Rapid detection of Pneumocystis carinii using a direct fluorescent monoclonal antibody stain

Non-invasive diagnosis of Pneumocystis jirovecii pneumonia: a systematic review and meta-analysis

BACKGROUND

Pneumocystis jirovecii pneumonia (PCP) is an opportunistic infection commonly affecting immunocompromised people. Diagnosis usually requires invasive techniques to obtain respiratory specimens. Minimally invasive detection tests have been proposed, but their operating characteristics are poorly described.

OBJECTIVES

To systematically review and meta-analyse the performance of minimally invasive PCP detection tests to inform diagnostic algorithms.

DATA SOURCES

Medline, Embase, Cochrane Library (inception to 15 October 2020).

STUDY ELIGIBILITY CRITERIA

Studies of minimally invasive PCP detection tests were included if they contained a minimum of ten PCP cases.

PARTICIPANTS

Adults at risk of PCP.

TESTS

Non-invasive PCP detection tests.

REFERENCE STANDARD

Diagnosis using the combination of clinical and radiographical features with invasive sampling.

ASSESSMENT OF RISK BIAS

Using the QUADAS-2 tool.

METHODS

We used bivariate and, when necessary, univariate analysis models to estimate diagnostic test sensitivity and specificity.

RESULTS

Fifty-two studies were included; most studies (40) comprised exclusively human immunodeficiency virus (HIV) -infected individuals; nine were mixed (HIV and non-HIV), two were non-HIV and one study did not report HIV status. Sampling sites included induced sputum, nasopharyngeal aspirate, oral wash and blood. The four testing modalities evaluated were cytological staining, fluorescent antibody, PCR and lactate dehydrogenase. Induced sputum had the most data available; this modality was both highly sensitive at 99% (95% CI 51%-100%) and specific at 96% (95% CI 88%-99%). Induced sputum cytological staining had moderate sensitivity at 50% (95% CI 39%-61%) and high specificity at 100% (95% CI 100%-100%), as did fluorescent antibody testing with sensitivity 74% (95% CI 62%-87%) and specificity 100% (95% CI 91%-100%).

CONCLUSION

There are several promising minimally invasive PCP diagnostic tests available, some of which may reduce the need for invasive respiratory sampling. Understanding the operating characteristics of these tests can augment current diagnostic strategies and help establish a more confident clinical diagnosis of PCP. Further studies in non-HIV infected populations are needed.

Fungal pneumonia in kidney transplant recipients

Fungal pneumonia is a dreaded complication encountered after kidney transplantation, complicated by increased mortality and often associated with graft failure. Diagnosis can be challenging because the clinical presentation is non-specific and diagnostic tools have limited sensitivity and specificity in kidney transplant recipients and must be interpreted in the context of the clinical setting. Management is difficult due to the increased risk of dissemination and severity, multiple comorbidities, drug interactions and reduced immunosuppression which should be applied as an important adjunct to therapy. This review will focus on the main causes of fungal pneumonia in kidney transplant recipients including Pneumocystis, Aspergillus, Cryptococcus, mucormycetes and Histoplasma. Epidemiology, clinical presentation, laboratory and radiographic features, specific characteristics will be discussed with an update on diagnostic procedures and treatment.

Diagnosing Pneumocystis jirovecii pneumonia: A review of current methods and novel approaches

Pneumocystis jirovecii can cause life-threatening pneumonia in immunocompromised patients. Traditional diagnostic testing has relied on staining and direct visualization of the life-forms in bronchoalveolar lavage fluid. This method has proven insensitive, and invasive procedures may be needed to obtain adequate samples. Molecular methods of detection such as polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), and antibody-antigen assays have been developed in an effort to solve these problems. These techniques are very sensitive and have the potential to detect Pneumocystis life-forms in noninvasive samples such as sputum, oral washes, nasopharyngeal aspirates, and serum. This review evaluates 100 studies that compare use of various diagnostic tests for Pneumocystis jirovecii pneumonia (PCP) in patient samples. Novel diagnostic methods have been widely used in the research setting but have faced barriers to clinical implementation including: interpretation of low fungal burdens, standardization of techniques, integration into resource-poor settings, poor understanding of the impact of host factors, geographic variations in the organism, heterogeneity of studies, and limited clinician recognition of PCP. Addressing these barriers will require identification of phenotypes that progress to PCP and diagnostic cut-offs for colonization, generation of life-form specific markers, comparison of commercial PCR assays, investigation of cost-effective point of care options, evaluation of host factors such as HIV status that may impact diagnosis, and identification of markers of genetic diversity that may be useful in diagnostic panels. Performing high-quality studies and educating physicians will be crucial to improve the rates of diagnosis of PCP and ultimately to improve patient outcomes.

