Immunocompetent Patients Research Articles

Encephalitis in Immunocompromised vs Immunocompetent Patients: A Comparative Study.

Encephalitis is characterized by brain parenchymal inflammation caused by infection or autoimmunity. There are limited recent data on how immunocompromised patients with encephalitis differ from the general encephalitis population. This retrospective study of 2 large medical institutions compares clinical characteristics and outcomes of immunocompromised and immunocompetent patients with all-cause encephalitis. Of the 657 patients, 151 (23%) were immunocompromised. Immunocompromised patients were more likely to have an infectious etiology, comorbidities, inflammatory cerebrospinal fluid (CSF) profile, abnormal neuroimaging, and worse clinical outcomes as assessed by discharge Glasgow Outcome Scale (GOS) and in-hospital mortality (all P < .05). The most commonly identified etiologies in immunocompromised patients were herpes simplex virus (HSV) and varicella zoster virus. HSV accounted for similar proportions in the immunocompromised (18%) and immunocompetent (14%) groups, though it was more commonly associated with a CSF neutrophilia in the immunocompromised group (P = .001). Strikingly, >10% of immunocompromised patients with encephalitis had autoimmune causes, two-thirds of which were checkpoint inhibitor associated. Factors associated with poor GOS on discharge differed, with poorer outcomes in the infectious group associated with immunocompromised state and poorer outcomes in the autoimmune group associated with immunocompetent state. Immunocompromised patients with encephalitis have differing causes, atypical clinical presentations, higher in-hospital mortality, and distinct factors associated with poor outcome as compared with immunocompetent patients. While HSV and opportunistic infections cause encephalitis in the immunocompromised, the diagnosis of autoimmune encephalitis should also be considered and can be checkpoint inhibitor associated.

Peripheral blood CD4+ and CD8+ T cell responses to Cryptococcus candidate vaccine antigens in human subjects with and without cryptococcosis.

Peripheral blood CD4+ and CD8+ T cell responses to Cryptococcus candidate vaccine antigens in human subjects with and without cryptococcosis.

Molecular characterization of autochthonous Hepatitis E virus detected from a human acute infection in the Calabria Region, Southern Italy.

Molecular characterization of autochthonous Hepatitis E virus detected from a human acute infection in the Calabria Region, Southern Italy.

Rare and remarkable: A concise review unmasking the enigmas of fungal Rhinosinusitis

Fungal rhinosinusitis is a rare and complex form of rhinosinusitis, and it has been traditionally associated with immunocompromised individuals. However, recent reports have shown a rising incidence even among immunocompetent patients. The disease presents with a broad spectrum of clinical manifestations, ranging from mild non-invasive forms to invasive types that can be life-threatening. Diagnosis remains challenging due to non-specific clinical signs and imaging findings, often requiring histopathological examination for confirmation. Management strategies are highly variable and depend on the subtype, involving a combination of surgical intervention, corticosteroids, antifungal agents, and, in some cases, biologic therapies. Despite its clinical significance, literature on fungal rhinosinusitis remains limited. This review aims to provide clinicians with a concise summary of current knowledge on diagnosing and managing fungal rhinosinusitis, aiming to improve awareness and guide effective clinical practice.

EFICÁCIA DA TERAPIA FOTODINÂMICA NO TRATAMENTO DA HERPES SIMPLES TIPO I

This study presents a series of clinical case reports on the application of Antimicrobial Photodynamic Therapy (aPDT) in the treatment of lesions caused by Herpes Simplex Virus Type I (HSV-1). This viral infection is known for its recurrent episodes, which significantly affect patients’ quality of life due to pain, aesthetic discomfort, and social stigma. Traditionally, treatment involves the use of antiviral medications such as Acyclovir, which may present limitations related to viral resistance and potential side effects. In this context, aPDT emerges as a minimally invasive therapeutic approach that combines a photosensitizing agent with light of a specific wavelength, generating reactive oxygen species capable of selectively destroying infected cells. This study aimed to report three clinical cases treated with aPDT, using 0.005% methylene blue and a 660 nm diode laser on patients with vesicular-phase herpetic lesions. All cases showed significant improvement in symptoms, with pain relief and reduced inflammation within 24 hours after treatment. The outcomes corroborate existing literature regarding the efficacy of aPDT as an adjunctive therapy in managing recurrent labial herpes, especially in immunocompetent patients. Furthermore, the study highlights the practicality, safety, and lack of relevant side effects, making aPDT a viable option in dental practice. It is concluded that aPDT is a promising alternative, particularly for individuals seeking complementary, effective, and low-risk therapies. Nevertheless, further studies with larger samples and standardized clinical protocols are needed to support the widespread use of this technique in daily clinical practice.

