Leukotriene B4-induced neutrophil extracellular traps impede the clearance of Pneumocystis.

Pneumocystis pneumonia (PCP) is a fungal pulmonary disease with high mortality in immunocompromised patients. Neutrophils are essential in defending against fungal infections; however, their role in PCP is controversial. Here we aim to investigate the effects of neutrophil extracellular traps (NETs) on Pneumocystis clearance and lung injury using a mouse model of PCP. Intriguingly, although neutrophils play a fundamental role in defending against fungal infections, NETs failed to eliminate Pneumocystis, but instead impaired the killing of Pneumocystis. Mechanically, Pneumocystis triggered Leukotriene B4 (LTB4)-dependent neutrophil swarming, leading to agglutinative NET formation. Blocking Leukotriene B4 with its receptor antagonist Etalocib significantly reduced the accumulation and NET release of neutrophils in vitro and in vivo, enhanced the killing ability of neutrophils against Pneumocystis, and alleviated lung injury in PCP mice. This study identifies the deleterious role of agglutinative NETs in Pneumocystis infection and reveals a new way to prevent NET formation, which provides new insights into the pathogenesis of PCP.

CD40 Expression by B cells is Required for Optimal Immunity to Murine Pneumocystis Infection.

CD40-CD40L interactions are critical for controlling Pneumocystis infection. However, which CD40-expressing cell populations are important for this interaction have not been well-defined. We used a cohousing mouse model of Pneumocystis infection, combined with flow cytometry and qPCR, to examine the ability of different populations of cells from C57BL/6 mice to reconstitute immunity in CD40 knockout (KO) mice. Unfractionated splenocytes, as well as purified B cells, were able to control Pneumocystis infection, while B cell depleted splenocytes and unstimulated bone-marrow derived dendritic cells (BMDCs) were unable to control infection in CD40 KO mice. Pneumocystis antigen-pulsed BMDCs showed early, but limited, control of infection. Consistent with recent studies that have suggested a role for antigen presentation by B cells, using cells from immunized animals, B cells were able to present Pneumocystis antigens to induce proliferation of T cells. Thus, CD40 expression by B cells appears necessary for robust immunity to Pneumocystis.

Adjunctive glucocorticoid therapy for Pneumocystis jirovecii pneumonia in solid organ transplant recipients: A multicenter cohort, 2015-2020.

Solid organ transplant recipients (SOTRs) frequently receive adjunctive glucocorticoid therapy (AGT) for Pneumocystis jirovecii pneumonia (PJP). This multicenter cohort of SOTRs with PJP admitted to 20 transplant centers in Canada, the United States, Europe, and Australia, was examined for whether AGT was associated with a lower rate of all-cause intensive care unit (ICU) admission, 90-day death, or a composite outcome (ICU admission or death). Of 172 SOTRs with PJP (median [IQR] age: 60 (51.5-67.0) years; 58 female [33.7%]), the ICU admission and death rates were 43.4%, and 20.8%, respectively. AGT was not associated with a reduced risk of ICU admission (adjusted odds ratio [aOR] [95% CI]: 0.49 [0.21-1.12]), death (aOR [95% CI]: 0.80 [0.30-2.17]), or the composite outcome (aOR [95% CI]: 0.97 [0.71-1.31]) in the propensity score-adjusted analysis. AGT was not significantly associated with at least 1 unit of the respiratory portion of the Sequential Organ Failure Assessment score improvement by day 5 (12/37 [32.4%] vs 39/111 [35.1%]; P = .78). We did not observe significant associations between AGT and ICU admission or death in SOTRs with PJP. Our findings should prompt a reevaluation of routine AGT administration in posttransplant PJP treatment and highlight the need for interventional studies.

18q Deletion Syndrome Presenting with Late-Onset Combined Immunodeficiency.

