Journal of medical microbiology最新文献

Introduction. Aspergillosis represents a significant global health threat, with increasing concerns about azole resistance.Hypothesis/Gap Statement. There is limited evidence on the prevalence and distribution of azole resistance among clinical Aspergillus isolates.Aim. This study investigated the prevalence of azole resistance in clinical Aspergillus isolates and evaluated different susceptibility testing methods.Methodology. A total of 125 Aspergillus spp. isolates were collected from clinical samples (abscess, corneal abscess, biopsy, tissue and respiratory samples). Species identification was performed using conventional morphological methods and Matrix assisted laser desorption Ionization time of flight massspectrometry (MALDI-TOF) MS. Azole susceptibility testing was conducted using the gradient test (E-test), the agar plate screening method and broth microdilution for voriconazole (VOR), itraconazole (ITR) and posaconazole (POS). Molecular analysis was performed to detect cyp51A gene mutations associated with resistance.Results. Among 125 isolates, species distribution was 44% Aspergillus fumigatus, 33.6% Aspergillus flavus, 5% Aspergillus terreus, 3% Aspergillus niger and 14% Aspergillus spp. Using gradient testing, A. fumigatus showed 1.8% resistance to VOR, 5.45% to ITR and 1.8% to POS, with one isolate resistant to all azoles. A. terreus showed 16.7% resistance to VOR, A. niger 25% resistance to ITR and Aspergillus spp. showed various resistance patterns. The agar plate method detected resistance with 100% susceptibility/specificity for non-fumigatus species but 33.3% susceptibility for A. fumigatus ITR resistance. CypA-L98H mutations were detected in six isolates and CypA-M220 mutations in seven isolates.Conclusion. This study confirms the presence of azole resistance in clinical Aspergillus isolates with species-specific variations. The agar plate screening method shows promise for non-fumigatus species but requires optimization for A. fumigatus.

Introduction. Helicobacter pylori infection is a major global health concern, and its increasing antibiotic resistance poses significant challenges to eradication therapy. Traditional methods for detecting H. pylori resistance are time-consuming and labour-intensive.Hypothesis/Gap Statement. The limitations of traditional methods highlight a critical need for a rapid, accurate and comprehensive approach to detect H. pylori resistance that can inform personalized treatment strategies and improve eradication outcomes.Aim. This study aimed to explore the potential of Raman spectroscopy as a rapid and accurate method for detecting H. pylori resistance to clarithromycin and levofloxacin.Methodology. We employed Raman spectroscopy to analyse the metabolic fingerprints of H. pylori strains treated with different concentrations of antibiotics. Principal component analysis and deuterium oxide labelling techniques were used to differentiate between resistant and susceptible strains.Results. Our results demonstrated that Raman spectroscopy can accurately predict H. pylori antibiotic resistance within 4-6 h, significantly reducing detection time compared with traditional methods.Conclusion. This study provides a promising approach for rapid and accurate detection of H. pylori antibiotic resistance, enabling personalized treatment strategies and improving eradication outcomes.

Introduction. Biofilms have been implicated as a potential cause of chronic rhinosinusitis (CRS), with patients showing an increased prevalence of biofilms, likely contributing to antibiotic ineffectiveness in these individuals. In many environments, biofilms are polymicrobial, with interspecies interactions promoting bacterial survival and encouraging robust growth. Improvements in visualization techniques for biofilms have enabled species-specific identification, leading to a growing body of literature using these techniques and examining severity in different phenotypes of CRS.Gap Statement. It is unclear whether sinus biofilms are typically poly- or monomicrobial, and if they are correlated with clinical severity in CRS.Aim. We conducted a scoping review to determine how prevalent biofilms were in sinus tissue of patients with CRS. Furthermore, we correlated disease severity with the presence of biofilms.Methodology. We searched PubMed, Scopus, Medline and Web of Science databases for all studies which directly visualized biofilms on tissue from patients with CRS. After screening 1,853 search results, 39 studies were included for analysis in this review.Results. Patients with CRS had a higher prevalence of biofilms compared with controls. We found no significant difference in the proportion of biofilms detected across visualization techniques or based on CRS phenotyping. Fifteen studies reported disease severity by biofilm status; most reported greater severity in patients with biofilms, although only some were statistically significant. Nine studies used techniques capable of detecting polymicrobial biofilms, all of which found a subset of polymicrobial biofilms.Conclusion. Our findings demonstrate an increased prevalence of biofilms in patients with CRS, which may correspond to increased disease severity. The evidence for biofilms being polymicrobial is compelling, although it is based on a small number of studies.

