Point-Counterpoint: Should Serum β-d-Glucan Testing Be Used for the Diagnosis of Pneumocystis jirovecii Pneumonia?

Negative serum (1,3) -β-D-glucan has a low power to exclude Pneumocystis jirovecii pneumonia (PJP) in HIV-uninfected patients with positive qPCR

OBJECTIVE

The current study evaluated the diagnostic performance of serum (1,3)-beta-D Glucan (BDG) in differentiating PJP from P. jirovecii-colonization in HIV-uninfected patients with P. jirovecii PCR-positive results.

METHODS

This was a single-center retrospective study between 2019 and 2021. The diagnosis of PJP was based on the following criteria: detection of P. jirovecii in sputum or BAL specimen by qPCR or microscopy; Meet at least two of the three criteria: (1) have respiratory symptoms of cough and/or dyspnea, hypoxia; (2) typical radiological picture findings; (3) receiving a complete PJP treatment. After exclusion, the participants were divided into derivation and validation cohorts. The derivation cohort defined the cut-off value of serum BDG. Then, it was verified using the validation cohort.

RESULTS

Two hundred and thirteen HIV-uninfected patients were enrolled, with 159 PJP and 54 P. jirovecii-colonized patients. BDG had outstanding specificity, LR, and PPV for PJP in both the derivation (90.00%, 8.900, and 96.43%) and the validation (91.67%, 9.176, and 96.30%) cohorts at ≥ 117.7 pg/mL. However, it had lower sensitivity and NPV in the derivation cohort (89.01% and 72.97%), which was even lower in the validation cohort (76.47% and 57.89%). Of note, BDG ≥ 117.7 pg/mL has insufficient diagnostic efficacy for PJP in patients with lung cancer, interstitial lung disease (ILD) and nephrotic syndrome. And although lymphocytes, B cells, and CD4+ T cells in PJP patients were significantly lower than those in P. jirovecii-colonized patients, the number and proportion of peripheral blood lymphocytes did not affect the diagnostic efficacy of serum BDG.

CONCLUSIONS

Serum BDG ≥ 117.7 pg/mL could effectively distinguish P. jirovecii-colonization from infection in qPCR-positive HIV-uninfected patients with infectious diseases, solid tumors (excluding lung cancer), autoimmune or inflammatory disorders, and hematological malignancies. Of note, for patients with lung cancer, ILD, and nephrotic diseases, PJP should be cautiously excluded at BDG < 117.7 pg/mL.

Pneumocystis jirovecii Pneumonia after Heart Transplantation: Two Case Reports and a Review of the Literature

Post-transplant Pneumocystis jirovecii pneumonia (PcP) is an uncommon but increasingly reported disease among solid organ transplantation (SOT) recipients, associated with significant morbidity and mortality. Although the introduction of PcP prophylaxis has reduced its overall incidence, its prevalence continues to be high, especially during the second year after transplant, the period following prophylaxis discontinuation. We recently described two cases of PcP occurring more than one year after heart transplantation (HT) in patients who were no longer receiving PcP prophylaxis according to the local protocol. In both cases, the disease was diagnosed following the diagnosis of a viral illness, resulting in a significantly increased risk for PcP. While current heart transplantation guidelines recommend Pneumocystis jirovecii prophylaxis for up to 6-12 months after transplantation, after that period they only suggest an extended prophylaxis regimen in high-risk patients. Recent studies have identified several new risk factors that may be linked to an increased risk of PcP infection, including medication regimens and patient characteristics. Similarly, the indication for PcP prophylaxis in non-HIV patients has been expanded in relation to the introduction of new medications and therapeutic regimens for immune-mediated diseases. In our experience, the first patient was successfully treated with non-invasive ventilation, while the second required tracheal intubation, invasive ventilation, and extracorporeal CO2 removal due to severe respiratory failure. The aim of this double case report is to review the current timing of PcP prophylaxis after HT, the specific potential risk factors for PcP after HT, and the determinants of a prompt diagnosis and therapeutic approach in critically ill patients. We will also present a possible proposal for future investigations on indications for long-term prophylaxis.