Klebsiella pneumoniae infective endocarditis originating from asymptomatic prostatitis presenting with papilloedema.

SummaryKlebsiella pneumoniae is emerging as a pathogen of global concern due to an increasing incidence of hypervirulent pathotypes causing life-threatening infections, including infective endocarditis (IE). A man in his 30s who was previously fit and well, presented to our eye casualty with headaches, papilloedema and fever. Blood cultures grew K. pneumoniae and transthoracic echocardiography detected IE of the aortic and mitral valves. Fluorodeoxyglucose positron emission tomography revealed focal increased accumulation at the right side of the prostate. The patient was treated for K. pneumoniae subacute IE of the aortic and mitral valves, originating from asymptomatic prostatitis. Our case highlights that young, healthy, immunocompetent patients can develop IE from K. pneumoniae It also demonstrates that papilloedema can be a presenting sign of this disease. To our knowledge, there are no previous reports of IE presenting with papilloedema.

A Lymphocyte Subset-Based Prediction Model for Refractory Community-Acquired Pneumonia in Immunocompetent Patients

Background/Objectives: Refractory community-acquired pneumonia (r-CAP) has become a thorny issue in clinical practice, especially after the COVID-19 pandemic, even in immunocompetent patients, as conventionally defined. In this study, we aimed to identify the risk factors for immunocompetent patients with r-CAP. Methods: This was a single-center retrospective study. In total, we collected clinical data from 82 patients with r-CAP in whom the first-line antibiotic therapy failed and 82 patients with general CAP (g-CAP) who recovered with first-line antibiotics, matched at a ratio of 1:1, admitted to Beijing Shijitan Hospital, Capital Medical University, from 1 January 2022, to 31 December 2023. The differences between the two groups (clinical characteristics, peripheral blood cell count, lymphocyte subsets, and regular laboratory indicators) were analyzed using paired t, paired Wilcoxon, Chi-square, or Fisher’s exact tests, and univariate and multivariate logistics regression analyses were conducted to identify the independent risk factors. A model for predicting indicators with statistical significance was established and proved with the receiver operating characteristic (ROC) curve. Results: Warm season, a history of chronic obstructive pulmonary disease, longer time from onset to admission (TO-A), higher percentages of CD4+ T, CD8+ T, and double-negative T (DNT) lymphocytes, as well as higher levels of C-reactive protein (CRP), low-density lipoprotein cholesterin (LDL-C), serum sodium ion (Na+), and free-calcium ion (FCa2+) were regarded as independent risk factors, while T lymphocyte percentage (T%) and total cholesterol (TC) were identified as protective factors. The combined multivariate model using all the above factors proved to be sensitive and specific (AUC = 0.8711, p &lt; 0.0001, R2 = 0.4235), and thus better than the respective univariate models. Conclusions: Increased CD4+ T%Lym, CD8+ T%Lym, and DNT%Lym, warm season, a history of COPD, longer TO-A, and increased levers of CRP, LDL-C, Na+, and FCa2+ potentially cause CAP to be refractory, while the T lymphocyte count, namely, the overall cellular immunity, was impaired in r-CAP patients, and increased TC levels could be beneficial to pneumonia recovery.

Scopulariopsis brevicaulis : The "arsenic fungus"-adifficult-to-treat pathogen

Scopulariopsis (S.)brevicaulis is ahuman pathogenic hyalohyphomycete from the Microascaceae family, which plays arole in dermatological practice, particularly as apathogen of onychomycosis. Less commonly, it is the causative agent of skin mycoses, even in immunocompetent patients, as well as of systemic infections. In culture, brown-cinnamon colored colonies with apowdery surface are observed. Conidia are produced in annellid chains, have atruncated base, and aspiny-verrucous surface at maturity. S.brevicaulis can also be differentiated using some commercial polymerase chain reaction (PCR) kits. Since the pathogen also frequently occurs in the environment, its clinical relevance must be confirmed by further investigations, especially by histopathology and/or repeated detection. Therapy is difficult because there is sometimes intrinsic resistance to common antifungal agents. The significance of resistance testing is still limited due to alack of standardization. Furthermore, differences in pathogenicity between individual isolates appear to exist. According to the guidelines, topical therapy is recommended for onychomycosis by S.brevicaulis, and systemic/topical combined therapy for mixed infections (dermatophyte + S.brevicaulis). S.brevicaulis is also of environmental toxicological importance because it can release volatile arsenic derivatives from arsenic-containing compounds in the presence of carbohydrates, which has also led to the name "arsenic fungus".