Introduction. Melissococcus plutonius is the causative agent of European foulbrood (EFB), a disease of honey bees that is endemic in many areas of the USA. Only one antibiotic, oxytetracycline (OTC), is approved for EFB management, and there have been reports of recalcitrance.Gap Statement. Resistant strains of M. plutonius have been identified in Canada and Japan, but methodology differs between studies, making reliable comparisons difficult. Additionally, no M. plutonius isolates from the USA have yet been tested for susceptibility to OTC, despite decades of use.Aim. Here, we determine the impact of media, time and persistence on the results of commonly used growth and antibiotic resistance assays using regionally representative M. plutonius isolates.Methodology. Twelve genetically diverse isolates of M. plutonius were tested for susceptibility to OTC using previously published assays, but with variations in media and time to determine factors that may be impacting results.Results. Media composition and incubation time dramatically impact antibiotic susceptibility assays for M. plutonius, differing widely between strains, likely due to differences in OTC stability. Assays that ended when growth appeared on antibiotic-free agar showed that all strains remained susceptible to OTC with an MIC of 2-4 µg ml^-1. However, M. plutonius remains viable after OTC efficacy wanes, with some strains able to persist at room temperature for at least 3.5 years.Conclusion. To standardize antibiotic susceptibility testing for M. plutonius, we recommend the use of M110 media due to stability and speed of growth. However, all strains of M. plutonius persist on M110 beyond the window of OTC efficacy, complicating assay results and interpretation, and additional research is needed to determine the clinical implications of these findings.

Introduction. Host genetics plays a pivotal role in determining disease susceptibility among individuals infected with Mycobacterium tuberculosis. Scavenger receptors (SRs) such as CD36 and SR-B1 mediate pathogen recognition and lipid uptake, both of which are central to mycobacterial entry and immune modulation.Gap Statement. Polymorphisms rs1761667 and rs3211938 in CD36 and rs4238001 in SR-B1 have not been investigated in any population in relation to both latent tuberculosis infection (LTBI) and active tuberculosis (TB).Aim. To genotype CD36 and SR-B1 polymorphisms and evaluate their association with TB and LTBI. To predict the functional/regulatory impact of these SNPs and compare their allele frequencies with global datasets.Methodology. Polymorphisms were genotyped using amplification refractory mutation system PCR within a case-control design. Genotype frequencies were compared using Fisher's exact chi-square test. Functional and regulatory effects were predicted using PolyPhen-2 and RegulomeDB, while the 1000 Genomes database was used for population comparison.Results. The homozygous AA genotype of SR-B1 rs4238001 was strongly associated with active TB (P=0.00), while the heterozygous GA genotype showed a protective association with LTBI (P=0.00). For CD36, the homozygous GG genotype of rs3211938 was associated with protection against active TB (P=0.02) but exhibited the opposite pattern in LTBI (P<0.00). Moreover, the heterozygous GA genotype of rs1761667 was significantly linked to increased risk of LTBI (P=0.00). In silico functional prediction classified rs4238001 as missense and rs3211938 as nonsense variant. Regulatory analysis indicated that rs4238001 and rs1761667 affect transcription in TB-relevant tissues. Population analysis highlighted variation in allele frequencies across groups.Conclusion. Polymorphisms in SR-B1 and CD36 show distinct associations with LTBI and TB, suggesting contrasting genetic influences on infection establishment and disease onset. These findings reveal a novel host genetic component of TB pathogenesis and warrant validation in larger, multiethnic cohorts.

