Pneumocystis jirovecii--from a commensal to pathogen: clinical and diagnostic review

Consensus Multilocus Sequence Typing Scheme for Pneumocystis jirovecii

Pneumocystis jirovecii is an opportunistic human pathogenic fungus causing severe pneumonia mainly in immunocompromised hosts. Multilocus sequence typing (MLST) remains the gold standard for genotyping of this unculturable fungus. However, the lack of a consensus scheme impedes a global comparison, large scale population studies and the development of a global MLST database. To overcome this problem this study compared all genetic regions (19 loci) currently used in 31 different published Pneumocystis MLST schemes. The most diverse/commonly used eight loci, β-TUB, CYB, DHPS, ITS1, ITS1/2, mt26S and SOD, were further assess for their ability to be successfully amplified and sequenced, and for their discriminatory power. The most successful loci were tested to identify genetically related and unrelated cases. A new consensus MLST scheme consisting of four genetically independent loci: β-TUB, CYB, mt26S and SOD, is herein proposed for standardised P. jirovecii typing, successfully amplifying low and high fungal burden specimens, showing adequate discriminatory power, and correctly identifying suspected related and unrelated isolates. The new consensus MLST scheme, if accepted, will for the first time provide a powerful tool to investigate outbreak settings and undertake global epidemiological studies shedding light on the spread of this important human fungal pathogen.

Innate Inspiration: Antifungal Peptides and Other Immunotherapeutics From the Host Immune Response

The purpose of this review is to describe antifungal therapeutic candidates in preclinical and clinical development derived from, or directly influenced by, the immune system, with a specific focus on antimicrobial peptides (AMP). Although the focus of this review is AMP with direct antimicrobial effects on fungi, we will also discuss compounds with direct antifungal activity, including monoclonal antibodies (mAb), as well as immunomodulatory molecules that can enhance the immune response to fungal infection, including immunomodulatory AMP, vaccines, checkpoint inhibitors, interferon and colony stimulating factors as well as immune cell therapies. The focus of this manuscript will be a non-exhaustive review of antifungal compounds in preclinical and clinical development that are based on the principles of immunology and the authors acknowledge the incredible amount of in vitro and in vivo work that has been conducted to develop such therapeutic candidates.

Epidemiology of Pneumocystis jirovecii Pneumonia and (Non-)use of Prophylaxis

Objectives:Pneumocystis jirovecii pneumonia (PCP) is an AIDS-defining illness. In patients with HIV, the benefit of PCP prophylaxis is well-defined when the CD4 T-cell count decreases below 200 cells/μL. In other immunocompromised patients, the value of PCP prophylaxis is not always as well-established. This study aimed to describe the epidemiology of PCP in recent years and assess how many patients with PCP did or did not receive prophylaxis in the month preceding the infection. Material and Methods: A multicenter retrospective study was performed in 3 tertiary care hospital. A list of patients that underwent broncho-alveolar lavage sampling and Pneumocystis jirovecii (PJ) PCR testing was retrieved from the microbiology laboratories. An in-house PJ quantitative PCR (qPCR) was used in each center. A cycle threshold (Ct) value of ≤ 28.5-30 was considered a probable PCP. For patients with a positive PJ qPCR but above this threshold, a predefined case definition of possible PCP was defined as a qPCR Ct value ≤ 34-35 and both of the following criteria: 1. Clinical and radiological features compatible with PCP and 2. The patient died or received PCP therapy and survived. Patient files from those with a qPCR Ct value ≤ 35 were reviewed to determine whether the patient fulfilled the case definition and if PCP prophylaxis had been used in the weeks preceding the PCP. Disease-specific guidelines, as well as hospital-wide guidelines, were used to evaluate if prophylaxis could be considered indicated. Results: From 2012 to 2018, 482 BAL samples were tested. Two hundred and four had a qPCR Ct value ≤ 35 and were further evaluated: 90 fulfilled the definition of probable and 63 of possible PCP while the remaining 51 were considered colonized. Seventy-four percentages of the patients with PCP were HIV-negative. Only 11 (7%) of the 153 patients had received prophylaxis, despite that in 133 (87%) cases prophylaxis was indicated according to guidelines. Conclusion: In regions where HIV testing and treatment is available without restrictions, PCP is mainly diagnosed in non-HIV immunocompromised patients. More than four out of five patients with PCP had not received prophylaxis. Strategies to improve awareness of antimicrobial prophylaxis guidelines in immunocompromised patients are urgently needed.

