Therapy and Management of Pneumocystis jirovecii Infection

The Road Ahead: Advancing Antifungal Vaccines and Addressing Fungal Infections in the Post-COVID World

In impoverished nations, the COVID-19 pandemic has led to a widespread occurrence of deadly fungal diseases like mucormycosis. The limited availability of effective antifungal treatments and the emergence of drug-resistant fungal strains further exacerbate the situation. Factors such as systemic steroid use, intravenous drug misuse, and overutilization of broad-spectrum antimicrobials contribute to the prevalence of hospital-acquired infections caused by drug-resistant fungi. Fungal infections exploit compromised immune status and employ intricate mechanisms to evade immune surveillance. The immune response involves the innate and adaptive immune systems, leading to phagocytic and complement-mediated elimination of fungi. However, resistance to antifungals poses a challenge, highlighting the importance of antifungal prophylaxis and therapeutic vaccination. Understanding the host-fungal immunological interactions and developing vaccines are vital in combating fungal infections. Further research is needed to address the high mortality and morbidity associated with multidrug-resistant fungal pathogens and to develop innovative treatment drugs and vaccines. This review focuses on the global epidemiological burden of fungal infections, host-fungal immunological interactions, recent advancements in vaccine development and the road ahead.

Risk Factors of Pneumocystis jirovecii Pneumonia in Patients with Inflammatory Bowel Disease: A Nationwide Population-Based Study

Background/Aims

: Pneumocystis jirovecii pneumonia (PJP) is a rare but potentially fatal infection. This study was conducted to investigate the risk factors for PJP in inflammatory bowel disease (IBD) patients.

Methods

: This nationwide, population-based study was conducted in Korea using claims data. Cases of PJP were identified in patients diagnosed with ulcerative colitis (UC) or Crohn's disease (CD) between 2010 and 2017, and the clinical data of each patient was analyzed. Dual and triple therapy was defined as the simultaneous prescription of two or three of the following drugs: steroids, calcineurin inhibitors, immunomodulators, and biologics.

Results

: During the mean follow-up period (4.6±2.3 years), 84 cases of PJP were identified in 39,462 IBD patients (31 CD and 53 UC). For CD patients, only age at diagnosis >40 years (hazard ratio [HR], 6.12; 95% confidence interval [CI], 1.58 to 23.80) was significantly associated with the risk of PJP, whereas in UC patients, diagnoses of diabetes (HR, 2.51; 95% CI, 1.19 to 5.31) and chronic obstructive pulmonary disease (HR, 3.41; 95% CI, 1.78 to 6.52) showed significant associations with PJP risk. Triple therapy increased PJP risk in both UC (HR, 3.90; 95% CI, 1.54 to 9.88) and CD patients (HR, 5.69; 95% CI, 2.32 to 14.48). However, dual therapy increased PJP risk only in UC patients (HR, 2.53; 95% CI, 1.36 to 4.70). Additionally, 23 patients (27%) received intensive care treatment, and 10 (12%) died within 30 days.

Conclusions

: PJP risk factors differ in CD and UC patients. Considering the potential fatality of PJP, prophylaxis should be considered for at-risk IBD patients.

Deep mutational scanning of Pneumocystis jirovecii dihydrofolate reductase reveals allosteric mechanism of resistance to an antifolate

Pneumocystis jirovecii is a fungal pathogen that causes pneumocystis pneumonia, a disease that mainly affects immunocompromised individuals. This fungus has historically been hard to study because of our inability to grow it in vitro. One of the main drug targets in P. jirovecii is its dihydrofolate reductase (PjDHFR). Here, by using functional complementation of the baker's yeast ortholog, we show that PjDHFR can be inhibited by the antifolate methotrexate in a dose-dependent manner. Using deep mutational scanning of PjDHFR, we identify mutations conferring resistance to methotrexate. Thirty-one sites spanning the protein have at least one mutation that leads to resistance, for a total of 355 high-confidence resistance mutations. Most resistance-inducing mutations are found inside the active site, and many are structurally equivalent to mutations known to lead to resistance to different antifolates in other organisms. Some sites show specific resistance mutations, where only a single substitution confers resistance, whereas others are more permissive, as several substitutions at these sites confer resistance. Surprisingly, one of the permissive sites (F199) is without direct contact to either ligand or cofactor, suggesting that it acts through an allosteric mechanism. Modeling changes in binding energy between F199 mutants and drug shows that most mutations destabilize interactions between the protein and the drug. This evidence points towards a more important role of this position in resistance than previously estimated and highlights potential unknown allosteric mechanisms of resistance to antifolate in DHFRs. Our results offer unprecedented resources for the interpretation of mutation effects in the main drug target of an uncultivable fungal pathogen.

The Development and Evaluation of a Prediction Model for Kidney Transplant-Based Pneumocystis carinii Pneumonia Patients Based on Hematological Indicators

BACKGROUND

This study aimed to develop a simple predictive model for early identification of the risk of adverse outcomes in kidney transplant-associated Pneumocystis carinii pneumonia (PCP) patients.

