PCR diagnosis of Pneumocystis pneumonia: a bivariate meta-analysis

Infectious complications after hematopoietic stem cell transplantation: current status and future perspectives in Korea

Hematopoietic stem cell transplantation (HSCT) is a treatment for hematologic malignancies, immune deficiencies, or genetic diseases, ect. Recently, the number of HSCTs performed in Korea has increased and the outcomes have improved. However, infectious complications account for most of the morbidity and mortality after HSCT. Post-HSCT infectious complications are usually classified according to the time after HSCT: pre-engraftment, immediate post-engraftment, and late post-engraftment period. In addition, the types and risk factors of infectious complications differ according to the stem cell source, donor type, conditioning intensity, region, prophylaxis strategy, and comorbidities, such as graft-versushost disease and invasive fungal infection. In this review, we summarize infectious complications after HSCT, focusing on the Korean perspectives.

Acute Respiratory Failure Before ICU Admission: A Practical Approach

Acute respiratory failure (ARF) is a common and life-threatening event in cancer patients. It is the leading cause of admission to ICU among the patients with hematologic and solid malignancies and is often associated with poor outcome. Timely identification of the cause of ARF and the initiation of the appropriate therapy may improve the survival. Pulmonary infections represent the leading cause of ARF in those patients, and unless proven otherwise, ARF must be considered as an infectious emergency. Noninfectious causes of ARF include cardiogenic and noncardiogenic pulmonary edema, acute pulmonary embolism, and complications related both to the underlying malignancy and the toxic effects of chemotherapy.

This chapter reviews the most common causes of ARF in oncologic patients and discusses the diagnostic and therapeutic approach before ICU admission.

Treatment of Pneumocystis jirovecii pneumonia in HIV-infected patients: a review

INTRODUCTION

Pneumocystis pneumonia is a potentially life-threatening pulmonary infection that occurs in immunocompromised individuals and HIV-infected patients with a low CD4 cell count. Trimethoprim-sulfamethoxazole has been used as the first-line agent for treatment, but mutations within dihydropteroate synthase gene render potential resistance to sulfamide. Despite advances of combination antiretroviral therapy (cART), Pneumocystis pneumonia continues to occur in HIV-infected patients with late presentation for cART or virological and immunological failure after receiving cART. Areas covered: This review summarizes the diagnosis and first-line and alternative treatment and prophylaxis for Pneumocystis pneumonia in HIV-infected patients. Articles for this review were identified through searching PubMed. Search terms included: 'Pneumocystis pneumonia', 'Pneumocystis jirovecii pneumonia', 'Pneumocystis carinii pneumonia', 'trimethoprim-sulfamethoxazole', 'primaquine', 'trimetrexate', 'dapsone', 'pentamidine', 'atovaquone', 'echinocandins', 'human immunodeficiency virus infection', 'acquired immunodeficiency syndrome', 'resistance to sulfamide' and combinations of these terms. We limited the search to English language papers that were published between 1981 and March 2017. We screened all identified articles and cross-referenced studies from retrieved articles. Expert commentary: Trimethoprim-sulfamethoxazole will continue to be the first-line agent for Pneumocystis pneumonia given its cost, availability of both oral and parenteral formulations, and effectiveness or efficacy in both treatment and prophylaxis. Whether resistance due to mutations within dihydropteroate synthase gene compromises treatment effectiveness remains controversial. Continued search for effective alternatives with better safety profiles for Pneumocystis pneumonia is warranted.

