Diagnostic microbiology and infectious disease最新文献

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.

Urinary tract infections (UTIs) are among the most common bacterial infections worldwide, driving significant antibiotic use. The gold standard methods like urine culture, are very time consuming and may delay the right treatments at right time. Rapid diagnosis with point-of-care tests (POCTs) have emerged as potential alternatives, offering potential benefits in pathogen identification (ID) and antimicrobial susceptibility testing (AST). The main objective of this review is to evaluate the diagnostic accuracy of the POCTs in view of sensitivity, specificity, and dual assessment of pathogen ID with AST. The literature search was conducted across PubMed, MEDLINE, Europe PMC, and Google Scholar, limited to English-language publications, and covered studies up to April 30, 2025, the date of completion before manuscript submission. The review included diagnostic test accuracy studies, cross-sectional diagnostic validation studies, randomized and non-randomized controlled trials, and prospective comparative studies that enrolled both male and female patients across all age groups in primary care, outpatient, or tertiary healthcare settings with a suspicion of UTI. The comparator in all studies was standard urine culture and sensitivity. The data extraction was done by four investigators independently, rated risk of bias and assessed the quality using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) framework. The assessment of diagnostic test accuracy were analyzed with 95% CI. Fourteen studies were included in the review. Meta-analysis was performed on 12 studies for pathogen ID and 9 studies for AST, yielding pooled sensitivity and specificity estimates for both outcomes. Pooled sensitivity and specificity were 92.2% and 92.7% for pathogen ID, and 92.1% and 89.2% for AST. Time-to-result ranged <1 h to 24 hours. High diagnostic accuracy aids clinical efficacy, though heterogeneity and enactment barriers remain. POCTs have shown potential accuracy for UTI diagnosis and AST, facilitating rapid decisions, but further validation and cost studies remain necessary.

We evaluated the susceptibility of 8,123 Gram-positive bacteria from patients with skin and skin structure infections at 33 US hospitals. Ceftobiprole inhibited 99.8% of Staphylococcus aureus, including 99.5% of methicillin-resistant isolates, at ≤2 mg/L. Ceftobiprole was highly active against β-hemolytic streptococci, coagulase-negative staphylococci, viridans group streptococci, and Enterococcus faecalis isolates.

Serological methods are currently the most widely used approach for diagnosing tularemia. Identifying and evaluating immunoreactive antigens of Francisella tularensis could significantly enhance the development of an advanced diagnostic method for tularemia. This study aimed to assess three F. tularensis recombinant proteins of F. tularensis for their potential application in serodiagnosis. In the present study, three proteins were selected for evaluation. Outer membrane protein A (FopA, FTT0583), a conserved hypothetical protein (FTT0975), and GroEL protein (FTT1696). Genes from F. tularensis subsp. Holarctica LVS NCTC 10857 were cloned and expressed using the pET28a-E. coli BL21 system. The recombinant proteins were analyzed by SDS-PAGE and confirmed via western blot. After purification, immunoblot assays were performed on sera from tularemia patients and healthy controls to detect anti-F. tularensis IgG antibodies. Successful cloning of all three genes was confirmed by PCR, restriction enzyme digestion, and sequencing. The recombinant proteins were effectively expressed and purified. Immunoblotting with sera from tularemia patients showed seroreactivity rates of 36% for FopA, 24% for FTT0975, and 52% for GroEL. The diagnostic values for combination of these proteins were as follows: FopA-FTT0975 (44%), GroEL-FTT0975 (58%), FopA-GroEL (64%), and FopA-GroEL-FTT0975 (66%). No false positives were found in control sera. Although all three recombinant proteins exhibited moderate diagnostic value individually, they demonstrated enhanced performance when combined. Therefore, these proteins are recommended for use alongside other immunogenic proteins in the development of improved diagnostic tests for tularemia.