METHODS

This study encompassed 103 patients diagnosed with PCP, who received treatment at our hospital between 2018 and 2023. Among these participants, 20 were categorized as suffering from severe PCP, and, regrettably, 13 among them succumbed. Through the application of machine learning techniques and multivariate logistic regression analysis, two pivotal variables were discerned and subsequently integrated into a nomogram. The efficacy of the model was assessed via receiver operating characteristic (ROC) curves and calibration curves. Additionally, decision curve analysis (DCA) and a clinical impact curve (CIC) were employed to evaluate the clinical utility of the model. The Kaplan-Meier (KM) survival curves were utilized to ascertain the model's aptitude for risk stratification.

RESULTS

Hematological markers, namely Procalcitonin (PCT) and C-reactive protein (CRP)-to-albumin ratio (CAR), were identified through machine learning and multivariate logistic regression. These variables were subsequently utilized to formulate a predictive model, presented in the form of a nomogram. The ROC curve exhibited commendable predictive accuracy in both internal validation (AUC = 0.861) and external validation (AUC = 0.896). Within a specific threshold probability range, both DCA and CIC demonstrated notable performance. Moreover, the KM survival curve further substantiated the nomogram's efficacy in risk stratification.

CONCLUSIONS

Based on hematological parameters, especially CAR and PCT, a simple nomogram was established to stratify prognostic risk in patients with renal transplant-related PCP.

Molecular Study of Pneumocystis jirovecii in Respiratory Samples of HIV Patients in Chile

Pneumocystis is an opportunistic fungus that causes potentially fatal pneumonia (PCP) in immunocompromised patients. The objective of this study was to determine the prevalence of P. jirovecii in HIV patients through phenotypic and molecular study, to investigate the genetic polymorphisms of P. jirovecii at the mitochondrial gene mtLSU and at the nuclear dihydropteroate synthase gene (DHPS), and by analysis of molecular docking to study the effect of DHPS mutations on the enzymatic affinity for sulfamethoxazole. A PCP prevalence of 28.3% was detected, with mtLSU rRNA genotypes 3 (33.3%) and 2 (26.6%) being the most common. A prevalence of 6.7% (1/15) mutations in the DHPS gene was detected, specifically at codon 55 of the amino acid sequence of dihydropteroate synthase. Molecular docking analysis showed that the combination of mutations at 55 and 98 codons is required to significantly reduce the affinity of the enzyme for sulfamethoxazole. We observed a low rate of mutations in the DHPS gene, and molecular docking analysis showed that at least two mutations in the DHPS gene are required to significantly reduce the affinity of dihydropteroate synthase for sulfamethoxazole.

Computed tomography-based radiomics improves non-invasive diagnosis of Pneumocystis jirovecii pneumonia in non-HIV patients: a retrospective study

BACKGROUND

Pneumocystis jirovecii pneumonia (PCP) could be fatal to patients without human immunodeficiency virus (HIV) infection. Current diagnostic methods are either invasive or inaccurate. We aimed to establish an accurate and non-invasive radiomics-based way to identify the risk of PCP infection in non-HIV patients with computed tomography (CT) manifestation of pneumonia.

METHODS

This is a retrospective study including non-HIV patients hospitalized for suspected PCP from January 2010 to December 2022 in one hospital. The patients were randomized in a 7:3 ratio into training and validation cohorts. Computed tomography (CT)-based radiomics features were extracted automatically and used to construct a radiomics model. A diagnostic model with traditional clinical and CT features was also built. The area under the curve (AUC) were calculated and used to evaluate the diagnostic performance of the models. The combination of the radiomics features and serum β-D-glucan levels was also evaluated for PCP diagnosis.

RESULTS

A total of 140 patients (PCP: N = 61, non-PCP: N = 79) were randomized into training (N = 97) and validation (N = 43) cohorts. The radiomics model consisting of nine radiomic features performed significantly better (AUC = 0.954; 95% CI: 0.898-1.000) than the traditional model consisting of serum β-D-glucan levels (AUC = 0.752; 95% CI: 0.597-0.908) in identifying PCP (P = 0.002). The combination of radiomics features and serum β-D-glucan levels showed an accuracy of 95.8% for identifying PCP infection (positive predictive value: 95.7%, negative predictive value: 95.8%).

CONCLUSIONS

Radiomics showed good diagnostic performance in differentiating PCP from other types of pneumonia in non-HIV patients. A combined diagnostic method including radiomics and serum β-D-glucan has the potential to provide an accurate and non-invasive way to identify the risk of PCP infection in non-HIV patients with CT manifestation of pneumonia.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT05701631).

Molecular Analysis of Dihydropteroate Synthase Gene Mutations in Pneumocystis jirovecii Isolates among Bulgarian Patients with Pneumocystis Pneumonia

Pneumocystis jirovecii pneumonia (PCP) is a significant cause of morbidity and mortality in immunocompromised people. The widespread use of trimethoprim-sulfamethoxazole (TMP-SMZ) for the treatment and prophylaxis of opportunistic infections (including PCP) has led to an increased selection of TMP-SMZ-resistant microorganisms. Sulfa/sulfone resistance has been demonstrated to result from specific point mutations in the DHPS gene. This study aims to investigate the presence of DHPS gene mutations among P. jirovecii isolates from Bulgarian patients with PCP. A total of 326 patients were examined via real-time PCR targeting the P. jirovecii mitochondrial large subunit rRNA gene and further at the DHPS locus. P. jirovecii DNA was detected in 50 (15.34%) specimens. A 370 bp DHPS locus fragment was successfully amplified in 21 samples from 19 PCP-positive patients, which was then purified, sequenced, and used for phylogenetic analysis. Based on the sequencing analysis, all (n = 21) P. jirovecii isolates showed DHPS genotype 1 (the wild type, with the nucleotide sequence ACA CGG CCT at codons 55, 56, and 57, respectively). In conclusion, infections caused by P. jirovecii mutants potentially resistant to sulfonamides are still rare events in Bulgaria. DHPS genotype 1 at codons 55 and 57 is the predominant P. jirovecii strain in the country.