The impact of bronchoalveolar lavage fluid metagenomics next-generation sequencing on the diagnosis and management of patients with suspected pulmonary infection

ObjectivesThis study aimed to enhance the comprehension of the practical utility of bronchoalveolar lavage fluid (BALF) metagenomic next-generation sequencing (mNGS) in the clinical management of patients with suspected pneumonia.MethodsWe retrospectively analyzed 296 individuals who underwent BALF mNGS and conventional microbial tests (CMTs) for suspected pneumonia. We compared the clinical characteristics between patients with pulmonary infection (PI) and those without pulmonary infection (NPI). The detection rate of mNGS and CMTs in different groups of patients were compared. The Sankey diagram was used to present the results of the influence of mNGS on diagnosis and treatment.ResultsComparison between PI and NPI showed that individuals with fever, concurrent malignant tumors, consolidation or ground-glass opacity on chest CT(Computed tomography) images, and elevated inflammatory markers on blood tests were more likely to develop lung infections. Analysis of the rate of positive detection between CMTs and mNGS in various subgroups revealed that mNGS had a significantly higher positive detection rate in patients with pulmonary infections (87.95% vs. 71.06%, p&amp;lt;0.001), in immunocompetent patients (86.91% vs. 68.08%, p&amp;lt;0.001), and in patients with malignant tumors (92.31% vs. 69.23%, p=0.035). Furthermore, mNGS helped initiate appropriate antibiotic treatment and confirmed the effectiveness of empirical treatment. Compared to immunocompetent patients, BALF mNGS in immunocompromised individuals with suspected lung infections yielded higher rates of accurate diagnosis (62.86% vs. 42.79%, p = 0.027) and more effective treatment (71.43% vs. 58.56%, p = 0.148).ConclusionsBALF mNGS identified a greater variety of pathogens than CMTs. Immunocompromised patients with suspected pneumonia may benefit more from BALF mNGS.

Histoplasmosis in Immunocompromised and Immunocompetent Patients in Guadeloupe

Background: Histoplasma capsulatum is an environmentally acquired dimorphic fungus. Infection results in histoplasmosis, a clinical syndrome often underdiagnosed and that may progress to life-threatening disseminated infection not only in immunocompromised individuals but also, following high-level exposure, in immunocompetent hosts. Epidemiological data from Caribbean regions, and particularly from Guadeloupe, remain limited. Methods: We performed a retrospective cohort study of all microbiologically confirmed histoplasmosis cases managed at the University Hospital of Guadeloupe between January 2014 and October 2024. Demographic, clinical, diagnostic, therapeutic, and outcome data were retrieved from medical records and analyzed using descriptive statistics. Results: Forty-two patients met the inclusion criteria, corresponding to an estimated annual incidence rate of 1 per 100,000 inhabitants. The median age was 52 years, and the male-to-female ratio was 4:1. An underlying immunocompromising condition was present in 85% of cases, most commonly HIV infection (48%). Common clinical features included weight loss (97%), fever (89%), and pulmonary manifestations (81%). The mean time to diagnosis from hospital admission was 3.5 ± 10.3 days. Direct microscopy was positive in 67% of cases, and culture was positive in 88% of cases. Intravenous liposomal amphotericin B constituted the initial therapy in 71% of patients. Overall, the in-hospital mortality was 29%, rising to 40% among HIV-positive individuals. The 30-day survival rate was 71%. Conclusions: Histoplasmosis in Guadeloupe is under-recognized and associated with appreciable morbidity and mortality in both immunocompromised and immunocompetent patients. The wider availability of rapid diagnostics and heightened clinical vigilance are essential to shorten diagnostic delays and improve outcomes in this Caribbean population.

Is intravenous aciclovir overused in possible viral encephalitis? a retrospective review.

