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

Pneumocystis Pneumonia After Allogeneic Hematopoietic Cell Transplantation: A Case-Control Study on Epidemiology and Risk Factors on Behalf of the Infectious Diseases Working Party of the European Society for Blood and Marrow Transplantation

Pneumocystis pneumonia (PCP) is a life-threatening complication after allogeneic hematopoietic cell transplantation (allo-HCT). However, allo-HCT procedures have evolved toward older patients, unrelated donors, and reduced-intensity conditioning, possibly modifying the risks. Polymerase chain reaction (PCR), widely used nowadays, is more sensitive than microscopy diagnostic methods. This study aimed to assess the factors associated with PCP in allo-HCT recipients within 2 years of HCT and managed according to current procedures. This multicenter, nested case-control study included PCP cases diagnosed by PCR, cytology, or immunofluorescence on bronchoalveolar lavage fluid between 2016 and 2018. Two controls per case were selected from the ProMISe registry and matched for the center, transplant date, and underlying disease. Fifty-two cases and 104 controls were included among the 5452 patients who underwent allo-HCT in the participating centers. PCP occurred at a median of 11.5 months after transplantation. The mortality rate was 24% on day 30 after the PCP diagnosis and 37% on day 90. The clinical presentation and mortality rates of the 24 patients diagnosed using only PCR were not different from those diagnosed with microscopy methods. Our study demonstrates a substantial incidence of, and mortality from, PCP, after allogeneic HCT despite well-established prophylactic approaches. In our experience, PCP nowadays occurs later after transplant than previously reported, justifying the prolongation of prophylaxis after six months in many cases. Allo-HCT recipients diagnosed with PCR as the only PCP marker should benefit from specific treatment as for other patients.

Current Concepts in the Diagnosis and Management of Pneumocystis Pneumonia in Solid Organ Transplantation

Pneumocystis infection manifests predominantly as an interstitial pneumonia in immunocompromised patients. Diagnostic testing in the appropriate clinical context can be highly sensitive and specific and involves radiographic imaging, fungal biomarkers, nucleic acid amplification, histopathology, and lung fluid or tissue sampling. Trimethoprim-sulfamethoxazole remains the first-choice agent for treatment and prophylaxis. Investigation continues to promote a deeper understanding of the pathogen's ecology, epidemiology, host susceptibility, and optimal treatment and prevention strategies in solid organ transplant recipients.

Exhaled Pneumocystis jirovecii output and detection of asymptomatic exhalation by facemask sampling in HIV-uninfected, immunocompromised patients

BACKGROUND

Pneumocystis jirovecii pneumonia (PJP) transmission is poorly defined. Previous studies have sampled air of rooms occupied by HIV-infected patients with PJP, while natural and direct exhalations of HIV-uninfected subjects remain under-investigated. Here, clinical facemasks were used to examine and quantify potential P. jirovecii exhalations from HIV-uninfected patients with suspected PJP and to determine whether pathogen exhalation was definable clinically or radiologically.

METHODS

Forty-five patients in Leicester (England), highly suspected of having PJP based on European Conference on Infections in Leukaemia (ECIL-5) guidelines, each wore one facemask carrying a gelatine/PVA sampling matrix for 1 h while respiring normally. Mask contamination with P. jirovecii was assessed using a modified quantitative polymerase chain reaction targeting mitochondrial large subunit (MtLSU). Radiological findings on chest X-ray (CXR) and computed tomography (CT) were graded and analysed for correlation with P. jirovecii signals alongside relevant clinical and laboratory findings.

RESULTS

P. jirovecii was detected in seven of 20 patients diagnosed with PJP and three of 19 patients with suspected but undiagnosed PJP. The median captured signal was 8.59 × 10⁴ MtLSU copies/mask (interquartile range (IQR) = 3.01 × 10⁵-1.81 × 10⁴). Blood β-D-glucan test results correlated with the mask detection data (r = 0.65; P<0.0001) but other clinical indices and radiological features did not. Five of the 10 P. jirovecii-exhalers exhibited normal CXR with a median exhalation burden 1.28 × 10⁵ copies/mask (IQR = 1.51 × 10⁵-2.27 × 10⁴). Two P. jirovecii-exhalers (7.64 × 10⁴ copies/mask) were asymptomatic.

CONCLUSION

P. jirovecii was exhaled sufficiently during normal respiration to be detectable in facemasks worn by HIV-uninfected patients. Neither clinical nor radiological features correlated with P. jirovecii exhalation.

The Use of Host Biomarkers for the Management of Invasive Fungal Disease

Invasive fungal disease (IFD) causes severe morbidity and mortality, and the number of IFD cases is increasing. Exposure to opportunistic fungal pathogens is inevitable, but not all patients with underlying diseases increasing susceptibility to IFD, develop it. IFD diagnosis currently uses fungal biomarkers and clinical risk/presentation to stratify high-risk patients and classifies them into possible, probable, and proven IFD. However, the fungal species responsible for IFD are highly diverse and present numerous diagnostic challenges, which culminates in the empirical anti-fungal treatment of patients at risk of IFD. Recent studies have focussed on host-derived biomarkers that may mediate IFD risk and can be used to predict, and even identify IFD. The identification of novel host genetic variants, host gene expression changes, and host protein expression (cytokines and chemokines) associated with increased risk of IFD has enhanced our understanding of why only some patients at risk of IFD actually develop disease. Furthermore, these host biomarkers when incorporated into predictive models alongside conventional diagnostic techniques enhance predictive and diagnostic results. Once validated in larger studies, host biomarkers associated with IFD may optimize the clinical management of populations at risk of IFD. This review will summarise the latest developments in the identification of host biomarkers for IFD, their use in predictive modelling and their potential application/usefulness for informing clinical decisions.

A comprehensive clinical guide for Pneumocystis jirovecii pneumonia: a missing therapeutic target in HIV-uninfected patients

INTRODUCTION

Pneumocystis jirovecii is an opportunistic, human-specific fungus that causes Pneumocystis pneumonia (PCP). PCP symptoms are nonspecific. A patient with P. jirovecii and another lung infection faces a diagnostic challenge. It may be difficult to determine which of these agents is responsible for the clinical symptoms, preventing effective treatment. Diagnostic and treatment efforts have been made more difficult by the rising frequency with which coronavirus 2019 (COVID-19) and PCP co-occur.

AREAS COVERED

Herein, we provide a comprehensive review of clinical and pharmacological recommendations along with a literature review of PCP in immunocompromised patients focusing on HIV-uninfected patients.

