Pneumocystis jirovecii pneumonia (PJP) is an opportunistic fungal infection that predominantly affects immunocompromised individuals. Reports in immunocompetent children are rare. We report the case of a previously healthy 5½‑year‑old Saudi girl who presented with fever, dry cough, and progressive respiratory distress. Her condition rapidly deteriorated, requiring pediatric intensive care admission and mechanical ventilation due to severe acute respiratory distress syndrome. Her course was complicated by pneumothorax, pneumomediastinum, and extensive surgical emphysema. Extensive microbiological investigations were negative except for bronchoalveolar lavage demonstrating Pneumocystis jirovecii using Gomori methenamine silver staining. The patient was treated with intravenous trimethoprim-sulfamethoxazole and supportive intensive care management with gradual clinical recovery. Immunological evaluation, including lymphocyte subsets, immunoglobulin levels, complement levels, vaccine antibody responses, and whole‑exome sequencing, revealed no evidence of primary or secondary immunodeficiency. Long‑term follow‑up for more than 10 years showed no recurrent severe infections. This case highlights that PJP may rarely occur in immunocompetent children and can present with life‑threatening respiratory failure. Awareness of this possibility is important in severe unexplained pneumonia.

Necrotizing fasciitis (NF) is a rare but life-threatening soft tissue infection characterized by rapid progression, systemic toxicity, and high mortality. While Group A Streptococcus is the most common pathogen, Pseudomonas aeruginosa is an uncommon cause, typically reported in immunocompromised patients. We present the case of a 77-year-old male with chronic lymphocytic leukemia (CLL), chronic kidney disease, and other comorbidities who initially presented to an outside facility with three days of fever and left lower extremity pain. He was admitted with presumed cellulitis, and blood cultures grew Pseudomonas aeruginosa. Despite appropriate antibiotic therapy with vancomycin and ceftriaxone, the patient developed worsening pain, septic shock, rhabdomyolysis, and renal failure, prompting transfer to our facility for higher-level care. Examination revealed tense swelling of the left lower extremity, multiple bullae, and severe pain. Given concern for Pseudomonas NF, he underwent emergent above-the-knee amputation, followed by multiple debridements. He was subsequently transferred for advanced plastic surgical closure in stable condition. Pseudomonas aeruginosa remains a rare but severe cause of NF, particularly in immunocompromised patients with hematologic malignancies. Immunosuppression likely contributed to the unusual pathogen and aggressive clinical course in this case. Delayed diagnosis appears to be associated with increased mortality, underscoring the importance of timely blood cultures, broad-spectrum empiric coverage, and urgent surgical intervention. This case highlights the critical need for early recognition of Pseudomonas-associated NF and consideration of strict guidelines for high-risk populations to improve outcomes.

Dengue fever poses a significant diagnostic and therapeutic challenge in immunocompromised hosts, particularly in solid organ transplant recipients. We report a severe case in a patient during the early post-operative period following liver transplantation for hepatocellular carcinoma, who was concurrently receiving adjuvant chemotherapy with oxaliplatin and fluorouracil. This unique confluence of iatrogenic immunosuppression and chemotherapy-induced myelosuppression resulted in a life-threatening presentation characterized by grade 3 bone marrow suppression, severe anemia, overt gastrointestinal hemorrhage from gastric ulcers and colonic erosions, and acute kidney injury, necessitating intensive care management. Diagnosis was confirmed via dengue virus RNA testing, which was critical in differentiating the etiology from other potential causes of fever and pancytopenia in this complex setting. Management required a delicate balance of aggressive multidisciplinary supportive care, including endoscopic hemostasis and judicious blood product support, alongside cautious adjustment of immunosuppressive therapy to control the viral infection without precipitating graft rejection. This case underscores the severe, multifaceted complications dengue can precipitate in patients with dual vulnerabilities from transplantation and oncological therapy, highlighting the imperative for high clinical suspicion, rapid molecular diagnostics, and a coordinated, multidisciplinary approach to navigate competing clinical priorities and achieve a successful outcome.