Successful management of concurrent COVID-19 and Pneumocystis Jirovecii Pneumonia in kidney transplant recipients: a case series

BACKGROUND

Pneumocystis pneumonia (PCP) is a life-threatening pulmonary fungal infection that predominantly affects immunocompromised individuals, including kidney transplant recipients. Recent years have witnessed a rising incidence of PCP in this vulnerable population, leading to graft loss and increased mortality. Immunosuppression, which is essential in transplant recipients, heightens susceptibility to viral and opportunistic infections, magnifying the clinical challenge. Concurrently, the global impact of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been profound. Kidney transplant recipients have faced severe outcomes when infected with SARS-CoV-2, often requiring intensive care. Co-infection with COVID-19 and PCP in this context represents a complex clinical scenario that requires precise management strategies, involving a delicate balance between immunosuppression and immune activation. Although there have been case reports on management of COVID-19 and PCP in kidney transplant recipients, guidance on how to tackle these infections when they occur concurrently remains limited.

CASE PRESENTATIONS

We have encountered four kidney transplant recipients with concurrent COVID-19 and PCP infection. These patients received comprehensive treatment that included adjustment of their maintenance immunosuppressive regimen, anti-pneumocystis therapy, treatment for COVID-19 and other infections, and symptomatic and supportive care. After this multifaceted treatment strategy, all of these patients improved significantly and had favorable outcomes.

CONCLUSIONS

We have successfully managed four kidney transplant recipients co-infected with COVID-19 and PCP. While PCP is a known complication of immunosuppressive therapy, its incidence in patients with COVID-19 highlights the complexity of dual infections. Our findings suggest that tailored immunosuppressive regimens, coupled with antiviral and antimicrobial therapies, can lead to clinical improvement in such cases. Further research is needed to refine risk assessment and therapeutic strategies, which will ultimately enhance the care of this vulnerable population.

The Impact of Patient Age and Corticosteroids in Patients With Sulfonamide Hepatotoxicity

INTRODUCTION

Sulfonamides are widely used to treat and prevent various bacterial and opportunistic infections. The aim of this study was to describe the clinical presentation and outcomes of a large cohort of patients with sulfonamide hepatotoxicity.

METHODS

Between 2004 and 2020, 105 patients with hepatotoxicity attributed to trimethoprim/sulfamethoxazole (TMP-SMZ) (n = 93) or other sulfonamides (n = 12) were enrolled. Available liver biopsies were reviewed by a single hepatopathologist.

RESULTS

Among the 93 TMP-SMZ cases, 52% were female, 7.5% younger than 20 years, and the median time to drug-induced liver injury (DILI) onset was 22 days (range: 3-157). Younger patients were significantly more likely to have rash, fever, eosinophilia, and a hepatocellular injury pattern at onset that persisted at the peak of liver injury compared with older patients ( P < 0.05). The 18 (19%) TMP-SMZ patients treated with corticosteroids had more severe liver injury and a higher mortality but a trend toward more rapid normalization of their laboratory abnormalities compared with untreated patients. During follow-up, 6.2% of the TMP-SMZ patients died or underwent liver transplantation. Chronic DILI developed in 20% and was associated with cholestatic injury at onset and higher peak total bilirubin levels.

DISCUSSION

Sulfonamide hepatotoxicity is characterized by a short drug latency with frequent hypersensitivity features at onset. Subject age is an important determinant of the laboratory profile at presentation, and patients with cholestasis and higher total bilirubin levels were at increased risk of developing chronic DILI. Corticosteroids may benefit a subgroup of patients with severe injury, but further studies are needed.

Monitoring, prophylaxis, and treatment of infections in patients with MM receiving bispecific antibody therapy: consensus recommendations from an expert panel

Bispecific antibodies (BsAbs) are emerging as an important novel class of immunotherapeutic agents for the treatment of multiple myeloma (MM), and are set to be more widely used in clinical practice. However, this new class of therapies is associated with a distinct adverse event (AE) profile that includes cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, as well as AEs leading to increased infection risk such as cytopenias and hypogammaglobulinemia, and infections themselves. As preliminary data with this class of agents shows an increased risk of infections as compared with conventional MM treatment regimens, such as immunomodulatory drugs, proteasome inhibitors, and anti-CD38 monoclonal antibodies (mAbs), guidance on infection monitoring, prophylaxis and treatment is required. This review provides consensus recommendations from a panel of 13 global experts, following a meeting in August 2022. The meeting objective was to review existing literature and identify relevant information on infections with all BsAbs in patients with MM, as well as to discuss clinical experience of experts in managing these infections. The recommendations outlined here can be used to guide management of infection risk factors, such as hypogammaglobulinemia and neutropenia. In addition, they can be used to guide the monitoring, prophylaxis, and treatment of bacterial, viral and fungal infections, including emerging infections of interest, such as coronavirus 2019 (COVID-19), and the use of vaccinations prior to and during BsAb treatment. The recommendations have been graded by the panel based on level of data available. Key recommendations include universal herpes simplex and varicella zoster virus prophylaxis, screening for hepatitis B virus reactivation risk in all patients, monthly intravenous immunoglobulin treatment for immunoparesis and in the absence of life-threatening infectious manifestations, use of colony-stimulating factors in patients with Grade 3 neutropenia, universal pneumocystis jirovecii pneumonia prophylaxis and no routine anti-fungal prophylaxis.