Patients with chromosome 18q deletion syndrome generally experience hypogammaglobulinemia. Herein, we describe two patients with chromosome 18q deletion syndrome who presented with late-onset combined immune deficiency (LOCID), which has not been previously reported. Patient 1 was a 29-year-old male with 18q deletion syndrome, who was being managed for severe motor and intellectual disabilities at the Yamabiko Medical Welfare Center for 26 years. Although the patient had few infections, he developed Pneumocystis pneumonia at the age of 28. Patient 2, a 48-year-old female with intellectual disability and congenital malformations, was referred to Tokyo Medical and Dental University Hospital with abnormal bilateral lung shadows detected on her chest radiography. Computed tomography showed multiple lymphadenopathies and pneumonia. A lymph node biopsy of the inguinal region revealed granulomatous lymphadenitis, and a chromosomal examination revealed 18q deletion. Array-based genomic hybridization analysis revealed deletion at 18q21.32-q22.3 for patient 1 and at 18q21.33-qter for patient 2. Immune status work-up of the two patients revealed panhypogammaglobulinemia, decreased number of memory B cells and naïve CD4+ and/or CD8+ cells, reduced response on the carboxyfluorescein diacetate succinimidyl ester T-cell division test, and low levels of T-cell receptor recombination excision circles and Ig κ-deleting recombination excision circles. Consequently, both patients were diagnosed with LOCID. Although patients with 18q deletion syndrome generally experience humoral immunodeficiency, the disease can be further complicated by cell-mediated immunodeficiency, causing combined immunodeficiency. Therefore, patients with 18q deletion syndrome should be regularly tested for cellular/humoral immunocompetence.

Dynamics of host immune responses and a potential function of Trem2hi interstitial macrophages in Pneumocystis pneumonia.

BACKGROUND: Pneumocystis pneumonia (PCP) is a life-threatening opportunistic fungal infection with a high mortality rate in immunocompromised patients, ranging from 20 to 80%. However, current understanding of the variation in host immune response against Pneumocystis across different timepoints is limited. METHODS: In this study, we conducted a time-resolved single-cell RNA sequencing analysis of CD45+ cells sorted from lung tissues of mice infected with Pneumocystis. The dynamically changes of the number, transcriptome and interaction of multiply immune cell subsets in the process of Pneumocystis pneumonia were identified according to bioinformatic analysis. Then, the accumulation of Trem2hi interstitial macrophages after Pneumocystis infection was verified by flow cytometry and immunofluorescence. We also investigate the role of Trem2 in resolving the Pneumocystis infection by depletion of Trem2 in mouse models. RESULTS: Our results characterized the CD45+ cell composition of lung in mice infected with Pneumocystis from 0 to 5 weeks, which revealed a dramatic reconstitution of myeloid compartments and an emergence of PCP-associated macrophage (PAM) following Pneumocystis infection. PAM was marked by the high expression of Trem2. We also predicted that PAMs were differentiated from Ly6C+ monocytes and interacted with effector CD4+ T cell subsets via multiple ligand and receptor pairs. Furthermore, we determine the surface markers of PAMs and validated the presence and expansion of Trem2hi interstitial macrophages in PCP by flow cytometry. PAMs secreted abundant pro-inflammation cytokines, including IL-6, TNF-α, GM-CSF, and IP-10. Moreover, PAMs inhibited the proliferation of T cells, and depletion of Trem2 in mouse lead to reduced fungal burden and decreased lung injury in PCP. CONCLUSION: Our study delineated the dynamic transcriptional changes in immune cells and suggests a role for PAMs in PCP, providing a framework for further investigation into PCP's cellular and molecular basis, which could provide a resource for further discovery of novel therapeutic targets.

MiR-150 levels are related to in-hospital mortality in non-HIV Pneumocystis pneumonia patients.