Pulmonary co-infections by Pneumocystis jirovecii and Aspergillus fumigatus in non-HIV patients: A report of two cases and literature review

Pneumocystis jirovecii is the causative agent of Pneumocystis pneumonia (PcP), a common and often life-threatening opportunistic infection in HIV-infected patients. However, non-HIV, immunocompromised patients are at risk of PcP as well, whereas the mortality appears to be higher among these patients. Pneumocystis co-infections with other microorganisms are less frequent and only sparse reports of combined PcP and invasive pulmonary fungal infections exist in the literature, especially in the non-HIV patients. Two cases of pulmonary co-infections by P. jirovecii and Aspergillus fumigatus are presented. Both patients were non-HIV infected, the first one was suffering from crescentic IgA nephropathy under immunosuppressive treatment and the second from resistant non-Hodgkin lymphoma under chemotherapy. Both patients were treated with intravenous trimethoprim/sulphamethoxazole (TMP/SMX) combined with voriconazole. The first patient showed gradual clinical improvement while the outcome for the second patient was unfavourable. In addition, a literature review of the previous published cases of co-infection by P. jirovecii and other fungi in non-HIV patients was performed. Our target was to provide comprehensive information on this kind of infections, highlighting the importance of clinical suspicion.

Infection in Organ Transplantation

The prevention, diagnosis, and management of infectious disease in transplantation are major contributors to improved outcomes in organ transplantation. The risk of serious infections in organ recipients is determined by interactions between the patient's epidemiological exposures and net state of immune suppression. In organ recipients, there is a significant incidence of drug toxicity and a propensity for drug interactions with immunosuppressive agents used to maintain graft function. Thus, every effort must be made to establish specific microbiologic diagnoses to optimize therapy. A timeline can be created to develop a differential diagnosis of infection in transplantation based on common patterns of infectious exposures, immunosuppressive management, and antimicrobial prophylaxis. Application of quantitative molecular microbial assays and advanced antimicrobial therapies have advanced care. Pathogen-specific immunity, genetic polymorphisms in immune responses, and dynamic interactions between the microbiome and the risk of infection are beginning to be explored. The role of infection in the stimulation of alloimmune responses awaits further definition. Major hurdles include the shifting worldwide epidemiology of infections, increasing antimicrobial resistance, suboptimal assays for the microbiologic screening of organ donors, and virus-associated malignancies. Transplant infectious disease remains a key to the clinical and scientific investigation of organ transplantation.

Diagnosis and management of Pneumocystis jirovecii infection

INTRODUCTION

Pneumocystis jirovecii is a ubiquitous fungus, which causes pneumonia in humans. Diagnosis was hampered by the inability to culture the organism, and based on microscopic examination of respiratory samples or clinical presentation. New assays can assist in the diagnosis and even aid with the emergence of resistant infections. Areas covered: This manuscript will provide background information on Pneumocystis pneumonia (PcP). Diagnosis, from radiological to non-microbiological (e.g. Lactate dehydrogenase) and microbiological investigations (Microscopy, PCR, β-D-Glucan) will be discussed. Recommendations on prophylactic and therapeutic management will be covered. Expert commentary: PcP diagnosis using microscopy is far from optimal and false negatives will occur. With an incidence of 1% or less, the pre-test probability of not having PcP is 99% and testing is suited to excluding disease. Microscopy provides a high degree of diagnostic confidence but it is not infallible, and its lower sensitivity limits its application. Newer diagnostics (PCR, β-D-Glucan) can aid management and improve performance when testing less invasive specimens, such as upper respiratory samples or blood, alleviating clinical pressure. Combination testing may allow PcP to be both diagnosed and excluded, and molecular testing can assist in the detection of emerging resistant PcP.

Efficiency of interleukin 6 and interferon gamma in the differentiation of invasive pulmonary aspergillosis and pneumocystis pneumonia in pediatric oncology patients

OBJECTIVE

Invasive pulmonary aspergillosis (IPA) and Pneumocystis pneumonia (PCP) are two types of pulmonary fungal infection that are not easy to differentiate. The purpose of this study was to investigate the role of inflammatory cytokines in the differential diagnosis of IPA and PCP.

METHODS

A total of 227 pediatric oncology patients diagnosed with acute pneumonia were enrolled. They were divided into three groups: IPA, PCP, and 'others'. The cytokine levels in these groups were compared, including interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-10, IL-6, IL-4, and IL-2.