Next-generation sequencing technology for the diagnosis of Pneumocystis pneumonia in an immunocompetent female: A case report

BACKGROUND

Pneumocystis pneumonia (PCP) is a serious fungal infection usually seen in patients with human immunodeficiency virus, and it is more frequently found and has a high fatality rate in immunocompromised people. Surprisingly, it rarely occurs in immunocompetent patients. However, the clinical diagnosis of this pathogen is made more difficult by the difficulty of obtaining accurate microbiological evidence with routine tests. This case reports a PCP patient with normal immune function who was diagnosed through next-generation sequencing (NGS).

CASE SUMMARY

A 23-year-old female who had no special disease in the past was admitted to the hospital with a persistent fever and cough. Based on the initial examination results, the patient was diagnosed with bipulmonary pneumonia, and empirical broad-spectrum antibiotic therapy was administered. However, due to the undetermined etiology, the patient's condition continued to worsen. She was transferred to the intensive care unit because of acute respiratory failure. After the diagnosis of Pneumocystis jirovecii infection through NGS in bronchoalveolar lavage fluid and treatment with trimethoprim/sulfamethoxazole and caspofungin, the patient gradually recovered and had a good prognosis.

CONCLUSION

This case emphasizes that, for patients with normal immune function the possibility of PCP infection, although rare, cannot be ignored. NGS plays an important role in the diagnosis of refractory interstitial pneumonia and acute respiratory failure.

Gaining an Understanding of Pneumocystosis in Wales

Pneumocystis pneumonia (PcP) is a serious complication of many significant immunocompromising conditions. Prior incidence estimates in Wales are based on PcP's presentation in the HIV and transplant populations. The objectives were to describe the incidence of PcP in Wales using laboratory reporting measures and assess the impact of underlying immunosuppression cause on mortality. All positive PCR results for PcP between 2015 and 2018 were identified. The total number of unique positives with clinical and radiological correlation was 159 patients, a mean of 39.75 annually. The healthcare records of these patients were reviewed. The mortality at one month was 35.2% and 49.1% at one year. HIV remains the commonest cause of immunosuppression but has lower mortality than non-HIV conditions (12% vs. 59% at one year, p < 0.00001). Non-HIV conditions were categorised as life-threatening and non-life threatening but had a non-significant mortality (66% vs. 54%; p = 0.149), highlighting the negative impact of PcP. An incidence of PcP in Wales of 1.23-1.26 cases per 100,000 has been identified, 32-35% greater than the upper limit previously estimated. There is high mortality in non-HIV patients regardless of immunosuppression cause. A heightened awareness of PcP in these groups will hasten diagnosis and potentially improve mortality.

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.

Pyrimethamine 3D printlets for pediatric toxoplasmosis: design, pharmacokinetics, and anti-toxoplasma activity

OBJECTIVES

The focus of the present research is to develop printlet formulations of pyrimethamine (PMT).

METHODS

Printlets formulation of PMT were developed by screening design by varying laser scanning speed, Kollidon® VA 64, polyvinylpyrrolidone, and disintegrant.

RESULTS

Laser scanning speed, Kollidon® VA, and disintegrant had statistically significant effect on hardness, disintegration time, and/or dissolution (p < 0.05). Dissolution was almost 100% in 30 min. X-ray powder diffraction indicated partial amorphous transformation of the crystalline drug. Pharmacokinetic and anti-toxoplasma activity profiles of the printlets and compressed tablets were superimposable with no statistical difference (p > 0.05).

CONCLUSION

Clinical performance of the printlets would be similar to the compressed tablets.

Pneumocystis pneumonia in COVID-19 patients: A comprehensive review

The admitted patients of intensive care units with coronavirus disease 2019 (COVID-19) meet the challenges of subsequent infections. Opportunistic fungal infections such as Pneumocystis pneumonia (PCP) are among the important factors in the context of COVID-19 patients affecting illness severity and mortality. We reviewed the literature on COVID-19 patients with PCP to identify features of this infection. Although studies confirmed at least the presence of one immunosuppressive condition in half of PCP patients, this disease can also occur in immunocompetent patients who developed the immunosuppressive condition during Covid-19 treatment. The major risk factors associated with COVID-19 patients with PCP can be considered low lymphocyte counts and corticosteroid therapy. Diagnostic and treatment options are complicated by the overlapping clinical and radiologic characteristics of PCP and COVID-19 pneumonia. Therefore, physicians should comprehensively evaluate high-risk patients for PCP prophylaxis.

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.

Strongyloides stercoralis hyperinfection syndrome mimicking pseudomembranous enteritis, complicated by Escherichia coli bacteremia and Pneumocystis jirovecii pneumonia in a patient after immunosuppressive therapy: a case report

Background

Strongyloidiasis, caused by Strongyloides stercoralis (S. stercoralis), is endemic worldwide, especially in countries with warm and humid climates. Strongyloides stercoralis hyperinfection syndrome (SHS) is an extremely serious manifestation of strongyloidiasis, which results from an acute exacerbation of auto-infection and is often fatal.