EXPERT OPINION

PCP may be masked by identifying co-existing pathogens that are not necessarily responsible for the observed infection. Patients with severe form COVID-19 should be examined for underlying immunodeficiency, and co-infections must be considered as co-infection with P. jirovecii may worsen COVID-19's severity and fatality. PCP should be investigated in patients with PCP risk factors who come with pneumonia and suggestive radiographic symptoms but have not previously received PCP prophylaxis. PCP prophylaxis should be explored in individuals with various conditions that impair the immune system, depending on their PCP risk.

Comparison of PneumID real-time PCR assay with Amplex eazyplex LAMP assay for laboratory diagnosis of Pneumocystis jirovecii Pneumonia

We compared PneumID PCR with Amplex eazyplex LAMP assay for the diagnosis of Pneumocystis jirovecii pneumonia (PJP). Both assays enable accurate diagnosis of definite PJP. Cut-off cycle threshold of the PneumID assay was < 26.68 while the cut-off time-to-positivity of the eazyplex assay was 16:02 (minutes:seconds). The positive and negative percentage agreement of eazyplex assay with PneumID assay was 75.0% and 100.0% respectively, while the overall agreement was substantial with kappa = 0.80. For both assays, establishment of cut-off values to differentiate probable PJP from colonization was not feasible as results overlapped.

Clinical Utilization of DiaSorin Molecular Polymerase Chain Reaction in Pneumocystis Pneumonia

BACKGROUND

Pneumocystis jirovecii polymerase chain reaction (PCR) testing is a sensitive diagnostic tool but does not distinguish infection from colonization. Cycle threshold (CT) may correlate with fungal burden and could be considered in clinical decision making. Clinical use of PCR and significance of CT values have not previously been examined with the DiaSorin Molecular platform.

METHODS

Retrospective review of P jirovecii PCR, CT values and clinical data from 18 months in a multihospital academic health system. The diagnostic performance of PCR with respect to pathology and correlation of CT with severity were examined.

RESULTS

Ninety-nine of 1006 (9.8%) assays from 786 patients in 919 encounters were positive. Among 91 (9.9%) encounters in which P jirovecii pneumonia (PJP) was treated, 41 (45%) were influenced by positive PCR. Negative PCR influenced discontinuation of therapy in 35 cases. Sensitivity and specificity of PCR were 93% (95% CI, 68%-100%) and 94% (95% CI, 91%-96%) with respect to pathology. CT values from deep respiratory specimens were significantly different among treated patients (P = .04) and those with positive pathology results (P < .0001) compared to patients not treated and those with negative pathology, respectively, and was highly predictive of positive pathology results (area under the curve = 0.92). No significant difference was observed in comparisons based on indicators of disease severity.

CONCLUSIONS

Pneumocystis jirovecii PCR was a highly impactful tool in the diagnosis and management of PJP, and use of CT values may have value in the treatment decision process in select cases. Further investigation in a prospective manner is needed.

Detection of Pneumocystis jirovecii and Toxoplasma gondii in patients with lung infections by a duplex qPCR assay

Pneumocystis pneumonia (PCP) and pulmonary toxoplasmosis (PT) are caused by Pneumocystis jirovecii and Toxoplasma gondii. The clinical symptoms and imaging of PCP and PT are indistinguishable. A duplex qPCR was developed to differentiate between these two pathogens. In testing 92 clinical samples to validate the performance of this method for P. jirovecii detection, it identified 31 positive samples for P. jirovecii infection, consistent with clinical diagnosis. Among the remainder of the 61 clinical samples with suspected PCP, yet showing as negative by the conventional PCR diagnosis approach, 6 of them proved positive using our new assay. Our new approach also produced similar results in identification of T. gondii infections, giving a result of 2 positive and 20 negative in clinical samples. An investigation was undertaken on the prevalence of P. jirovecii and T. gondii infections using 113 samples from lung infection patients. 9% (10/113) were shown to be positive with infections of P. jirovecii, 2% with T. gondii (2/113) and 5% (6/113) were co-infected with both pathogens. Although this duplex qPCR can detect individual P. jirovecii and T. gondii infection, and co-infection of both pathogens, further large-scale investigations are needed to validate its performance, especially in T. gondii detection. Our assay provides a rapid and accurate tool for PCP and PT diagnosis in immunocompromised population and clinical surveillance of these infections in patients with no immune defects.

Pneumocystis jirovecii and Toxoplasma gondii are opportunistic pathogens that can cause pneumocystis pneumonia (PCP) and pulmonary toxoplasmosis (PT) in immunocompromised patients. Due to the non-specific clinical symptoms and similar imaging of lung pathology, these two deadly diseases are difficult to be clinically differential diagnosed. Early diagnosis of these infections would reduce medical costs, morbidity and mortality. A duplex qPCR method was developed for the detection of both P. jirovecii and T. gondii infection simultaneously. This new assay provides a potential application for diagnosis and surveillance of both PCP and PT. Further investigation for the prevalence of P. jirovecii and T. gondii infections indicated that P. jirovecii and T. gondii involvement in lung infection has been seriously underestimated.

Is It Possible to Differentiate Pneumocystis jirovecii Pneumonia and Colonization in the Immunocompromised Patients with Pneumonia?

Respiratory sample staining is a standard tool used to diagnose Pneumocystis jirovecii pneumonia (PjP). Although molecular tests are more sensitive, their interpretation can be difficult due to the potential of colonization. We aimed to validate a Pneumocystis jirovecii (Pj) real-time PCR (qPCR) assay in bronchoscopic bronchoalveolar lavage (BAL) and oropharyngeal washes (OW). We included 158 immunosuppressed patients with pneumonia, 35 lung cancer patients who underwent BAL, and 20 healthy individuals. We used a SYBR green qPCR assay to look for a 103 bp fragment of the Pj mtLSU rRNA gene in BAL and OW. We calculated the qPCR cut-off as well as the analytical and diagnostic characteristics. The qPCR was positive in 67.8% of BAL samples from the immunocompromised patients. The established cut-off for discriminating between disease and colonization was Ct 24.53 for BAL samples. In the immunosuppressed group, qPCR detected all 25 microscopy-positive PjP cases, plus three additional cases. Pj colonization in the immunocompromised group was 66.2%, while in the cancer group, colonization rates were 48%. qPCR was ineffective at diagnosing PjP in the OW samples. This new qPCR allowed for reliable diagnosis of PjP, and differentiation between PjP disease and colonization in BAL of immunocompromised patients with pneumonia.