Pneumocystis pneumonia (PCP) is a common opportunistic infection that occurs in immunocompromised patients. Compared with HIV patients, PCP in non-HIV patients tends to follow up a more urgent course and poorer prognosis. Therefore, markers that could predict survival of PCP patients in non-HIV population are of great value. MiRNA-150 has been widely studied in many diseases since it has been identified as a vital regulator of immune cell differentiation and activation. We thus conduct this study aiming to evaluate the prognostic value of miR-150 level in non-HIV PCP. First, the expression levels of miR-150 were compared between PCP patients and healthy volunteers. The miR-150 levels in immune cells were also detected in PCP mouse models. Then the prognostic value of miR-150 was further assessed in another PCP population (n = 72). The expression levels of miR-150 were measured by reverse transcription real-time PCR (RT-PCR) technique. Our data demonstrated significantly decreased miR-150 expression levels in PCP patients and mouse models compared to controls. The miR-150 levels also decreased in various immune cells of PCP mouse models. With a cut-off value of 3.48, the area under the curve, sensitivity, specificity of miR-150 to predicate PCP mortality were 0.845, 68.2% and 96.0%, respectively. In conclusion, miR-150 expression value might serve as a potential biomarker to identify PCP patients at high risk of death.

Pneumocystis pneumonia (PCP) remains a fatal risk for immunosuppressed patients. MiR-150 takes part in immune regulation, and thus is involved in infection control. Our study indicated that the miR-150 expression may act as a potential biomarker for predicting mortality of PCP patients.

High prevalence of pneumocystis pneumonia in interstitial lung disease: a retrospective study.

BACKGROUND: Interstitial lung disease (ILD) is a new risk category for pneumocystis pneumonia (PCP) with a high mortality rate. The definite diagnostic criteria of PCP in ILD patients have not been established until now. The aims of this study were to identify potential risk factors of PCP in patients with ILD, and to evaluate the performance of metagenomic next-generation sequencing (mNGS), CD4 + T cell count, (1-3)-ß-D-Glucan (BG) and lactate dehydrogenase (LDH) in the diagnosis of PCP in ILD patients. METHODS: This is a retrospective, single-center, case-control study. ILD patients who underwent mNGS from December 2018 to December 2022 were included in the study. Based on the diagnosis criteria of PCP, these patients were divided into PCP-ILD and non-PCP-ILD groups. The potential risk factors for PCP occurrence in ILD patients were analysed via logistic regression. The diagnostic efficacy of mNGS was compared with serological biomarkers. RESULTS: 92 patients with ILD were enrolled, 31 of which had a definite PCP and were assigned to the PCP-ILD group while 61 were to the non-PCP-ILD group. The infection rate of PJ in ILD patients was 33.7% (31/92). The history of glucocorticoid therapy, CD4 + T cell count, BG level and traction bronchiectasis on HRCT were associated with PCP occurrence in ILD patients. LDH level did not reach statistical significance in the logistic regression analysis. mNGS was confirmed as the most accurate test for PCP diagnosis in ILD patients. CONCLUSION: ILD is a new risk group of PCP with high PCP prevalence. Clinicians should pay close attention to the occurrence of PCP in ILD patients who possess the risk factors of previous glucocorticoid therapy, decreased CD4 + T cell count, increased BG level and absence of traction bronchiectasis on HRCT. mNGS showed the most excellent performance for PCP diagnosis in ILD patients. Peripheral blood CD4 + T cell count and BG level are alternative diagnostic methods for PCP in ILD patients. However, the diagnostic value of serum LDH level was limited in ILD patients.

Outcome of Pneumocystis pneumonia in transplant and non-transplant HIV-negative immunocompromised patients.

