Journal of medical microbiology最新文献

Dientamoeba fragilis is a gastrointestinal parasite of controversial clinical significance. From its discovery until today, contradictory articles have been published on whether infection is correlated with symptoms, treatment is associated with recovery and whether infection is associated with elevated intestinal inflammatory markers (faecal calprotectin). Additionally, there is no consensus on the infective stage of the lifecycle. Competing theories propose that either Enterobius vermicularis ova act as a vector for the transmission of trophozoites or that the cyst stage, which is rarely found, is responsible for infection. In this review, we aim to critique these contradictions to determine if D. fragilis should be considered a pathogen in clinical practice. The frequent limitation of studies is challenges in setting up a reliable, healthy control group and the reliability of diagnostic methods. Many studies are opportunistic in design, using samples that have been submitted for routine pathology testing. Even if all pathology tests are negative for infectious agents, the current health status of people who are submitting samples for pathology testing is unlikely to be the best option, just the most available one. Of greater concern is the reliability of some diagnostic methods. Some studies have suggested that at least one of the lab-based real-time PCR assays used for the diagnosis of D. fragilis has issues with false positives in human samples. This calls into question much of the evidence that has been published on D. fragilis being a commensal instead of a pathogen. As such, D. fragilis should be considered a potential pathogen when investigating gastrointestinal illness. Developing better guidelines on determining when D. fragilis is the causative agent of symptoms and when to treat are important topics for future research.

Introduction. Growing evidence indicates significant interactions between the intestinal microflora and drugs commonly used to treat coronary heart disease.Hypothesis/Gap Statement. Despite this, research specifically investigating the relationship between proprotein convertase subtilisin/kexin type 9 inhibitors and alterations in the gut microbiota has not been previously published.Aim. This study aimed to identify changes in the gut microbiota potentially associated with evolocumab use in patients with acute myocardial infarction (AMI).Methodology. In this prospective study, 26 AMI patients receiving statins (≥8 weeks) were administered evolocumab (420 mg/4 weeks) alongside standard therapy. Eighteen age-matched healthy volunteers served as controls. 16S rRNA sequencing (NCBI SRA: PRJNA1154993) was subsequently performed on samples from these groups to analyse the gut microbiota community.Results. No significant α-diversity differences were observed among groups (P>0.05). Firmicutes dominated AMI-evolocumab baseline (0 W: 76.32%) versus post-treatment (8 W: 65.22%) and controls (60.40%), while Bacteroidota increased post-treatment (0 W: 15.07%→8 W: 19.99%; control: 27.11%). The second most abundant phyla were Proteobacteria and Actinobacteria. In addition, the differences in the microbial structure among the three groups were as follows: at the genus level, the results of the genus difference analysis revealed significant differences in the abundances of nine types of bacteria among the three groups. Compared with those in the AMI-evolocumab (0 W) group, the abundances of beneficial bacteria, such as Odoribacter and Parabacteroides, were increased in the AMI-evolocumab (8 W) group.Conclusion. Our research showed that evolocumab can regulate the gut microbiota of patients with AMI to promote a healthier state, which is beneficial for patients with AMI.

Introduction. Chronic wounds are notoriously difficult to treat and are associated with decreased limb function, reduced quality of life and significant morbidity. Their recurrent nature, despite aggressive antibiotic therapy, is due in part to the presence of polymicrobial biofilms. Pseudomonas aeruginosa and Staphylococcus aureus are two of the most frequently co-isolated pathogens in these infections and are known to form complex biofilms that hinder treatment.Hypothesis. We hypothesized that co-existence and competitive dynamics between P. aeruginosa and S. aureus in chronic wound infections are influenced by strain-specific interactions and may not rely solely on well-characterized inhibitory mechanisms such as 2-alkyl-4-quinolone (AQ) production by P. aeruginosa impacting on S. aureus fitness.Aim. To establish a polymicrobial chronic wound infection model and assess the contribution of AQ signalling and strain-specific interactions on co-existence.Methodology. We used a modified chronic wound biofilm model to co-culture matched and mismatched clinical isolate pairs of P. aeruginosa and S. aureus, collected from two different chronic wound patients. Viable bacterial counts (c.f.u.) were quantified over an 8-day period. AQ production by each P. aeruginosa strain was quantified using liquid chromatography-MS.Results. A stable culture of P. aeruginosa strains was achieved, but distinct behaviours between each S. aureus strain were seen. One matched clinical isolate pair maintained stable c.f.u. levels of both species throughout the 8-day model, indicating a compatible co-existence. In contrast, mismatched pairs showed early loss of S. aureus viability and the emergence of small colony variants after 4 days, not seen in matched pair growth. Interestingly, the most competitive P. aeruginosa strain exhibited undetectable levels of all AQs tested, indicating that its dominance was not due to AQ-mediated antagonism, as has previously been described.Conclusion. Our findings demonstrate that stable dual-species biofilm formation in chronic wounds is strain-dependent and that P. aeruginosa can impact on S. aureus fitness through AQ-independent mechanisms. These results highlight the importance of using clinical isolates in biofilm research and caution against generalizing findings from laboratory strains to complex clinical infections.

Introduction. Rectovaginal colonization with Streptococcus agalactiae in pregnant women is a risk factor for invasive infections of the newborns. Various culture-based approaches are available (selective vs. non-selective media±enrichment).Hypothesis/Gap Statement. Comprehensive head-to-head comparisons of culture-based methods for S. agalactiae screening in pregnant women are largely missing.Aim. We compared the test accuracy of six culture-based approaches for the detection of S. agalactiae.Methodology. We performed a cross-sectional study on vaginal or rectovaginal swabs (in liquid Amies medium) from pregnant women. Samples were analysed in parallel in six study arms using (i) colistin nalidixic acid (CNA) agar, (ii) chromogenic S. agalactiae selective agar, (iii) CNA agar after enrichment in thioglycolate broth, (iv) chromogenic agar after enrichment in thioglycolate broth, (v) CNA agar after enrichment in Todd-Hewitt broth and (vi) chromogenic agar after enrichment in Todd-Hewitt broth. The test accuracy was calculated for each study arm using a composite reference standard.Results. In total, 244 pregnant women were included (median age: 32 years, median weeks of pregnancy: 28 3/7). Positivity was comparable between approaches with direct inoculation on solid media (study arms i and ii, 15.6-18.0%) and with primary enrichment (study arms iii-vi, 17.6-18.9%). Each study arm had a specificity of 100%, while the sensitivity varied between 81% (CNA agar alone, study arm i) and 98% (Todd-Hewitt broth for enrichment followed by subculture on chromogenic agar, study arm vi).Conclusion. Enrichment in Todd-Hewitt broth followed by subculture on chromogenic agar had the highest sensitivity (98%, specificity: 100%) for the detection of S. agalactiae in pregnant women.

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. 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.