Quantitative PCR to Discriminate Between Pneumocystis Pneumonia and Colonization in HIV and Non-HIV Immunocompromised Patients

Pneumocystis pneumonia (PCP) is an opportunistic infection that commonly occurs in immunocompromised individuals. A definite diagnosis of PCP can be made only when the organism is identified in a respiratory specimen. It remains unclear whether qPCR can differentiate patients with PCP from those with Pneumocystis jirovecii colonization. In this study, we retrospectively collected data from HIV and non-HIV patients during 2013-2019. A diagnosis of definite, probable PCP, or PCP excluded was made based on clinical criteria, radiological reports, and three standard laboratory staining methods with blinding to qPCR data. Data from qPCR that was performed to determine the fungal burden (DNA copies/μl) in the BAL specimens of 69 HIV and 286 non-HIV patients were then obtained and reviewed. Receiver Operating Characteristic (ROC) curve analysis was performed to determine the upper and lower cut-off values for PCP diagnosis in HIV and non-HIV groups. In the non-HIV group, the lower cut-off value of 1,480 DNA copies/μl yielded a sensitivity of 100% (95% confidence interval [CI], 91.0-100), specificity of 72.9% (95% CI, 64.0-80.7), a positive predictive value (PPV) of 54.9% (95% CI, 47.6-62.1), and a negative predictive value (NPV) of 100% with Youden index of 0.73 for PCP diagnosis. In this group, the upper cut-off value of 9,655 DNA copies/μl showed the sensitivity of 100% (95% CI, 91.0-100) and specificity of 95.8% (95% CI, 90.4-98.6) with PPV of 88.6% (95% CI, 76.8-94.8) and a NPV of 100% with Youden index of 0.96 for PCP diagnosis. Regarding the HIV group, the lower cut-off value of 1,480 DNA copies/μl showed the sensitivity of 100% (95% CI, 92.5-100%) and specificity of 91.7% (95% CI, 61.5-99.8) with PPV of 97.9% (95% CI, 87.8-99.7) and a NPV of 100% with Youden index of 0.92 for PCP diagnosis. The sensitivity and specificity of the upper cut-off value of 12,718 DNA copies/μl in this group were 97.9% (95%CI, 88.7-100) and 100% (95%CI, 73.5-100), respectively. The values above the upper cut-off point had a PPV of 100% (95% CI, N/A) and a NPV of 92.3% (95% CI, 63.3-98.8) with Youden index of 0.98 for PCP diagnosis in the HIV group.

Semiquantitative Real-Time PCR to Distinguish Pneumocystis Pneumonia from Colonization in a Heterogeneous Population of HIV-Negative Immunocompromised Patients

Pneumocystis jirovecii is a threat to iatrogenically immunosuppressed individuals, a heterogeneous population at rapid growth. We assessed the ability of an in-house semiquantitative real-time PCR assay to discriminate Pneumocystis pneumonia (PCP) from colonization and identified risk factors for infection in these patients. Retrospectively, 242 PCR-positive patients were compared according to PCP status, including strata by immunosuppressive conditions, human immunodeficiency virus (HIV) infection excluded. Associations between host characteristics and cycle threshold (CT) values, semiquantitative real-time PCR correlates of fungal loads in lower respiratory tract specimens, were investigated. CT values differed significantly according to PCP status. Overall, a CT value of 36 allowed differentiation between PCP and colonization with sensitivity and specificity of 71.3% and 77.1%, respectively. A CT value of less than 31 confirmed PCP, whereas no CT value permitted exclusion. A considerable diversity was uncovered; solid organ transplant (SOT) recipients had significantly higher fungal loads than patients with hematological malignancies. In SOT recipients, a CT cutoff value of 36 resulted in sensitivity and specificity of 95.0% and 83.3%, respectively. In patients with hematological malignancies, a higher CT cutoff value of 37 improved sensitivity to 88.5% but reduced specificity to 66.7%. For other conditions, assay validity appeared inferior. Corticosteroid usage was an independent predictor of PCP in a multivariable analysis and was associated with higher fungal loads at PCP expression. Semiquantitative real-time PCR improves differentiation between PCP and colonization in immunocompromised HIV-negative individuals with acute respiratory syndromes. However, heterogeneity in disease evolution requires separate cutoff values across intrinsic and iatrogenic predisposition for predicting non-HIV PCP. IMPORTANCE Pneumocystis jirovecii is potentially life threatening to an increasing number of individuals with compromised immune systems. This microorganism can cause severe pneumonia in susceptible hosts, including patients with cancer and autoimmune diseases and people undergoing solid organ transplantation. Together, these patients constitute an ever-diverse population. In this paper, we demonstrate that the heterogeneity herein has important implications for how we diagnose and assess the risk of Pneumocystis pneumonia (PCP). Specifically, low loads of microorganisms are sufficient to cause infection in patients with blood cancer compared to those in solid organ recipients. With this new insight into host versus P. jirovecii biology, clinicians can manage patients at risk of PCP more accurately. As a result, we take a significant step toward offering precision medicine to a vulnerable patient population. One the one hand, these patients have propensity for adverse effects from antimicrobial treatment. On the other hand, this population is susceptible to life-threatening infections, including PCP.

Development and Evaluation of a Fully Automated Molecular Assay Targeting the Mitochondrial Small Subunit rRNA Gene for the Detection of Pneumocystis jirovecii in Bronchoalveolar Lavage Fluid Specimens

The fungal pathogen Pneumocystis jirovecii causes Pneumocystis pneumonia. Although the mitochondrial large subunit rRNA gene (mtLSU) is commonly used as a PCR target, a mitochondrial small subunit rRNA gene (mtSSU)-targeted MultiCode PCR assay was developed on the fully automated ARIES platform for detection of P. jirovecii in bronchoalveolar lavage fluid specimens in 2.5 hours. The assay showed a limit of detection of 800 copies/mL (approximately equal to 22 organisms/mL), with no cross-reactivity with other respiratory pathogens. Compared with the reference Pneumocystis-specific direct fluorescent antibody assay (DFA) and mtLSU-targeted PCR assay, the new assay demonstrated sensitivity of 96.9% (31/32) and specificity of 94.6% (139/147) in detecting P. jirovecii in 180 clinical bronchoalveolar lavage fluid specimens. This assay was concordant with all DFA-positive samples and all but one mtLSU PCR-positive sample, and detected eight positive samples that were negative by DFA and mtLSU PCR. Receiver operating characteristic curve analysis revealed an area under the curve of 0.98 and a threshold cycle (C_T) cutoff of 39.1 with sensitivity of 90.9% and specificity of 99.3%. The detection of 39.1 <C_T < 40.0 indicates the presence of a low load of the organism and needs further determination of either colonization or probable/possible Pneumocystis pneumonia. Overall, the new assay demonstrates excellent analytical and clinical performance and may be more sensitive than mtLSU PCR target for the detection of P. jirovecii.

Clinical Performance of (1,3) Beta-D Glucan for the Diagnosis of Pneumocystis Pneumonia (PCP) in Cancer Patients Tested With PCP Polymerase Chain Reaction

BACKGROUND

Serum (1,3)-beta-D glucan (BDG) is increasingly used to guide the management of suspected Pneumocystis pneumonia (PCP). BDG lacks specificity for PCP, and its clinical performance in high-risk cancer patients has not been fully assessed. Polymerase chain reaction (PCR) for PCP detection is highly sensitive, but cannot differentiate between colonization and infection. We evaluated the diagnostic performance of serum BDG in conjunction with PCP PCR on respiratory samples in patients with cancer and unexplained lung infiltrates.