BACKGROUND: Previous studies showed HIV-negative immunocompromised patients are susceptible to Pneumocystis pneumonia (PCP). However, the PCP outcome has not been compared among HIV-negative immunocompromised patients. METHODS: In this retrospective cohort study at the University Health Network, we included all HIV-negative immunocompromised patients who fulfilled the European Organization for Research and Treatment of Cancer (EORTC) PCP diagnosis criteria from December 2018 to December 2019. We compared the demographics, comorbidities, course of illness, and PCP outcome (28-day mortality and composite outcome [i.e., death or intensive care unit (ICU) admission]) between solid organ transplant (SOT) and non-SOT patients. RESULTS: Of 160 non-HIV patients with PCP diagnoses, 118 patients fulfilled EORTC criteria (76 males [64.4%], median [range] age: 65.5 [21-87] years). PCP presentation in SOT recipients (n = 14) was more severe than non-SOT patients (n = 104): acute presentation (onset <7 days before admission: 11/14 [78.6%] vs. 51/104 [56%], p = .037), shortness of breath (100% vs. 75/104 [74.3%], p = .037), median [range] O2 saturation (88% [75%, 99%] vs. 92%[70%, 99%], p = .040), and supplemental O2 requirement (12/14 [85.7%] vs. 59/104 [56.7%], p = .044). The mortality [4/14, (28.6%) vs. 15/104 (14.4%), p = .176], ICU admission (10/14 [71.4%] vs. 18/104 [17.3%], p < .0001), and mechanical ventilation (8/14 [57.1%] vs. 18/104 [17.3%], p = .0007) in SOT patients was different from non-SOT patients. In multivariable analysis, SOT recipients were at greater risk of composite outcome than non-SOT patients (aOR [CI95%]: 12.25 [3.08-48.62], p < .001). CONCLUSION: PCP presentation and outcomes in SOT recipients are more severe than in non-SOT patients. Further studies are required to explore the biological reasons for this difference.

Pulmonary co-infections by Pneumocystis jirovecii and Herpesviridae: a seven-year retrospective study.

BACKGROUND: Pneumocystis jirovecii (P. jirovecii) is an opportunistic fungus responsible for Pneumocystis pneumonia (PCP) in deeply immunocompromised patients and for pulmonary colonization in individuals with mild immunosuppression or impaired respiratory function. PCP and Cytomegalovirus (CMV) co-infections have been widely described whereas those involving other Herpesviruses (HVs) such as Epstein-Barr virus (EBV), Herpes simplex virus type 1 and type 2 (HSV-1 and -2), and Varicella zoster virus (VZV) remain scarce. To date, no data are available concerning HVs co-infections in P. jirovecii colonization. METHODS: Our main objective was to evaluate the frequency of HVs in bronchoalveolar lavage fluid (BALF) samples from patients with PCP or with pulmonary colonization. The secondary objective was to assess the relationship between HVs and the mortality rate in PCP patients. A retrospective single-center study over a seven-year period was conducted. All patients with P. jirovecii detected using PCR in a BALF sample and for whom a PCR assay for HVs detection was performed were included in the study. RESULTS: One hundred and twenty-five patients were included, corresponding to 77 patients with PCP and 48 colonized patients. At least one HV was detected in 54/77 (70.1%) PCP patients and in 28/48 (58.3%) colonized patients. EBV was the most frequent in both groups. Furthermore, the 30-day survival rate in PCP patients was significantly lower with [EBV + CMV] co-infection than that with EBV co-infection, [EBV + HSV-1] co-infection and without HV co-infection. CONCLUSION: Our results show that the frequency of HV, alone or in combination is similar in PCP and colonization. They also suggest that [EBV + CMV] detection in BALF samples from PCP patients is associated with an increased mortality rate, underlying the significance to detect HVs in the course of PCP.

Sulfamethoxazole-trimethoprim for pneumocystis pneumonia prophylaxis, causes of discontinuation and thrombocytopenia observed during administration: A single-center retrospective study.