Timely administration of IV aciclovir reduces mortality in herpes simplex virus (HSV) encephalitis (Sköldenberg in Lancet, 1984), (Whitley in N Engl J Med, 1986). Early diagnosis, however, is challenging due to non-specific symptoms and delays in obtaining key investigation results. Empiric treatment with intravenous (IV) aciclovir in cases of suspected meningitis to cover for possible concurrent viral encephalitis is an approach not supported by the National Institute for Clinical Excellence (NICE) ( https://www.nice.org.uk/guidance/ng240 , 2024). Such practice exposes patients to the risk of iatrogenic nephrotoxicity and neurotoxicity. Our objectives were to evaluate the diagnostic approach to suspected viral encephalitis and appropriateness of aciclovir prescription. This was a retrospective cohort study of 410 patients over 16years old prescribed IV aciclovir for suspected central nervous system infection at Royal Free London NHS Foundation Trust between December 2021 and February 2024. 29% of patients fulfilled diagnostic criteria for possible or probable encephalitis while 5% did not fulfil any of the criteria. 38% had no microbiological or serological testing for HSV or varicella zoster virus.Discharge diagnoses included 5% with viral encephalitis (2% confirmed on cerebrospinal fluid testing) and 6% with meningitis, while the commonest diagnosis was delirium (11% of patients). While acknowledging clinical uncertainty and attendant risks of missing a diagnosis of true viral encephalitis, in line with NICE guidelines we suggest a review of routine prescription of IV aciclovir in suspected meningitis and emphasise the importance of altered mental status as a useful distinguishing feature between viral encephalitis and meningitis in immunocompetent patients.

Rare Urinary Tract Infection by Rodentibacter pneumotropicus (formerly, Pasteurella pneumotropica) in an Immunocompetent Patient

Patient: Male, 37-year-oldFinal Diagnosis: Urinary tract infectionSymptoms: Diarrhea • fever • hematuria • leukocytosis • lower urinary tract symptoms • nausea • right lumbar pain • weight lossClinical Procedure: —Specialty: Microbiology and Virology • UrologyObjective: Rare diseaseBackgroundPasteurella pneumotropica has been reclassified as Rodentibacter pneumotropicus after advancements in genetic and phenotypic analyses revealed genetic diversity and phylogenetic distinctions within the pneumotropica complex. This reorganization resolved issues of misclassification and provided a clearer framework for understanding the epidemiology and clinical relevance of these organisms. R. pneumotropicus is a gram-negative bacillus commonly found in the respiratory tracts of mammals, particularly rodents. However, it rarely infects humans. This case is notable for presenting a urinary tract infection caused by R. pneumotropicus in an immunocompetent patient, a rare manifestation highlighting the need to consider less-common pathogens in daily clinical practice to choose the correct treatments.Case ReportThis case describes a 37-year-old immunocompetent man who initially presented to a hospital in Mexico with gastrointestinal symptoms and later developed urinary issues following a ureteroscopy for a proximal ureteral stone. Despite initial treatment with meropenem and paracetamol, the patient had persistent fever and leukocytosis. According to the available material at the hospital, a urine culture was done subsequently and it revealed R. pneumotropicus, formerly known as Pasteurella pneumotropica, which was sensitive to fluoroquinolones. The patient underwent transurethral resection of the prostate and was treated with ciprofloxacin, leading to successful symptom resolution.ConclusionsThis case highlights the rarity of urinary tract infections caused by R. pneumotropicus in immunocompetent individuals. These findings underscore the importance of considering uncommon microorganisms in differential diagnoses and ensuring precise identification and sensitivity testing to guide effective treatment. Also, it provides evidence supporting the ability of R. pneumotropicus to infect immunocompetent individuals, raising several questions related to its infection mechanisms.

Invasive pneumococcal disease with multiple septic emboli and septic arthritis in an immunocompetent patient

We report a case of an immunocompetent male, on the early 70s, with a background of cardiovascular disease who presented with cough with hemoptoic sputum and progressive fatigue. He was diagnosed with invasive Streptococcus pneumoniae infection manifesting as pneumonia and bacteraemia, complicated by multiple septic emboli (cerebral, cerebellar, splenic, renal) and septic arthritis. Despite broad-spectrum antibiotic therapy and organ support, the patient deteriorated and died within a week. This case highlights the potential for severe and rare complications of invasive pneumococcal infection, even in patients without overt immunodeficiency.

