Journal of medical microbiology最新文献

Introduction. Hantaan virus (HTNV) predominantly infects human vascular endothelial cells (ECs) and causes increased vascular permeability, triggering haemorrhagic fever with renal syndrome, mainly in Asia. Previous studies have shown that endothelial permeability is regulated in part by the break of cell-cell adherens junctions (AJs). However, the intracellular mechanisms by which HTNV induces EC hyperpermeability via AJs remain unclear.Hypothesis. We hypothesize that HTNV activates TLR4, and its downstream TRAF6 interacts with SFK, leading to the phosphorylation of adhesion junction-associated proteins and increased cell permeability.Aim. The present study aimed to investigate the molecular mechanism by which Src family kinases (SFKs) modulate AJs and affect permeability.Methodology. Real-time PCR (RT-PCR) and Western blot were used to assess TLR4, TRAF6 and SFK expression; Western blot was used to analyse the protein expression of AJs; small interfering RNAs (siRNAs) were used to inhibit gene expression in the human umbilical vein endothelial cells (HUVECs) and the distribution of vascular endothelial cadherin (VE-cadherin) was observed by immunofluorescence.Results. HUVECs infected by HTNV displayed a lower permeability after a siRNA knockdown of TLR4 (si-TLR4). Moreover, HTNV increased the expression of TRAF6 and the phosphorylation of Src and AJs. After siRNA knockdown of TRAF6 (si-TRAF6), a decrease in the phosphorylation of Src and VE-cadherin was observed in HTNV-infected ECs compared to that in siRNA controls.Conclusion. These data, for the first time, indicated that HTNV-induced upregulation of AJ phosphorylation is regulated by the TLR4/TRAF6/SFK signalling pathway.

Introduction. DNA topoisomerases are essential enzymes that allow cells to effectively manage the topological states of DNA. Due to the ubiquitous nature of their functions, topoisomerases have become promising treatment targets for various conditions, ranging from microbial infections to cancer.Hypothesis. The botanicals, Coptis chinensis (Chinese goldthread) and Salvia officinalis (common sage), are herbs that boast a long history of traditional use for their effectiveness in treating a myriad of health concerns, including microbial infections and cancer, which could be associated with topoisomerase inhibitory activity.Aim. This study sought to evaluate the antimicrobial and anticancer properties of these botanical extracts and determine if this activity was due to the presence of anti-topoisomerase activity.Methodology. Using various bacterial genera, vaccinia virus, cancerous cell lines and topoisomerase activity assays, the activity of these extracts was evaluated.Results. This study demonstrated that ethanolic extracts of these botanicals had potent anti-Gram-positive bacterial activity, antiviral activity and anticancer activity. Furthermore, this activity likely correlated with the ability of the extracts to inhibit topoisomerases II and IV and for Salvia officinalis, topoisomerase I.Conclusion. These results support the potential therapeutic value of C. chinensis and S. officinalis for the treatment of health concerns.

Multidrug-resistant (MDR) bacteria pose a growing threat to global health, prompting exploration of alternative therapies. This study uses bioinformatic modelling to assess ozone therapy as an adjunct treatment, analysing both linear and non-linear (chaotic) frameworks. Results suggest that ozone exerts bactericidal effects and modulates immune responses, partly through the production of 4-hydroxynonenal. Simulations indicate that ozone-induced adaptive chaos may enhance immune resilience and accelerate bacterial clearance compared to antibiotics alone. However, the findings are theoretical, and the short half-life of ozone limits direct impact, emphasizing the need for experimental validation. Ozone therapy shows promise, but its role in adaptive chaos requires further study to determine its clinical viability, despite a large number of reports showing an undisputable action of medical ozone against MDR bacteria.

Introduction. Bacterial infections and antimicrobial resistance are significant threats to global public health, both of which spread through contamination of solid surfaces. We have previously developed an antimicrobial surface technology that directly bonds the broad-spectrum biocide chlorhexidine to steel surfaces. These surfaces were shown to kill bacteria within minutes of contact and to be effective against bacteria evolved in the laboratory for resistance to chlorhexidine in solution.Hypothesis/Gap Statement. We hypothesized that resistance to these surfaces could exist outside of the naive and chlorhexidine-resistant laboratory strains tested previously. We also sought to test whether strains that were resistant to chlorhexidine in solution were also resistant to chlorhexidine-based antimicrobial surfaces.Aim. To test the efficacy of these surfaces against a range of bacteria isolated from the hospital environment and to compare this to the resistance of these bacteria to chlorhexidine in solution or when dissolved in solid media.Methodology. Ninety-one isolates of mixed bacterial species were obtained from Queen Elizabeth Hospital Birmingham. The isolates, along with laboratory strains of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, were tested for sensitivity to chlorhexidine-coated steel surfaces in a 30-min exposure simulated splash assay. Resistance to chlorhexidine in solution was also assayed by solid and broth media MIC assays.Results. We demonstrate that within 30 min of incubation, the surfaces reduced the survival of all 91 isolates. Over 85% of these isolates were killed (exhibiting a 7-8 log reduction compared with control surfaces), whilst 12% experienced a 3-4 log reduction. We also show that resistance to the surfaces did not correlate with resistance to freely diffusible chlorhexidine in liquid or solid media.Conclusion. The results demonstrate the efficacy of chlorhexidine-coated surfaces against a broad range of bacterial isolates from the hospital environment and imply the potential for a mode of exposure to dictate the effectiveness of different antimicrobial resistance mechanisms. Future studies should investigate the genetic mechanisms providing resistance to chlorhexidine-coated surfaces and whether these differ in the capacity to provide resistance to chlorhexidine in different modes of exposure.