Mucormycosis ranks third among invasive mycoses after Candidiasis and Aspergillosis and is associated with high mortality. Its incidence has increased with the rising number of immunosuppressed patients. In developing countries, the most common predisposing factor is uncontrolled diabetes mellitus (DM), whereas in developed countries it is immunosuppressive conditions. To examine local epidemiological data, predisposing factors, diagnostic and therapeutic options and survival in our center eighty-six adult mucormycosis patients between 2000 and 2020 were retrospectively analyzed. Thirty-nine (45.35%) were male, 47 (54.65%) were female, and the median age was 52 years (IQR, 42.5-62). The most frequent clinical presentation was sinus involvement, observed in 77 cases (89.53%). Of these, 38 (44.18%) were sinonasal, 5 (5.81%) sinoorbital, 9 (10.47%) rhinocerebral, and 25 (29.07%) rhino-orbito-cerebral mucormycosis. The remaining 9 cases (10.47%) had pulmonary mucormycosis. Predisposing factors included hematologic diseases in 51 patients (59.30%), DM in 33 (38.37%), solid organ transplantation (SOT) in 7 (8.14%), and solid organ malignancy in 7 (8.14%). The most common symptoms were fever (70.93%), swelling around the eyes and face (51.16%), pain (40.7%), erythema (34.88%), nasal discharge (30.23%), and headache (25.58%). Most frequent physical examination findings were necrotic lesions in the oral cavity and sinuses (87.21%), ophthalmoplegia (29.07%), ptosis (26.74%), vision loss (25.58%), and proptosis (22.09%). In all cases, amphotericin B formulations were preferred as initial therapy. Patients who received combination therapy (n = 14), 13 used posaconazole (POS) + liposomal amphotericin B (L-AmB) and one patient used itraconazole (ITC) + L-AmB. POS was administered to 14 patients receiving sequential oral therapy. The median duration of amphotericin B therapy was 46.5 days (IQR, 14.7-84.5), and the median total duration of antifungal therapy was 46.5 days (IQR, 14.7-90.3). The most common adverse effect of amphotericin B formulations was hypokalemia [L-AmB 68.75%, amphotericin B deoxycholate (AmB-D) 54.84%, amphotericin B lipid complex (ABLC) 50%]. At least one surgical intervention was performed in 74.42% of cases. The 12-week mortality rate was 48.84%, overall mortality rate was 61.63%. In analysis advanced age [12-week: OR: 1.04 (95% CI: 1.01-1.07), p = 0.011; overall: OR: 1.04 (95% CI: 1.01-1.07), p = 0.026 respectively], coexistence of both hematologic disease and DM [12-week OR: 5.73 (95% CI: 1.16-28.33), p = 0.032] associated with mortality. No significant difference was observed in 12-week mortality between surgical and non-surgical patients (p = 0.107). In contrast, overall mortality was significantly higher in the non-surgical group (81.8% vs. 54.7%, p = 0.024). In univariable logistic regression analysis, surgical intervention was associated with a 73.2% reduction in the odds of overall mortality (OR: 0.268, 95% CI: 0.082-0.882, p = 0.030). In the multivariable logistic regression analysis, age was the only variable significantly associated with 12-week and overall mortality (respectively, p = 0.004 and p = 0.026). Each one-year increase in age was associated with an OR of 1.05 (95% CI: 1.02-1.09) for 12-week mortality and 1.04 (95% CI: 1.01-1.07) for overall mortality. In conclusion; our study showed that despite advanced diagnostic methods and antifungals, mortality remained high, sinus involvement was the most frequent involvement, surgical debridement increased survival, but increasing age was associated with poor prognosis.

Although rare, neoehrlichiosis in humans caused by N. mikurensis has gained increasing attention as an emerging tick-borne zoonosis, especially in immunocompromised patients in Europe. Here we report on a case of human neoehrlichiosis in Germany, which occurred in a 66-year-old woman with a history of granulomatosis with polyangiitis (GPA), B-cell depletion therapy, and secondary antiphospholipid syndrome. While undergoing long-term treatment for GPA with the monoclonal anti-CD20 antibody rituximab, the patient was hospitalized because of a prolonged fever of unknown origin (FUO) and hyperinflammatory syndrome. Neoehrlichiosis was diagnosed directly through eubacterial 16S rRNA PCR screening of EDTA whole blood from the patient, followed by genetic sequence analysis of the amplicon. In addition to a systemic infection, the patient also suffered from complicating myocarditis. Her condition eventually improved after treatment with doxycycline and a follow-up PCR revealed that the neoehrlichia DNA was finally cleared from her blood. Our findings provide further evidence that human neoehrlichiosis is endemic in Germany and suggest that N. mikurensis can also cause myocarditis. Consequently, in potential areas of endemicity, N. mikurensis should be considered in immunocompromised individuals with FUO and signs of infection.