Diagnosis of Pneumocystis jirovecii Pneumonia in Pediatric Patients in Serbia, Greece, and Romania. Current Status and Challenges for Collaboration

Pneumocystis jirovecii can cause fatal Pneumocystis pneumonia (PcP). Many children have been exposed to the fungus and are colonized in early age, while some individuals at high risk for fungal infections may develop PcP, a disease that is difficult to diagnose. Insufficient laboratory availability, lack of knowledge, and local epidemiology gaps make the problem more serious. Traditionally, the diagnosis is based on microscopic visualization of Pneumocystis in respiratory specimens. The molecular diagnosis is important but not widely used. The aim of this study was to collect initial indicative data from Serbia, Greece, and Romania concerning pediatric patients with suspected PcP in order to: find the key underlying diseases, determine current clinical and laboratory practices, and try to propose an integrative future molecular perspective based on regional collaboration. Data were collected by the search of literature and the use of an online questionnaire, filled by relevant scientists specialized in the field. All three countries presented similar clinical practices in terms of PcP prophylaxis and clinical suspicion. In Serbia and Greece the hematology/oncology diseases are the main risks, while in Romania HIV infection is an additional risk. Molecular diagnosis is available only in Greece. PcP seems to be under-diagnosed and regional collaboration in the field of laboratory diagnosis with an emphasis on molecular approaches may help to cover the gaps and improve the practices.

The impact of cytomegalovirus infection on clinical severity and outcomes in kidney transplant recipients with Pneumocystis jirovecii pneumonia

Cytomegalovirus (CMV) infection is associated with Pneumocystis jirovecii pneumonia (PJP) in kidney transplant recipients (KTRs), but its impact on clinical severity and outcomes in KTRs with PJP is unknown. We reviewed 1994 medical records of KTRs from January 1997 to March 2019. PJP or CMV infection was diagnosed by polymerase chain reaction or culturing using blood or respiratory specimens. We divided patients into PJP and PJP+CMV groups, and evaluated the clinical severity and outcomes. Fifty two patients had PJP (2.6%) in the whole study cohort. Among patients with PJP, 38 (73.1%) had PJP alone and 14 (26.9%) had combined PJP and CMV co-infection. The PJP+CMV group showed worse laboratory findings (serum albumin and C-reactive protein, P = 0.010 for both) and higher requirement of continuous renal replacement therapy than the PJP group (P = 0.050). The pneumonia severity was worse in the PJP+CMV group than in the PJP group (P < 0.05), and CMV infection was a high risk factor of pneumonia severity (odds ratio 16.0; P = 0.002). The graft function was worse in the PJP+CMV group (P < 0.001), and the incidence of graft failure was higher in the PJP+CMV group than in the PJP group (85.7% vs 36.8%; P < 0.001). Mortality was double in the PJP+CMV group than in the PJP group, but not statistically significant (21.4% vs 10.5%; P = 0.370). Our results show that approximately one in four patients with PJP after kidney transplantation develops CMV with increased clinical severity and risk of graft failure. The possibility of increased clinical severity and worse clinical outcomes by CMV co-infection should be considered in KTRs with PJP.

