Diagnostic microbiology and infectious disease最新文献

Invasive pulmonary aspergillosis (IPA), primarily caused by Aspergillus fumigatus and A. flavus, is a life-threatening fungal infection with high mortality rates. This study investigated novel resistance mechanisms to caspofungin (CAS) in clinical Aspergillus isolates with particular focus on genetic alterations in the CoQ5 gene and their functional implications. One hundred and forty-eight Aspergillus isolates from IPA cases were undergone antifungal susceptibility testing, genotyping and phylogenetic analyses, mutations and gene expression studies of Fks1 and CoQ5 genes, and three-dimensional structural analysis of wild-type and mutant CoQ5 proteins. The etiologic agents of IPA comprised A. flavus (72.3%) and A. fumigatus (27.7%). Caspofungin (CAS) resistance was reported in 7.4% of A. flavus and 9.7% of A. fumigatus isolates. Genetic analysis identified a novel mutation in the CoQ5 gene (T371C) resulting in an amino acid substitution (Y102H) in a CAS-resistant A. flavus isolate. Structural modeling suggests this variant may impair protein stability and mitochondrial function, potentially contributing to resistance through indirect mechanisms. The definitive establishment of causality and direct contribution of CoQ5 mutations to caspofungin susceptibility requires further functional validation by employing targeted genetic manipulation and phenotypic validation to directly interrogate the role of the Y102H variant in the resistance mechanism.

Background: Bacterial endosymbionts contribute to Mucorales virulence but are rarely recognized in human infection. We describe the first clinically characterized case of Mycetohabitans endofungorum isolated from blood preceding disseminated mucormycosis.

Case: A 47-year-old immunocompetent man developed fulminant hepatitis. During pre-transplant evaluation, imaging revealed pulmonary nodules and a thoracic aortic mycotic aneurysm. Blood cultures grew an unidentifiable gram-negative coccobacillus with Vibrio-like morphology. Bronchoalveolar lavage and induced sputum cultures grew Rhizopus species. Despite maximal medical therapy, he was not a surgical candidate because of extensive vascular involvement. Subsequent 16S sequencing identified the bloodstream isolate as M. endofungorum, an obligate intracellular endosymbiont of Mucorales fungi.

Discussion: Isolation of M. endofungorum in blood may signal invasive mucormycosis. Even in patients without published risk factors, transient physiologic stress and barrier disruption may permit fungal invasion. Early recognition of bacterial endosymbionts could provide a valuable diagnostic clue in invasive fungal disease.

Worldwide distribution of dandruff associated scalp infections is caused by lipophilic Malassezia spp. This rationale lead the study to investigate the prevalence and etiologic species in a cross-sectional study involving 300 subjects who visited dermatology hospitals to seek treatment in K.R. Hospital, JSS Hospital and CSI Holdsworth Memorial Mission Hospital, Mysuru region, Karnataka, India. With the consent of participants, dandruff flakes samples were collected. The presence of Malassezia spp. were assessed by morphological and biochemical characterization, where six major yeast groups M. furfur (36%), M. globosa (21%), M. restricta (18%), M. sympodialis (12%), M. japonica (8%) and M. obtusa (5%) causing dandruff were found to be present in 79.6% of collected test samples. High resistant patterns to antimycotic data of minimal inhibitory concentration (MIC90) to Fluconazole, Ketoconazole and Miconazole indicated the emergence of multi azole resistant Malassezia spp. The isolates being pathogenic was hemolysis positive. The dandruff specific isolates M. furfur, M. restricta and M. globosa exhibited typical phospholipase activity indicating the pan-genome attributes for inducing severe itching along with scalp infections in infected individuals. It was evident from SEM data that Malassezia spp. had characteristics of yeast like structure with collarets appearing during blastospore formation. Further with M13RAPD-PCR, ITS-PCR, epidemiological specificity and genotypic relatedness of isolates to Malassezia spp. was confirmed and 18S rDNA sequences were submitted to NCBI database with the accession numbers PP189840 to PP189845. The data acquired during study can be of prime diagnostic method for timely management and accurate analysis of dandruff caused by Malassezia spp. at global settings.

Norovirus is a major cause of acute gastroenteritis (AGE) globally. GII.17[P17] has been reported in the last decade as a prevalent norovirus genotype worldwide. We documented the circulation of norovirus GII.17[P17] isolates during an AGE outbreak occurring in western Romania, in 2024. Norovirus whole-genome sequences were obtained by Illumina technology and used for inferring phylogeny and to identify amino acid substitutions harboured by the VP1 major capsid protein and by the RNA-dependent RNA polymerase (RdRp). Phylogenetic analyses indicated high degree of relatedness between the Romanian isolates and the strains reported in Europe, United States, Argentina, and Japan between 2023 and 2025. All of these viruses belong to the Romania-2021 GII.17[P17] cluster, which also comprises isolates identified in Russia between 2021 and 2023. Substitutions in previously described VP1 epitope regions and in RdRp were detected. Continuous monitoring is needed to establish if the dominance of this cluster is local and transitory, as seen before for GII.17, or if it will become pandemic.