Case presentation

We present a case of SHS mimicking pseudomembranous enteritis with a final definitive diagnosis of a triple infection including S. stercoralis, Escherchia coli (E. coli) and Pneumocytis jirovecii (P. jirovecii) that occurred in a microscopic polyangiitis (MPA) patient after immunosuppressive therapy. SHS, together with E. coli bacteremia and Pneumocytis jirovecii pneumonia (PJP) in the same patient, is rare in clinical practice, which is first reported worldwide, to our knowledge. After the diagnosis was confirmed, the treatment protocol was quickly adjusted; however, the patient’s life could not be saved.

Conclusion

This case reminds us of the necessity to consider strongyloidiasis as a differential diagnosis in immunocompromised populations who live in or have visited to S. stercoralis endemic areas, especially patients with suspected pseudomembranous enteritis, even if stool examination, serological tests, and eosinophilia are negative. For this group, it is advisable to complete the relevant endoscopy and/or PCR as soon as possible. The fundamental solution to prevent this catastrophic outcome is to implement effective preventive measures at multiple levels, including physicians, patients, and relevant authorities.

Trimethoprim-Sulfamethoxazole (Bactrim) Dose Optimization in Pneumocystis jirovecii Pneumonia (PCP) Management: A Systematic Review

(1) Background: Pneumocystis jirovecii pneumonia (PCP) has a substantial impact on the morbidity and mortality of patients, especially those with autoimmune disorders, thus requiring optimal dosing strategies of Trimethoprim-Sulfamethoxazole (TMP-SMX). Therefore, to ensure the safety of TMP-SMX, there is a high demand to review current evidence in PCP patients with a focus on dose optimization strategies; (2) Methods: Various databases were searched from January 2000 to December 2021 for articles in English, focusing on the dose optimization of TMP-SMX. The data were collected in a specific form with predefined inclusion and exclusion criteria. The quality of each article was evaluated using a Newcastle-Ottawa Scale (NOS) for retrospective studies, Joanna Briggs Institute (JBI) critical checklist for case reports, and Cochrane bias tool for randomized clinical trials (RCTs); (3) Results: Thirteen studies met the inclusion criteria for final analysis. Of the 13 selected studies, nine were retrospective cohort studies, two case reports, and two randomized controlled trials (RCT). Most of the studies compared the high-dose with low-dose TMP-SMX therapy for PCP. We have found that a low dose of TMP-SMX provides satisfactory outcomes while reducing the mortality rate and PCP-associated adverse events. This strategy reduces the economic burden of illness and enhances patients' compliance to daily regimen plan; (4) Conclusions: The large-scale RCTs and cohort studies are required to improve dosing strategies to prevent initial occurrence of PCP or to prevent recurrence of PCP in immune compromised patients.

An overview of using fungal DNA for the diagnosis of invasive mycoses

INTRODUCTION

Fungal PCR has undergone considerable standardization and together with the availability of commercial assays, external quality assessment schemes and extensive performance validation data, is ready for widespread use for the screening and diagnosis of invasive fungal disease (IFD).

AREAS COVERED

Drawing on the experience and knowledge of the leads of the various working parties of the Fungal PCR initiative, this review will address general considerations concerning the use of molecular tests for the diagnosis of IFD, before focussing specifically on the technical and clinical aspects of molecular testing for the main causes of IFD and recent technological developments.

EXPERT OPINION

For infections caused by Aspergillus, Candida and Pneumocystis jirovecii, PCR testing is recommended, combination with serological testing will likely enhance the diagnosis of these diseases. For other IFD (e.g. Mucormycosis) molecular diagnostics, represent the only non-classical mycological approach towards diagnoses and continued performance validation and standardization has improved confidence in such testing. The emergence of antifungal resistance can be diagnosed, in part, through molecular testing. Next-generation sequencing has the potential to significantly improve our understanding of fungal phylogeny, epidemiology, pathogenesis, mycobiome/microbiome and interactions with the host, while identifying novel and existing mechanisms of antifungal resistance and novel diagnostic/therapeutic targets.

Successful treatment of a kidney transplant patient with COVID-19 and late-onset Pneumocystis jirovecii pneumonia

Background

Solid transplant patients are susceptible to Pneumocystis jirovecii pneumonia (PJP). While the vast majority of PJP cases occur within the first 6 months after transplantation, very few PJP cases are seen beyond 1 year post-transplantation (late-onset PJP). PJP and coronavirus disease 2019 (COVID-19, caused by infection with SARS-CoV-2) share quite a few common clinical manifestations and imaging findings, making the diagnosis of PJP often underappreciated during the current COVID-19 pandemic. To date, only 1 case of kidney transplantation who developed COVID-19 and late-onset PJP has been reported, but this patient also suffered from many other infections and died from respiratory failure and multiple organ dysfunction syndrome. A successful treatment of kidney patients with COVID-19 and late-onset PJP has not been reported.

Case presentation

We present a case of a 55-year-old male kidney transplant patient with COVID-19 who also developed late-onset PJP. He received a combined treatment strategy, including specific anti-pneumocystis therapy, symptomatic supportive therapy, adjusted immunosuppressive therapy, and use of antiviral drugs/antibiotics, ending with a favorable outcome.