RESULTS

Of the six cytokines, only IL-6 and IFN-γ levels were elevated in patients with acute pneumonia. IL-6 was comparable between patients with IPA and PCP (52.0 pg/ml vs. 25.8 pg/ml, p=0.092), while IFN-γ was much higher in patients with PCP (19.9 pg/ml vs. 8.9 pg/ml, p=0.001). The accuracy of IL-6 and the ratio of IL-6/IFN-γ in predicting IPA were 69.0% and 72.0%, respectively, while the accuracy of IFN-γ to predict PCP was 67.2%. IL-6 >140 pg/ml and IL-6/IFN-γ >9.0 presented specificities of 90% in predicting IPA, while IFN-γ >40 pg/ml presented specificity of 90% in predicting PCP.

CONCLUSIONS

IL-6 is predominantly elevated in IPA, while IFN-γ is significantly increased in PCP. These are helpful tools for the differential diagnosis of IPA and PCP.

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.

Pneumocystis jirovecii pneumonia in a patient with pustular psoriasis with an IL-36RN deficiency treated with infliximab: Case report and review of the literature

Pneumocystis jirovecii pneumonia (PCP) is a relatively rare complication in non-HIV patients receiving immunosuppressive treatment. Since the introduction of tumour necrosis factor-α inhibitors cases of this complication have increased. We report the case of a 54-year-old, HIV-negative patient, who presented to our department with a long history of pustular psoriasis with poor response to traditional treatments. During the last admission he developed a severe flare that was unresponsive to cyclosporine, therefore infliximab was initiated. After the third dose he developed PCP that required admission to the intensive care unit, with a positive response to i.v. administration of trimethoprim/sulfamethoxazole. During follow up a mutation in the IL36RN gene compatible with an IL-36RN deficiency was found and anakinra was started, with rapid improvement of his psoriasis. PCP is a severe complication in patients receiving immunosuppressive therapy and is probably underreported by dermatologists. There are no clinical guidelines for PCP prophylaxis in dermatological patients who will receive immunosuppressive or biological treatments. We believe that it is necessary to report the cases of PCP to assess the real impact of this complication and develop appropriate prophylaxis guidelines.

Pneumocystis pneumonia suspected cases in 604 non-HIV and HIV patients

BACKGROUND

Pneumocystis pneumonia (PCP) is one of the most devastating fungal diseases in patients with impaired immunity. Effective antiviral therapies have reduced the burden of PCP among AIDS patients, but an increase in the prevalence of this disease among persons receiving immunosuppressive therapies has been reported.

METHODS

We retrospectively reviewed HIV and non-HIV PCP patients diagnosed in our department during a nine year period. Data were collected from the local database completed during the diagnosis procedure. For each patient, demographic, clinical, radiological, biological and therapeutic data were analyzed.

RESULTS

A total of 21,274 bronchoalveolar samples were received from patients suspected of pneumocystosis during the study period, leading to a discharge diagnosis of PCP for 604 patients (143 HIV-positive and 461 HIV-negative). The ratio of non-HIV versus HIV patients presenting PCP increased from 1.7 to 5.6 during the study period. The mortality rate at day 14 was 16%, occurring mostly in non-HIV patients (20.6% compared to 1.4%, P<0.0001), while non-HIV patients were less symptomatic at diagnosis than AIDS patients.

CONCLUSIONS

This study presents one of the higher number of HIV and non-HIV patients presenting with PCP in a single center. Pneumocystosis is now a crucial health challenge for patients receiving immunosuppressive therapy, with a high mortality rate. This study highlights the need for international guidelines for prophylaxis of PCP in non-HIV patients.

How to manage lung infiltrates in adults suffering from haematological malignancies outside allogeneic haematopoietic stem cell transplantation