Profile of pneumocystis infection in a tertiary care institute in North India

CONTEXT

Pneumocystis jirovecii pneumonia (PcP) is still remains a common opportunistic disease in human immunodeficiency virus (HIV) infected individuals. Study on PcP in developing countries are scarce.

AIMS

To study the occurrence of P. jirovecii infection in clinically suspected individuals in a tertiary care institute.

SETTINGS AND DESIGN

Retrospective study conducted in a tertiary care hospital.

MATERIALS AND METHODS

Two years data regarding respiratory sample analysis, HIV status, and cluster of differentiation 4 (CD4) cell count of clinically suspected pneumocystis infection patients with known/unknown HIV status were analyzed.

RESULTS

Data of 45 eligible patients were analyzed. The majority of the patients were male (between 21 and 50 years of age). Total 26 (57.7%) patients were HIV reactive, of which 14 had CD4 count of <200 cells/mm³. 20 patients (9 HIV reactive and 11 unknown HIV status) were confirmed with pneumocystosis by direct fluorescent antibody (DFA) staining. Four of 14 HIV reactive individuals who had CD4 count of <200 cells/mm³ and 5 of 12 HIV reactive individuals who had CD4 count of >200 cells/mm³ were positive for pneumocystosis.

CONCLUSIONS

Pneumocystis pneumonia is still prevalent in North India and is mainly affecting patients in economically productive and sexually active age group. To diagnose pneumocystosis, DFA is an easily available method in resource-limited settings. Appreciating the actual HIV or immunodeficiency status and the CD4 profile of an individual with symptoms of pneumocystis infection will help the clinicians in early diagnosis and initiation appropriate therapy in individuals living with the disease.

ECIL guidelines for the diagnosis of Pneumocystis jirovecii pneumonia in patients with haematological malignancies and stem cell transplant recipients

The Fifth European Conference on Infections in Leukaemia (ECIL-5) convened a meeting to establish evidence-based recommendations for using tests to diagnose Pneumocystis jirovecii pneumonia (PCP) in adult patients with haematological malignancies. Immunofluorescence assays are recommended as the most sensitive microscopic method (recommendation A-II: ). Real-time PCR is recommended for the routine diagnosis of PCP ( A-II: ). Bronchoalveolar lavage (BAL) fluid is recommended as the best specimen as it yields good negative predictive value ( A-II: ). Non-invasive specimens can be suitable alternatives ( B-II: ), acknowledging that PCP cannot be ruled out in case of a negative PCR result ( A-II: ). Detecting β-d-glucan in serum can contribute to the diagnosis but not the follow-up of PCP ( A-II: ). A negative serum β-d-glucan result can exclude PCP in a patient at risk ( A-II: ), whereas a positive test result may indicate other fungal infections. Genotyping using multilocus sequence markers can be used to investigate suspected outbreaks ( A-II: ). The routine detection of dihydropteroate synthase mutations in cases of treatment failure is not recommended ( B-II: ) since these mutations do not affect response to high-dose co-trimoxazole. The clinical utility of these diagnostic tests for the early management of PCP should be further assessed in prospective, randomized interventional studies.

Profile of pneumocystis infection in a tertiary care institute in North India

CONTEXT

Pneumocystis jirovecii pneumonia (PcP) is still remains a common opportunistic disease in human immunodeficiency virus (HIV) infected individuals. Study on PcP in developing countries are scarce.

AIMS

To study the occurrence of P. jirovecii infection in clinically suspected individuals in a tertiary care institute.

SETTINGS AND DESIGN

Retrospective study conducted in a tertiary care hospital.

MATERIALS AND METHODS

Two years data regarding respiratory sample analysis, HIV status, and cluster of differentiation 4 (CD4) cell count of clinically suspected pneumocystis infection patients with known/unknown HIV status were analyzed.

RESULTS

Data of 45 eligible patients were analyzed. The majority of the patients were male (between 21 and 50 years of age). Total 26 (57.7%) patients were HIV reactive, of which 14 had CD4 count of <200 cells/mm³. 20 patients (9 HIV reactive and 11 unknown HIV status) were confirmed with pneumocystosis by direct fluorescent antibody (DFA) staining. Four of 14 HIV reactive individuals who had CD4 count of <200 cells/mm³ and 5 of 12 HIV reactive individuals who had CD4 count of >200 cells/mm³ were positive for pneumocystosis.

