Journal of medical microbiology最新文献

Introduction. Vibrio cholerae is a diverse species of bacteria that causes watery diarrhoea, vomiting and stomach cramps and is the aetiological agent of cholera.Gap statement. Despite the global upsurge in notifications of cholera and concerns over the impact of climate change, systematic analysis of national and international surveillance data describing the microbiology and epidemiology of V. cholerae is sparse.Aim. We reviewed the microbiology and epidemiology of V. cholerae isolated from travellers returning to the UK.Methodology. All human isolates of V. cholerae detected from 2004 to 2024 were extracted from UK Health Security Agency reference laboratory surveillance systems. Microbiological data were analysed and linked to available epidemiological data and genome sequences for all isolates from 2016 to 2024.Results. There were 984 notifications of V. cholerae from 2004 to 2024 (an average of 51 each year), of which 266 (27.0%) belonged to serogroup O1. There were over 180 different sequence types (STs), of which cholera toxin producing ST69 was the predominant type (n=99, 28.2%). The highest number of isolates was in 2010 (n=74), while the lowest was in 2020 (n=8) and 2021 (n=4) due to travel restrictions imposed during the COVID-19 pandemic. Children under the age of 10 and the middle-aged and elderly population were most susceptible to infection, and 51.6% of the cases were male. There was a seasonal peak in August and September. Travel was reported by 92.9% of cases, and the most frequently reported travel destinations were India, Pakistan and Kenya.Conclusion. From the UK perspective, to assess the risk to food safety and to more accurately determine the clinical burden of V. cholerae, we recommend (i) widespread molecular testing of shellfish to monitor the emergence of V. cholerae in UK waters due to climate change and (ii) comprehensive testing of faecal specimens from non-travellers with gastrointestinal symptoms. Public health surveillance and information sharing at the global level is essential to assess the impact of investment in water, sanitation and hygiene initiatives for the prevention of cholera.

Introduction. Direct detection of Borrelia burgdorferi by culture is considered the gold standard for confirming Lyme disease (LD). However, B. burgdorferi culture is not routinely used in clinical practice or research due to its lengthy protocol and low success rate. This study aimed to streamline the process by integrating a specific quantitative PCR (qPCR) screening early into the B. burgdorferi culture workflow for identification of cultures that are likely to yield viable spirochetes.Methods. Thirty-two blood plasma and 11 cerebrospinal fluid (CSF) samples were collected from 32 children with serologically confirmed LD and incubated in modified Kelly-Pettenkofer medium for up to 9 weeks, with weekly assessments for viable spirochetes using microscopy. After 3 weeks, the presence of B. burgdorferi DNA in culture was assessed by qPCR targeting the B. burgdorferi flagellin B gene. The estimated copy number of the target template was compared to the assay's 95% limit of detection (LOD).Results. After 9 weeks of incubation, viable spirochetes were observed in 2 (n=2/32, 6.3%) plasma cultures and 3 (n=3/11, 27.3%) CSF cultures. These were only observed in cultures showing copy numbers above 95% LOD in qPCR testing at week 3 (n=2/3 plasma cultures, 66.7%; n=3/3 CSF cultures, 100.0%).Conclusion. Culturing B. burgdorferi is challenging and, despite a high workload, often not successful. qPCR may serve as an effective screening tool for B. burgdorferi cultures, enabling the culturing process to be streamlined by prioritizing cultures with target copy numbers exceeding the 95% LOD of the qPCR assay.

Introduction. The increasing resistance and the pathogen's complex multi-drug resistance mechanisms made the selection of effective antimicrobial treatments more challenging for Pseudomonas aeruginosa (P. aeruginosa). The study aimed to explore the effect of Scutellaria baicalensis, Prunella vulgaris and antimicrobial peptide LL-37 on the virulence factors of P. aeruginosa.Hypothesis. Previous studies have shown that extracts from traditional Chinese medicines, Scutellaria baicalensis and Prunella vulgaris, can also enhance the effects of antibiotics and reduce antibiotic resistance in P. aeruginosa. Antimicrobial peptide LL-37 shows the potential as a new-generation candidate for treating multi-drug-resistant bacteria, which has advantages over traditional antibiotics, whilst the combination role between Scutellaria baicalensis, Prunella vulgaris and LL-37 in P. aeruginosa remains unknown.Aim. We explored whether the combined use of Scutellaria baicalensis, Prunella vulgaris and LL-37 can exert antibacterial effects through the quorum sensing (QS) system.Methodology. The minimal inhibitory concentrations of Scutellaria baicalensis, Prunella vulgaris and LL-37 were determined for PAO1 and PA-ΔlasI/rhlI using micro broth dilution. The antibacterial activity of Scutellaria baicalensis combined with LL-37 and Prunella vulgaris combined with LL-37 was also assessed. The growth abilities of PAO1 were analysed after being treated with Scutellaria baicalensis, Prunella vulgaris and LL-37, respectively. Elastase secretion was measured using Congo red-elastic proteinase assays. And the expressions of QS genes (lasI, rhlR) were analysed by real-time PCR.Results. Single or combined treatments of Scutellaria baicalensis and LL-37 and Prunella vulgaris and LL-37 would significantly reduce elastase secretion. There were no significant differences in proliferation between the groups at any timepoint. All treatments downregulated lasI and rhlR gene expressions.Conclusion. Scutellaria baicalensis, Prunella vulgaris and antimicrobial peptide LL-37 all down-regulate the QS system-related genes of P. aeruginosa, inhibiting the secretion of virulence factors and reducing bacterial toxicity.

