Diagnosis of Pneumocystis carinii pneumonia by multiple lobe, site-directed bronchoalveolar lavage with immunofluorescent monoclonal antibody staining in human immunodeficiency virus-infected patients receiving aerosolized pentamidine chemoprophylaxis

A novel diagnostic approach for Pneumocystis jirovecii pneumonia using fine-needle aspiration, electromagnetic navigational bronchoscopy and rapid on-site evaluation

Cavitary lung lesions are common in patients with human immunodeficiency virus infections. Both atypical infections and thoracic malignancies can manifest as a cavitary pulmonary lesion. Standard bronchoscopy is commonly used to evaluate these abnormalities but is limited in its ability to fully assess for cancer and infection. Bronchoalveolar lavage samples are likely to aid in the diagnosis of infection but are less useful in the evaluation of malignancy. In addition, many of these pulmonary lesions are located in the periphery of the lung and are not accessible for tissue sampling by standard bronchoscopy. We present a unique presentation of Pneumocystis jirovecii pneumonia and discuss the utility of electromagnetic navigational bronchoscopy in the evaluation of immunocompromised patients with peripheral cavitary lung lesion.

Pulmonary Infections in Immunocompromised Hosts: Clinical

Pulmonary infections in immunocompromised patients remain a significant contributor to mortality, morbidity, and health care-associated costs in such a vulnerable patient population. Their epidemiology is changing, set forth by new trends in immunosuppressive regimens and also prophylaxis. The host characteristics, presenting clinical symptomatology, along with radiographic patterns, have also evolved. The microbiology diagnostics are now enriched with nonculture methods for better identification of the causative pathogens. Chest imaging remains the cornerstone of the initial workup. Our article will examine the new trends in epidemiology, clinical findings, and diagnostics for immunocompromised patients with pulmonary infections (transplant recipients, neutropenic hosts, HIV-infected patients, and patients with autoimmune conditions). We will also review the differential diagnosis that most of the times includes malignancies and drug or radiation-related toxicities.

Aspiration techniques for bronchoalveolar lavage in translational respiratory research: Paving the way to develop novel therapeutic moieties

Bronchoalveolar lavage (BAL) is a simple, yet informative tool in understanding the immunopathology of various lung diseases via quantifying various inflammatory cells, cytokines and growth factors. At present, this traditional method is often blended with several robust and sophisticated molecular and biological techniques sustaining the significance and longevity of this technique. Crucially, the existence of slightly distinct approaches and variables employed at different laboratories around the globe in performing BAL aspiration indeed demands an utmost need to optimize and develop an effective, cost-effective and a reproducible technique. This mini review will be of importance to the biological translational scientist, particularly respiratory researchers in understanding the fundamentals and approaches to apply and consider with BAL aspiration techniques. This will ensure generating a meaningful and clinically relevant data which in turn accelerate the development of new and effective therapeutic moieties for major respiratory conditions.

Pneumocystis jirovecii detection in asymptomatic patients: what does its natural history tell us?

Pneumocystis jirovecii is an unusual ascomycetous fungus that can be detected in the lungs of healthy individuals. Transmission from human to human is one of its main characteristics in comparison with other fungi responsible for invasive infections. P. jirovecii is transmitted through the air between healthy individuals, who are considered to be the natural reservoir, at least transiently. In immunocompromised patients, P. jirovecii multiplies, leading to subacute infections and acute life-threatening pneumonia, called Pneumocystis pneumonia [PCP]. PCP is caused by genotypically distinct mixtures of organisms in more than 90% of cases, reinforcing the hypothesis that there is constant inhalation of P. jirovecii from different contacts over time, although reactivation of latent organisms from previous exposures may be possible. Detection of P. jirovecii DNA without any symptoms or related radiological signs has been called “colonization”. This situation could be considered as the result of recent exposure to P. jirovecii that could evolve towards PCP, raising the issue of cotrimoxazole prophylaxis for at-risk quantitative polymerase chain reaction (qPCR)-positive immunocompromised patients. The more accurate way to diagnose PCP is the use of real-time quantitative PCR, which prevents amplicon contamination and allows determination of the fungal load that is mandatory to interpret the qPCR results and manage the patient appropriately. The detection of P. jirovecii in respiratory samples of immunocompromised patients should be considered for potential risk of developing PCP. Many challenges still need to be addressed, including a better description of transmission, characterization of organisms present at low level, and prevention of environmental exposure during immunodepression.