INTRODUCTION: The development of pneumocystis pneumonia (PCP) has recently become a growing concern; thus, its prevention has become increasingly important. Sulfamethoxazole-trimethoprim (ST) is a cost-effective first-line and prophylactic treatment for PCP. However, ST administration criteria for PCP prophylaxis remain unclear and are often discontinued because of adverse events (AEs). In this study, we aimed to investigate the causes of ST discontinuation and the associated AEs using objective data. METHODS: We retrospectively analyzed the data of 162 patients admitted to Kansai Medical University Hospital between January 2018 and December 2020, who received ST for PCP prophylaxis. We compared clinical characteristics, laboratory data, and incidence of AEs between ST non-discontinuation and ST discontinuation groups. Additionally, we divided the patients into non-developing and developing thrombocytopenia (≥ Grade 1) groups based on the investigation results. RESULTS: No patients developed PCP while receiving ST. The most common causes of ST discontinuation were thrombocytopenia (37%), liver dysfunction (20%), and rash (18%). Multivariate analysis revealed thrombocytopenia (≥ Grade 1) as a factor significantly associated with ST discontinuation. Furthermore, we identified three factors correlated with thrombocytopenia (≥ Grade 1): age ≥50 years, lymphocyte count <1000/µL, and platelet count <180,000/µL. CONCLUSIONS: Patients with the aforementioned factors are at higher risk of developing thrombocytopenia (≥ Grade 1) during ST administration for PCP prophylaxis. Therefore, platelet count monitoring is essential to enhance safety and efficacy of ST treatment. Nonetheless, further research is warranted to explore additional implications and interventions.

Seronegative HIV-1 infection in a Japanese man presenting with Pneumocystis pneumonia: Analysis of long-term antibody response and literature review.

Seronegative human immunodeficiency virus (HIV) infection, where an HIV-specific antibody response is lacking even in chronic or late-stage HIV infections, is extremely rare. Here, we report the case of a 50-year-old Japanese man presenting with Pneumocystis pneumonia who did not produce antibodies against HIV-1 until the initiation of antiretroviral therapy (ART). Fourth-generation antigen-antibody testing temporarily reverted from weakly positive to negative soon after initiating ART, likely due to a reduction in viral load (assessed by p24 antigen levels). His HIV-1 antibody titers remained low or indeterminate even after four years of ART. A literature review suggested that the absence of HIV-1-specific antibody production may be associated with unimpeded HIV replication and rapid CD4+ T cell decline. Seronegative HIV infection can lead to deferred diagnosis and treatment, thereby increasing the risk of transmitting the virus to others or developing opportunistic illnesses. It is important to combine multiple tests for diagnosis, depending on the medical condition. Further studies are required to investigate the host factors involved in the production of HIV-1-specific antibodies.

Description of a Murine Model of Pneumocystis Pneumonia.

Pneumocystis pneumonia is a serious lung infection caused by an original ubiquitous fungus with opportunistic behavior, referred to as Pneumocystis jirovecii. P. jirovecii is the second most common fungal agent among invasive fungal infections after Candida spp. Unfortunately, there is still an inability to culture P. jirovecii in vitro, and so a great impairment to improve knowledge on the pathogenesis of Pneumocystis pneumonia. In this context, animal models have a high value to address complex interplay between Pneumocystis and the components of the host immune system. Here, we propose a protocol for a murine model of Pneumocystis pneumonia. Animals become susceptible to Pneumocystis by acquiring an immunocompromised status induced by iterative administration of steroids within drinking water. Thereafter, the experimental infection is completed by an intranasal challenge with homogenates of mouse lungs containing Pneumocystis murina. The onset of clinical signs occurs within 5 weeks following the infectious challenge and immunosuppression can then be withdrawn. At termination, lungs and bronchoalveolar lavage (BAL) fluids from infected mice are analyzed for fungal load (qPCR) and immune response (flow cytometry and biochemical assays). The model is a useful tool in studies focusing on immune responses initiated after the establishment of Pneumocystis pneumonia.

Treatment With Reduced-Dose Trimethoprim-Sulfamethoxazole Is Effective in Mild to Moderate Pneumocystis jirovecii Pneumonia in Patients With Hematologic Malignancies.