CONCLUSIONS

Pneumocystis pneumonia is still prevalent in North India and is mainly affecting patients in economically productive and sexually active age group. To diagnose pneumocystosis, DFA is an easily available method in resource-limited settings. Appreciating the actual HIV or immunodeficiency status and the CD4 profile of an individual with symptoms of pneumocystis infection will help the clinicians in early diagnosis and initiation appropriate therapy in individuals living with the disease.

British Society for Medical Mycology best practice recommendations for the diagnosis of serious fungal diseases

Invasive fungal diseases are an important cause of morbidity and mortality in a wide range of patients, and early diagnosis and management are a challenge. We therefore did a review of the scientific literature to generate a series of key recommendations for the appropriate use of microbiological, histological, and radiological diagnostic methods for diagnosis of invasive fungal diseases. The recommendations emphasise the role of microscopy in rapid diagnosis and identification of clinically significant isolates to species level, and the need for susceptibility testing of all Aspergillus spp, if treatment is to be given. In this Review, we provide information to improve understanding of the importance of antigen detection for cryptococcal disease and invasive aspergillosis, the use of molecular (PCR) diagnostics for aspergillosis, and the crucial role of antibody detection for chronic and allergic aspergillosis. Furthermore, we consider the importance of histopathology reporting with a panel of special stains, and emphasise the need for urgent (<48 hours) and optimised imaging for patients with suspected invasive fungal infection. All 43 recommendations are auditable and should be used to ensure best diagnostic practice and improved outcomes for patients.

Pneumocystis jirovecii colonization in Chronic Obstructive Pulmonary Disease (COPD)

Chronic obstructive pulmonary disease (COPD) is associated with a chronic inflammatory response in airways and lung parenchyma that results in significant morbidity and mortality worldwide. Cigarette smoking considered as an important risk factor plays a role in pathogenesis of disease. Pneumocystis jirovecii is an atypical opportunistic fungus that causes pneumonia in immunosuppressed host, although the low levels of its DNA in patients without signs and symptoms of pneumonia, which likely represents colonization. The increased prevalence of P. jirovecii colonization in COPD patients has led to an interest in understanding its role in the disease. P. jirovecii colonization in these patients could represent a problem for public health since colonized patients could act as a major reservoir and source of infection for susceptible subjects. Using sensitive molecular techniques, low levels of P. jirovecii DNA have been detected in the respiratory tract of certain individuals. It is necessary to elucidate the role of P. jirovecii colonization in the natural history of COPD patients in order to improve the clinical management of this disease. In the current review paper, we discuss P. jirovecii colonization in COPD patients.

Pneumocystis Pneumonia in Patients Treated With Long-Term Steroid Therapy for Symptom Palliation

We report 3 cases of pneumocystis pneumonia (PCP) in patients with advanced cancer who received palliative care. All patients received long-term steroid therapy for symptom management. A diagnosis of PCP was based on clinical symptoms and a positive Pneumocystis jiroveci polymerase chain reaction test from induced sputum specimens. Despite appropriate treatment, only 1 patient recovered from PCP. Long-term steroid, often prescribed in palliative care settings, is the most common risk factor for PCP in non-HIV patients. Pneumocystis pneumonia may cause distressing symptoms such as severe dyspnea, and the mortality rate is high. Therefore, it is important to consider PCP prophylaxis for high-risk patients and to diagnose PCP early and provide appropriate treatment to alleviate PCP-related symptoms and avert unnecessary shortening of a patient’s life expectancy.

Colonization by Pneumocystis jirovecii and its role in disease

Although the incidence of Pneumocystis pneumonia (PCP) has decreased since the introduction of combination antiretroviral therapy, it remains an important cause of disease in both HIV-infected and non-HIV-infected immunosuppressed populations. The epidemiology of PCP has shifted over the course of the HIV epidemic both from changes in HIV and PCP treatment and prevention and from changes in critical care medicine. Although less common in non-HIV-infected immunosuppressed patients, PCP is now more frequently seen due to the increasing numbers of organ transplants and development of novel immunotherapies. New diagnostic and treatment modalities are under investigation. The immune response is critical in preventing this disease but also results in lung damage, and future work may offer potential areas for vaccine development or immunomodulatory therapy. Colonization with Pneumocystis is an area of increasing clinical and research interest and may be important in development of lung diseases such as chronic obstructive pulmonary disease. In this review, we discuss current clinical and research topics in the study of Pneumocystis and highlight areas for future research.