Pulmonary complications affect up to 40% of patients with severe neutropenia lasting for more than 10 d. As they are frequently associated with fever and elevation of C‐reactive protein or other signs of inflammation, they are mostly handled as pneumonia. However, the differential diagnosis is broad, and a causative microbial agent remains undetected in the majority of cases. Pulmonary side effects from cytotoxic treatment or pulmonary involvement by the underlying malignancy must always be taken into account and may provide grounds for invasive diagnostic procedures in selected patients. Pneumocystis jirovecii (in patients not receiving co‐trimoxazole as prophylaxis), multi‐resistant gram‐negative bacilli, mycobacteria or respiratory viruses may be involved. High‐risk patients may be infected by filamentous fungi, such as Aspergillus spp., but these infections are seldom proven when treatment is initiated. Microorganisms isolated from cultures of blood, bronchoalveolar lavage or respiratory secretions need careful interpretation as they may be irrelevant for determining the aetiology of pulmonary infiltrates, particularly when cultures yield coagulase‐negative staphylococci, enterococci or Candida species. Non‐culture based diagnostics for detecting Aspergillus galactomannan, beta‐D‐glucan or DNA from blood, bronchoalveolar lavage or tissue samples can facilitate the diagnosis, but must always be interpreted in the context of clinical and imaging findings. Systemic antifungal treatment with mould‐active agents, given in combination with broad‐spectrum antibiotics, improves clinical outcome when given pre‐emptively. Co‐trimoxazole remains the first‐line treatment for Pneumocystis pneumonia, while cytomegalovirus pneumonia will respond to ganciclovir or foscarnet in most cases. The clinical outcome of acute respiratory failure can also be successful with proper intensive care, when indicated.

Development and validation of a Pneumocystis jirovecii real-time polymerase chain reaction assay for diagnosis of Pneumocystis pneumonia

BACKGROUND

Pneumocystis jirovecii (PJ), a pathogenic fungus, causes severe interstitial Pneumocystis pneumonia (PCP) among immunocompromised patients. A laboratory-developed real-time polyermase chain reaction (PCR) assay was validated for PJ detection to improve diagnosis of PCP.

METHODS

Forty stored bronchoalveolar lavage (BAL) samples (20 known PJ positive [PJ+] and 20 known PJ negative [PJ-]) were initially tested using the molecular assay. Ninety-two sequentially collected BAL samples were then analyzed using an immunofluorescence assay (IFA) and secondarily tested using the PJ real-time PCR assay. Discrepant results were resolved by retesting BAL samples using another real-time PCR assay with a different target. PJ real-time PCR assay performance was compared with the existing gold standard (ie, IFA) and a modified gold standard, in which a true positive was defined as a sample that tested positive in two of three methods in a patient suspected to have PCP.

RESULTS

Ninety of 132 (68%) BAL fluid samples were collected from immunocompromised patients. Thirteen of 92 (14%) BALs collected were PJ+ when tested using IFA. A total of 40 BAL samples were PJ+ in the present study including: all IFA positive samples (n=13); all referred PJ+ BAL samples (n=20); and seven additional BAL samples that were IFA negative, but positive using the modified gold standard. Compared with IFA, the PJ real-time PCR had sensitivity, specificity, and positive and negative predictive values of 100%, 91%, 65% and 100%, respectively. Compared with the modified gold standard, PJ real-time PCR had a sensitivity, specificity, and positive and negative predictive values of 100%.

CONCLUSION

PJ real-time PCR improved detection of PJ in immunocompromised patients.

Consensus guidelines for diagnosis, prophylaxis and management of Pneumocystis jirovecii pneumonia in patients with haematological and solid malignancies, 2014

Pneumocystis jirovecii infection (PJP) is a common cause of pneumonia in patients with cancer-related immunosuppression. There are well-defined patients who are at risk of PJP due to the status of their underlying malignancy, treatment-related immunosuppression and/or concomitant use of corticosteroids. Prophylaxis is highly effective and should be given to all patients at moderate to high risk of PJP. Trimethoprim-sulfamethoxazole is the drug of choice for prophylaxis and treatment, although several alternative agents are available.