Clinical review: Respiratory failure in HIV-infected patients--a changing picture

Respiratory failure in HIV-infected patients is a relatively common presentation to ICU. The debate on ICU treatment of HIV-infected patients goes on despite an overall decline in mortality amongst these patients since the AIDS epidemic. Many intensive care physicians feel that ICU treatment of critically ill HIV patients is likely to be futile. This is mainly due to the unfavourable outcome of HIV patients with Pneumocystis jirovecii pneumonia who need mechanical ventilation. However, the changing spectrum of respiratory illness in HIV-infected patients and improved outcome from critical illness remain under-recognised. Also, the awareness of certain factors that can affect their outcome remains low. As there are important ethical and practical implications for intensive care clinicians while making decisions to provide ICU support to HIV-infected patients, a review of literature was undertaken. It is notable that the respiratory illnesses that are not directly related to underlying HIV disease are now commonly encountered in the highly active antiretroviral therapy (HAART) era. The overall incidence of P. jirovecii as a cause of respiratory failure has declined since the AIDS epidemic and sepsis including bacterial pneumonia has emerged as a frequent cause of hospital and ICU admission amongst HIV patients. The improved overall outcome of HIV patients needing ICU admission is related to advancement in general ICU care, including adoption of improved ventilation strategies. An awareness of respiratory illnesses in HIV-infected patients along with an appropriate diagnostic and treatment strategy may obviate the need for invasive ventilation and improve outcome further. HIV-infected patients presenting with respiratory failure will benefit from early admission to critical care for treatment and support. There is evidence to suggest that continuing or starting HAART in critically ill HIV patients is beneficial and hence should be considered after multidisciplinary discussion. As a very high percentage (up to 40%) of HIV patients are not known to be HIV infected at the time of ICU admission, the clinicians should keep a low threshold for requesting HIV testing for patients with recurrent pneumonia.

Aromatic diamidines as antiparasitic agents

Parasitic infections are widespread in developing countries and frequently associated with immunocompromised patients in developed countries. Consequently, such infections are responsible for a significant amount of human mortality, morbidity and economic hardship. A growing consensus has identified the urgent need for the development of new antiparasitic compounds, mostly due to the large number of drug-resistant parasites and the fact that currently available drugs are expensive, highly toxic, require long treatment regimens and frequently exhibit significantly reduced activity towards certain parasite strains and evolutive stages. In this context, the activity of aromatic diamidines has been explored against a widespread range of micro-organisms, and the authors' present aim is to review the current status of chemotherapy with these compounds against human parasitic infections.

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.

The pulmonary physician in critical care 1: pulmonary investigations for acute respiratory failure

This is the first in a series of reviews of the role of the pulmonary physician in critical care medicine. The investigation of mechanically ventilated patients is discussed, with particular reference to those presenting with acute respiratory failure and diffuse pulmonary infiltrates.

Pneumocystis carinii

Pneumocystis carinii is an atypical fungus that causes pneumonia in immunocompromised individuals. P. carinii comprises a heterogeneous group of organisms that have been isolated from a wide range of mammalian host species. P. carinii infection is host species specific, the P. carinii organisms that infect humans have only been found in humans. This review discusses the application of molecular techniques to the study of the biology and epidemiology of P. carinii infection. It addresses the use of DNA amplification for the detection and diagnosis of P. carinii pneumonia. Studies investigating the reservoir of infectious P. carinii organisms, the routes of transmission of the infection, and the emergence of drug resistant strains of P. carinii are also discussed.

Role of bronchoscopy in AIDS

The differential diagnosis of pulmonary disorders in the HIV-infected individual is broad. Clinical features and chest radiographs may point towards a diagnosis but cannot reliably establish one. It is important to know the conditions in which bronchoscopy, BAL, and TBB are likely to be diagnostic, just as it is to know when other invasive or noninvasive procedures may be more useful. Finally, the incidence of transmission of infections such as tuberculosis during bronchoscopy and cross-contamination of patients with an improperly sterilized bronchoscope, cannot be overemphasized.

Diagnosis of lower respiratory tract infections: what we have and what would be nice

STUDY OBJECTIVES

To review the various methods used to diagnose lower respiratory tract infections.

DESIGN

Review of literature with appropriate references to various techniques proposed to diagnose pneumonia.

INTERVENTION

Compare and contrast different proposed approaches to diagnose pneumonia.