C-type Lectins in Immunity to Lung Pathogens

The respiratory tract is tasked with responding to a constant and vast influx of foreign agents. It acts as an important first line of defense in the innate immune system and as such plays a crucial role in preventing the entry of invading pathogens. While physical barriers like the mucociliary escalator exert their effects through the clearance of these pathogens, diverse and dynamic cellular mechanisms exist for the activation of the innate immune response through the recognition of pathogen-associated molecular patterns (PAMPs). These PAMPs are recognized by pattern recognition receptors (PRRs) that are expressed on a number of myeloid cells such as dendritic cells, macrophages, and neutrophils found in the respiratory tract. C-type lectin receptors (CLRs) are PRRs that play a pivotal role in the innate immune response and its regulation to a variety of respiratory pathogens such as viruses, bacteria, and fungi. This chapter will describe the function of both activating and inhibiting myeloid CLRs in the recognition of a number of important respiratory pathogens as well as the signaling events initiated by these receptors.

Severe hypercalcemia preceding a diagnosis of Pneumocystis jirovecii pneumonia in a liver transplant recipient

Background

Incidence of the opportunistic infection Pneumocystis jirovecii pneumonia (PJP) in solid organ transplant patients ranges from 5 to 15% with a mortality of up to 38%.

Case presentation

We present a liver transplant recipient who developed hypoxemic respiratory failure related to PJP soon after treatment for allograft rejection. His presentation was preceded by severe hypercalcemia of 14.6 mg/dL and an ionized calcium of 1.7 mmol/L which remained elevated despite usual medical management and eventually required renal replacement therapy. As approximately 5% of PJP cases have granulomas, here we review the role of pulmonary macrophages and inflammatory cytokines in the pathophysiology of granuloma-mediated hypercalcemia. We also discuss the interpretation of our patient’s laboratory studies, response to medical therapy, and clinical risk factors which predisposed him to PJP.

Conclusions

It is important for clinicians to consider PJP as an etiology of granulomatous pneumonia and non-parathyroid hormone mediated hypercalcemia in chronically immunosuppressed organ transplant recipients for timely diagnosis and management.

Development of substituted pyrido[3,2-d]pyrimidines as potent and selective dihydrofolate reductase inhibitors for pneumocystis pneumonia infection

Pneumocystis pneumonia (PCP) caused by Pneumocystis jirovecii (pj) can lead to serious health consequences in patients with an immunocompromised system. Trimethoprim (TMP), used as first-line therapy in combination with sulfamethoxazole, is a selective but only moderately potent pj dihydrofolate reductase (pjDHFR) inhibitor, whereas non-clinical pjDHFR inhibitors, such as, piritrexim and trimetrexate are potent but non-selective pjDHFR inhibitors. To meet the clinical needs for a potent and selective pjDHFR inhibitor for PCP treatment, fourteen 6-substituted pyrido[3,2-d]pyrimidines were developed. Comparison of the amino acid residues in the active site of pjDHFR and human DHFR (hDHFR) revealed prominent amino acid differences which could be exploited to structurally design potent and selective pjDHFR inhibitors. Molecular modeling followed by enzyme assays of the compounds revealed 15 as the best compound of the series with an IC₅₀ of 80 nM and 28-fold selectivity for inhibiting pjDHFR over hDHFR. Compound 15 serves as the lead analog for further structural variations to afford more potent and selective pjDHFR inhibitors.

Pneumocystis jirovecii-related spontaneous pneumothorax, pneumomediastinum and subcutaneous emphysema in a liver transplant recipient: a case report

BACKGROUND

Pneumocystis pneumonia (PCP) is a common opportunistic infection caused by Pneumocystis jirovecii. Its incidence at 2 years or more after liver transplant (LT) is < 0.1%. PCP-related spontaneous pneumothorax and/or pneumomediastinum is rare in patients without the human immunodeficiency virus, with an incidence of 0.4-4%.