Pneumocystis jirovecii dihydropteroate synthase (DHPS) genotypes in non-HIV-immunocompromised patients: a tertiary care reference health centre study

Studies on Pneumocystis jirovecii dihydropteroate synthase (DHPS) genotypes among non-HIV immunocompromised patients from developing countries are rare. In the present prospective investigation, 24 (11.8%) cases were found to be positive for Pneumocystis jirovecii out of 203 non-HIV patients with a clinical suspicion of Pneumocystis pneumonia (PCP). Dihydropteroate synthase (DHPS) genotype 1 (Thr55+Pro57) was noted in 95.8% P. jirovecii isolates in the present study in contrast to only 4.1% of patients with DHPS genotype 4 (Thr55Ala + Pro57Ser).

PCR diagnosis of Pneumocystis carinii on sputum and bronchoalveolar lavage samples in immuno-compromised patients

The polymerase chain reaction (PCR) technique was compared with Wright-Giemsa (WG), Gomori methenamine silver (GMS) stains and an immunofluorescence assay (IFA) for detection of Pneumocystis carinii in immuno-compromised patients. Specimens of 21 bronchoalveolar lavages (BAL) and 139 sputum samples, were obtained from 157 patients (38 with AIDS and 119 with HIV) from four hospitals in Khon Kaen, Thailand. A true positive required at least two positives by techniques considered gold standard tests. Eleven (52.38%) BAL and 13 (9.35%) sputum specimens were positive. PCR produced the highest sensitivity and negative predictive values for the BAL (100% for each) vs. sputum samples at 84.62 and 98.41 percent, respectively. The specificity of PCR was 90% and 98.41% for BAL and sputum samples, respectively. We suggest PCR is an important tool for the epidemiological study of P. carinii in high-risk individuals.

The Utility of Sputum Induction for Diagnosis of Pneumocystis Pneumonia in Immunocompromised Patients without Human Immunodeficiency Virus

Sputum induction for the diagnosis of Pneumocystis pneumonia (PCP) is widely used for patients with acquired immunodeficiency syndrome (AIDS), but its utility for patients with other forms of immunocompromise is less well defined. Immunocompromised patients with PCP who do not have human immunodeficiency virus (HIV) infection have a lower burden of organisms, and sputum induction may consequently have lower diagnostic yield in these patients. However, this retrospective review of the experience at a tertiary referral center suggests that sputum induction has clinical utility for diagnosing PCP in immunocompromised patients without HIV infection.

Laboratory diagnosis of invasive mycoses

Rising numbers of immunocompromised patients have led to an ever-increasing population at risk of invasive fungal disease. Much has been achieved in the laboratory diagnosis of these infections, such as advances in blood culture systems, and the development of new biochemical, antigen detection assays, and molecular methodologies. More standardized susceptibility testing guidelines provide for better therapeutic interventions. In an era of economic cutbacks in health care, future challenges include the development of cost-effective and technically simplified systems, which provide early detection and identification of common and emerging fungal pathogens. It will, however, take some time to establish the clinical relevance of these new methodologies in different patient populations.

PCR-based quantification of Pneumocystis carinii in in vitro systems

In many laboratories, PCR has become a routine method for the sensitive diagnosis of Pneumocystis carinii in patient samples. In contrast, quantification of fungal numbers in in vitro setups still largely relies on more conventional procedures such as histological stainings. These are time consuming and their applications are limited when dealing with small fungal numbers contaminated with tissue and cellular debris. This study presents a sensitive and rapid method for P. carinii quantification based on PCR analysis that can be easily integrated into standard detection procedures without requiring any major additional steps. P. carinii-specific PCR performed with total DNA extracted from both standard samples with known fungal numbers and experimental samples was quantified relative to PCR products of a standard concentration from a control plasmid added prior to DNA extraction. This measure controlled for variations in DNA extraction and PCR efficiency among the samples to be compared. The correlation between analyzed P. carinii-specific DNA and the actual fungal numbers employed was highly significant.