RESULTS

Bronchoscopic techniques appear more clear cut for certain nonbacterial pathogens. Their role in immunocompromised patients is more clear cut, while in the nonimmunocompromised patient, invasive diagnostic techniques probably provide a higher certainty of the final diagnosis of the patient. Recent interest has focused on nonbronchoscopic techniques for the mechanically ventilated patient. None of these techniques has been demonstrated to change clinical outcome.

CONCLUSIONS

Diagnosis of lower respiratory tract infection has to be tailored for the individual patient. Decision about which procedure to do is influenced by the patient's underlying immune status, level of illness, and response to empiric therapy.

Rapid detection of Pneumocystis carinii in bronchoalveolar lavage specimens from human immunodeficiency virus-infected patients: use of a simple DNA extraction procedure and nested PCR

We report on the development of a rapid nested PCR protocol for the detection of Pneumocystis carinii DNA in bronchoalveolar lavage (BAL) specimens in which the protocol included the use of a commercially available DNA extraction kit (GeneReleaser). GeneReleaser enabled us to obtain amplification-ready DNA within 20 min without requiring the purification of the DNA. The nested PCR was performed with the primers pAZ102-E, pAZ102-H, and pAZ102-L2 (A. E. Wakefield, F. J. Pixley, S. Banerji, K. Sinclair, R. F. Miller, E. R. Moxon, and J. M. Hopkin, Lancet 336:451-453, 1990.). Results were obtained in about 4 h with the adoption of denaturation, annealing, and extension steps shortened to 20 seconds. The sensitivity of the nested PCR was tested with a P. carinii cyst suspension and was found to be less than one cyst (one to eight nuclei). The detection limit was the same with the use of GeneReleaser or proteinase K-phenol chloroform for DNA extraction. The nested PCR assay was prospectively compared with staining with Giemsa and methenamine silver stains for the detection of P. carinii in 127 BAL samples from 105 human immunodeficiency virus-infected patients investigated for acute respiratory illness. Twenty-five BAL specimens (20%) were positive by staining and the nested PCR and 25 (20%) were negative by staining and positive by the nested PCR. These 25 BAL specimens with conflicting results were obtained from 23 patients, 82% of whom were receiving prophylactic therapy against P. carinii pneumonia (PCP). Only two patients were diagnosed with possible PCP. The final diagnosis was not PCP for 20 patients who were considered to be colonized or to have a low level of infection. This colonization is not of clinical importance but is of epidemiological importance. Our rapid, simple, and sensitive amplification protocol may be performed in clinical laboratories for the routine diagnosis of PCP with BAL specimens.

Acute respiratory failure in the HIV-seropositive patient

Since approximately 40% to 65% of patients with AIDS will develop pulmonary disease, HIV-seropositive patients represent a large cohort of immunosuppressed individuals with the potential to progress to respiratory failure requiring mechanical ventilation and admission to the intensive care unit. This article reviews the cause, pathophysiology, diagnostic approach, and management of acute respiratory failure requiring mechanical ventilation in HIV-seropositive patients. Prognostic factors and survival rates for episodes of respiratory failure are also discussed. In addition, an overview of acute respiratory failure in pediatric AIDS patients is presented.

Approach to the patient with pulmonary disease

The approach to the HIV-infected patient with pulmonary disease is summarized by the algorithms in Figures 3 and 4. These are not intended to be followed in a rigid step-wise fashion. Rather, the practitioner's knowledge of the patient with his or her accompanying medical risks influences the path taken, including the depth and the speed of the evaluation. For example, the patient with cough who is afebrile and breathing at 18 breaths a minute, with a normal chest radiograph and a CD4 count of 350 cells/mm3, is reasonably treated with a macrolide or cephalosporin for bacterial bronchitis and clinical follow-up while awaiting cultures (see Fig. 4). A febrile patient with a cough productive of thin mucus, but known to have a CD4 count of 60 cells/mm3 should be started on anti-PCP therapy while being evaluated for PCP with an induced sputum and if nondiagnostic, a bronchoscope despite a normal chest radiograph. Screening can be as simple as placing an oximeter on the patient's finger in the clinic. If the oxygen saturation of a patient with a normal chest radiograph is low, then the patient should be hospitalized and begun on treatment for PCP while diagnostic evaluation is initiated. If the oxygen saturation is normal, the patient can be exercised to elicit desaturation. If there is no desaturation, PCP is unlikely. If the results are equivocal (i.e., a decrease in saturation, but less than 3%), rest and exercise arterial blood gases can be performed, along with a Dlco-Gallium scanning can be done in patients known to have abnormal Dlco or those who cannot exercise. Patients with focal infiltrates who have acute onset of symptoms (see Fig. 4) commonly have bacterial infections, but the possibility of PCP or TB should not be dismissed. Induced sputum should be examined if TB or PCP is suspected. Patients who are severely ill might go quickly to bronchoscopy without awaiting improvement on empiric therapy. The patient with diffuse infiltrates (see Fig. 4) needs no screening because the presence of disease is apparent from the radiograph. The diagnostic part quickly leads to bronchoscopy for these patients and the initiation of therapy for PCP when suspected. In patients with known pulmonary KS, gallium scanning can be helpful to rule out acute infection, but bronchoscopy is warranted if the patient is severely ill, or at high risk for PCP. This approach should avoid unnecessary procedures in patients with simple bacterial infections, without missing opportunistic infections and tumors.