CASE PRESENTATION

A 65-year-old woman who had split-graft deceased-donor LT for primary biliary cirrhosis developed fever, dyspnea and dry coughing at 25 months after transplant. Her immunosuppressants included tacrolimus, mycophenolate mofetil, and prednisolone. PCP infection was confirmed by molecular detection of Pneumocystis jirovecii,in bronchoalveolar lavage. On day-10 trimethoprim-sulphamethoxazole, her chest X-ray showed subcutaneous emphysema bilaterally, right pneumothorax and pneumomediastinum. Computed tomography of the thorax confirmed the presence of right pneumothorax, pneumomediastinum and subcutaneous emphysema. She was managed with 7-day right-sided chest drain and a 21-day course of trimethoprim-sulphamethoxazole before discharge.

CONCLUSION

Longer period of PCP prophylaxis should be considered in patients who have a higher risk compared to general LT patients. High index of clinical suspicion, prompt diagnosis and treatment with ongoing patient reassessment to detect and exclude rare, potentially fatal but treatable complications are essential, especially when clinical deterioration has developed.

Chloroquine Analogues as Leads against Pneumocystis Lung Pathogens

The impact of Pneumocystis pneumonia (PcP) on morbidity and mortality remains substantial for immunocompromised individuals, including those afflicted by HIV infection, organ transplantation, cancer, autoimmune diseases, or subject to chemotherapy or corticosteroid-based therapies. Previous work from our group has shown that repurposing antimalarial compounds for PcP holds promise for treatment of this opportunistic infection. Following our previous discovery of chloroquine analogues with dual-stage antimalarial action both in vitro and in vivo, we now report the potent action of these compounds on Pneumocystis carinii in vitro Identification of chloroquine analogues as anti-PcP leads is an unprecedented finding.

Simultaneous bilateral pneumothorax in an immunocompromised HIV patient with Pneumocystis jirovecii pneumonia

Pneumocystis in humans is caused by a unicellular and eukaryotic organism called P. jirovecii. The overall incidence of P. jirovecii pneumonia (PCP) has decreased with the use of highly active antiretroviral therapy and the use of chemoprophylaxis with trimethroprim sulfametoxazole (TMP/SMX) in cases of immunosuppressed patients. However, approximately 85% of patients with advanced HIV infections continue to experience this disease with inadequate management. Pneumocystis infection can present with spontaneous pneumothorax in 2-6% of cases [8] which can be a potentially fatal complication. We report the case of a 32-year-old man presented with P. jirovecii pneumonia who developed cystic lesions and spontaneous bilateral pneumothorax in spite of TMP/SMX treatment. We consider it an interesting clinical case because few simultaneous bilateral pneumothorax cases have been described directly related to the PCP.

Molecular diagnosis of Pneumocystis pneumonia in dogs

Pneumocystis pneumonia (PCP) is a life-threatening fungal disease that can occur in dogs. The aim of this study was to provide a preliminary genetic characterisation of Pneumocystis carinii f.sp.'canis' (P. canis) in dogs and thereby develop a reliable molecular protocol to definitively diagnose canine PCP. We investigated P. canis in a variety of lung specimens from dogs with confirmed or strongly suspected PCP (Group 1, n = 16), dogs with non-PCP lower respiratory tract problems (Group 2, n = 65) and dogs not suspected of having PCP or other lower respiratory diseases (Group 3, n = 11). Presence of Pneumocystis DNA was determined by nested PCR of the large and small mitochondrial subunit rRNA loci and by a real-time quantitative polymerase chain reaction (qPCR) assay developed using a new set of primers. Molecular results were correlated with the presence of Pneumocystis morphotypes detected in cytological/histological preparations. Pneumocystis DNA was amplified from 13/16 PCP-suspected dogs (Group 1) and from 4/76 dogs of control Groups 2 and 3 (combined). The latter four dogs were thought to have been colonized by P. canis. Comparison of CT values in 'infected' versus 'colonized' dogs was consistent with this notion, with a distinct difference in molecular burden between groups (CT ≤ 26 versus CT range (26 <CT < 35), respectively). Phylogenetic analyses showed that P. canis is specifically 'canine' associated, being separated from other mammalian Pneumocystis species, thereby confirming the accuracy of qPCR amplicon for Pneumocystis in dogs. Using qPCR, Pneumocystis DNA can be detected in specimens from the respiratory tract and a CT value can be interpreted to distinguish infection versus colonization.