Diagnostic testing for community-acquired pneumonia

The microbial cause of community-acquired pneumonia can be identified by noninvasive means in the majority of cases, usually within a few days of presentation. The Gram stain and culture of a pretreatment sputum sample are the most useful tests, but have significant limitations. Methods for detecting pneumococcal antigen in respiratory secretions are particularly helpful in patients who have received antibiotics before evaluation. Testing for specific pathogens such as L. pneumophila, M. pneumoniae, or C. pneumoniae should be guided by clinical suspicion in individual circumstances. Invasive procedures are most helpful in patients suspected of having infection with opportunistic or resistant pathogens, and in those whose initial management has been unsuccessful.

Pneumonia in AIDS patients in the critical care unit

Despite advances in prophylaxis and the reduction of mortality and morbidity resulting from highly active antiretroviral therapy, neumocystis pneumonia remains a common problem in HIV-infected patients. There are many possible causes for the continued prevalence of this condition. This article examines the characteristics, and some of the complex causes of P. carinii pneumonia in AIDS patients.

Extrapulmonary pneumocystosis

Extrapulmonary pneumocystosis is an exceedingly rare complication of Pneumocystis carinii pneumonia (PCP). Prior to the advent of the human immunodeficiency virus type 1 (HIV-1) epidemic, only 16 cases of extrapulmonary pneumocystosis in individuals who were immunocompromised by a variety of underlying diseases had been reported. Since the beginning of the HIV-1 and related PCP epidemic, at least 90 cases of extrapulmonary pneumocystosis have been reported. This review briefly presents a history of the discovery of P. carinii and its recognition as a human pathogen, the controversy regarding its taxonomy, and the epidemiology of this organism. A more detailed analysis of the incidence of extrapulmonary pneumocystosis in HIV-1-infected individuals and its occurrence despite widespread prophylaxis for PCP with either aerosolized pentamidine or systemic dapsone-trimethoprim is presented. The clinical features of published cases of extrapulmonary pneumocystosis in non-HIV-1-infected individuals are summarized and contrasted with those in HIV-1 infected individuals. The diagnosis of extrapulmonary pneumocystosis is discussed, and because clinical microbiologists and pathologists are the key individuals in establishing the diagnosis, the characteristic microscopic morphology of P. carinii as its appears when stained with a variety of stains is presented and reviewed. The review concludes with a brief discussion of treatments for extrapulmonary pneumocystosis.

Detection of Pneumocystis carinii in tracheal aspirates of intubated patients using calcofluor-white (Fungi-Fluor) and immunofluorescence antibody (Genetic Systems) stains

OBJECTIVE

To compare the detection rate of Pneumocystis carinii in endotracheal aspirates with that rate in bronchoalveolar lavage fluid, using calcofluor-white (Fungi-Fluor) and immunofluorescence antibody (Genetic Systems) staining methods.

DESIGN

Prospective, consecutive cases.

SETTING

Medical intensive care unit at Ben Taub General Hospital.

PATIENTS

Thirty-one intubated patients admitted with respiratory failure and suspected P. carinii pneumonia.

INTERVENTIONS

An endotracheal aspirate specimen was obtained after maximally advancing a closed-system suction catheter, instilling aliquot portions of saline, and suctioning the lavage fluid. This procedure was followed within 30 mins by fiberoptic bronchoscopy and bronchoalveolar lavage.

MEASUREMENTS AND MAIN RESULTS

Endotracheal aspirate and bronchoalveolar lavage specimens from each patient were mixed with Saccomano's fixative, blended, and centrifuged. Using a modified method for P. carinii cysts, the sediment was stained with the test calcofluor-white stain Solution A and the test antibody stain. The test antibody stain on the bronchoalveolar lavage specimens was positive for P. carinii for 13 patients and was used as the standard for comparison. In the endotracheal aspirate specimens, the test antibody stain detected 12 (92%) P. carinii-positive patients while the test calcofluor-white stain detected ten (77%) P. carinii-positive patients.

CONCLUSIONS

We described a simple method for obtaining, processing, and staining endotracheal aspirate specimens for P. carinii. Obtaining an endotracheal aspirate specimen did not require specially trained personnel or a specialized and more expensive catheter, and was not associated with any complications.

Diagnostic yield of bronchoalveolar lavage and bronchoscopic lung biopsy for detection of Pneumocystis carinii

OBJECTIVE

To assess the need to perform a bronchoscopic lung biopsy (BLB) in addition to bronchoalveolar lavage (BAL) to obtain a definitive diagnosis of Pneumocystis carinii pneumonia.

DESIGN

We retrospectively reviewed the results of concurrently collected paired BAL and BLB specimens to determine the diagnostic yield of both methods for the detection of P. carinii organisms.