Rasamsonia species are thermophilic fungi that primarily cause infection in immunocompromised patients. R.argillacea species complex is frequently misidentified as a pathogen due to its morphological similarity to the genera Penicillium and Paecilomyces and its incidence remains undetermined. This situation further complicates the process of timely diagnosis and treatment. Rasamsonia species can be identified using internal transcribed spacer (ITS) sequence analysis, which is considered the primary fungal barcode. Accurate species identification is imperative for the administration of appropriate antifungal treatment. In this report, a case of acute myeloid leukaemia (AML) with R.argillacea growth was presented. A 69-year-old female patient diagnosed with AML who was undergoing chemotherapy was admitted to the hospital due to febrile neutropenia. Despite the administration of appropriate antibiotic therapy, the patient's fever did not respond and her respiratory distress worsened. A subsequent chest computerized tomography scan revealed the presence of bilateral nodular lesions and halo findings in some nodules. The empirical liposomal amphotericin B was initiated at a dosage of 3 mg/kg/day. Following a 17-day course of empirical amphotericin B therapy, the patient exhibited an escalation in respiratory distress and an increase in her blood galactomannan (GM) level (Platelia™ Aspergillus Ag; Bio-Rad, France). Consequently, intravenous (IV) voriconazole was administered at a loading dose of 2x6 mg/kg followed by a maintenance dose of 2x4 mg/kg. Notwithstanding the administration of voriconazole therapy, the patient's blood GM levels persisted at elevated levels on three separate occasions. Consequently, a bronchoalveolar lavage (BAL) sample was obtained for further analysis. However, no growth was detected in the bronchoalveolar lavage (BAL) culture. The BAL GM level was found to be elevated (optic indices: 4.38). The patient developed increasing respiratory distress and confusion and was intubated. A deep tracheal aspirate (DTA) sample was collected. The patient died shortly thereafter. Velvety, beige-colored colonies were observed in the culture media to which the DTA sample inoculated. Microscopic examination of the culture using a lactophenol cotton blue stain revealed cylindrical conidia, rough-walled conidiophores and long, pointed phialides. The isolate was identified as R.argillacea using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (Bruker, Bremen, Germany). This isolate could not be identified based on colony morphology and microscopic appearance; however, it was identified as R. argillacea using the ribosomal DNA ITS region. Its antifungal susceptibility was then assessed using the microdilution method according to the Clinical and Laboratory Standards Institute M38-A2 guidelines. The minimum inhibitory concentrations (MICs) for the antifungal drugs were as follows: fluconazole >64 μg/mL, itraconazole 0.5 μg/mL, voriconazole >16 μg/mL, posaconazole 0.5 μg/ mL, anidulafungin ≤0.015 μg/mL, micafungin 0.03 μg/mL and amphotericin B 1 μg/mL. In this case, the patient died without the causative agent being identified. Although it cannot be definitively stated that R. argillacea was the cause of the patient's mortality due to the lack of an autopsy, this case was presented because it is the first suspected case of R. argillacea isolated and confirmed by molecular methods in Türkiye and to highlight the importance of not neglecting Rasamsonia species which are rare mold fungi.

Severe fever with thrombocytopenia syndrome virus (SFTSV) and Heartland virus (HRTV) are emerging tick-borne bandaviruses. They have high case fatality rates (10%), and no FDA-approved vaccines exist for disease prevention. SFTSV and HRTV are therefore identified as priority pathogens. A recombinant vesicular stomatitis virus (rVSV) vaccine, which replaces the original VSV glycoprotein with the SFTSV glycoproteins, shows early promise for SFTSV as it induces strong immune responses that are protective against lethal challenge. However, rVSV-SFTSV is highly attenuated in cell culture, which may be due to incompatibility between the assembly sites of SFTSV (the Golgi and ERGIC) and that of VSV (the plasma membrane). In this study, we identify a noncanonical COPI binding motif found in the cytoplasmic tail of SFTSV glycoproteins and demonstrate that an amino acid substitution in this motif (K1071A) inhibits binding to COPI. This mutation results in increased surface expression of SFTSV glycoproteins, improved incorporation onto VSV virions, and enhanced replication of rVSV-SFSTV in vitro. A mutation in a homologous site (K1074A) of HRTV has similar results, and rVSV-HRTV K1074A exhibits increased replication in vitro and in vivo . We show that vaccination with rVSV-HRTV K1074A results in improved induction of neutralizing antibody responses in immunocompetent C57BL/6 mice, and neutralizing antibodies elicited by vaccination are protective when administered to severely immunocompromised mice via passive transfer. Overall, our study identifies a mutation that improves the efficacy of the rVSV-SFTSV vaccine candidate and introduces the first vaccine candidate directly addressing HRTV infections.