Ecthyma gangrenosum (EG) is an uncommon manifestation of Pseudomonas aeruginosa bloodstream infection (BSI), which mostly affects immunocompromised individuals. We describe the case of a 30-year-old woman with hyperthyroidism on methimazole who developed fever, skin and gingival lesions after returning from Nepal, where she experienced insect bites and discontinued methimazole. She presented with severe neutropenia and hemorrhagic and bullous gingival and face skin lesions. Isolation from blood cultures of P. aeruginosa prompted the start of antibiotic therapy with ciprofloxacin, leading to an improvement in clinical conditions, resolution of leukopenia and healing of lesions. Meanwhile, Dengue virus IgM seroconversion was detected. Dengue virus infection may have caused transient immunosuppression, contributing to the development of EG. The lack of worsening neutropenia after reintroducing methimazole further supports Dengue virus infection as the underlying cause. This case underlines the potential role of Dengue virus in causing immunosuppression, predisposing to BSI from P. aeruginosa and EG.

Eravacycline is a third-generation tetracycline, a fluorocycline agent with two modifications that distinguish it from tigecycline. Eravacycline demonstrated effectiveness against various gram-positive and gram-negative facultatively anaerobic bacteria, including multidrug resistant Enterobacterales, Acinetobacter baumannii, staphylococci, enterococci, and pneumococci. However, whereas numerous studies focused on the impact of eravacycline on facultative anaerobic microbes, there is limited data regarding its efficacy against anaerobes. The aim of the present review was to compare eravacycline activity to that of other antibiotics used against anaerobic/microaerophilic bacteria and to assess potential benefits of the newer agent in anaerobic or mixed aerobic-anaerobic infections. We encompassed information from the literature published in English and included our own pilot study. Compared to most comparator antibiotics, eravacycline was more effective against anaerobes, including Bacteroides/Parabacteroides, Prevotella, Fusobacterium, Clostridioides difficile and other clostridial species, as well as gram-positive anaerobic cocci, and Cutibacterium acnes. Most frequently, eravacycline MICs were ≥4 to ≥8-fold lower than those of most comparator antibiotics. In addition, eravacycline did not trigger an infection with C. difficile and is considered a tolerable medication. So far, only the injectable eravacycline administration for complicated intraabdominal infections has been approved. However, more studies in more countries are needed to assess its usefulness for combination treatment and still not labeled indications.

We report a case of a Chinese male patient with a history of Hepatolithiasis who was admitted for abdominal pain, fever, and chills. Imaging studies suggested cholangitis and Hepatolithiasis. Blood cultures revealed two rare fastidious anaerobes-Olsenella uli and Christensenella hongkongensis-confirmed by MALDI-TOF MS and 16S rDNA full-length sequencing. These organisms failed to grow on standard solid media but were successfully isolated using a self-prepared solid medium formulated based on the nutrient solution from blood culture bottles. This suggests that for anaerobic bacteria with positive blood cultures but negative routine cultures, the use of such media may improve isolation rates. This case demonstrates that although such infections are extremely rare, mortality may correlate with the severity of underlying disease. Successful identification provides a reference method for isolating and identifying fastidious bacteria in similar cases.

Direct matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) enables rapid identification of microorganisms in urinary tract infections (UTIs), accelerating diagnosis and guiding early antimicrobial therapy alongside conventional culture. However, there is no universally established threshold for significant bacteriuria determined by flow cytometry in clinical decision-making. This study analyzed 652 urine samples from suspected UTI patients at Hospital Clínico Universitario de Valencia (Jan 2023-Nov 2024). Flow cytometry was used to determine bacterial load (bacteria/µL) and Gram staining before MALDI-TOF MS and culture processing. The overall concordance between MALDI-TOF MS and culture was 96.5%. Samples successfully identified by MALDI-TOF MS had a significantly higher median bacterial load than those not identified. Receiver operating characteristic (ROC) analysis established 15,606 bacteria/µL as the optimal cut-off for MALDI-TOF MS processing (sensitivity: 83.3%, specificity: 50%, PPV: 70.9%, NPV: 67.2%). This differs from the conventional ≥ 10⁵ CFU/mL threshold, suggesting MALDI-TOF MS remains effective at lower bacterial loads, thus improving resource efficiency. Additionally, lateral flow immunochromatographic (LFIC) assays facilitated rapid detection of resistance mechanisms, aiding empirical antimicrobial therapy. Our findings support the utility of flow cytometry in efficiently selecting candidate samples for MALDI-TOF MS, enhancing clinical decision-making in UTI management.

Hafnia alvei is a rare cause of human infection and possesses a chromosomal AmpC β-lactamase. Among 30 adults with H. alvei bacteremia, 60% had pancreaticobiliary cancer, with the biliary tract as the most common source. Resistance did not develop in any of the 10 patients treated with third-generation cephalosporins.

Fusarium species are important opportunistic fungal pathogens. Diabetic foot infection (DFI) involves diverse causative pathogens however, the potential for fungal etiologies is often overlooked. We describe a case of DFI following foot trauma. Despite prior broad-spectrum antimicrobial therapy, the wound failed to heal and presented persistent swelling and pain. Microbiological re-evaluation and molecular identification confirmed the causative agent as Fusarium keratoplasticum (F. keratoplasticum), a pathogenic species within Fusarium solani species complex (FSSC). The isolate exhibited high MICs against most antifungals, thus systemic antifungal therapy was withheld. Successful management was achieved through systematic surgical debridement combined with silver-ion dressings, resulting in pathogen eradication and complete wound healing. Currently, F. keratoplasticum infections remain extremely limited, particularly those definitively confirmed to species level. This case broadens the pathogen spectrum of DFI and highlights the need for comprehensive etiologic evaluation in therapy-refractory wounds, offering a non-pharmacological strategy for resistant fungal infections.