Usefulness of Serum as a Non-Invasive Sample for the Detection of Histoplasma capsulatum Infections: Retrospective Comparative Analysis of Different Diagnostic Techniques and Quantification of Host Biomarkers

Diagnosis of histoplasmosis is challenging. A rapid, sensitive, and specific method is essential. Serum is a non-invasive and easy sample to obtain in any hospital. The diagnostic accuracy of different techniques that use serum has been evaluated. Forty-one serum samples from patients with proven or probable histoplasmosis were analyzed. Different diagnostic techniques based on the detection of antibodies (ID Fungal Antibody System), antigens (Histoplasma GM EIA and PlateliaTM Aspergillus Ag), and DNA (“in-house” real-time PCR (RT-PCR) were tested and compared. Additionally, the quantification of cytokines and biomarkers related to histoplasmosis was performed. Global results from 27 samples in which all the tests were performed showed that the sensitivity of the Histoplasma GM EIA kit was 87.5% in patients with disseminated infection and HIV as an underlying disease; in immunocompetent (IC) patients, it was 54.5%. The detection of Histoplasma spp. with the ID Fungal Antibody System was positive in 90.9% of IC and in 62.5% of HIV patients. The Platelia-Asp kit had a low performance in both groups of patients (37.5% in HIV and 9% in non-HIV), and, finally, RT-PCR was better in immunosuppressed patients (44% in HIV vs. 27% in non-HIV). The combination of diagnostic techniques increased the detection of Histoplasma infection in inmunosupressed patients. Overall, patient groups infected with H. capsulatum (Hc) showed higher IL-8, IL-6, IL-1β, TNF-α, and IL-18 median values compared to non-Hc-infected controls. The effectiveness of diagnostic techniques on serum samples is highly influenced by the patient’s clinical presentation and underlying condition. Consequently, a thorough assessment of the patient’s clinical presentation and disease phenotype is crucial in selecting the most suitable diagnostic method.

A Case of Canine-Transmitted Postoperative Staphylococcus schleiferi Sinusitis.

We present the first documented acute bacterial sinus infection with Staphylococcus schleiferi in a 58-year-old male recovering from endoscopic sinus surgery recovering on postoperative oral corticosteroids. The patient reported, within 1 month of surgery, treating an outer ear infection in his dog that was culture positive for Staphylococcus schleiferi and Corynebacterium sp. and developing an acute exacerbation of his sinus symptoms with increased purulent drainage, facial pain, and increased aural fullness. Nasal endoscopy was notable for purulence and thick mucus in multiple sinuses, which was positive on culture for S. schleiferi. He underwent treatment with trimethoprim/sulfamethoxazole that resolved the active infection. S. schleiferi has shown only rare transmission to a human host in both immunocompetent and immunocompromised patients. Often, this bacterial pathogen will present as a skin infection or outer ear infection in canines and serves as the potential source of infection in humans as they treat their canine companions. This marks the first documented case of acute bacterial sinusitis caused by this bacterial pathogen in the human literature and warrants continued observation as another potential zoonotic pathogen that may cause sinus exacerbations in susceptible populations.

Diagnostic value of bronchoalveolar lavage fluid metagenomic next-generation sequencing for pulmonary infections in patients with connective tissue disease: A retrospective study

Pulmonary infection is common in connective tissue diseases (CTDs) patients because of immunodeficiency. The basic characteristics of pathogens in this set of patients may differs from immunocompetent patients and largely unclear. We aimed to understand these characteristics by metagenomic next-generation sequencing (mNGS) detection in bronchoalveolar lavage fluid (BALF) from CTDs and explored the primary disease features of this group of patients. Eighty-one CTD patients who were suspected pulmonary infection and received mNGS of BALF as well as conventional microbiologic testing (CMT) were enrolled consecutively. We analysed the types of CTDs, whether accompanied with interstitial lung disease, comparison between performance of mNGS and CMT, and distribution of clinically relevant pathogens, etc. Of the 81 cases, 62 were clinically diagnosed with pulmonary infection. Among all patients, idiopathic inflammatory myopathy accounted for the highest proportion of cases infected, especially anti-MDA5 dermatomyositis and anti-synthetase syndrome. Patients in the pulmonary infection group had been previously treated with higher percentages of anti-rheumatic drugs than those in the non-infection group. The sensitivity of mNGS was higher than that of CMT (80.6% vs. 66.1%). Among the microbes detected by mNGS, the most common bacterial pathogen was Pseudomonas aeruginosa, and the most frequently fungi was Pneumocystis jirovecii. As for the specific pathogens, mNGS had great advantages over CMT in identifying Pneumocystis jirovecii. Idiopathic inflammatory myopathy was the disease most susceptible to pulmonary infections among CTDs. mNGS showed high efficiency for the detection of pathogens that cause pneumonia in BALF from patients with CTDs, especially for Pneumocystis jirovecii.

Differential Expression of Host miRNAs During Ad14 and Ad14p1 Infection.