BACKGROUND: Recent studies have reported that reduced-dose trimethoprim-sulfamethoxazole (TMP-SMX) may be effective in the treatment of Pneumocystis jirovecii pneumonia (PJP), but data are lacking for patients with hematologic malignancies. METHODS: This retrospective study included all adult hematologic patients with PJP between 2013 and 2017 at 6 Swedish university hospitals. Treatment with 7.5-15 mg TMP/kg/day (reduced dose) was compared with >15-20 mg TMP/kg/day (standard dose), after correction for renal function. The primary outcome was the change in respiratory function (Δpartial pressure of oxygen [PaO2]/fraction of inspired oxygen [FiO2]) between baseline and day 8. Secondary outcomes were clinical failure and/or death at day 8 and death at day 30. RESULTS: Of a total of 113 included patients, 80 patients received reduced dose and 33 patients received standard dose. The overall 30-day mortality in the whole cohort was 14%. There were no clinically relevant differences in ΔPaO2/FiO2 at day 8 between the treatment groups, either before or after controlling for potential confounders in an adjusted regression model (-13.6 mm Hg [95% confidence interval {CI}, -56.7 to 29.5 mm Hg] and -9.4 mm Hg [95% CI, -50.5 to 31.7 mm Hg], respectively). Clinical failure and/or death at day 8 and 30-day mortality did not differ significantly between the groups (18% vs 21% and 14% vs 15%, respectively). Among patients with mild to moderate pneumonia, defined as PaO2/FiO2 >200 mm Hg, all 44 patients receiving the reduced dose were alive at day 30. CONCLUSIONS: In this cohort of 113 patients with hematologic malignancies, reduced-dose TMP-SMX was effective and safe for treating mild to moderate PJP.

Efficacy of initial caspofungin plus trimethoprim/sulfamethoxazole for severe PCP in patients without human immunodeficiency virus infection.

BACKGROUND: The number of pneumocystis pneumonia (PCP) cases is increasing in immunocompromised patients without human immunodeficiency virus infection (HIV), causing serious morbidity with high mortality. Trimethoprim/sulfamethoxazole (TMP/SMZ) monotherapy has limited effectiveness in the treatment of PCP. Clinical data on whether initial caspofungin plus TMP/SMZ for this disease is superior to monotherapy in non-HIV-infected patients are limited. We aimed to compare the clinical effectiveness of these regimens for severe PCP in non-HIV patients. METHODS: A retrospective study reviewed 104 non-HIV-infected patients with confirmed PCP in the intensive care unit between January 2016 and December 2021. Eleven patients were excluded from the study because TMP/SMZ could not be used due to severe hematologic disorders or clinical data were missing. All enrolled patients were divided into three groups according to different treatment strategies: Group 1 received TMP/SMZ monotherapy, Group 2 received caspofungin combined with TMP/SMZ as first-line therapy, and Group 3 initially received TMP/SMZ monotherapy and later received caspofungin as salvage therapy. The clinical characteristics and outcomes were compared among the groups. RESULTS: A total of 93 patients met the criteria. The overall positive response rate of anti-PCP treatment was 58.06%, and the overall 90-day all-cause mortality rate was 49.46%. The median APACHE II score was 21.44. The concurrent infection rate was 74.19%, among whom 15.05% (n = 14) of those patients had pulmonary aspergillosis, 21.05% (n = 20) had bacteremia, and 23.65% (n = 22) had CMV infections. The patients who received initial caspofungin combination with TMP/SMZ had the best positive response rate (76.74%) compared to others (p = 0.001). Furthermore, the group that received initial caspofungin combined with TMP/SMZ had a 90-day all-cause mortality rate (39.53%) that was significantly different from that of the shift group (65.51%, p = 0.024), but this rate showed no statistically significant difference compared with that in the monotherapy group (48.62%, p = 0.322). None of the patients had serious adverse events from caspofungin therapy. CONCLUSIONS: For non-HIV-infected patients with severe PCP, initial combination therapy with caspofungin and TMP/SMZ is a promising first-line treatment option compared with TMP/SMZ monotherapy and combination therapy as salvage therapy.