Pneumocystis pneumonia diagnosed by repeated measurements of β-D-glucan levels

β-D-glucan is extensively employed as a supplementary diagnostic tool for Pneumocystis pneumonia (PCP) and typically yields positive results in most cases. We present a case of a 73-year-old woman with a history of rheumatoid arthritis, who was receiving biological agents and was admitted due to pneumonia. Initially, the β-D-glucan test was negative. However, as the disease progressed, it eventually turned positive, leading to the diagnosis of PCP. The patient was treated with corticosteroids and trimethoprim-sulfamethoxazole, resulting in pneumonia resolution. Our findings suggest that repeated assessment of β-D-glucan levels holds diagnostic value in patients without human immunodeficiency virus infection.

Pneumocystis jiroveci Pneumonia: A Review of Management in Human Immunodeficiency Virus (HIV) and Non-HIV Immunocompromised Patients

Pneumocystis jirovecii pneumonia is an opportunistic fungal infection that was mainly associated with pneumonia in patients with advanced human immunodeficiency virus (HIV) disease. There has been a decline in Pneumocystis jirovecii pneumonia incidence in HIV since the introduction of antiretroviral medications. However, its incidence is increasing in non-HIV immunocompromised patients including those with solid organ transplantation, hematopoietic stem cell transplantation, solid organ tumors, autoimmune deficiencies, and primary immunodeficiency disorders. We aim to review and summarize the etiology, epidemiology, clinical presentation, diagnosis, and management of Pneumocystis jirovecii pneumonia in HIV, and non-HIV patients. HIV patients usually have mild-to-severe symptoms, while non-HIV patients present with a rapidly progressing disease. Induced sputum or bronchoalveolar lavage fluid can be used to make a definitive diagnosis of Pneumocystis jirovecii pneumonia. Trimethoprim-sulfamethoxazole is considered to be the first-line drug for treatment and has proven to be highly effective for Pneumocystis jirovecii pneumonia prophylaxis in both HIV and non-HIV patients. Pentamidine, atovaquone, clindamycin, and primaquine are used as second-line agents. While several diagnostic tests, treatments, and prophylactic regimes are available at our disposal, there is need for more research to prevent and manage this disease more effectively.

Misdiagnosed Pneumocystis Pneumonia as COVID-19: A Case Report

Nonspecific clinical features and imaging findings of COVID-19 may lead to misdiagnosis with other diseases that have specific risks and treatments. Here a patient is reported with Pneumocystis Pneumonia with an undiagnosed HIV disease who was treated for COVID-19 with no response after one week. COVID-19 was diagnosed by CT findings but PCR was negative. Further evaluation for ground glass opacities confirmed AIDS and clinical response to Pneumocystis Pneumonia treatment.

Usefulness of ß-d-Glucan Assay for the First-Line Diagnosis of Pneumocystis Pneumonia and for Discriminating between Pneumocystis Colonization and Pneumocystis Pneumonia

According to the immunodepression status, the diagnosis of Pneumocystis jirovecii pneumonia (PjP) may be difficult. Molecular methods appear very sensitive, but they lack specificity because Pj DNA can be detected in Pneumocystis-colonized patients. The aim of this study was to evaluate the value of a serum ß-d-Glucan (BDG) assay for the diagnosis of PjP in a large cohort of HIV-negative and HIV-positive patients, either as a first-line diagnostic test for PjP or as a tool to distinguish between colonization and PjP in cases of low fungal load. Data of Pj qPCR performed on bronchopulmonary specimens over a 3-year period were retrieved retrospectively. For each result, we searched for a BDG serum assay performed within ±5 days. Among the 69 episodes that occurred in HIV-positive patients and the 609 episodes that occurred in immunocompromised HIV-negative patients, we find an equivalent sensitivity of BDG assays compared with molecular methods to diagnose probable/proven PjP, in a first-line strategy. Furthermore, BDG assay can be used confidently to distinguish between infected and colonized patients using a 80 pg/mL cut-off. Finally, it is necessary to search for causes of false positivity to increase BDG assay performance. BDG assay represents a valuable adjunctive tool to distinguish between colonization and infection.