Targeting species specific amino acid residues: Design, synthesis and biological evaluation of 6-substituted pyrrolo[2,3-d]pyrimidines as dihydrofolate reductase inhibitors and potential anti-opportunistic infection agents

To combine the potency of trimetrexate (TMQ) or piritrexim (PTX) with the species selectivity of trimethoprim (TMP), target based design was carried out with the X-ray crystal structure of human dihydrofolate reductase (hDHFR) and the homology model of Pneumocystis jirovecii DHFR (pjDHFR). Using variation of amino acids such as Met33/Phe31 (in pjDHFR/hDHFR) that affect the binding of inhibitors due to their distinct positive or negative steric effect at the active binding site of the inhibitor, we designed a series of substituted-pyrrolo[2,3-d]pyrimidines. The best analogs displayed better potency (IC₅₀) than PTX and high selectivity for pjDHFR versus hDHFR, with 4 exhibiting a selectivity for pjDHFR of 24-fold.

Non-culture based assays for the detection of fungal pathogens

Traditional, culture based methods for the diagnosis of fungal infections are still considered as gold standard, but they are time consuming and low sensitive. Therefore, in order to overcome the limitations, many researchers have focused on the development of new immunological and molecular based rapid assays that could enable early diagnosis of infection and accurate identification of fungal pathogens causing superficial and invasive infection. In this brief review, we highlighted the advantages and disadvantages of conventional diagnostic methods and possibility of non-culture based assays in diagnosis of superficial fungal infections and presented the overview on currently available immunochromatographic assays as well as availability of biomarkers detection by immunodiagnostic procedures in prompt and accurate diagnosis of invasive fungal infections. In addition, we presented diagnostic efficiency of currently available molecular panels and researches in this area.

The lung microbiome in patients with pneumocystosis

Backround

Pneumocystis jirovecii pneumonia (PCP) is an opportunistic fungal infection that is associated with a high morbidity and mortality in immunocompromised individuals. In this study, we analysed the microbiome of the lower respiratory tract from critically ill intensive care unit patients with and without pneumocystosis.

Methods

Broncho-alveolar fluids from 65 intubated and mechanically ventilated intensive care unit patients (34 PCP+ and 31 PCP- patients) were collected. Sequence analysis of bacterial 16S rRNA gene V3/V4 regions was performed to study the composition of the respiratory microbiome using the Illumina MiSeq platform.

Results

Differences in the microbial composition detected between PCP+ and PCP- patients were not statistically significant on class, order, family and genus level. In addition, alpha and beta diversity metrics did not reveal significant differences between PCP+ and PCP- patients. The composition of the lung microbiota was highly variable between PCP+ patients and comparable in its variety with the microbiota composition of the heterogeneous collective of PCP- patients.

Conclusions

The lower respiratory tract microbiome in patients with pneumocystosis does not appear to be determined by a specific microbial composition or to be dominated by a single bacterial species.

Electronic supplementary material

The online version of this article (10.1186/s12890-017-0512-5) contains supplementary material, which is available to authorized users.

Managing the oncologic patient with suspected pneumonia in the intensive care unit

INTRODUCTION

Solid cancer patients are frequently admitted in intensive care units for critical events. Improving survival rates in this setting is considered an achievable goal today. Respiratory failure is the main reason for admission, representing a primary target for research.