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. 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. 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. The correlation between antibiotic exposure and adverse outcomes in patients with acute-on-chronic liver failure (ACLF) remains controversial, and the underlying mechanism is unclear.Hypothesis/Gap Statement. This study hypothesizes that antibiotic exposure in ACLF patients alters gut microbiota, which affects the outcome of ACLF.Aim. To explore the effect of antibiotic exposure on gut microbiota that affects the outcome of ACLF.Methodology. A retrospective matched study of ACLF patients and the ACLF rat model was used to assess adverse outcomes associated with antibiotic exposure. The gut microbiota of the ACLF patients and the ACLF rat model were sequenced using the Illumina MiSeq platform.Results. Twenty-three ACLF patients who were exposed to antibiotics and 46 matched controls who were not exposed to antibiotics were enrolled. The survival rates at 4, 12 and 24 weeks were significantly lower in the exposure group than in the non-exposure group. In the ACLF rat model, hepatitis in the antibiotic-exposure group became more severe, and the alanine transaminase levels were higher than those of the non-exposure group. The gut microbiota diversity was decreased in the ACLF patients with antibiotic exposure, and the proportions of Enterococcaceae and Peptostreptococcaceae were increased, while those of Lachnospiraceae, Bifidobacteriaceae and Bacteroidaceae were decreased. In the rat model, antibiotic exposure induced Gram-positive and Gram-negative bacterial eradication, and Klebsiella became the dominant micro-organism.Conclusion. Antibiotic exposure aggravated hepatitis and had no survival benefit for ACLF. The underlying mechanism may be related to dysbiosis in the gut microbiota.

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. Escherichia coli is a dominant cause of neonatal sepsis for which no prevention measures currently exist. Lactoferrin (LF) is an iron-sequestering antibacterial protein that has been noticed to decrease neonatal late-onset sepsis.Hypothesis/Gap Statement. LF's effect on in vitro growth of neonatal E. coli clinical isolates causing septicaemia is unknown. The prevalence of iron acquisition virulence genes which contribute to pathogenicity outcomes in these strains has also not been described in detail.Aim. To evaluate bovine lactoferrin's (bLF) effects on the in vitro growth of neonatal septicaemia E. coli isolates, and to determine the presence of iron acquisition virulence genes in these isolates.Methodology. E. coli clinical strains isolated from blood of septic neonates, including the archetypal RS218 strain, all representing prevalent phylogroups and multi-locus sequence types among neonatal invasive strains were studied. Strains were grown in batch growth with 0, 0.1, 1.0 and 10 mg ml^-1 bLF. OD measurements over time were used to generate growth curves, and the area under these curves was statistically compared using ANOVA or Kruskal-Wallis tests. Whole-genome sequencing (WGS) data were used to identify iron acquisition genes.Results. For all strains, growth decrease with 10 mg ml^-1 bLF compared to zero was highly significant (P<0.001), and with 1 mg ml^-1 for some strains (P≤0.02). WGS showed that all neonatal strains carried several iron acquisition virulence genes, including chuA, fyuA, irp2 and sitA. Additional siderophore genes were found in some strains.Conclusion. bLF is effective in impairing growth of neonatal sepsis-causing E. coli regardless of the presence of multiple iron acquisition virulence genes.

Short-chain fatty acids (SCFAs) are essential gut microbiota metabolites with significant effects that are well recognized for their anti-inflammatory benefits, yet their pro-inflammatory and pleiotropic properties have received little attention in literature. SCFAs produced by gut bacteria from one to five carbons engage with a network of G-protein-coupled receptors such as FFAR2/GPR43, FFAR3/GPR41, Olfr78 and monocarboxylate transporters (MCT-1-MCT-4) to influence host physiology. Through established signalling pathways including Mitogen-Activated Protein Kinase (MAPK), mTOR and Gαi/Gαq, SCFAs serve as acetyl CoA precursors that facilitate lipogenesis, gluconeogenesis and cholesterol synthesis while also activating NFκB and reactive oxygen species pathways (e.g. succinate), potentially resulting in vascular inflammation. While SCFAs typically suppress inflammation through histone deacetylase inhibition and immune regulation, pro-inflammatory roles emerge in specific settings. Within immune compartments, SCFAs exhibit cell-specific effects, from priming cell-driven pro-inflammatory roles in one type of immune cell to suppression of inflammatory mediators in others. Moreover, SCFAs can lead to fibrotic remodelling, an intensified form of inflammation in both intestinal and distant tissues. This review aims to demonstrate the complex biphasic bridge between aggravation and resolution influenced by factors such as cell type, study methodologies, receptors, dose dependency, age, metabolic changes and inherent properties and concludes with the significance of particular and accurate research approaches to mimic the true environment and observe SCFA effects employing humanized mice, gut-on-chip systems and organoids for more precise and relevant results.