a clinicopathological study

Pulmonary Kaposi's sarcoma may contribute to respiratory dysfunction in patients with acquired immune deficiency syndrome (AIDS) and features of pneumonitis. Opportunistic infections are readily recognised in endoscopic material, but pulmonary Kaposi's sarcoma is easily missed, so that patients are deprived of specific treatment. The clinical and pathological findings from nine cases of pulmonary Kaposi's sarcoma have been reviewed; these were found among 84 patients with AIDS and pneumonitis undergoing fibreoptic bronchoscopy and bronchoalveolar lavage. Diagnosis was established before death in eight patients (in five by bronchial biopsy and in three by open lung biopsy). Examination of lavage fluid showed alveolar haemorrhage in six patients. It is concluded that: (1) fibreoptic bronchoscopy may be useful in the diagnosis of endobronchial lesions of Kaposi's sarcoma; (2) alveolar haemorrhage in patients with AIDS is suggestive of pulmonary Kaposi's sarcoma. Factors that may cause difficulties in diagnosis include the focal nature of some lesions and the pleural or parenchymatous location of others. In addition, in the lung as in the skin, the early stages of Kaposi's sarcoma resemble granulation tissue. Such lesions are far more difficult to recognise than is the late nodular stage.

Unusual remission of Pneumocystis carinii pneumonia in a patient with the acquired immune deficiency syndrome

Pneumocystis carinii is a well-recognized cause of pneumonia in patients with immune deficiency, and when untreated, mortality approaches 100 percent. Although rare cases suggesting spontaneous recovery (usually accompanied by resolving immune deficiency) have been reported, spontaneous resolution of P. carinii pneumonia in patients with the acquired immune deficiency syndrome (AIDS) has not been described. A patient with AIDS in whom Pneumocystis pneumonia developed and remitted without appropriate therapy is described. This case suggests that the immunologic defects of AIDS are not fixed and that fluctuations in the degree of immunocompetence may allow for clinical recovery from opportunistic infections associated with AIDS even without appropriate therapy.

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.

Activity of antifolates against Pneumocystis carinii dihydrofolate reductase and identification of a potent new agent

The therapy of Pneumocystis carinii (PC) pneumonia is often unsuccessful, particularly in patients with acquired immune deficiency syndrome (AIDS). Because of difficulties in growing the organism in vitro or obtaining purified organisms, current treatment choices have been made with little information on the metabolic effects of therapeutic agents on PC. This report quantitates the effects of the commonly used antifolates as well as the classic antineoplastic antifolate methotrexate and a lipid-soluble analogue, trimetrexate, on the target enzyme, dihydrofolate reductase (DHFR), in the PC organisms. Trimethoprim and pyrimethamine were found to be weak inhibitors (ID50 = 39,600 and 2,800 nM, respectively), while methotrexate and trimetrexate were potent reductase inhibitors (ID50 = 1.4 and 26.1 nM, respectively). transport studies with radiolabeled compounds showed that compounds with the classic folate structure (methotrexate and leucovorin) were not taken up by the intact PC organisms. In contrast, trimetrexate exhibited rapid uptake. These results suggest a major therapeutic advantage may be gained by combining a potent, readily transported PC DHFR inhibitor such as trimetrexate with the reduced folate leucovorin to achieve a highly potent antiprotozoan effect while preventing toxicity to mammalian cells.

Acquired immunodeficiency syndrome of childhood

AIDS of childhood is reviewed in this timely article, including care of the child with infectious complications, and other current and future management concerns.

Potent in vitro and in vivo antitoxoplasma activity of the lipid-soluble antifolate trimetrexate

Trimetrexate, a highly lipid-soluble quinazoline antifolate now undergoing trials as an anticancer agent, was found to be a potent inhibitor of the dihydrofolate reductase (DHFR) isolated from Toxoplasma gondii. The concentration required for 50% inhibition of protozoal DHFR was 1.4 nM. As an inhibitor of this enzyme, trimetrexate was almost 600-fold (amount of antifolate required to inhibit catalytic reaction by 50%) and 750-fold (inhibition constant) more potent than pyrimethamine, the DHFR inhibitor currently used to treat toxoplasma infection. When the protozoan was incubated with 1 microM trimetrexate, the drug rapidly reached high intracellular concentrations. Since toxoplasma organisms lack a transmembrane transport system for physiologic folates, host toxicity can be prevented by co-administration of the reduced folate, leucovorin, without reversing the antiprotozoal effect. The effectiveness of trimetrexate against toxoplasma was demonstrated both in vitro and vivo. Proliferation of toxoplasma in murine macrophages in vitro was completely inhibited by exposure of these cells to 10(-7) M trimetrexate for 18 h. When used alone, trimetrexate was able to extend the survival of T. gondii-infected mice.

Comparison of histologic and quantitative techniques in evaluation of therapy for experimental Pneumocystis carinii pneumonia

Pneumocystis carinii pneumonia was induced in rats by the administration of corticosteroids, and histologic and quantitative techniques were compared in the evaluation of the severity of the disease and response to therapy. A highly significant correlation was found between the histologic score of the extent of alveolar involvement (the standard method of assessment) and the number of P. carinii cysts and nuclei in lung homogenates, lung weight, and lung weight/body weight ratio. Clear differences were noted between rats which responded well and rats which responded poorly to therapy by all techniques. Quantitation of P. carinii cysts and nuclei revealed a 10(4)-fold reduction in organism burden with successful treatment. Thus, these techniques should be helpful in the development of testing of new antimicrobial agents in the rat model of pneumocystosis.

Successful treatment with aerosolized pentamidine of Pneumocystis carinii pneumonia in rats

We examined both the therapeutic efficacy and tissue distribution of aerosolized pentamidine in immunosuppressed rats with Pneumocystis carinii pneumonia. In rats immunosuppressed by 5 weeks of pretreatment with dexamethasone, a 2-week course of 5 mg of aerosolized pentamidine per kg per day, administered free or encapsulated in the drug carrier system (liposomes), eradicated P. carinii pneumonia in 75% of treated animals. At this dose, extrapulmonary drug uptake as measured by a sensitive high-pressure liquid chromatography assay was negligible. No significant differences in tissue distribution were noted between aerosolized free and liposome-encapsulated pentamidine. In rats receiving dexamethasone for 6 weeks prior to treatment with pentamidine, both lung uptake and therapeutic efficacy of aerosolized pentamidine (5 mg/kg per day) were substantially reduced. Aerosolized pentamidine appears to be an effective therapy for P. carinii pneumonia in rats and produces significantly lower extrapulmonary drug deposition than parenteral administration. The severity of P. carinii involvement at the time of treatment influences both the level of drug delivery to the lung and the response to aerosolized pentamidine therapy.