METHODS

We performed a retrospective analysis of adult patients evaluated for PCP at our institution from 2012 to 2015, using serum BDG and PCP PCR. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the serum BDG at different thresholds were evaluated using PCP PCR alone or in conjunction with clinical presentation in PCP PCR-positive patients.

RESULTS

With PCP PCR alone as the reference method, BDG (≥80 pg/mL) had a sensitivity of 69.8%, specificity of 81.2%, PPV of 34.6%, and NPV of 95.2% for PCP. At ≥200 pg/mL in patients with a positive PCR and a compatible PCP clinical syndrome, BDG had a sensitivity of 70%, specificity of 100%, PPV of 100%, and NPV of 52.0% for PCP.

CONCLUSIONS

Patients negative by both BDG and PCR were unlikely to have PCP. In patients with a compatible clinical syndrome for PCP, higher BDG values (>200 pg/mL) were consistently associated with clinically-significant PCP infections among PCP PCR-positive oncology patients.

Targeted therapies for autoimmune/idiopathic nonmalignant diseases: risk and management of opportunistic infections

INTRODUCTION

The management of patients affected by autoimmune/idiopathic diseases has been revolutionized by the development of targeted therapies (TT). However, the use of TT is complicated by several adverse events, like opportunistic infections (OIs). The potential of TT to predispose to OIs mainly depends on the site of action; nevertheless, such associations are far from being deterministic, because many factors could increase the infection risk.

AREAS COVERED

The impact on the infective risk of different TT used for autoimmune/idiopathic diseases is far from being completely understood. Indeed, many post-marketing reports documented severe or unexpected infections in patients treated with TT that did not emerge during registrative trials. In this review, the authors attempt to provide an easy and practical update about the 'infectious' safety of TT and examine the management strategies of OIs and other infections more frequently observed in the course of treatment with TT.

EXPERT OPINION

The authors suggest to precisely schedule the clinical management of these subjects, both to prevent and eventually treat promptly the TT-related infectious complications. A coordinated approach should be implemented from different medical specialties to improve the overall understanding of safety of TT and, in general, the management of opportunistic infections in immune-compromised hosts.

Diagnostic accuracy of (1→3)-β-D-glucan to predict Pneumocystis jirovecii pneumonia in non-HIV-infected patients

Background

Pneumocystis jirovecii pneumonia (PCP) is a common and potentially fatal opportunistic infection in immunocompromised non-HIV individuals. There are problems with clinical and diagnostic protocols for PCP that lack sensitivity and specificity. We designed a retrospective study to compared several methods that were used in diagnostics of PCP.

Patients and methods

One hundred and eight immunocompromised individuals with typical clinical picture for PCP and suspicious radiological findings were included in the study. Serum samples were taken to measure the values of (1→3)-β-D-glucan (Fungitell, Associates of Cape Cod, USA). Lower respiratory tract samples were obtained to perform direct immunofluorescence (DIF, MERIFLUOR® Pneumocystis, Meridian, USA) stain and real-time PCR (qPCR).

Results

Fifty-four (50%) of the 108 patients in our study had (1→3)-β-D-glucan > 500 pg/ml. Patients that had (1→3)-β-D-glucan concentrations < 400 pg/ml in serum, had mean threshold cycles (Ct) 35.43 ± 3.32 versus those that had (1→3)-β-D-glucan concentrations >400 pg/mL and mean Ct of 28.97 ± 5.27 (P < 0.001). If we detected P. jirovecii with DIF and qPCR than PCP was proven. If the concentration of (1→3)-β-D-glucan was higher than 400 pg/ml and Ct of qPCR was below 28.97 ± 5.27 than we have been able be certain that P. jirovecii caused pneumonia (odds ratio [OR] 2.31, 95% confidence interval [CI] 1.62–3.27, P < 0.001).

Conclusions

Measurement of (1→3)-β-D-glucan or qPCR alone could not be used to diagnose PCP. Diagnostic cut-off value for (1→3)-β-D-glucan > 400pg/ml and qPCR below 30 Ct, allow us to conclude that patient has PCP. If the values of (1→3)-β-D-glucan are < 400 pg/ml and qPCR is above 35 Ct than colonization with P. jirovecii is more possible than PCP.

Ability of quantitative PCR to discriminate Pneumocystis jirovecii pneumonia from colonization

Introduction.

Pneumocystis jirovecii pneumonia (PCP) is a severe disease affecting immunocompromised patients. Diagnosis is difficult due to the low sensitivity of direct examination and inability to grow the pathogen in culture. Quantitative PCR in bronchoalveolar lavage fluid (BAL) has high sensitivity, but limited specificity for distinguishing PCP from colonization.

Aim.

To assess the performance of an in-house quantitative PCR to discriminate between PCP and colonization.

Methodology.

This was a single-centre retrospective study including all patients with a positive PCR result for P. jirovecii in BAL between 2009 and 2017. Irrespective of PCR results, PCP was defined as the presence of host factors and clinical/radiological criteria consistent with PCP and (i) the presence of asci at direct examination of respiratory sample or (ii) anti-PCP treatment initiated with clinical response and absence of alternative diagnosis. Colonization was considered for cases who did not receive anti-PCP therapy with a favourable outcome or an alternative diagnosis. Cases who did not meet the above mentioned criteria were classified as ‘undetermined’.

Results.

Seventy-one patients with positive P. jirovecii PCR were included (90 % non-HIV patients). Cases were classified as follows: 37 PCP, 22 colonization and 12 undetermined. Quantitative PCR values in BAL were significantly higher in patients with PCP versus colonization or undetermined (P<0.0001). The cut-off of 5×10³ copies/ml was able to discriminate PCP cases from colonization with 97 % sensitivity, 82 % specificity, 90 % positive predictive value and 95 % negative predictive value.

Conclusions.

Our quantitative PCR for P. jirovecii in BAL was reliable to distinguish PCP cases from colonization in this predominantly non-HIV population.

[Pneumocystis jirovecii and quantitative PCR: Pneumonia or colonization?]

BACKGROUND

Quantitative PCR to detect Pneumocystis jirovecii (Pj) is a new tool for the diagnosis of Pneumocystis jirovecii pneumonia (PJP). The yield of this technique, in cases of low fungal burden, when the standard technique using immunofluorescence (IF) is negative, needs to be evaluated.