Adenovirus is a frequent cause of mild, usually self-limited infections in infants and young children. Severe infections occur in immunocompromised patients but are rarely observed in healthy, immunocompetent adults. However, there have been outbreaks of infections with different adenoviral (Ad) types around the world that have resulted in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) in some of those infected. Ad14p1 is the predominant circulating strain of Ad14 worldwide that has caused ARDS. An explanation for the severity of illness caused by Ad14p1 infection in immunocompetent patients is unknown. Previously, we have shown that A549 cells infected with Ad14 repress macrophage pro-inflammatory responses, whereas cells infected with Ad14p1 fail to repress macrophages and instead can increase pro-inflammatory responses. Adenoviral infection has been shown to modulate host miRNA expression, and we hypothesized that differences in miRNA expression between Ad14- and Ad14p1-infected cells might explain the differential responses of macrophages to Ad14- and Ad14p1-infected cells. Analysis of host miRNA showed that 98 miRNAs are differentially expressed when infection reaches full cytopathic effect (CPE), the same point at which Ad14 and Ad14p1 CPE corpses induce differential inflammatory responses in macrophages. Only 10 of the miRNAs that were enriched in Ad14 CPE corpses were expressed at levels that are potentially biologically relevant. Pathway enrichment analysis showed that the differentially expressed miRNAs might explain the increased pathogenesis of Ad14p1 through strain-related loss of modulation of cytokine expression when compared with prototype Ad14. Overall, the data suggest a role for viral regulation of host miRNA expression in pathogenesis by regulating host inflammatory responses through the delivery of de-regulated miRNAs by viral CPE corpses to macrophages.

A rare case of cytomegalovirus brain abscess in immunocompetent patient

Abstract Cytomegalovirus (CMV), a member of the herpesvirus family, is a common opportunistic infection affecting the global population. Depending on health, economic, and social factors, CMV prevalence ranges between 45% and 100% of the population. While it primarily causes severe complications in immunosuppressed patients, it can also affect immunocompetent individuals, often asymptomatically. Although central nervous system involvement is rare, it can lead to serious complications. Brain abscesses co-infected with CMV are uncommon, and co-infection with Staphylococcus aureus has not been previously reported. Here, we present the case of a 53-year-old immunocompetent male with a history of type 2 diabetes mellitus, endocarditis, and mitral valve replacement surgery, who was admitted to the hospital with left limb weakness. Imaging revealed a brain abscess, and PCR tests confirmed the presence of S. aureus and CMV. This case report discusses the medical management during his hospitalization.

Rapidly progressive pulmonary abscess initially misdiagnosed as lung cancer: the role of Peptostreptococcus stomatis and Parvimonas micra

Pulmonary abscess is a serious infectious disease characterized by localized lung tissue necrosis, primarily caused by anaerobic or facultative anaerobic bacterial infections. While the Streptococcus anginosus group (SAG) is a well-established pathogen in pulmonary abscess formation, recent findings suggest that strict anaerobes such as Peptostreptococcus stomatis and Parvimonas micra can also contribute to deep-seated infections. However, their role in rapidly progressive pulmonary abscesses has not been previously documented. Here, we present a case of a rapidly progressive pulmonary abscess caused by Peptostreptococcus stomatis and Parvimonas micra in an immunocompetent patient, initially misdiagnosed as lung cancer. This case highlights the importance of differentiating infectious lung lesions from malignancies and underscores the clinical utility of metagenomic next-generation sequencing (mNGS) in diagnosing rare anaerobic infections, offering valuable insights for precise diagnostic and therapeutic strategies.

Atypical mycobacteriosis of the skin

A60-year-old immunocompetent patient presented with painless subcutaneous nodules on the right hand and forearm that progressed over several weeks. Nodules were clinically classified as asoft tissue tumor of primarily mesenchymal origin. After extirpation of two nodules for diagnostic clarification, histology showed achronic granulomatous inflammation of the dermis and subcutis with central eosinophilic necrosis including cell debris. Light microscopy showed no acid-fast rods, but molecular diagnostics revealed DNA of Mycobacterium haemophilum as anontuberculoid mycobacterium (NTM). The infection was identified as the cause of the nodules based on the classic histomorphology of necrotizing-granulomatous inflammation in addition to PCR-based pathogen diagnostics. This case illustrates the clinical presence of mycobacterial infections, especially in extrapulmonary and extranodal localizations. In addition to cutaneous foci of infection, NTM infections may cause multisystem disease involving the joint system, depending on the host's immunocompetence, which can be treated with antibiotics.