Introduction. Streptococcus pneumoniae remains a major pathogen causing invasive diseases in children worldwide. Although pneumococcal conjugate vaccines (PCVs) have significantly reduced the disease burden, non-vaccine serotypes and antimicrobial resistance continue to be of concern.Hypothesis/ Gap Statement. The epidemiology of paediatric invasive pneumococcal disease (IPD) and antimicrobial resistance patterns in Japan following the coronavirus disease 2019 pandemic and prior to the introduction of PCV15 and PCV20 has not been fully characterized.Aim. To investigate the recent distribution of pneumococcal serotypes, antimicrobial susceptibility and genetic characteristics of isolates derived from paediatric patients in Japan from 2020 to 2023.Methodology. We conducted a nationwide, prospective surveillance study from March 2020 to April 2023. A total of 151 pneumococcal isolates (126 from IPD cases and 25 from non-IPD cases) were collected from children under 15 years of age. Serotyping, antimicrobial susceptibility testing and whole-genome sequencing were performed to assess epidemiological and genomic features.Results. No patient mortality was reported, but sequelae were observed in 4 (3.2%) of 125 IPD patients. The most common serotypes in IPD were 15B/C (23.0%), 15A (11.1%) and 24B (10.3%). Among 126 IPD isolates, the vaccine coverage rates for PCV13, 15 and 20 were 0.8, 13.5 and 42.1%, respectively. Overall resistance rates to penicillin (PEN), cefotaxime, meropenem (MEM) and erythromycin (ERY) were 31.8, 15.9, 18.5 and 88.7%, respectively. Serotypes 15A-CC63 and 35B-CC558 showed high resistance rates to β-lactams, including MEM. Genomic analysis revealed that the predominant genotypes were 15B/C-CC199, 15A-CC63, 24B-CC2754 and 10A-CC5236.Conclusion. Non-vaccine and PEN-, MEM- and ERY-resistant clones, particularly 15A-CC63 and 35B-CC558, were prevalent among paediatric pneumococci in Japan. Even with PCV20, less than half of the IPD isolates were covered; this underscores the need for ongoing genomic surveillance, antimicrobial stewardship and consideration of expanded-valency vaccines targeting additional serotypes, such as 15A and 35B.

Introduction. Streptococcus pneumoniae is a leading cause of pneumonia, meningitis and other invasive diseases. The increasing prevalence of antibiotic resistance in S. pneumoniae has become a major public health concern, complicating clinical treatment and highlighting the need for continuous surveillance.Gap Statement. Although previous studies have reported the antimicrobial resistance, serotype distribution and molecular characteristics of S. pneumoniae in some regions of China, systematic and whole-genome sequencing-based epidemiological data for Sichuan Province remain limited. Currently, there is a lack of comprehensive understanding regarding the predominant serotypes, resistance profiles, virulence gene carriage and their relationship with global clonal complexes in this region. In particular, data supporting the assessment of vaccine-covered serotypes and the transmission risk of multidrug-resistant strains are insufficient.Aim. This study aimed to investigate the prevalence, serotype distribution, antimicrobial resistance and molecular characteristics of S. pneumoniae isolates in Sichuan Province, providing genomic evidence to support rational antibiotic use and optimize immunization strategies.Methodology. A total of 105 clinical S. pneumoniae strains were collected in 2023 through the China Pathogen Identification Net. The serotypes, molecular types and antibiotic resistance of the strains were determined by whole-genome sequencing, sequence analysis and antimicrobial susceptibility test.Results. The leading serotypes were 19F (34.29%), 19A (10.48%), 3(7.62%) and 6E (7.62%). The dominant sequence types (STs) were ST271 (30.48%) and ST320 (10.48%), with CC271 and GPSC1 being the predominant groups. Vaccine coverage rates were 45.71% for PCV7/PCV10, 64.76% for PCV13, 69.52% for PCV20 and 70.48% for PPV23. All isolates were susceptible to linezolid and vancomycin, but high resistance was observed to erythromycin (92.38%), clindamycin (82.86%), tetracycline (86.87%) and trimethoprim/sulfamethoxazole (60.95%). The multidrug resistance (MDR) rate was 85.71%. Nine resistance genes were identified, with erm(B) and tet(M) being the most prevalent.Conclusion. Our study provides reliable information, including the prevalence, molecular characterization and antimicrobial resistance of S. pneumoniae isolates in Sichuan Province of China in 2023. The high MDR rate and predominance of vaccine-covered serotypes highlight the urgent need for enhanced surveillance, rational antibiotic use and broader implementation of pneumococcal vaccines, including the potential introduction of PCV20.