Pneumocystis carinii

Improved understanding of Pneumocystis carinii, in particular the widespread use of chemoprophylaxis, has resulted in a declining incidence of infection in patients infected with HIV since the late 1980s. Despite these advances, P. carinii pneumonia continues to represent an important cause of pulmonary disease in HIV-seropositive individuals who do not receive chemoprophylaxis or when breakthrough episodes occur. This article reviews the history, biology, clinical manifestations, prognostic markers, therapy, and chemoprophylaxis of P. carinii pneumonia in HIV-seropositive patients.

Pulmonary disease

This article has presented the reader with an overview of the pulmonary disorders that develop during the course of HIV disease with special emphasis on the more commonly encountered entities. This information is intended to prepare the clinician to recognize the hallmark characteristics of the various diseases as well as atypical features. Despite the advances in basic understanding of the clinicopathologic consequences of infection with HIV, a cure has not been realized. There has, however, been success in controlling some of the major pulmonary problems that adversely affect both the quality and the length of life for persons with AIDS. For most complications of HIV infection, prognosis ultimately depends not only on treatment of the specific problem, but also controlling the relentless process of progressive immunosuppression. Continued research into treatment or prevention of HIV infection itself is needed, but at present prevention, rapid diagnosis, and treatment of recognized problems remain an intermediary goal.

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.

Small volume bronchoalveolar lavage used in diagnosing Pneumocystis carinii pneumonia in HIV-infected patients

To determine the volume of bronchoalveolar lavage (BAL) fluid necessary to diagnose Pneumocystis carinii pneumonia (PCP) in immunocompromised patients, specimens from 25 patients were evaluated. Twenty-one patients were HIV infected. BAL was performed using three to four 60-mL aliquots of room temperature, sterile, saline solution. Each syringe of BAL effluent was numbered and its volume was measured. Immunofluorescent stains were performed on about 8-mL aliquots of the initial, final, and aggregate BAL specimens, and a modified Giemsa stain was also performed on a 0.4-mL aliquot of the aggregate specimen. Of 25 patients, Pneumocystis carinii organisms were identified in 9 with HIV infection, in whom all BAL specimens were positive with both immunofluorescence and Giemsa stains. In 16 patients, BAL specimens were negative for P carinii on both immunofluorescent and modified Giemsa testing. Both staining methods were 100% specific (95% confidence interval [CI], 83 to 100%) and 100% sensitive (95% CI, 72 to 100%). The volume of BAL effluent in the initial specimens positive for P carinii ranged from 15 to 25 mL. We conclude that in this small group of patients, PCP was accurately diagnosed from a single 60-mL BAL specimen stained with immunofluorescence methods.

Rapid simple and nested polymerase chain reaction for the diagnosis of Pneumocystis carinii pneumonia