MATERIAL AND METHODS

During a 3-year period, the BAL fluid specimens stained with a commercially available direct immunofluorescence monoclonal antibody (DFA) reagent and the BLB specimens stained with Grocott methenamine-silver nitrate (GMS) were assessed for the presence of P. carinii. BAL fluid was routinely collected from multiple sites and combined into a single specimen for testing.

RESULTS

During the 3-year period of study, 119 patients were identified who had paired BAL fluid and BLB specimens tested for the presence of P. carinii. Of the 119 patients, 16 had either BAL fluid that could not be interpreted or BLB tissue that was inadequate. Of the other 103 patients, 21 had P. carinii pneumonia. The sensitivity of the DFA method on BAL fluid and of the GMS method on BLB was 95% and 43%, respectively.

CONCLUSION

For detection of P. carinii, the diagnostic yield is significantly higher for DFA-stained BAL specimens than for GMS-stained BLB specimens.

Detection of infection or infectious agents by use of cytologic and histologic stains

A wide variety of stains are useful for detection of different organisms or, for viruses, the cytopathologic changes they induce, in smears prepared directly from clinical specimens and in tissue sections. Other types of stains, such as hematoxylin and eosin, are used routinely to stain tissue sections and are most valuable for assessing the immunologic response of the host to the invading pathogen. In many cases, the pattern of inflammation provides important clues to diagnosis and helps to guide the selection of additional "special" stains used predominantly for diagnosis of infectious diseases. A stain may be nonspecific, allowing detection of a spectrum of organisms, as do the Papanicolaou stain and silver impregnation methods, or detection of only a limited group of organisms, as do the different acid-fast techniques. Some nonspecific stains, such as the Gram stain, are differential and provide valuable preliminary information concerning identification. Immunohistochemical stains, on the other hand, are specific for a particular organism, although in some cases cross-reactions with other organisms occur. Despite the wealth of information that can be gleaned from a stained smear or section of tissue, however, the specific etiology of an infection often cannot be determined on the basis of only the morphology of the organisms seen; culture data are essential and must be considered in the final diagnosis.

Detection of Pneumocystis carinii with direct fluorescence antibody and calcofluor white stain

Direct fluorescence monoclonal antibody stain (DFA) was compared prospectively, with calcofluor white (CFW) stain for the diagnosis of Pneumocystis carinii in 163 respiratory specimens from 97 patients. The patient population included persons with HIV infection (58%), bone marrow transplant recipients (10%), immunosuppressed patients owing to chemotherapy (21%) and others (11%). Nineteen specimens including 12 sputa, six bronchoalveolar lavage fluids (BALs) and one induced sputum were positive by DFA. In contrast, only six sputa, and five BALs were positive by CFW. All specimens positive by CFW were also positive by DFA. Of 86 sputa that were negative by either method 29 were followed by more invasive sample collections. Three specimens were followed by induced sputum collection, 18 by BAL, six by lung biopsy, and two by pleural fluid aspiration. All the subsequent induced sputa, pleural fluids, and lung biopsies were negative by both methods. However, four of 18 subsequent BALs (22%) were positive by both methods, provided at least two CFW stained slides were examined per specimen. Except for expectorated sputum, it is concluded that CFW is a rapid and inexpensive test to detect P. carinii in most respiratory specimens.

Laboratory implementation of a rapid three-stain technique for detection of microorganisms from lower respiratory specimens