Conclusions

This case highlights the importance of prompt and differential diagnosis of PJP in kidney transplant patients with SARS-CoV-2 infection. Further studies are required to clarify if kidney transplant patients with COVID-19 could be prone to develop late-onset PJP and how these patients should be treated.

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.

Diagnosis of invasive fungal disease in coronavirus disease 2019: approaches and pitfalls

PURPOSE OF REVIEW

This review will comment on the current knowledge for the diagnosis of the main causes of COVID-19-associated invasive fungal disease (IFD); it will discuss the optimal strategies and limitations and wherever available, will describe international recommendations.

RECENT FINDINGS

A range of secondary IFDs complicating COVID-19 infection have been described and while COVID-19-associated pulmonary aspergillosis was predicted, the presentation of significant numbers of COVID-19-associated candidosis and COVID-19-associated mucormycosis was somewhat unexpected. Given the range of IFDs and prolonged duration of risk, diagnostic strategies need to involve multiple tests for detecting and differentiating various causes of IFD. Although performance data for a range of tests to diagnose COVID-19-associated pulmonary aspergillosis is emerging, the performance of tests to diagnose other IFD is unknown or based on pre-COVID performance data.

SUMMARY

Because of the vast numbers of COVID-19 infections, IFD in COVID-19 critical-care patients represents a significant burden of disease, even if incidences are less than 5%. Optimal diagnosis of COVID-19-associated IFD requires a strategic approach. The pandemic has highlighted the potential impact of IFD outside of the typical high-risk clinical cohorts, given the ever-increasing population at risk of IFD and enhanced surveillance of fungal infections is required.

Evaluation of the Performance of the Associates of Cape Cod STAT Assay for the Diagnosis of Invasive Fungal Disease in Critical-Care Patients with COVID-19

During the COVID-19 pandemic, there have been increasing reports of invasive fungal disease (IFD) in critical care, where rapid access to (1-3)-β-d-glucan (BDG) testing may have enhanced diagnosis. The potential benefit of rapidly accessible BDG results is limited by local availability of BDG testing, with low demand resulting in testing being performed in specialist centers. The recent release of the Associates of Cape Cod STAT assay provides a simple, low-throughput BDG platform, potentially increasing accessibility. During the pandemic, BDG testing using the Fungitell assay (FA) was a critical component of screening for IFD in our critical care. The performance of the STAT was retrospectively determined through a case-control study of 107 serum samples from critical-care COVID-19 patients with IFD defined according to international guidelines. The STAT demonstrated excellent qualitative (observed agreement, 97.2%; kappa, 0.94) and quantitative (Spearman's coefficient, 0.8962) agreement with the FA. Sample positivity was greater (P < 0.0001) in samples from cases (67.7%) versus controls (6.1%). Using the manufacturer's threshold (≥1.2), sensitivity and specificity for the detection of proven/probable IFD were 67.9% and 93.9%, respectively. Using a lower positivity threshold of ≥0.87 increased sensitivity to 71.4% without compromising specificity. When the STAT BDG index was >2.86, specificity was 100%. The STAT provides a simple, comparable alternative to the FA for detecting BDG. Sensitivity is moderate, and specificity is excellent for the diagnosis of IFD in the critical-care COVID-19 patient. The potential for enhancing access to BDG testing through the uptake of STAT at centers where FA is not available is beneficial, especially during the COVID-19 pandemic.

Major pulmonary complications following Hematopoietic stem cell transplantation: What the pulmonologist needs to know

Hematopoietic stem cell transplantation (HSCT) is used for treatment of a myriad of both malignant and non-malignant disorders. However, despite many advances over the years which have resulted in improved patient mortality, this subset of patients remains at risk for a variety of post-transplant complications. Pulmonary complications of HSCT are categorized into infectious and non-infectious and occur in up to one-third of patients undergoing HSCT. Infectious etiologies include bacterial, viral and fungal infections, each of which can have significant mortality if not identified and treated early in the course of infection. Advances in the diagnosis and management of infectious complications highlight the importance of non-infectious pulmonary complications related to chemoradiation toxicities, immunosuppressive drugs toxicities, and graft-versus-host disease. This report aims to serve as a guide and clinical update of pulmonary complications following HSCT for the general pulmonologist who may be involved in the care of these patients.

Narrative review of the relationship between COVID-19 and PJP: does it represent coinfection or colonization?

Background

Pneumocystis jirovecii (P. jirovecii) is increasingly identified on lower respiratory tract specimens of COVID-19 patients. Our narrative review aims to determine whether the diagnosis of pneumocystis jirovecii pneumonia (PJP) in COVID-19 patients represents coinfection or colonization based on the evidence available in the literature. We also discuss the decision to treat COVID-19 patients with coinfection by PJP.

Methods

A literature search was performed through the Pubmed and Web of Science databases from inception to March 10, 2021.

Results

We identified 12 COVID-19 patients suspected to have PJP coinfection. All patients were critically ill and required mechanical ventilation. Many were immunosuppressed from HIV or long-term corticosteroids and other immunosuppressive agents. In both the HIV and non-HIV groups, severe lymphocytopenia was encountered with absolute lymphocyte and CD4+T cell count less than 900 and 200 cells/mm, respectively. The time to PJP diagnosis from the initial presentation was 7.8 (range 2–21) days. Serum lactate dehydrogenase and beta-D-glucan were elevated in those coinfected with PJP. All patients were treated with anti-PJP therapy, predominantly sulfamethoxazole-trimethoprim with corticosteroids. The overall mortality rate was 41.6%, and comparable for both HIV and non-HIV groups.