AREAS COVERED

This review presents a diagnostic and therapeutic algorithm for pneumonia and other severe respiratory events in the solid cancer population. It aims to increase awareness of the risk factors and the different etiologies in this changing scenario in which neutropenia no longer seems to be a decisive factor in poor outcome. Bacterial pneumonia is the leading cause, but opportunistic diseases and non-infectious etiologies, especially unexpected adverse effects of radiation, biological drugs and monoclonal antibodies, are becoming increasingly frequent. Options for respiratory support and diagnostics are discussed and indications for antibiotics in the management of pneumonia are detailed. Expert commentary: Prompt initiation of critical care to facilitate optimal decision-making in the management of respiratory failure, early etiological assessment and appropriate antibiotic therapy are cornerstones in management of severe pneumonia in oncologic patients.

Changing epidemiology of Pneumocystis pneumonia, Northern Ireland, UK and implications for prevention, 1 July 2011-31 July 2012

PURPOSE

There is a lack of consensus about which non-human immunodeficiency virus (HIV) patient groups would benefit from prophylaxis. Here, we analysed an enhanced Pneumocystis jirovecii database to describe the epidemiology of Pneumocystis pneumonia (PCP) and P. jirovecii colonizations in Northern Ireland (NI) with a view to identifying risk groups who may benefit from prophylaxis.

METHODOLOGY

We prospectively collected information on demographics, clinical severity and clinical features for all hospital inpatients in NI aged ≥18 years with P. jirovecii confirmed in any respiratory tract sample. We defined P. jirovecii colonization or PCP according to clinical symptoms and radiological findings. We compared P. jirovecii colonization to PCP using exact logistic regression and presented the odds ratios (OR), 95 % confidence intervals (CI) and likelihood ratio test P-values.Results/Key findings. Overall, 36/49 (73 %) of P. jirovecii detections were categorized as PCP. A total of 28/36 (78 %) were in non-HIV patients, of which 18 (64 %) had cancer. The odds of PCP compared to P. jirovecii colonization were eight times higher in those with current exposure to chemotherapy (OR 8.73; 95 % CI 0.84, ∞), 16 times higher for those diagnosed with HIV (OR 16.2; 95 % CI 1.71, ∞) and 12 times higher for those ever exposed to another immunosuppressive drug (OR 12.1; 95 % CI 1.94, ∞).

CONCLUSION

The greatest burden of PCP is now in the non-HIV group, particularly cancer patients. We recommend increasing clinician awareness of PCP risk and strengthening prevention guidelines in non-HIV patients, and promoting the consideration of prophylaxis on a case-by-case basis.

Addressing Antiretroviral Therapy-Associated Drug-Drug Interactions in Patients Requiring Treatment for Opportunistic Infections in Low-Income and Resource-Limited Settings

An increasing number of human immunodeficiency virus (HIV)-infected patients are achieving virologic suppression on antiretroviral therapy (ART) limiting the use of primary and secondary antimicrobial prophylaxis. However, in low-income and resource-limited settings, half of those infected with HIV are unaware of their diagnosis, and fewer than 50% of patients on ART achieve virologic suppression. Management of comorbidities and opportunistic infections among patients on ART may lead to inevitable drug-drug interactions (DDIs) and even toxicities. Elderly patients, individuals with multiple comorbidities, those receiving complex ART, and patients living in low-income settings experience higher rates of DDIs. Management of these cytochrome P450-mediated, nonmediated, and drug transport system DDIs is critical in HIV-infected patients, particularly those in resource-limited settings with few options for ART. This article critically analyzes and provides recommendations to manage significant DDIs and drug toxicities in HIV-infected patients receiving ART.

Recognition and Clinical Presentation of Invasive Fungal Disease in Neonates and Children

Invasive fungal diseases (IFDs) are devastating opportunistic infections that result in significant morbidity and death in a broad range of pediatric patients, particularly those with a compromised immune system. Recognizing them can be difficult, because nonspecific clinical signs and symptoms or isolated fever are frequently the only presenting features. Therefore, a high index of clinical suspicion is necessary in patients at increased risk of IFD, which requires knowledge of the pediatric patient population at risk, additional predisposing factors within this population, and the clinical signs and symptoms of IFD. With this review, we aim to summarize current knowledge regarding the recognition and clinical presentation of IFD in neonates and children.