METHODS

We retrospectively reviewed the charts of all patients with a positive PCR but negative IF test (PCR+/IF-) in bronchoalveolar lavage (BAL) fluid performed over one year. We used an algorithm based on underlying immunosuppression, clinical picture, thoracic CT scan appearances, existence of an alternative diagnosis and the patient's outcome on treatment. Using this, each case was classified as probable PJP, possible PJP or colonization.

RESULTS

Among the 416 BAL performed, 48 (12%) were PCR+/IF- and 43 patients were analyzed. Patients were mostly male (56%) with a median age of 60 years. Thirty-five (84%) were immunocompromised: 4 (9%) HIV-infected patients, 26 (60%) with hematologic or solid organ cancer, 3 (7%) were renal transplant recipients. Seven (16%) were classified as probable PPJ and 9 (21%) as possible PJP. Patients with a probable or possible PJP were more frequently admitted to the ICU (P<0.02) and had higher risk of death (P<0.01) when compared to those with colonization. Median PCR levels were very low and were not different between PJP or colonized patients (P=0.23).

CONCLUSIONS

Among patients with a positive Pj PCR in BAL but with negative IF, only 37% had probable or possible PJP and PCR could not discriminate PJP from colonization.

Outbreak-Causing Fungi: Pneumocystis jirovecii

Pneumocystis jirovecii pneumonia (PCP) is an important cause of morbidity in immunocompromised patients, with a higher mortality in non-HIV than in HIV patients. P. jirovecii is one of the rare transmissible pathogenic fungi and the only one that depends fully on the host to survive and proliferate. Transmissibility among humans is one of the main specificities of P. jirovecii. Hence, the description of multiple outbreaks raises questions regarding preventive care management of the disease, especially in the non-HIV population. Indeed, chemoprophylaxis is well codified in HIV patients but there is a trend for modifications of the recommendations in the non-HIV population. In this review, we aim to discuss the mode of transmission of P. jirovecii, identify published outbreaks of PCP and describe molecular tools available to study these outbreaks. Finally, we discuss public health and infection control implications of PCP outbreaks in hospital setting for in- and outpatients.

Pneumocystis jiroveci in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of Pneumocystis jiroveci fungal infection transplant recipients. Pneumonia (PJP) may develop via airborne transmission or reactivation of prior infection. Nosocomial clusters of infection have been described among transplant recipients. PJP should not occur during prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX). Without prophylaxis, PJP risk is greatest in the first 6 months after organ transplantation but may develop later. Risk factors include low lymphocyte counts, cytomegalovirus infection (CMV), hypogammaglobulinemia, treated graft rejection or corticosteroids, and advancing patient age (>65). Presentation typically includes fever, dyspnea with hypoxemia, and cough. Chest radiographic patterns generally reveal diffuse interstitial processes best seen by CT scans. Patients generally have PO₂  < 60 mm Hg, elevated serum lactic dehydrogenase (LDH), and elevated serum (1 → 3) β-d-glucan assay. Specific diagnosis uses respiratory specimens with direct immunofluorescent staining; invasive procedures may be required. Quantitative PCR is a useful adjunct to diagnosis. TMP-SMX is the drug of choice for therapy; drug allergy should be documented before resorting to alternative therapies. Adjunctive corticosteroids may be useful early. Routine PJP prophylaxis is recommended for at least 6-12 months post-transplant, preferably with TMP-SMX.

Comparative Evaluation Between the RealStar Pneumocystis jirovecii PCR Kit and the AmpliSens Pneumocystis jirovecii (carinii)-FRT PCR Kit for Detecting P. jirovecii in Non-HIV Immunocompromised Patients

BACKGROUND

Real-time PCR is more sensitive than microscopic examination for detecting Pneumocystis jirovecii. We compared the performance of two assays for detecting P. jirovecii DNA: the RealStar Pneumocystis jirovecii PCR Kit 1.0 CE (Altona Diagnostics, Hamburg, Germany) and the AmpliSens Pneumocystis jirovecii (carinii)-FRT PCR kit (InterLabService Ltd., Moscow, Russia).

METHODS

We used 159 samples from the lower respiratory tract (112 bronchoalveolar lavage [BAL] fluid, 37 sputum, and 10 endotracheal aspirate [ETA] samples) of non-HIV immunocompromised patients. Nested PCR and sequencing were used to resolve discordant results. The performance of the two assays was evaluated according to clinical categories (clinical Pneumocystis pneumonia [PCP], possible PCP, or unlikely PCP) based on clinical and radiological observations.

RESULTS

The positive and negative percent agreement values were 100% (95% confidence interval [CI], 85.4-100%) and 96.6% (95% CI, 90.9-98.9%), respectively, and kappa was 0.92 (95% CI, 0.84-0.99). P. jirovecii DNA load was significantly higher in the clinical PCP group than in the other groups (P<0.05). When stratified by sample type, the positive rate for BAL fluids from the clinical PCP group was 100% using either assay, whereas the positive rate for sputum/ETA samples was only 20%.

CONCLUSIONS

The two assays showed similar diagnostic performance and detected low P. jirovecii burden in BAL fluids. Both assays may be useful as routine methods for detecting P. jirovecii DNA in a clinical laboratory setting, though their results should be interpreted considering sample type.

Pneumocystis jirovecii pneumonia prophylaxis in allogeneic hematopoietic cell transplant recipients: can we always follow the guidelines?

Pneumocystis jirovecii pneumonia (PCP) is a life-threatening disease in allogeneic hematopoietic cell transplantation (HCT) recipients. Trimethoprim-sulfamethoxazole (TMP-SMX) is the preferred prophylaxis but has significant toxicity. We assessed 139 consecutive HCT patients for PCP prophylaxis in our center. According to our procedures, TMP-SMX should be given as first-line prophylaxis from engraftment. In case of intolerance, atovaquone (ATO) or aerosolized pentamidine may be given. Thirteen (9.3%) patients did not receive prophylaxis because they early died. Of the 126 prophylaxed patients, 113 (90%) received TMP-SMX and 13 (10%) received ATO as first-line regimen. However, only 51/113 (45%) patients received TMP-SMX as the sole prophylaxis: 60 patients were switched to ATO because of side effect. There were 18 PCP cases: 3 occurred before engraftment, 7 occurred under ATO, 3 occurred while prophylaxis was pending the resolution of side effects, and 5 occurred after stopping prophylaxis. No cases occurred under TMP-SMX while 7 (9.6%) cases occurred under first-(n = 13) or second (n = 60)-line ATO. There are many concerns about PCP prophylaxis after HCT: patients may develop PCP before engraftment or several months after stopping immunosuppressors, and half of them do not receive TMP-SMX all along the at-risk periods. New prophylactic drugs and strategies should be evaluated.