Conclusion

As the current evidence is restricted to case reports, the true incidence, risk factors, and prognosis of COVID-19 patients with PJP coinfections cannot be accurately determined. Comorbidities of poorly controlled HIV with lymphocytopenia and multiple immunosuppressive therapies are likely predisposing factors for PJP coinfection.

Dapsone-induced methemoglobinemia in pediatrics post-renal transplant

Dapsone has been utilized for the prevention of Pneumocystis jirovecii pneumonia in immunosuppressed patients including pediatric kidney transplant recipients, in whom trimethoprim-sulfamethoxazole (TMP-SMX) is contraindicated. Dapsone adverse effects include methemoglobinemia, but there are no reports of the burden and impact of methemoglobinemia in pediatric kidney recipients that are taking dapsone for PJP prophylaxis. We conducted a retrospective chart review of all pediatric kidney recipients who had received dapsone at any time posttransplant. The indication, duration, and adverse effects of dapsone therapy were assessed. In addition, methemoglobin levels were assessed, and summary statistics performed. Data demonstrated that more than half of the patients on dapsone were not screened for methemoglobinemia. Of those screened, there was a significantly higher acquired-methemoglobinemia (77%) than previously reported in the literature. We also demonstrate significantly more anemia in patients on dapsone. Methemoglobinemia did not affect patient or graft survival and resolved with cessation of dapsone. We conclude that pediatric kidney recipients often develop methemoglobinemia and / or anemia on dapsone. We recommend if pediatric transplant recipients are prescribed dapsone, routine testing for methemoglobinemia and anemia should be done.

Favourable outcome after prolonged veno-venous extracorporeal membrane oxygenation (V-V ECMO) support for Pneumocystis jirovecii pneumonia in a renal transplant recipient

A 27-year-old man, with a history of renal transplantation, presented with acute kidney failure and Pneumocystis jirovecii pneumonia. The patient developed severe acute respiratory failure and required support by veno-venous extracorporeal membrane oxygenation for a total of 59 days. During this period, the patient had extremely low tidal volumes using a lung protective ventilation strategy and intermittent prone positioning was used to optimise oxygenation. There was full recovery of pulmonary and partial recovery of renal function.

Pneumocystis Pneumonia: Immunity, Vaccines, and Treatments

For individuals who are immunocompromised, the opportunistic fungal pathogen Pneumocystis jirovecii is capable of causing life-threatening pneumonia as the causative agent of Pneumocystis pneumonia (PCP). PCP remains an acquired immunodeficiency disease (AIDS)-defining illness in the era of antiretroviral therapy. In addition, a rise in non-human immunodeficiency virus (HIV)-associated PCP has been observed due to increased usage of immunosuppressive and immunomodulating therapies. With the persistence of HIV-related PCP cases and associated morbidity and mortality, as well as difficult to diagnose non-HIV-related PCP cases, an improvement over current treatment and prevention standards is warranted. Current therapeutic strategies have primarily focused on the administration of trimethoprim-sulfamethoxazole, which is effective at disease prevention. However, current treatments are inadequate for treatment of PCP and prevention of PCP-related death, as evidenced by consistently high mortality rates for those hospitalized with PCP. There are no vaccines in clinical trials for the prevention of PCP, and significant obstacles exist that have slowed development, including host range specificity, and the inability to culture Pneumocystis spp. in vitro. In this review, we overview the immune response to Pneumocystis spp., and discuss current progress on novel vaccines and therapies currently in the preclinical and clinical pipeline.

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.

Neumonía por Pneumocystis Jirovecii en paciente adolescente inmunosuprimido no VIH positivo: Un reporte de caso

La neumonía en el paciente inmunocomprometido es un reto diagnóstico al cual el clínico se enfrenta cada vez con más frecuencia , al momento de hablar de infiltrados en vidrio esmerilado es menester tener siempre en cuenta la posibilidad de neumonía por Pneumocystis Jirovecii, que por mucho tiempo se pensó como una enfermedad propia del huésped inmunosuprimido con VIH, a través del tiempo se ha manifestado en pacientes con trasplantes de órgano sólido y de precursores hematopoyéticos, asociado a autoinmunidad, al uso crónico de corticoesteroides y más recientemente al uso de terapia biológicas. La descripción de esta enfermedad y sus métodos diagnósticos en huéspedes inmunosuprimidos no VIH no es del todo claro, sabemos que el tratamiento de elección en estos casos es el trimetropin-sulfametoxazol (TMP-SMX) el cual no cuenta con evidencia de alta calidad al momento de plantear una dosis ni un tiempo de duración establecidos. Presentamos el caso de un paciente con diagnóstico de glomerulonefritis por enfermedad de cambios mínimos corticodependiente y quien desarrolló neumonía por Pneumocystis Jirovecii confirmada por histopatología quien recibió tratamiento y tuvo un desenlace positivo.