Pulmonary toxoplasmosis is a rare but potentially fatal opportunistic infection, most often reported in HIV-infected individuals. Its occurrence in non-HIV immunocompromised patients-particularly those with hematologic malignancies like multiple myeloma (MM)-is exceedingly rare and diagnostically challenging due to nonspecific clinical and radiologic features. While Toxoplasma gondii infection is typically mild in immunocompetent hosts, it can cause severe disease in immunocompromised populations. A literature review was conducted using PubMed, Scopus, and Google Scholar (January 2000-May 2025) with keywords: 'pulmonary toxoplasmosis,' 'multiple myeloma,' 'non-HIV,' 'immunocompromised,' and 'BAL PCR.' Only English-language case reports and reviews were included, with emphasis on studies from endemic regions and the past five years. We report a 49-year-old Iranian man with newly diagnosed IgG kappa MM who presented with fever, chills, vomiting, and dyspnea. Chest CT revealed a 4.2 × 3.8 cm consolidation in the posterior segment of the right lower lobe. T. gondii infection was confirmed via bronchoalveolar lavage (BAL) through tachyzoite detection on Giemsa stain and molecular identification using qPCR and nested PCR targeting the Gra6 gene. He showed transient clinical improvement and was discharged on hospital day 7. Unfortunately, he died at home within 48 hours due to MM progression, before anti-toxoplasmosis therapy was initiated. This case underscores the diagnostic difficulty of pulmonary toxoplasmosis in non-HIV immunocompromised patients and the importance of molecular BAL testing. Prophylactic measures such as co-trimoxazole should be considered in high-risk MM patients. Guidelines must address screening and management in this vulnerable population.

Listeria monocytogenes is an opportunistic Gram-positive intracellular pathogen that predominantly affects elderly and immunocompromised individuals. Central nervous system involvement may result in meningitis or meningoencephalitis, with hydrocephalus representing a rare but serious complication associated with high morbidity and mortality. This case report describes a 62-year-old woman with Sjögren's syndrome on methotrexate who presented with fever, headache, and altered mental status. Imaging revealed communicating hydrocephalus, and CSF analysis confirmed Listeria monocytogenes meningitis via multiplex PCR. Management was complicated by penicillin allergy and subsequent hypersensitivity to trimethoprim-sulfamethoxazole, eventually requiring a transition to oral linezolid. Targeted therapy led to the resolution of hydrocephalus and significant neurological recovery by discharge. This case highlights the importance of considering Listeria in immunocompromised patients and the necessity of alternative antimicrobial strategies when faced with rare complications and complex drug allergies.

Infective manifestations of hematological malignancies can be traced to a variety of pathogens, necessitating broad spectrum empiric antibiotic coverage, and prompt identification of pathogenic microbes to improve clinical outcomes. We present a case of Morganella morganii leading to pneumonia as the presenting illness in a previously undiagnosed, functionally neutropenic adult presenting with acute myeloid leukemia with monocytic differentiation. Our patient was a 64 year old man with no prior medical care who presented with complaints of progressive abdominal pain, productive cough and fevers. Chest radiography revealed no organized consolidations, and computed tomographic imaging of the chest showed bibasilar atelectasis and trace pleural effusions. Laboratory analysis revealed marked leukocytosis with predominant monocytosis, and circulating blasts, suggestive of acute myeloid leukemia with monocytic differentiation, later confirmed with bone marrow biopsy. The patient was initially started on guideline directed empiric therapy for respiratory infection, with sputum cultures later found to be growing Morganella morganii, necessitating a change in antimicrobial therapy, following which the patient showed clinical improvement. To our knowledge, this is the first reported case of Morganella morganii pneumonia presenting at the initial diagnostic encounter of de novo acute myelomonocytic leukemia. This report underscores the need for prompt microbiologic evaluation, broad empiric coverage with early de-escalation, and inclusion of M. morganii in the differential diagnosis of pneumonia in functionally neutropenic patients when standard pathogens are not identified. This case highlights the need to recognize atypical Gram-negative organisms as potential pathogens in these populations, even in the absence of characteristic radiographic findings.

Listeria monocytogenes (LM) is a food-borne pathogen that can cause severe invasive infections, particularly in immunocompromised or elderly patients. Bacterial co-infections are frequently reported in COVID-19 patients, with both COVID-19-induced immune dysregulation and immunosuppressive therapies such as corticosteroids specifically creating risk for more unusual pathogens such as LM. We report a case of a 78-year-old woman with underlying cirrhosis due to non-alcoholic steatohepatitis who presented with fever and weakness, tested positive for COVID-19, and rapidly developed evidence of LM peritonitis with bacteremia and meningoencephalitis after dexamethasone initiation. Clinicians should maintain a high index of suspicion for listeriosis in acutely encephalopathic or septic patients with risk factors, especially during the COVID-19 era and in those receiving immunosuppressive therapy.