A rapid, cost-effective method for the evaluation of lower respiratory specimen has become increasingly important in the diagnosis of pulmonary diseases in immunocompromised patients. In the past, the technically demanding, time-consuming, and expensive Gomori-methenamine-silver (GMS) stain was the principal means for the evaluation of these specimens. In this study, we compared the GMS stain with a new rapid, three-stain protocol for the evaluation of lower respiratory specimens. Lower respiratory specimens were obtained by bronchoalveolar lavage (BAL). Conventional Wright/Giemsa and Gram stains were utilized, as well as a contemporary strain, calcofluor white (CW). A cell count was performed on the BAL specimens, and cytospins were stained by the three stains. The calcofluor white-stained slides were examined with an epi-fluorescent microscope, whereas the other stains were evaluated with a conventional light microscope. Gomorimethenamine-silver (GMS), acid-fast bacillus (AFB), and Papanicolaou (PAP) stains were performed as controls. Thirty-two BAL procedures were performed in 20 (63%) male patients and 12 (37%) female patients. The clinical diagnosis was pneumonia in 31% of the patients, malignant hematologic disease in 28%, acute respiratory distress syndrome (ARDS) in 9%, and acquired immunodeficiency syndrome (AIDS) in 28%. Of these specimens, 78% were adequate for interpretation and 22% were inadequate. Bacteria were found in 50% (16/32) of all BALs, fungi were found in 9% (3/32), and Pneumocystis carinii was found in 9% (3/32). Gram-positive bacteria were most frequently found in patients with pneumonia (80%, 4/5), whereas P. carinii was identified in patients with AIDS. There were no false-positive results. One CW stain was equivocal for P. carinii due to high fluorescent background. Laboratory implementation of the rapid, three-staining technique was accomplished without difficulty in microbiology and hematology laboratory sections. Specimen evaluation with the rapid staining protocol was technically easy to perform; however, experience in ultraviolet fluorescent microscopy was crucial for interpretation of CW stain. All results were available in 2 hr, cost was reduced by 30%, and the assays were available 7 days/week. Further studies are ongoing to substantiate the sensitivity, specificity, and predictive value of this technique, as well as clinical guidelines for its optimal utilization.

The impact of prophylaxis on outcome and resource utilization in Pneumocystis carinii pneumonia

STUDY OBJECTIVE

Pneumocystis carinii pneumonia (PCP) is a major late complication of HIV infection associated with morbidity and mortality. Because chemoprophylaxis is highly effective, cases of PCP can be viewed as failures in the management of HIV disease.

METHODS

We reviewed demographic, clinical, and cost data for all cases of confirmed HIV-related PCP at The Johns Hopkins Hospital in 1991 to determine consequences of missed prophylaxis. We also analyzed hospital discharge data for Maryland in 1991 to assess hospital charges, length of stay, and outcome for all patients with a principal diagnosis of HIV-related PCP.

RESULTS

Pneumocystis carinii pneumonia was diagnosed in 79 patients. Of the 79 patients, 61 (77%) did not receive prophylaxis, including 26 who were not previously known to have HIV infection, 17 who did not have prophylaxis prescribed, and 18 who had prophylaxis prescribed, but were not compliant with the regimen. Patients not taking prophylaxis accounted for all 12 deaths ascribed to PCP. This group also accounted for 85% of the hospital days, 100% of the ICU days, and 89% of the inpatient charges. The total hospital charges were $849,540. Extrapolation of these figures for the state of Maryland suggest that the failure to receive prophylaxis in 1991 resulted in 62 patient deaths and a cost of approximately $4.7 million.

CONCLUSION

Patients who developed PCP despite prophylaxis had a better outcome and used fewer resources than patients not receiving preventive therapy. This study emphasizes the impact of PCP prophylaxis on the morbidity, mortality, and economics of HIV health care.

Development and evaluation of a rapid and simple procedure for detection of Pneumocystis carinii by PCR

We report the development of a simplified PCR-based assay for the detection of Pneumocystis carinii DNA in clinical specimens. The adoption of a rapid DNA extraction procedure and the introduction of a type of enzyme-linked immunosorbent assay for PCR product detection enabled this procedure to be carried out in a single working day in a clinical microbiology laboratory. The PCR assay was prospectively compared with an immunofluorescent-antibody (FA) staining method for the detection of P. carinii in induced sputum and bronchoalveolar lavage (BAL) specimens. The results of the study showed that, for induced sputum specimens, FA staining had a sensitivity of 78% (32 of 41 specimens) and a specificity of 100% (166 of 166 specimens); PCR was 100% (41 of 41 specimens) sensitive and 98% (162 of 166 specimens) specific. For BAL specimens, FA staining was 100% sensitive (21 of 21 specimens) and 100% specific (133 of 133 specimens), and PCR had a sensitivity of 100% (21 of 21 specimens) and a specificity of 99% (132 of 133 specimens). These results strongly suggest that use of our PCR-based assay could effect clinically useful improvements in the sensitivity of induced sputum specimens for the detection of P. carinii.