Relationship between clinical features and droplet digital PCR copy number in non-HIV patients with pneumocystis pneumonia.

OBJECTIVE: Droplet digital PCR (ddPCR) is a novel assay to detect pneumocystis jjrovecii (Pj) which has been defined to be more sensitive than qPCR in recent studies. We aimed to explore whether clinical features of pneumocystis pneumonia (PCP) were associated with ddPCR copy numbers of Pj. METHODS: A total of 48 PCP patients were retrospectively included. Pj detection was implemented by ddPCR assay within 4 h. Bronchoalveolar fluid (BALF) samples were collected from 48 patients with molecular diagnosis as PCP via metagenomic next generation sequencing (mNGS) or quantitative PCR detection. Univariate and multivariate logistic regression were performed to screen out possible indicators for the severity of PCP. The patients were divided into two groups according to ddPCR copy numbers, and their clinical features were further analyzed. RESULTS: Pj loading was a pro rata increase with serum (1,3)-beta-D glucan, D-dimmer, neutrophil percentage, procalcitonin and BALF polymorphonuclear leucocyte percentage, while negative correlation with albumin, PaO2/FiO2, BALF cell count, and BALF lymphocyte percentage. D-dimmer and ddPCR copy number of Pj were independent indicators for moderate/severe PCP patients with PaO2/FiO2 lower than 300. We made a ROC analysis of ddPCR copy number of Pj for PaO2/FiO2 index and grouped the patients according to the cut-off value (2.75). The high copy numbers group was characterized by higher level of inflammatory markers. Compared to low copy number group, there was lower level of the total cell count while higher level of polymorphonuclear leucocyte percentage in BALF in the high copy numbers group. Different from patients with high copy numbers, those with high copy numbers had a tendency to develop more severe complications and required advanced respiratory support. CONCLUSION: The scenarios of patients infected with high ddPCR copy numbers of Pj showed more adverse clinical conditions. Pj loading could reflect the severity of PCP to some extent.

Extrapulmonary Pneumocystis jirovecii infection in an advanced HIV-infected patient: A case report and literature review.

BACKGROUND: Pneumocystis jirovecii infection is the most common opportunistic infection that causes pneumonia in human immunodeficiency virus (HIV)-infected patients; however, extrapulmonary P. jirovecii infection is extremely rare after the use of antiretroviral therapy. Here, we present the second reported case of paraspinal mass caused by P. jirovecii infection in an advanced HIV-infected patient. CASE PRESENTATION: A 45-year-old woman presented with dyspnea on exertion, and significant weight loss within the preceding 4 months. Initial complete blood count (CBC) findings revealed pancytopenia with a hemoglobin (Hb) level of 8.9 g/dL, a white blood cell (WBC) count of 2180 cells/mm3 with 68% neutrophils, and a platelet count of 106,000 cells/mm3. Anti-HIV was positive with an absolute cluster of differentiation 4 (CD4) count of 16 cells/ mm3. A computed tomography scan of the chest revealed an enhancing soft tissue mass-like lesion at the right paravertebral region (T5-T10 level) and a thick-walled cavity lesion at the left lower lung. A CT-guided biopsy of the paravertebral mass was performed and histopathology revealed granulomatous inflammation consisting of dense aggregates of epithelioid cells and macrophages, and scattered foci of pink foamy to granular materials amidst the granulomatous inflammation. Gomori methenamine silver (GMS) staining revealed thin cystic-like structures (ascus) that were observed to be morphologically consistent with P. jirovecii. Molecular identification and DNA sequencing from the paraspinal mass was 100% identical to P. Jirovecii. The patient was successfully treated with oral trimethoprim-sulfamethoxazole for 3 weeks and antiretroviral therapy (ART) with tenofovir (TDF), lamivudine (3TC), and dolutegravir (DTG). A follow-up CT scan of the chest at 2 months after treatment showed a decrease in sizes of both the paravertebral mass and the cavitary lung lesion. CONCLUSIONS: Extrapulmonary pneumocystosis (EPCP) has become an extremely rare condition in HIV-infected patients after the widespread use of ART. EPCP should be considered in ART-naive HIV-infected patients suspected of having or diagnosed with Pneumocystis jirovecii pneumonia who present with atypical symptoms and/or signs. Histopathologic examination with GMS staining of affected tissue is necessary for the diagnosis of EPCP.