Inter-Specimen Imbalance of Mitochondrial Gene Copy Numbers Predicts Clustering of Pneumocystis jirovecii Isolates in Distinct Subgroups

The molecular detection of Pneumocystis jirovecii is an important therapy-relevant tool in microbiological diagnostics. However, the quantification of this pathogen in the past has revealed discordant results depending on the target gene. As the clinical variety of P. jirovecii infections ranges between life-threatening infections and symptom-free colonization, the question arises if qPCRs are reliable tools for quantitative diagnostics of P. jirovecii. P. jirovecii positive BALs were quantitatively tested for the copy numbers of one mitochondrial (COX-1) and two nuclear single-copy genes (KEX1 and DHPS) compared to the mitochondrial large subunit (mtLSU) by qPCR. Independent of the overall mtLSU copy number P. jirovecii clustered into distinct groups based on the ratio patterns of the respective qPCRs. This study, which compared different mitochondrial to nuclear gene ratio patterns of independent patients, shows that the mtLSU gene represents a highly sensitive qPCR tool for the detection of P. jirovecii, but does not display a reliable target for absolute quantification.

Molecular Demonstration of a Pneumocystis Outbreak in Stem Cell Transplant Patients: Evidence for Transmission in the Daycare Center

Pneumocystis jirovecii pneumonia (PCP) is a life-threatening infection in hematology. Although occasionally reported, the role of interhuman transmission of P. jirovecii in PCP, compared to that of reactivation, remains an unresolved question; the recommendation to isolate PCP patients in the hematology ward are not well evidence-based. Following an unexpected increase in the number of febrile pneumonia patients with P. jirovecii DNA detected in respiratory samples in our hematology ward, we explored 12 consecutive patients from November 2015 to May 2016. Genotyping of P jirovecii was performed using microsatellite markers. The frequency of simultaneous occupancy of these 12 patients in the same unit on the same day from 4 months prior to the first diagnosis was recorded. In three patients, the P. jirovecii genotype could not be determined because DNA was insufficient. One rare single genotype (Gt2) was found in four of the other nine, all allogeneic stem cell transplant recipients. The transmission map showed that these 4 patients had multiple opportunities to meet on the same day (median, 6.5; range, 4-10) at the daycare center. It was much less among the eight non-Gt2 patients (median, 1; range, 0-9; P = 0.048). This study, based on modern molecular technics, strongly suggests that interhuman transmission of P. jirovecii between allogeneic stem cell transplant recipients is possible. P. jirovecii DNA detected in respiratory specimens supports that isolation and respiratory precautions be recommended in such cases in the hematology ward.

Detection of Pneumocystis jirovecii in oral wash from immunosuppressed patients as a diagnostic tool

Background

Diagnosis of Pneumocystis jirovecii (PJ) pneumonia ordinarily requires invasive procedures that could be avoided by PCR methodologies, if these could be designed with adequate cut-off values for confounding background carriage.

Methods

We designed a novel quantitative real-time PCR assay to detect the mitochondrial large subunit rRNA gene of PJ in oral washes. To benchmark levels of PJ carriage versus infection, we tested asymptomatic immunosuppressed patients including Danish (n = 88) and West African HIV-infected (n = 142) patients, renal transplant recipients (n = 51), rheumatologic patients (n = 102), patients with inflammatory bowel diseases (n = 98), and healthy blood donors (controls, n = 50). The fungal burden in patients with PJ pneumonia (PCP, n = 7) was also investigated.

Results

Danish HIV-infected patients (with viremia/low CD4) and recent transplant recipients were at most risk of being carriers (prevalence of 23% and 16.7% respectively), whereas PJ was rarely detected among rheumatologic patients, patients with inflammatory bowel diseases, and untreated West African HIV patients. PJ was not detected among healthy controls. The fungal burden in patients with PCP fell rapidly on treatment.

Conclusions

The quantitative PCR method described could conceivably discriminate between carriage and disease, given suitable threshold values for the former, and predict treatment efficacy by measures of the fungal burden in daily oral washes.

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.

Pneumocystis jirovecii-induced chronic interstitial lung disease in Waldenström's macroglobulinemia

Infections with Pneumocystis jirovecii can result in asymptomatic colonization or induce life threatening clinical symptoms. However, there appears to be a 'gray area' between colonization and severe pneumonia that remains underestimated so far. We describe a case with chronic interstitial lung disease and chronic cough that was attributed to P. jirovecii. The patient's history of chronic cough, although very likely being fostered by the underlying Waldenström's macroglobulinemia and interstitial lung disease, was most likely caused by P. jirovecii infection. This gives raise to the hypothesis that P. jirovecii infections do not necessarily induce life threatening pneumonia. Consequently, serial testing is required in eligible patients with positive PCR results in order to discriminate between colonization, 'gray zone' infection, and beginning pneumonia.

Evaluation of the automated Becton Dickinson MAX real-time PCR platform for detection of Pneumocystis jirovecii

AIM

We evaluated the performance of the automated quantitative BD MAX (Becton Dickinson) real-time PCR platform for detecting Pneumocystis jirovecii.

MATERIALS & METHODS

A total of 34 retrospective and 137 prospective samples were included.

RESULTS

Retrospectively, all (100%) positive samples were correctly detected by this platform compared with a nested PCR. Among prospective samples, the overall sensitivity, specificity, positive likelihood ratio and negative likelihood ratio were 92.6%, 94.5%, 17.0 and 0.1, respectively. All bronchoalveolar lavage fluid (BALF)/bronchial washing samples were correctly identified by this platform. Samples from patients with colonization had significantly higher median amplification cycle threshold values than patients with P. jirovecii pneumonia.

CONCLUSION

The quantitative BD MAX real-time PCR is a rapid and highly sensitive modality for detecting P. jirovecii, especially in samples from bronchoalveolar lavage fluid/bronchial washing fluid.

Evaluation of a new commercial real-time PCR assay for diagnosis of Pneumocystis jirovecii pneumonia and identification of dihydropteroate synthase (DHPS) mutations

The PneumoGenius® real-time PCR assay is a new commercial multiplex real-time PCR method, which detects the Pneumocystis mitochondrial ribosomal large subunit (mtLSU) and two dihydropteroate synthase (DHPS) point mutations. To evaluate the clinical performance of this new real-time PCR assay we tested 120 extracted DNA samples from bronchoalveolar lavage specimens. These set of extracted DNA samples had already tested positive for Pneumocystis and patients had been classified in probable and unlikely PCP in a previous study. To evaluate de accuracy of the DHPS mutant's identification, an "in house" PCR and sequencing was performed. The sensitivity and specificity of PneumoGenius® PCR in discriminating between probable and unlikely Pneumocystis pneumonia (PCP) were 70% and 82% respectively. PneumoGenius® PCR was able to genotype more samples than "in house" DHPS PCR and sequencing. The same DHPS mutations were observed by both methods in four patients: two patients with a single mutation in position 171 (Pro57Ser) and two patients with a double mutation in position 165 (Thr55Ala) and in position 171 (Pro57Ser). A low rate of P. jirovecii (4.5%) harboring DHPS mutations was found, comparable to rates observed in other European countries. The PneumoGenius® real-time PCR is a suitable real-time PCR for PCP diagnosis and detection of DHPS mutants. The added value of DHPS mutation identification can assist in understanding the role of these mutations in prophylaxis failure or treatment outcome.