Introduction. Brucellosis is a zoonotic contact infectious disease caused by Brucella. Recently, researchers screened a series of Brucella effector proteins and identified the functions of most of them, which play important roles in the intracellular survival of Brucella.Hypothesis. We hypothesized that the BspC protein from Brucella melitensis M5-90 plays a significant role in the intracellular proliferation of Brucella.Aim. This study aimed to investigate the role of the Brucella melitensis M5-90 effector protein BspC in host cell processes, specifically its interaction with host proteins, and its effects on apoptosis, inflammation, oxidative stress, and global gene expression.Methodology. First, host proteins that interacted with BspC were identified from the cDNA library of a mouse macrophage cell line (RAW264.7) by yeast two-hybrid technology, and the key interacting proteins were confirmed by cotransformation. The pTT5-BspC recombinant plasmid was subsequently constructed and transfected into HEK293T cells. The expression of apoptosis-related proteins was assessed by Western blotting, the apoptosis rate was analysed by flow cytometry, the subcellular localization of proteins was observed by laser confocal microscopy and cytokines and oxidative stress indicators were assessed by ELISA and other kits. Furthermore, RNA-seq transcriptome sequencing was used to analyse the effects of BspC on the host gene expression profile.Results. Four host proteins (FDX1, DNAJA1, HSPA5 and PTPN2) that interacted with BspC were identified from the RAW264.7 cell cDNA library by yeast two-hybrid technology, and their interactions were confirmed by cotransformation. BspC protein expression in HEK293T cells significantly promoted cell apoptosis, as indicated by the upregulation of proapoptotic proteins (Bax, p53 and Caspase-3) and the downregulation of the antiapoptotic protein Bcl-2. Immunofluorescence staining revealed that BspC was localized in the cytoplasm and nucleus. In addition, BspC induced the secretion of proinflammatory cytokines (TNF-α, IL-1β and IL-6) and lactate dehydrogenase and reduced malondialdehyde levels by increasing the activities of SOD, CAT, GSH-PX and GSH, suggesting its regulation of the oxidative stress response. Transcriptome analysis revealed that BspC expression induced differential expression in 796 genes (209 upregulated and 587 downregulated), which were significantly enriched in the ECM-receptor interaction and MAPK and NF-κB signalling pathways.Conclusion. BspC may promote the immune escape and pathogenicity of Brucella by interfering with host cell apoptosis, the inflammatory response and the redox balance.

Introduction. Fungal keratitis, particularly in tropical and subtropical regions, poses significant therapeutic challenges due to biofilm formation by fungal pathogens. These biofilms confer increased resistance to antifungal treatments and are associated with poorer clinical outcomes.Hypothesis/Gap Statement. Despite growing recognition of their impact, there remains a lack of comprehensive synthesis on the role of fungal biofilms in corneal ulcers.Aim. This study aims to determine the impact of and how biofilm formation influences the chronicity and treatment outcomes in fungal corneal ulcers.Methodology. A comprehensive literature search was performed across PubMed, ScienceDirect, Scopus and the Cochrane Library in April 2025. Only English articles were included, and animal studies were excluded. Eligible studies included clinical and in vitro investigations that assessed biofilm formation in fungal corneal ulcers and its impact on antifungal susceptibility and treatment outcomes. This systematic review and meta-analysis were conducted in accordance with PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) 2020 guidelines and registered under PROSPERO (an international systematic review registry, ID:CRD420251017502). Independent data extraction was done by two reviewers. Data on MICs were synthesized using random-effects models, and heterogeneity was assessed with I² statistics and Cochran's Q test. Clinical outcomes were analysed narratively due to reporting variability.Results. Seven studies were included, spanning Brazil, India, China and Mexico, and covering both in vitro and clinical designs. Meta-analysis showed significantly increased MIC values for biofilm-forming fungal isolates: amphotericin B [pooled log_₂ fold change=5.31; 95% confidence interval (CI): 2.92-7.70], voriconazole (6.06; 95% CI: 2.25-9.87) and natamycin (1.25; 95% CI: 0.48-2.02). High heterogeneity was noted for amphotericin B and voriconazole, while results for natamycin were consistent. Narrative synthesis of clinical data indicated that biofilm formation is associated with prolonged healing times, increased recurrence rates, reduced visual acuity and higher complication risks.Conclusion. Biofilm formation by fungal pathogens significantly reduces antifungal susceptibility and worsens clinical outcomes in fungal keratitis. Elevated MIC, delayed healing and increased rates of complications emphasize the need for targeted biofilm-disrupting therapies and standardized diagnostic protocols. Future research should focus on developing clinical strategies that integrate biofilm assessment to improve patient outcomes.