Fungal Pathogens in CF Airways: Leave or Treat?

Chronic airway infection plays an essential role in the progress of cystic fibrosis (CF) lung disease. In the past decades, mainly bacterial pathogens, such as Pseudomonas aeruginosa, have been the focus of researchers and clinicians. However, fungi are frequently detected in CF airways and there is an increasing body of evidence that fungal pathogens might play a role in CF lung disease. Several studies have shown an association of fungi, particularly Aspergillus fumigatus and Candida albicans, with the course of lung disease in CF patients. Mechanistically, in vitro and in vivo studies suggest that an impaired immune response to fungal pathogens in CF airways renders them more susceptible to fungi. However, it remains elusive whether fungi are actively involved in CF lung disease pathologies or whether they rather reflect a dysregulated airway colonization and act as microbial bystanders. A key issue for dissecting the role of fungi in CF lung disease is the distinction of dynamic fungal-host interaction entities, namely colonization, sensitization or infection. This review summarizes key findings on pathophysiological mechanisms and the clinical impact of fungi in CF lung disease.

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.

Low Risk of Pneumonia From Pneumocystis jirovecii Infection in Patients With Inflammatory Bowel Disease Receiving Immune Suppression

BACKGROUND & AIMS

Use of immunosuppressants and inflammatory bowel disease (IBD) may increase the risk of pneumonia caused by Pneumocystis jirovecii (PJP). We assessed the risk of PJP in a population-based cohort of patients with IBD treated with corticosteroids, immune-suppressive medications, and biologics.

METHODS

We performed a population-based cohort study of residents of Olmsted County, Minnesota, diagnosed with Crohn's disease (n = 427) or ulcerative colitis (n = 510) from 1970 through 2011. Records of patients were reviewed to identify all episodes of immunosuppressive therapies and concomitant PJP prophylaxis through February 2016. We reviewed charts to identify cases of PJP, cross-referenced with the Rochester Epidemiology Project database (using diagnostic codes for PJP) and the Mayo Clinic and Olmsted Medical Center databases. The primary outcome was risk of PJP associated with the use of corticosteroids, immune-suppressive medications, and biologics by patients with IBD.

RESULTS

Our analysis included 937 patients and 6066 patient-years of follow-up evaluation (median, 14.8 y per patient). Medications used included corticosteroids (520 patients; 55.5%; 555.4 patient-years of exposure), immunosuppressants (304 patients; 32.4%; 1555.7 patient-years of exposure), and biologics (193 patients; 20.5%; 670 patient-years of exposure). Double therapy (corticosteroids and either immunosuppressants and biologics) was used by 236 patients (25.2%), with 173 patient-years of exposure. Triple therapy (corticosteroids, immunosuppressants, and biologics) was used by 70 patients (7.5%) with 18.9 patient-years of exposure. There were 3 cases of PJP, conferring a risk of 0.2 (95% CI, 0.01-1.0) to corticosteroids, 0.1 (95% CI, 0.02-0.5) cases per 100 patient-years of exposure to immunosuppressants, 0.3 (95% CI, 0.04-1.1) cases per 100 patient-years of exposure to biologics, 0.6 (95% CI, 0.01-3.2) cases per 100 patient-years of exposure to double therapy, and 0 (95% CI, 0.0-19.5) cases per 100 patient-years of exposure to triple therapy. Primary prophylaxis for PJP was prescribed to 37 patients, for a total of 24.9 patient-years of exposure.

CONCLUSIONS

In a population-based cohort of patients with IBD treated with corticosteroids, immunosuppressants, and biologics, there were only 3 cases of PJP, despite the uncommon use of PJP prophylaxis. Routine administration of PJP prophylaxis in these patients may not be warranted, although it should be considered for high-risk groups, such as patients receiving triple therapy.