Pneumocystis Pneumonia in Human Immunodeficiency Virus-infected Adults and Adolescents: Current Concepts and Future Directions

Pneumocystis jirovecii pneumonia (PCP) is one of the most common opportunistic infections in human immunodeficiency virus–infected adults. Colonization of Pneumocystis is highly prevalent among the general population and could be associated with the transmission and development of PCP in immunocompromised individuals. Although the microscopic demonstration of the organisms in respiratory specimens is still the golden standard of its diagnosis, polymerase chain reaction has been shown to have a high sensitivity, detecting Pneumocystis DNA in induced sputum or oropharyngeal wash. Serum β-D-glucan is useful as an adjunctive tool for the diagnosis of PCP. High-resolution computed tomography, which typically shows diffuse ground-glass opacities, is informative for the evaluation of immunocompromised patients with suspected PCP and normal chest radiography. Trimethoprim–sulfamethoxazole (TMP-SMX) is the first-line agent for the treatment of mild to severe PCP, although it is often complicated with various side effects. Since TMP-SMX is widely used for the prophylaxis, the putative drug resistance is an emerging concern.

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.

Molecular and nonmolecular diagnostic methods for invasive fungal infections

Invasive fungal infections constitute a serious threat to an ever-growing population of immunocompromised individuals and other individuals at risk. Traditional diagnostic methods, such as histopathology and culture, which are still considered the gold standards, have low sensitivity, which underscores the need for the development of new means of detecting fungal infectious agents. Indeed, novel serologic and molecular techniques have been developed and are currently under clinical evaluation. Tests like the galactomannan antigen test for aspergillosis and the β-glucan test for invasive Candida spp. and molds, as well as other antigen and antibody tests, for Cryptococcus spp., Pneumocystis spp., and dimorphic fungi, have already been established as important diagnostic approaches and are implemented in routine clinical practice. On the other hand, PCR and other molecular approaches, such as matrix-assisted laser desorption ionization (MALDI) and fluorescence in situ hybridization (FISH), have proved promising in clinical trials but still need to undergo standardization before their clinical use can become widespread. The purpose of this review is to highlight the different diagnostic approaches that are currently utilized or under development for invasive fungal infections and to identify their performance characteristics and the challenges associated with their use.

Diagnosis and antimicrobial therapy of lung infiltrates in febrile neutropenic patients (allogeneic SCT excluded): updated guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO)

Up to 25% of patients with profound neutropenia lasting for >10 days develop lung infiltrates, which frequently do not respond to broad-spectrum antibacterial therapy. While a causative pathogen remains undetected in the majority of cases, Aspergillus spp., Pneumocystis jirovecii, multi-resistant Gram-negative pathogens, mycobacteria or respiratory viruses may be involved. In at-risk patients who have received trimethoprim-sulfamethoxazole (TMP/SMX) prophylaxis, filamentous fungal pathogens appear to be predominant, yet commonly not proven at the time of treatment initiation. Pathogens isolated from blood cultures, bronchoalveolar lavage (BAL) or respiratory secretions are not always relevant for the etiology of pulmonary infiltrates and should therefore be interpreted critically. Laboratory tests for detecting Aspergillus galactomannan, β-D-glucan or DNA from blood, BAL or tissue samples may facilitate the diagnosis; however, most polymerase chain reaction assays are not yet standardized and validated. Apart from infectious agents, pulmonary side-effects from cytotoxic drugs, radiotherapy or pulmonary involvement by the underlying malignancy should be included into differential diagnosis and eventually be clarified by invasive diagnostic procedures. Pre-emptive treatment with mold-active systemic antifungal agents improves clinical outcome, while other microorganisms are preferably treated only when microbiologically documented. High-dose TMP/SMX is first choice for treatment of Pneumocystis pneumonia, while cytomegalovirus pneumonia is treated primarily with ganciclovir or foscarnet in most patients. In a considerable number of patients, clinical outcome may be favorable despite respiratory failure, so that intensive care should be unrestrictedly provided in patients whose prognosis is not desperate due to other reasons.