A single-center, person-month-based analysis of the risk of developing Pneumocystis pneumonia (PCP) in immunosuppressed non-HIV patients: Preventive effects of trimethoprim-sulfamethoxazole.

OBJECTIVE: We performed a retrospective study to evaluate the risk factors for acquiring Pneumocystis pneumonia (PCP) by pharmacologically immunosuppressed HIV-negative patients. METHODS: Patients who received corticosteroids, immunosuppressive agents, anticancer agents, and radiotherapy with or without trimethoprim-sulfamethoxazole (TMP-SMX) at Himeji Medical Center between 2010 and 2021 were evaluated. Drugs and doses of the treatments for each patient were divided by month into person-month units. Each person-month datum includes information on the administered drug (or radiotherapy), average doses, and whether the patient had PCP during the corresponding month. ROC curves with person-month data were generated for each treatment, and AUCs >0.7 were identified as possessing positive classification utility. The risks for PCP according to gender, age (grouped by median) and each treatment were examined by univariate analysis, followed by multivariate analysis to identify independent factors. RESULTS: Of a total of 17,733 patients (214,676 person-months), 32 developed PCP. The cut-off values by ROC analysis were 13.7 mg/day for corticosteroid (prednisolone equivalent), 0.92 mg/day (6.45 mg/week) for methotrexate (MTX), and 34.3 mg/day for TMP-SMX. The cut-off values for other treatments could not be estimated. The above three drugs and male sex were significant variables in univariate analysis and were all confirmed as independent factors by multivariate analysis. CONCLUSION: The results suggest that a monthly average dose of ≥13.7 mg/day of prednisolone, ≥0.92 mg/day of MTX and male sex are significant independent risk factors for PCP, and that prophylaxis with ≥34.3 mg/day of TMP-SMX is to be recommended.

Efficacy of sulfasalazine for the prevention of Pneumocystis pneumonia in patients with rheumatoid arthritis: A multicentric self-controlled case series study.

INTRODUCTION: Pneumocystis pneumonia (PCP) is an opportunistic lung infection and has been reported among patients with rheumatoid arthritis (RA). An animal study revealed that sulfasalazine enhances Pneumocystis clearance from the lung by accelerating macrophage activity. METHODS: The self-controlled case series (SCCS) method was used to investigate the association between sulfasalazine use and PCP development in patients with RA without the effect of time-invariant, interpatient confounders. PCP episodes which developed in patients with RA at five hospitals between 2003 and 2019 were identified. PCP was defined by the following criteria: 1) detection of Pneumocystis jirovecii in respiratory specimens by polymerase chain reaction; 2) clinical symptoms (pyrexia, dry cough, dyspnea or hypoxia); 3) diffuse interstitial infiltrate on chest imaging; and 4) absence of PCP prophylaxis. The PCP incidence rate ratio (IRR) was compared between periods with and without sulfasalazine use by conditional Poisson regression. RESULTS: Fifty episodes of PCP were identified in 49 patients. Thirty patients received sulfasalazine at some point during their observation. While 49 episodes of PCP developed in 170.3 person-years without sulfasalazine use, only one episode of PCP developed in 103.7 person-years with sulfasalazine use. Sulfasalazine use was associated with a decreased PCP risk (adjusted IRR <0.01; 95% confidence interval <0.01-0.03) after adjusting for age and glucocorticoid, methotrexate, and tumor necrosis factor inhibitor administration. CONCLUSION: Our study demonstrated a preventive effect of sulfasalazine against PCP in patients with RA.

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.

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.