Human immunodeficiency virus and fungal infections

The discovery of HIV was largely due to the presence of Pneumocystis pneumonia (PCP) in young patients that did not have the usual known causes of immune deficiencies in the early 1980s. Currently, treatment with highly active anti-retroviral therapy (HAART) and the use of prophylaxis for PCP have lowered the frequency of fungal infections; however, these infections continue to cause morbidity and mortality in those patients that fall out or are not in care. The frequency of specific fungal diseases in HIV patients will depend on the prevalence of fungi in the particular geographic location. Nowadays, superficial and invasive Candida infections, PCP, and cryptococci are the most frequent fungal infections seen in HIV positive patients worldwide. The role of pathology in diagnosing fungal infections is crucial because a lesion may be biopsied without obtaining mycology cultures, certain organisms may take several weeks to grow, or the sample sent to the mycology laboratory may not have the organism. Following we will describe fungal infections that are particularly frequent in HIV infected patients and their key pathological features.

[Pneumocystosis during HIV infection]

Pneumocystosis is an opportunistic disease caused by invasion of unicellular fungus Pneumocystic jirovecii which is responsible for febrile pneumonia among patients with cellular immunodeficiency especially those HIV infected. Despite the decreasing of its incidence due to the introduction of antiretroviral therapy, as well as anti-Pneumocystis prophylaxis among these patients, Pneumocystis pneumonia remains the first AIDS-defining event and a leading cause of mortality among HIV-infected patients. The usual radiological presentation is that of diffuse interstitial pneumonia. The diagnosis is confirmed by the detection of trophozoides and/or cysts P. jirovecii in bronchoalveolar lavage (BAL) samples using several staining techniques. The use of polymerase chain reaction in the BAL samples in conjunction with standard immunofluorescent or colorimetric tests have allowed for more has allowed for more rapid and accurate diagnosis. The standard regimen of treatment is the association of trimethoprim-sulfamethoxazole which has been utilized as an effective treatment with a favourable recovery. Early HIV diagnosis and antiretroviral therapy should reduce the incidence of this dreaded disease.

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.

Detection of Pneumocystis jirovecii by Quantitative PCR To Differentiate Colonization and Pneumonia in Immunocompromised HIV-Positive and HIV-Negative Patients

Pneumocystis jirovecii pneumonia (PCP) is an acute and life-threatening lung disease caused by the fungus Pneumocystis jirovecii The presentation of PCP in HIV-positive patients is well-known and consists of a triad of dyspnea, fever, and cough, whereas the presentation of PCP in HIV-negative patients is atypical and consists of a sudden outbreak, O2 desaturation, and a rapid lethal outcome without therapy. Despite the availability of direct and indirect identification methods, the diagnosis of PCP remains difficult. The cycle threshold (CT) values obtained by quantitative PCR (qPCR) allow estimation of the fungal burden. The more elevated that the fungal burden is, the higher the probability that the diagnosis is pneumonia. The purposes of the present study were to evaluate the CT values to differentiate colonization and pneumonia in a population of immunocompromised patients overall and patients stratified on the basis of their HIV infection status. Testing of bronchoalveolar lavage (BAL) fluid samples from the whole population of qPCR-positive patients showed a mean CT value for patients with PCP of 28 (95% confidence interval [CI], 26 to 30) and a mean CT value for colonized patients of 35 (95% CI, 34 to 36) (P < 10(-3)). For the subgroup of HIV-positive patients, we demonstrated that a CT value below 27 excluded colonization and a CT value above 30 excluded PCP with a specificity of 100% and a sensitivity of 80%, respectively. In the subgroup of HIV-negative patients, we demonstrated that a CT value below 31 excluded colonization and a CT value above 35 excluded PCP with a specificity of 80% and a sensitivity of 80%, respectively. Thus, qPCR of BAL fluid samples is an important tool for the differentiation of colonization and pneumonia in P. jirovecii-infected immunocompromised patients and patients stratified on the basis of HIV infection status with different CT values.