Systematic reviews and meta-analyses of diagnostic test accuracy

Systematic reviews of diagnostic test accuracy summarize the accuracy, e.g. the sensitivity and specificity, of diagnostic tests in a systematic and transparent way. The aim of such a review is to investigate whether a test is sufficiently specific or sensitive to fit its role in practice, to compare the accuracy of two or more diagnostic tests, or to investigate where existing variation in results comes from. The search strategy should be broad and preferably fully reported, to enable readers to assess the completeness of it. Included studies usually have a cross-sectional design in which the tests of interest, ideally both the index test and its comparator, are evaluated against the reference standard. They should be a reflection of the situation that the review question refers to. The quality of included studies is assessed with the Quality Assessment of Diagnostic Accuracy Studies-2 checklist, containing items such as a consecutive and all-inclusive patient selection process, blinding of index test and reference standard assessment, a valid reference standard, and complete verification of all included participants. Studies recruiting cases separately from (healthy) controls are regarded as bearing a high risk of bias. For meta-analysis, the bivariate model or the hierarchical summary receiver operating characteristic model is used. These models take into account potential threshold effects and the correlation between sensitivity and specificity. They also allow addition of covariates for investigatation of potential sources of heterogeneity. Finally, the results from the meta-analyses should be explained and interpreted for the reader, to be well understood.

Evaluation of PCR in bronchoalveolar lavage fluid for diagnosis of Pneumocystis jirovecii pneumonia: a bivariate meta-analysis and systematic review

BACKGROUND

As a promising tool, PCR in bronchoalveolar lavage fluid (BALF) has not been accepted as a diagnostic criterion for PJP.

OBJECTIVE

We undertook a systematic review of published studies to evaluate the diagnostic accuracy of PCR assays in BALF for PJP.

METHODS

Eligible studies from PubMed, Embase and Web of Science reporting PCR assays in BALF for diagnosing PJP were identified. A bivariate meta-analysis of the method's sensitivity, specificity, and positive and negative likelihood ratios with a 95% confidence interval (CI) were analyzed. The post-test probability was performed to evaluate clinical usefulness. A summary receiver operating characteristics (SROC) curve was used to evaluate overall performance. Subgroup analyses were carried out to analysis the potential heterogeneity.

RESULTS

Sixteen studies published between 1994 and 2012 were included. The summary sensitivity and specificity values (95% CI) of PCR in BALF for diagnosis of PJP were 98.3% (91.3%-99.7%) and 91.0% (82.7%-95.5%), respectively. The positive and negative likelihood ratios were 10.894 (5.569-21.309) and 0.018 (0.003-0.099), respectively. In a setting of 20% prevalence of PJP, the probability of PJP would be over 3-fold if the BALF-PCR test was positive, and the probability of PJP would be less than 0.5% if it was negative. The area under the SROC curve was 0.98 (0.97-0.99).

CONCLUSIONS

The method of PCR in BALF shows high sensitivity and good specificity for the diagnosis of PJP. However, clinical practice for the diagnosis of PJP should consider the consistent respiratory symptoms, radiographic changes and laboratory findings of the suspected patients.

Pneumocystis jirovecii (Pj) quantitative PCR to differentiate Pj pneumonia from Pj colonization in immunocompromised patients

Conventional polymerase chain reaction (PCR) in respiratory samples does not differentiate between Pneumocystis pneumonia (PCP) and Pneumocystis jirovecii (Pj) colonization. We used Pj real-time quantitative PCR (qPCR) with the objective to discriminate PCP from Pj colonization in immunocompromised patients. All positive Pj qPCR [targeting the major surface glycoprotein (MSG) gene] obtained in respiratory samples from immunocompromised patients presenting pneumonia at the Grenoble University Hospital, France, were collected between August 2009 and April 2011. Diagnoses were retrospectively determined by a multidisciplinary group of experts blinded to the Pj qPCR results. Thirty-one bronchoalveolar lavages and four broncho aspirations positive for the Pj qPCR were obtained from 35 immunocompromised patients. Diagnoses of definite, probable, and possible PCP, and pneumonia from another etiology were retrospectively made for 7, 4, 5, and 19 patients, respectively. Copy numbers were significantly higher in the “definite group” (median 465,000 copies/ml) than in the “probable group” (median 38,600 copies/ml), the “possible group” (median 1,032 copies/ml), and the “other diagnosis group” (median 390 copies/ml). With the value of 3,160 copies/ml, the sensitivity and specificity of qPCR for the diagnosis of PCP were 100 % and 70 %, respectively. With the value of 31,600 copies/ml, the sensitivity and specificity were 80 % and 100 %, respectively. The positive predictive value was 100 % for results with more than 31,600 copies/ml and the negative predictive value was 100 % for results with fewer than 3,160 copies/ml. qPCR targeting the MSG gene can be helpful to discriminate PCP from Pj colonization in immunocompromised patients, using two cut-off values, with a gray zone between them.