Dapsone for Pneumocystis jirovecii pneumonia prophylaxis - applying theory to clinical practice with a focus on drug interactions

Pneumocystis jirovecii pneumonia (PJP) is a potentially life-threatening infection that occurs in immunocompromised individuals. The incidence can be as high as 80% in some groups but can be reduced to less than 1% with appropriate prophylaxis. HIV-infected patients with a low CD4 count are at the highest risk of PJP. Others at substantial risk include haematopoietic stem cell and solid organ transplant recipients, those with cancer (particularly haematologic malignancies), and those receiving glucocorticoids, chemotherapeutic agents, and other immunosuppressive medications. Trimethoprim-sulfamethoxazole is an established first-line line agent for prevention and treatment of PJP. However, in some situations, this medication cannot be used and dapsone is considered a suitable cost-effective second line agent. However, information on potential interactions with drugs commonly used in immunosuppressed patients is lacking or contradictory. In this this article we review the metabolic pathway of dapsone with a focus on interactions and clinical significance particularly in patients with haematological malignancies. An understanding of this process should optimise the use of this agent.

Clinical Characteristics of Pneumocystis Pneumonia After Parental Renal Transplantation

Purpose

To analyze the clinical characteristics of Pneumocystis pneumonia (PCP) in renal transplant recipients, identify early sensitivity indicators, and optimize clinical strategies.

Patients and Methods

We retrospectively analyzed clinical data for 24 patients with confirmed PCP who underwent renal transplantation (RT) between 2010 and 2019, encompassing a mean follow-up of 29 (range, 11-49) d.

Results

A 71% incidence was observed for PCP during the first 6 months after RT. Progressive dyspnea (79%) was the most common symptom, followed by fever (75%) and dry cough (67%). In the initial phase of PCP, the most frequent computerized tomography (CT) finding was the presence of symmetric, apically distributed ground-glass opacities. Nine of 11 patients (82%) were diagnosed by induced sputum testing, 14 of 17 (82%) by bronchoalveolar lavage, and 1 of 24 (4%) by sputum smear. The 1,3-β-D-glucan level was elevated (mean, 259.16 ± 392.34 pg/mL) in 80% of patients, while 75% had elevated C-reactive protein levels (median, 37.85 mg/L). Two of 18 patients (11%) were positive for cytomegalovirus. All patients were treated with trimethoprim-sulfamethoxazole (3 doses of 1-6 g/kg) and third-generation cephalosporin or moxifloxacin monotherapy to prevent bacterial infection. The methylprednisolone dose (40-400 mg/d) varied according to illness. Most patients were treated using a nasal cannula or oxygen mask, and 2 by mechanical ventilation. CT showed improved lesions after treatment, and completely absorbed lesions or residual fibrosis at follow-up. The mean hospitalization cost was 14,644.73 ± 11,101.59 RMB.

Conclusion

Peak PCP incidence occurred during the first 6 months after surgery. Progressive dyspnea, fever, and dry cough are important indicators for PCP. Bilateral and diffuse ground-glass opacities involving both lung apexes are often the first indication for PCP diagnosis. Induced sputum testing may be the method-of-choice for pathogen detection. The cure rate can be improved through early antipathogen, glucocorticoid, and preventive anti-infection therapies, as well as respiratory support.

Pneumocystis pneumonia in a treatment-naive rheumatoid arthritis patient

A HIV-negative, newly diagnosed patient with rheumatoid arthritis (RA) was found to have pneumocystis jiroveci pneumonia. The infection was treated with three weeks of atovaquone and corticosteroids. Clinicians should be aware of pneumocystis pneumonia as an infection in RA patients not receiving treatment.

Vanishing bile duct syndrome arising in a patient with HIV infection sequentially treated with trimethoprim/sulfamethoxazole and dapsone

Trimethoprim/sulfamethoxazole is well known to cause intra-hepatic cholestasis which in rare instances can be prolonged and lead to vanishing bile duct syndrome. The risk regarding the potential for cross-reactivity between structurally related molecules such as dapsone and trimethoprim/sulfamethoxazole in causing hepatotoxicity is scarce. Herein, we report a case of vanishing bile duct syndrome following dapsone use in a patient with HIV infection and a recent history of trimethoprim/sulfamethoxazole-induced cholestasis. The patient had severe and protracted cholestasis during 2 years of follow-up and eventually died of liver failure.

Pneumocystis jirovecii pneumonia at chest High-resolution Computed Tomography (HRCT) in non-HIV immunocompromised patients: Spectrum of findings and mimickers

Pneumocystis jirovecii pneumonia (PJP) has emerged as a main issue in non Human Immunodeficiency Virus (HIV) immunocompromised hosts, exposing patients to high mortality rates, especially when the diagnosis is delayed. Since microbiological confirmation is often unfeasible or difficult to obtain, High-resolution Computed Tomography (HRCT) represents a main tool for guiding the diagnosis in the appropriate clinical scenario. Nevertheless, radiologists must be aware that PJP at HRCT is a multifaceted process, with a variety of common and less frequent findings, along with a broad spectrum of infectious (e.g., viral and certain fungal and bacterial pneumonias) and non-infectious (e.g., pulmonary oedema, diffuse alveolar haemorrhage, and drug toxicity) differential diagnoses. In this review we resume background clinical information on PJP in non-HIV immunocompromised patients, illustrate both typical and less frequent HRCT findings, and present the spectrum of infectious and non-infectious mimickers at HRCT, highlighting the similarities with PJP and providing clues for the differential diagnosis.