Comparison of different microbiological procedures for the diagnosis of Pneumocystis jirovecii pneumonia on bronchoalveolar-lavage fluid

BACKGROUND

The current diagnostic gold standard for Pneumocystis jirovecii is represented by microscopic visualization of the fungus from clinical respiratory samples, as bronchoalveolar-lavage fluid, defining "proven" P. jirovecii pneumonia, whereas qPCR allows defining "probable" diagnosis, as it is unable to discriminate infection from colonization. However, molecular methods, such as end-point PCR and qPCR, are faster, easier to perform and interpret, thus allowing the laboratory to give back the clinician useful microbiological data in a shorter time. The present study aims at comparing microscopy with molecular assays and beta-D-glucan diagnostic performance on bronchoalveolar-lavage fluids from patients with suspected Pneumocystis jirovecii pneumonia. Bronchoalveolar-lavage fluid from eighteen high-risk and four negative control subjects underwent Grocott-Gomori's methenamine silver-staining, end-point PCR, RT-PCR, and beta-D-glucan assay.

RESULTS

All the microscopically positive bronchoalveolar-lavage samples (50%) also resulted positive by end-point and real time PCR and all, but two, resulted positive also by beta-D-glucan quantification. End-point PCR and RT-PCR detected 10 (55%) and 11 (61%) out of the 18 samples, respectively, thus showing an enhanced sensitivity in comparison to microscopy. All RT-PCR with a Ct < 27 were confirmed microscopically, whereas samples with a Ct ≥ 27 were not.

CONCLUSIONS

Our work highlights the need of reshaping and redefining the role of molecular diagnostics in a peculiar clinical setting, like P. jirovecii infection, which is a rare but also severe and rapidly progressive clinical condition affecting immunocompromised hosts that would largely benefit from a faster diagnosis. Strictly selected patients, according to the inclusion criteria, resulting negative by molecular methods could be ruled out for P. jirovecii pneumonia.

Pneumocystis jiroveci pneumonia after total hip arthroplasty in a dermatomyositis patient: A case report

BACKGROUND

Pneumocystis jiroveci pneumonia (PJP) is a serious opportunistic infection that occurs mostly in patients with immunodeficiency and long-term immunosuppressive therapy. In non-human immunodeficiency virus-infected patients, the most important risk factor for PJP is the use of glucocorticoids in combination with other immunosuppressive treatments. The management of glucocorticoids during the perioperative period in patients with dermatomyositis requires special care.

CASE SUMMARY

We report a case of PJP in the perioperative period. A 61-year-old woman with a history of anti-melanoma differentiation-associated gene 5 (MDA5)-positive dermatomyositis and interstitial pneumonia was administered with long-term oral methylprednisolone and cyclosporine. The patient underwent right total hip arthroplasty in the orthopaedic department for bilateral osteonecrosis of the femoral head. She was given intravenous drip hydrocortisone before anesthesia and on the first day after surgery and resumed oral methylprednisolone on the second postoperative day. On the fifth day after surgery, the patient suddenly developed dyspnea. The computed tomography scan showed diffuse grid shadows and ground glass shadows in both lungs. Polymerase chain reaction testing of bronchoalveolar lavage fluid was positive for Pneumocystis jiroveci. The patient was eventually diagnosed with PJP and was administered with oral trimethoprim-sulfamethoxazole. At the 6-mo review, there was no recurrence or progression.

CONCLUSION

Continued perioperative glucocorticoid use in patients with anti-MDA5-positive dermatomyositis may increase the risk of PJP.

Efficacy of Low-Dose Trimethoprim/Sulfamethoxazole for the Treatment of Pneumocystis jirovecii Pneumonia in Deceased Donor Kidney Recipients

Background

Trimethoprim/sulfamethoxazole (TMP-SMX) is considered the first-choice treatment for Pneumocystis jirovecii pneumonia (PJP) in recipients of solid organ transplantation. However, this treatment is associated with various severe adverse events that might not be tolerable for some renal transplant recipients, and the optimal dose remains elusive. The present study assessed the efficacy of low-dose TMP-SMX in recipients of a deceased donor kidney.

Methods

A total of 37 adult deceased donor kidney recipients who suffered PJP between January 2015 and June 2020 were included. The survival rates of the patients and grafts, the rate of invasive ventilation, and adverse events, including gastrointestinal discomfort, hematologic side effects, hyperkalemia, and renal function impairments, were assessed.

Results

The patient and graft survival rates were both 100%. Two patients (5.4%) required invasive ventilation. Eight patients (21.6%) reported gastrointestinal discomfort, but none required dose reduction or discontinued treatment. The frequencies of hematologic side effects, hyperkalemia and impaired kidney function were 5.4% (2/37), 2.7% (1/37), and 2.7% (1/37), respectively.