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.

Recent advances in the diagnosis of Pneumocystis jirovecii pneumonia in HIV-infected adults

INTRODUCTION

Pneumocystis jirovecii pneumonia (PCP) is one of the most common opportunistic infections in HIV-infected adults. Although the microscopic demonstration of the organisms in respiratory specimens is still the golden standard of its diagnosis, recent advances in the diagnostic tools have been changing the situation.

AREAS COVERED

Colonization of Pneumocystis is highly prevalent among the general population and could be associated with the transmission and development of PCP in immunocompromised individuals. Nested or conventional polymerase chain reaction (PCR) has a high sensitivity, detecting Pneumocystis DNA in induced sputum or oropharyngeal wash, but often produces false positives. Although quantitative real-time PCR is promising for discriminating colonization from PCP, the targeted DNA sequences and the cut-off values remain to be standardized. Serum β-D-glucan is useful as an adjunctive tool for the diagnosis of PCP. High-resolution computed tomography, which typically shows diffuse ground-glass opacities, is informative for evaluation of immunocompromised patients with suspected PCP and normal chest radiography.

EXPERT OPINION

Although these new tools have been making the diagnosis of PCP less invasive and more accurate, any one of them can not make a definitive diagnosis by itself. The diagnostic criteria based on the combination of the testing ought to be established.

Prospective multicenter study of Pneumocystis jirovecii colonization among cystic fibrosis patients in France

Pneumocystis carriage was detected in 12.5% of 104 cystic fibrosis (CF) patients during a prospective multicenter French study, with a prevalence of genotype 85C/248C and geographic variations. It was significantly associated with the absence of Pseudomonas aeruginosa colonization and a greater forced expiratory volume in 1 s. Results are discussed considering the natural history of CF.

Clinical significance of quantifying Pneumocystis jirovecii DNA by using real-time PCR in bronchoalveolar lavage fluid from immunocompromised patients

Quantitative PCR (qPCR) is more sensitive than microscopy for detecting Pneumocystis jirovecii in bronchoalveolar lavage (BAL) fluid. We therefore developed a qPCR assay and compared the results with those of a routine immunofluorescence assay (IFA) and clinical data. The assay included automated DNA extraction, amplification of the mitochondrial large-subunit rRNA gene and an internal control, and quantification of copy numbers with the help of a plasmid clone. We studied 353 consecutive BAL fluids obtained for investigation of unexplained fever and/or pneumonia in 287 immunocompromised patients. No qPCR inhibition was observed. Seventeen (5%) samples were both IFA and qPCR positive, 63 (18%) were IFA negative and qPCR positive, and 273 (77%) were both IFA and qPCR negative. The copy number was significantly higher for IFA-positive/qPCR-positive samples than for IFA-negative/qPCR-positive samples (4.2 ± 1.2 versus 1.1 ± 1.1 log(10) copies/μl; P < 10(-4)). With IFA as the standard, the qPCR assay sensitivity was 100% for ≥2.6 log(10) copies/μl and the specificity was 100% for ≥4 log(10) copies/μl. Since qPCR results were not available at the time of decision-making, these findings did not trigger cotrimoxazole therapy. Patients with systemic inflammatory diseases and IFA-negative/qPCR-positive BAL fluid had a worse 1-year survival rate than those with IFA-negative/qPCR-negative results (P < 10(-3)), in contrast with solid-organ transplant recipients (P = 0.88) and patients with hematological malignancy (P = 0.26). Quantifying P. jirovecii DNA in BAL fluids independently of IFA positivity should be incorporated into the investigation of pneumonia in immunocompromised patients. The relevant threshold remains to be determined and may vary according to the underlying disease.