We have developed a rapid and easy extraction procedure for polymerase chain reaction (PCR) protocols. Using this simplified step, we evaluated the sensitivity and the specificity of a simple PCR using the primers of Wakefield et al, and of a nested PCR, using new internal primers selected by us, in a total of 89 bronochoalveolar lavage (BAL) fluid samples from 43 immunosuppressed patients. In 13 patients, Pneumocystis carinii pneumonia (PCP) was diagnosed by immunofluorescent antibody (IFA) staining performed on BAL cells cytospun on microscope slides. In seven of these patients we attempted to estimate the post-treatment persistence of P. carinii in BAL, by PCR. After a rapid 2-h extraction procedure, simple and nested PCR were positive in all cases of PCP. SImple and nested PCR both had a 100% sensitivity and a 98 and 84% specificity respectively, compared to IFA. After completion of treatment, BAL liquids from asymptomatic patients were no longer positive by both PCR techniques, whereas the BAL fluid of a patient who was still symptomatic was positive by simple and nested PCR. In follow-up BAL fluids of patients with proven PCP, persistence of P. carinii was detected for a longer period by nested PCR than by simple PCR. Simple PCR is a very rapid and sensitive assay for the diagnosis of PCP in BAL fluid and gives clear-cut results in the case of doubtful IFA staining results. Nested PCR seems to improve the sensitivity of the detection of P. carinii in BAL fluid, but the clinical relevance of a positive result remains to be investigated..

The role of two-segment bronchoalveolar lavage in the diagnosis of pulmonary infections

STUDY OBJECTIVE

To determine if performing bronchoalveolar lavage (BAL) from more than one lung segment augments the diagnostic yield in patients with pulmonary infection.

PATIENTS AND STUDY DESIGN

Seventy-six patients who underwent bisegmental BAL for the diagnosis or exclusion of pulmonary infection were studied prospectively.

MAIN RESULTS

In patients with AIDS, the concentration of Pneumocystis carinii was higher in the upper lobes than in the middle lobes, regardless of whether the patients had been receiving pentamidine prophylaxis. In patients without HIV infection, the number of P carinii clusters was much lower. In 2 of 5 HIV-negative patients, P carinii organisms were detectable but in one of two lavage specimens, whereas in only 1 of 19 AIDS patients, P carinii organisms were not found in both lavaged segments. In bacterial pneumonia, BAL fluid from a segment of the radiologically most involved area had a much higher cell concentration, percentage of neutrophils, and concentration of bacteria than from the segment that was not or less severely involved on chest radiograph. In two of nine patients with AIDS and cytomegalovirus (CMV) pneumonia, cytopathogenic CMV effects were not found in both lavaged segments. In one of eight patients, mycobacteria could be cultured only from one of two radiologically involved segments.

CONCLUSION

An increase in the diagnostic sensitivity by performing BAL in two lung segments is limited to cases where P carinii pneumonia is a relevant consideration in immunocompromised patients without HIV infection. In bacterial pneumonia, BAL can be performed in a single radiographically involved lung segment without a loss in diagnostic sensitivity. Since our study population of patients with CMV pneumonitis, mycobacterial infections, and fungal infections was small, no reliable conclusions are possible and BAL of more than one lung segment seems justified until more information is available.

Upper and middle lobe bronchoalveolar lavage to diagnose Pneumocystis carinii pneumonia

Pneumocystis carinii pneumonia (PCP) remains the most common lethal opportunistic pulmonary infection in patients infected with the human immunodeficiency virus (HIV). Although the use of prophylactic inhaled pentamidine has effectively reduced the frequency of primary and recurrent episodes of PCP, the aerosolization of pentamidine may have altered the localization of active PCP, resulting in more upper lobe disease. The distribution of disease may have also affected the diagnostic accuracy of standard bronchoalveolar lavage of the middle lobe, with a reduction in sensitivity from about 90 to 65%. In retrospective surveys of patients from our institution, Steiger and Fahy found that pooled multiple-lobe radiographic site-directed bronchoalveolar lavage resulted in diagnostic sensitivities of 91 and 100%, respectively. We performed a follow-up prospective study of 38 consecutive patients on aerosolized pentamidine in whom we lavaged both the middle lobe and an upper lobe. We found that bilobar lavage including routine lavage of an upper lobe increases the diagnostic sensitivity of bronchoalveolar lavage alone to 95% compared with 65% if lavage is performed only in the middle lobe (p < 0.05). Radiographic studies demonstrate a concordant increase in exclusive or predominant upper lobe disease in patients on aerosolized pentamidine, but our results indicate that PCP is recovered more frequently from the upper lobe regardless of the radiographic appearance. We conclude that all patients on prophylactic inhaled pentamidine should undergo bilobar lavage with the inclusion of an upper lobe in the initial evaluation of possible PCP. The diagnostic sensitivity of 95% makes bilobar bronchoalveolar lavage an acceptable sole initial diagnostic modality without the need for initial transbronchial lung biopsy.