Conclusion

Optimization of TMP-SMX dose may reduce the risk of adverse events without compromising efficacy for the treatment of PJP in deceased donor kidney recipients.

Low cut-off value of serum (1,3)-beta-D-glucan for the diagnosis of Pneumocystis pneumonia in non-HIV patients: a retrospective cohort study

Background

Non-human immunodeficiency virus (HIV) Pneumocystis pneumonia (PCP) is a fulminant disease with an increasing incidence. The serum beta-d-glucan (BDG) assay is used as an adjunct to the diagnosis of PCP; however, the cut-off value for this assay is not well-defined, especially in the non-HIV PCP population. Therefore, we aimed to identify the assay cut-off value for this population.

Methods

In this retrospective observational study, we reviewed the medical records of all patients (≥ 18 years old) with clinical suspicion of PCP who underwent evaluation of respiratory tract specimens between December 2008 and June 2014 at Kameda Medical Center. We created a receiver operating characteristic curve and calculated the area under the curve to determine the cut-off value for evaluating the inspection accuracy of the BDG assay.

Results

A total of 173 patients were included in the study. Fifty patients showed positive results in specimen staining, loop-mediated isothermal amplification assay, and polymerase chain reaction test, while 123 patients showed negative results. The receiver operating characteristic analyses suggested that the BDG cut-off level was 8.5 pg/mL, with a sensitivity and specificity of 76% and 76%, respectively.

Conclusions

The Wako-BDG cut-off value for the diagnosis of non-HIV PCP is 8.5 pg/mL, which is lower than the classical cut-off value from previous studies. Clinicians should potentially consider this lower BDG cut-off value in the diagnosis and management of patients with non-HIV PCP.

Trial registration: The participants were retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06895-x.

A Negative (1,3)-β-D-Glucan Result Alone Is Not Sufficient to Rule Out a Diagnosis of Pneumocystis Pneumonia in Patients With Hematological Malignancies

Background: Serum (1,3)-β-D-glucan (BG) testing is increasingly being used in the diagnostic armamentarium for invasive fungal diseases. Given its high sensitivity, some studies suggest that a negative BG result contributes to rule out a diagnosis of Pneumocystis pneumonia (PCP). However, recent reports described a suboptimal sensitivity in HIV-negative immunocompromised patients. In this study, we evaluated the performance of BG assay for PCP diagnosis in HIV-negative patients with diverse PCP risk factors. We also assessed the correlation between Pneumocystis jirovecii load in pulmonary samples and serum BG levels.

Methods: We retrospectively included HIV-negative patients with microscopically proven PCP and for whom a BG result was available. We also enrolled patients colonized by Pneumocystis as control group. Colonized patients were matched with PCP patients based on their underlying condition that exposed to PCP. Pulmonary fungal loads were determined by an in-house real-time PCR, and BG levels were measured by using the Fungitell® kit (Associates of Cape Cod, Inc.).

Results: Thirty-nine patients were included in each of the two groups. Thirty-four of 39 PCP patients and one of 39 colonized patient had a positive BG test, resulting in a sensitivity of 0.87 (95% CI: 0.73–0.94), a specificity of 0.97 (95% CI: 0.87–0.99), a positive predictive value of 0.97 (95% CI: 0.85–0.99), and a negative predictive value of 0.88 (95% CI: 0.75–0.95) for BG assay. Nonetheless, median BG level differed according to the underlying condition. Among the PCP group, the lowest median level of 211 pg/ml was observed in patients with hematological malignancy (HM) and differed significantly from that observed either in solid organ transplants (3,473 pg/ml) or in patients with autoimmune or inflammatory disorder (3,480 pg/ml). Indeed, the sensitivity of BG assay was estimated at 0.64 (95% CI: 0.35–0.85) in HM patients and was lower than the one observed in the whole PCP group. Furthermore, BG level and fungal burden correlated poorly among all PCP patients.

Conclusion: BG is not a reliable biomarker for ruling out PCP in HIV-negative patients with HM. Interpretation of a negative BG result should take into account, but not be limited to, the underlying condition predisposing to PCP.

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.