Prognostic factors for severe Pneumocystis jiroveci pneumonia of non-HIV patients in intensive care unit: a bicentric retrospective study

BACKGROUND

Pneumocystis jiroveci pneumonia (PJP) in non-HIV patients is still a challenge for intensivists. The aim of our study was to evaluate mortality predictors of PJP patients requiring Intensive care unit (ICU) admission.

METHODS

Retrospectively review medical records of patients with diagnosis of PJP admitted to four ICUs of two academic medical centers from October 2012 to October 2015.

RESULTS

Eighty-two patients were enrolled in the study. Overall hospital mortality was 75.6 %. Compared with survivors, the non-survivors had older age (55 ± 16 vs. 45 ± 17, p = 0.014), higher APACHE II score (20 ± 5 vs. 17 ± 5, p = 0.01), lower white blood cell count (7.68 ± 3.44 vs. 10.48 ± 4.62, p = 0.005), less fever (80.6%vs. 100 %, p = 0.033), more hypotension (58.1 % vs. 20 %, p = 0.003), more pneumomediastinum (29 % vs. 5 %, p = 0.027). Logistic regression analysis demonstrated that age [odds ratio (OR)1.051; 95 % CI 1.007-1.097; p = 0.022], white blood cell count [OR 0.802; 95 % CI 0.670-0.960; p = 0.016], and pneumomediastinum [OR 16.514; 95 % CI 1.330-205.027; p = 0.029] were independently associated with hospital mortality.

CONCLUSIONS

Mortality rate for non-HIV PJP patients requiring ICU admission was still high. Poor prognostic factors included age, white blood cell count and pneumomediastinum.

Copy Number Variation of Mitochondrial DNA Genes in Pneumocystis jirovecii According to the Fungal Load in BAL Specimens

Pneumocystis jirovecii is an unculturable fungus and the causative agent of Pneumocystis pneumonia, a life-threatening opportunistic infection. Although molecular diagnosis is often based on the detection of mtLSU rRNA mitochondrial gene, the number of copies of mitochondrial genes had not been investigated. We developed and optimized six real-time PCR assays in order to determine the copy number of four mitochondrial genes (mtSSU rRNA, mtLSU rRNA, NAD1, and CYTB) in comparison to nuclear genome (DHPS and HSP70) and tested 84 bronchoalveolar fluids of patients at different stages of the infection. Unexpectedly, we found that copy number of mitochondrial genes varied from gene to gene with mtSSU rRNA gene being more represented (37 copies) than NAD1 (23 copies), mtLSU rRNA (15 copies) and CYTB (6 copies) genes compared to nuclear genome. Hierarchical clustering analysis (HCA) allowed us to define five major clusters, significantly associated with fungal load (p = 0.029), in which copy number of mitochondrial genes was significantly different among them. More importantly, copy number of mtLSU rRNA, NAD1, and CYTB but not mtSSU rRNA differed according to P. jirovecii physiological state with a decreased number of copies when the fungal load is low. This suggests the existence of a mixture of various subspecies of mtDNA that can harbor different amplification rates. Overall, we revealed here an unexpected variability of P. jirovecii mtDNA copy number that fluctuates according to P. jirovecii’s physiological state, except for mtSSU that is the most stable and the most present mitochondrial gene.

A misleading false-negative result of Pneumocystis real-time PCR assay due to a rare punctual mutation: A French multicenter study

This article describes a previously unreported mutation at position 210 (C210T) of the mitochondrial large subunit ribosomal RNA (mtLSUrRNA) gene of Pneumocystis jirovecii, which led to a false-negative result of a real-time polymerase chain reaction (PCR) assay. Since the aforementioned real-time PCR assay is widely used in France, a French multicenter study was conducted to estimate the mutation frequency and its potential impact on the routine diagnosis of Pneumocystis pneumonia (PCP). Through analysis of data obtained from eight centers, the mutation frequency was estimated at 0.28%. This low frequency should not call into question the routine use of this PCR assay. Nonetheless, the occurrence of the false-negative PCR result provides arguments for maintaining microscopic techniques combined to PCR assays to achieve PCP diagnosis.

Low Titer Pneumocystis jirovecii Infections: More than Just Colonization?

Non-pneumonia Pneumocystis jirovecii colonization is thought to occur frequently in immunocompetent individuals. The aim was to analyze if P. jirovecii low-titer detections have more impact than just colonization. From our total cohort of patients for which P. jirovecii testing by qPCR was requested, we selected exclusively those that were fully immunocompetent. Patients were defined as fully immunocompetent if they did not receive immunosuppressive therapy, displayed regular antibody titers, and did not suffer from acquired, inherited or autoimmune diseases. Only those patients with complete medical records available were included. A retrospective analysis identified patients with P. jirovecii colonization and successful antibiotic therapy in response to laboratory pathogen detection. We identified 30 fully immunocompetent patients with P. jirovecii colonization suspected to suffer from infection with the pathogen, but with milder symptoms than pneumonia. All patients were successfully treated with cotrimoxazole against P. jirovecii and resolved from chronic cough and recurrent pulmonary infections. The fact that all patients displayed recovery from their clinical symptoms gives raise to the hypothesis that P. jirovecii infections may also occur in immunocompetent patients but with milder symptoms.

Diversity of Pneumocystis jirovecii during Infection Revealed by Ultra-Deep Pyrosequencing

Pneumocystis jirovecii is an uncultivable fungal pathogen responsible for Pneumocystis pneumonia (PCP) in immunocompromised patients, the physiopathology of which is only partially understood. The diversity of the Pneumocystis strains associated with acute infection has mainly been studied by Sanger sequencing techniques precluding any identification of rare genetic events (< 20% frequency). We used next-generation sequencing to detect minority variants causing infection, and analyzed the complexity of the genomes of infection-causing P. jirovecii. Ultra-deep pyrosequencing (UDPS) of PCR amplicons of two nuclear target region [internal transcribed spacer 2 (ITS2) and dihydrofolate reductase (DHFR)] and one mitochondrial DNA target region [the mitochondrial ribosomal RNA large subunit gene (mtLSU)] was performed on 31 samples from 25 patients. UDPS revealed that almost all patients (n = 23/25, 92%) were infected with mixtures of strains. An analysis of repeated samples from six patients showed that the proportion of each variant change significantly (by up to 30%) over time on treatment in three of these patients. A comparison of mitochondrial and nuclear UDPS data revealed heteroplasmy in P. jirovecii. The recognition site for the homing endonuclease I-SceI was recovered from the mtLSU gene, whereas its two conserved motifs of the enzyme were not. This suggests that heteroplasmy may result from recombination induced by unidentified homing endonucleases. This study sheds new light on the biology of P. jirovecii during infection. PCP results from infection not with a single microorganism, but with a complex mixture of different genotypes, the proportions of which change over time due to intricate selection and reinfection mechanisms that may differ between patients, treatments, and predisposing diseases.