An evaluation of four methods for the detection of Pneumocystis carinii in clinical specimens

We undertook a prospective evaluation of 4 methods for the detection of Pneumocystis carinii in clinical specimens and compared an indirect immunofluorescence assay (IFA) (Diagnostics Pasteur), and a fluorescent whitening agent (FWA) (Blankophor BA 267%, Bayer, Australia) with our standard methenamine silver (MeAg) and toluidine blue O (TB) stains. Two hundred and two specimens were received from 162 patients (133 HIV infected, 19 heart or heart-lung transplant recipients, and 10 "miscellaneous"). The specimens consisted of 132 induced sputa, 56 bronchoalveolar lavage specimens, 10 fine needle aspiration lung biopsies, and 4 pleural fluid specimens. P. carinii was detected in 44 (22%) of the specimens. The sensitivities for the detection of P. carinii pneumonia were IFA: 92% (95% CI, 83-100%), FWA: 57% (95% CI, 41-73%), MeAg: 54% (95% CI, 38-70%), and TB: 49% (95% CI, 33-65%). Discordant results were greatest in specimens from patients who were receiving specific anti-P. carinii prophylaxis, or who had received treatment for several days prior to sampling. IFA was the most sensitive test and relatively easy to perform. IFA was also the most expensive test. We found the FWA method a useful screening test as it is cheap and quick to perform. However, it is less sensitive than IFA, which should be performed on the negative specimens. With the increasing use of specific anti-P. carinii prophylaxis in HIV-infected patients, methods more specific and sensitive than MeAg and TB stains are required. We have found IFA to improve significantly the rate of detection of P. carinii in this patient group.

Evaluation of the sensitivity, specificity, and predictive value of monoclonal antibody 3F6 for the detection of Pneumocystis carinii pneumonia in bronchoalveolar lavage specimens and induced sputum

The sensitivity and specificity of different staining procedures for the detection of Pneumocystis carinii organisms were compared. Three conventional stains (Papanicolaou, Giemsa and Grocott's) and one immunocytochemical stain using 3F6 antibody were used on smears prepared from the same specimen. Bronchoalveolar lavage (BAL) and induced sputum (IS) specimens were used for this purpose. One hundred and sixty-five episodes from 142 patients were investigated by the four different staining techniques. Cysts of P. carinii were detected in 64 episodes from 63 patients. Immunocytochemical staining with 3F6 was found to be slightly more sensitive at detecting the cysts than Grocott's, Giemsa, or Papanicolaou stain.

Seroreactivity to Pneumocystis carinii in patients with AIDS versus other immunosuppressed patients

The aim was to study the humoral response to Pneumocystis carinii and its diagnostic use in patients with P. carinii pneumonia (PCP). The antibody response was measured by indirect immunofluorescence in AIDS patients versus other immunosuppressed patients with 122 episodes of confirmed PCP. During the early acute stage of the pneumonia, anti-P. carinii antibodies were found in 17% of AIDS and 24% of other immunosuppressed patients. In the second serum sample, antibodies were still found in 17% of the AIDS patients but in as many as 56% of the otherwise immunosuppressed patients. Antibodies were also found in 17% of HIV-positive and 15% of other immunosuppressed control patients, but only in 3% of immunocompetent controls (p < 0.001). Paired sera were available from 55 patients during 58 PCP episodes. Seroconversion or a fourfold rise in titre was detected in only 1/36 (3%) AIDS patients but in 10/22 (45%), (95% c.i.: 24-66%) other immunosuppressed patients (p < 0.001). We conclude that AIDS patients seem to have lost their ability to develop a humoral response to P. carinii during pneumonia, whereas many other immunosuppressed patients do respond. In these patients the serological test against P. carinii was of no diagnostic value in the acute phase of the infection, whereas when analysing paired sera it was a useful complement to the clinical diagnosis.

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.

Detection of Pneumocystis carinii in a rat model of infection by polymerase chain reaction

The polymerase chain reaction (PCR) was employed to detect Pneumocystis carinii in organs of infected rats. Using a pair of oligonucleotides designed to the dihydrofolate reductase (DHFR) gene of rat P. carinii, specific amplification of an expected 415 bp region of P. carinii DHFR DNA of this organism was achieved, while no amplification occurred with the human, Candida albicans, and Mycobacterium avium and tuberculosis DNAs. Using rat P. carinii isolated from in vitro cultures and infected lung homogenates, the minimum detection level by PCR on an ethidium bromide gel was about 200 organisms and by Southern analysis with radiolabelled DHFR probe the detection level improved to 20 organisms. This level of sensitivity is sufficient to detect P. carinii specific band on the gel in infected rat lung and other organs. This PCR technique is potentially useful for detecting P. carinii in bronchoalveolar lavage (BAL) fluids of AIDS patients and for quantifying the organisms in tissues and in in vitro cultures where a high background with conventional stains makes it harder to determine the number of organisms.