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 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.

Molecular diagnosis of infectious diseases using cytological specimens

Pathologists have an important role in the diagnosis of infectious disease (ID). In many cases, a definitive diagnosis can be made using cytopathology alone. However, several ancillary techniques can be used on cytological material to reach a specific diagnosis by identifying the causative agent and consequently defining the management of the patient. This review aims to present the effectiveness of the application of molecular studies on cytological material to diagnose IDs and discuss the advantages and disadvantages of the various molecular techniques according to the type of cytological specimen and the infectious agents.

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.

Impact of HIV Infection Status on Interpretation of Quantitative PCR for Detection of Pneumocystis jirovecii

Quantitative PCR (qPCR) is now a key diagnostic tool for Pneumocystis pneumonia. However, cutoffs to distinguish between infected and colonized patients according to their HIV status have not yet been determined. According to clinical, radiological, and biological data, we retrospectively classified bronchoalveolar lavage (BAL) samples subjected to qPCR over a 3-year period into four categories, i.e., definite PCP, probable PCP, Pneumocystis colonization, and no infection. Fungal burden was then analyzed according to the HIV status of the patients. Among 1,212 episodes of pneumonia screened in immunocompromised patients, 52 and 27 HIV-positive patients were diagnosed with a definite and probable PCP, whereas 4 and 22 HIV-negative patients had definite and probable PCP, respectively. Among patients with definite or a probable PCP, HIV-negative patients had a significantly lower burden than HIV-positive patients (P < 10(-4)). In both groups, the median fungal burden was significantly higher in patients with definite PCP than in colonized patients. A single cutoff at 1.5 × 10(4) copies/ml allowed to differentiate colonized and infected HIV-positive patients with 100% sensitivity and specificity. In HIV-negative patients, cutoff values of 2.87 × 10(4) and 3.39 × 10(3) copies/ml resulted in 100% specificity and sensitivity, respectively. Using cutoffs determined for the whole population would have led us to set aside the diagnosis of PCP in 9 HIV-negative patients with definite or probable PCP. qPCR appeared to be the most sensitive test to detect Pneumocystis in BAL samples. However, because of lower inocula in HIV-negative patients, different cutoffs must be used according to the HIV status to differentiate between colonized and infected patients.

Role of bronchoalveolar lavage in the diagnosis of pulmonary infiltrates in immunocompromised patients

PURPOSE OF REVIEW

To describe the role of bronchoalveolar lavage (BAL) in the evaluation of pulmonary disease in immunocompromised patients.

RECENT FINDINGS

Recent discoveries in this field are largely in two areas: the array of diagnostic testing performed on BAL fluid and technical details that can enhance the yield from this procedure. Regarding diagnostic testing, the addition of new assays, including Aspergillus galactomannan antigen assay, respiratory viral panels, and Pneumocystis jirovecii PCR, has improved the diagnostic yield of BAL over conventional cultures and stains. To improve the diagnostic yield of the procedure itself, it should be done early in the clinical course, with the BAL in the anatomic area most affected, and with a preprocedural computed tomography of the chest to properly plan the procedure.

SUMMARY

Bronchoscopic evaluation with BAL can provide important diagnostic information in immunocompromised patients with pulmonary diseases and should be routinely performed when clinically indicated and able to be completed safely.

Pneumocystis jirovecii Pneumonia in Rheumatoid Arthritis Patients: Risks and Prophylaxis Recommendations

Pneumocystis jirovecii infection causes fulminant interstitial pneumonia (Pneumocystis pneumonia, PCP) in patients with rheumatoid arthritis (RA) who are receiving biological and/or nonbiological antirheumatic drugs. Recently, we encountered a PCP outbreak among RA outpatients at our institution. Hospital-acquired, person-to-person transmission appears to be the most likely mode of this cluster of P. jirovecii infection. Carriage of P. jirovecii seems a time-limited phenomenon in immunocompetent hosts, but in RA patients receiving antirheumatic therapy, clearance of this organism from the lungs is delayed. Carriers among RA patients can serve as sources and reservoirs of P. jirovecii infection for other susceptible patients in outpatient facilities. Development of PCP is a matter of time in such carriers. Considering the poor survival rates of PCP cases, prophylactic antibiotics should be considered for RA patients who are scheduled to receive antirheumatic therapy. Once a new case of PCP occurs, we should take prompt action not only to treat the PCP patient but also to prevent other patients from becoming new carriers of P. jirovecii. Short-term prophylaxis with trimethoprim-sulfamethoxazole is effective in controlling P. jirovecii infection and preventing future outbreaks of PCP among RA 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.

Correlation Between Pneumocystis jirovecii Mitochondrial Genotypes and High and Low Fungal Loads Assessed by Single Nucleotide Primer Extension Assay and Quantitative Real-Time PCR

We designed a single nucleotide primer extension (SNaPshot) assay for Pneumocystis jirovecii genotyping, targeting mt85 SNP of the mitochondrial large subunit ribosomal RNA locus, to improve minority allele detection. We then analyzed 133 consecutive bronchoalveolar lavage (BAL) fluids tested positive for P. jirovecii DNA by quantitative real-time PCR, obtained from two hospitals in different locations (Hospital 1 [n = 95] and Hospital 2 [n = 38]). We detected three different alleles, either singly (mt85C: 39.1%; mt85T: 24.1%; mt85A: 9.8%) or together (27%), and an association between P. jirovecii mt85 genotype and the patient's place of hospitalization (p = 0.011). The lowest fungal loads (median = 0.82 × 10(3) copies/μl; range: 15-11 × 10(3) ) were associated with mt85A and the highest (median = 1.4 × 10(6) copies/μl; range: 17 × 10(3) -1.3 × 10(7) ) with mt85CTA (p = 0.010). The ratios of the various alleles differed between the 36 mixed-genotype samples. In tests of serial BALs (median: 20 d; range 4-525) from six patients with mixed genotypes, allele ratio changes were observed five times and genotype replacement once. Therefore, allele ratio changes seem more frequent than genotype replacement when using a SNaPshot assay more sensitive for detecting minority alleles than Sanger sequencing. Moreover, because microscopy detects only high fungal loads, the selection of microscopy-positive samples may miss genotypes associated with low loads.