Introduction. While Mycobacterium tuberculosis cells in sputum in sputum have been studied extensively, little is known of their properties in exhaled aerosols.Hypothesis. As differentially culturable tubercle bacteria (DCTB) are readily found in sputum, we hypothesized that DCTB might also be present in aerosols and potentially contribute to transmission.Aim. To test cough aerosols from recently diagnosed pulmonary tuberculosis (TB) patients for DCTB.Methodology. Cough-generated aerosols and sputum samples were collected from active pulmonary TB patients (n=27). A cough aerosol sampling system was modified to include both an Andersen Cascade Impactor using solid agar and a BioSampler liquid impactor. We performed the most probable number of assays to detect DCTB, using media supplemented with Mycobacterium tuberculosis culture filtrate (CF).Results. Briefly, 63% of patients (n=17) had advanced TB, and 55.6% (n=15) had a 3+ sputum smear for acid-fast bacilli. Evidence for DCTB was found in 8 patients' aerosols (29.5%) and more than half of the 19 sputum samples tested (n=10; 52.6%). Two patients had DCTB in only one of the collected samples (cough aerosols or sputum). Among cough aerosol specimens, two patients (7%) only had CF-dependent DCTB.Conclusion. We detected DCTB in sputum and evidence for their presence in cough samples from pulmonary TB patients. These data suggest that bacilli undetected by traditional mycobacterial cultures may be aerosolized from pulmonary TB patients.

Introduction. In cases where sputum is non-diagnostic or unavailable, bronchoscopy can yield high-value respiratory samples for tuberculosis (TB) diagnosis. Whilst Mycobacterium tuberculosis (MTB) complex culture remains the gold standard, molecular assays such as Xpert MTB/RIF Ultra (Xpert Ultra) are increasingly being used for rapid diagnosis.Gap Statement. Xpert Ultra is increasingly used for TB diagnosis and has been extensively evaluated on sputum specimens, but assessment of performance on bronchoscopy samples is more limited.Aim. To retrospectively evaluate the performance of Xpert Ultra on bronchoscopy specimens in comparison to culture in a low-incidence, high-resource setting.Methodology. Patients with a clinical suspicion of TB, who had non-diagnostic sputum or limited sputum production and underwent bronchoscopy between March 2019 and October 2023, were included in the study. Bronchoscopy specimens comprised bronchoalveolar lavages, bronchial washings and endobronchial ultrasound lymph node tissue biopsies. All included specimens underwent acid-fast bacilli (AFB) smear, mycobacterial culture and Xpert Ultra. Positive MTB culture was considered the reference standard for TB diagnosis.Results. One hundred thirty-five bronchoscopy samples from 126 patients were included. Cultures were positive for MTB in 47 out of 126 (37.3%) of included patients. Overall, positive percent agreement (PPA) and negative percent agreement (NPA) of Xpert Ultra to MTB culture were 93.6% and 98.7%, respectively. In 19 AFB smear-positive cases, Xpert Ultra had 100% PPA and NPA, whilst in 28 smear-negative cases, PPA and NPA were 89.3% and 98.6%, respectively. On average, positive culture results were available after 15.2 days of incubation (range, 5-42 days) versus 24 h for Xpert Ultra. Xpert Ultra PCR cycle threshold values correlated strongly with AFB-smear grade and time-to-culture positivity.Conclusion. Xpert Ultra performed on specimens collected via bronchoscopy demonstrated excellent agreement with culture, even in smear-negative cases. Our results support the use of the Ultra on bronchoscopy specimens for accurate and rapid TB diagnosis in a low-incidence setting.

Introduction. Campylobacteriosis is the leading cause of gastroenteritis worldwide, and Campylobacter species are the most frequently reported zoonotic, bacterial foodborne pathogens in England.Gap statement. Currently, less than 2.0% of Campylobacter isolates in England undergo strain identification and typing, resulting in limited insight into their molecular epidemiology.Aim. To assess the feasibility of using high-throughput whole-genome sequencing (WGS) to generate data for microbiological and epidemiological analysis by the implementation of a 3-month enhanced laboratory surveillance for Campylobacter spp. in England, and to make recommendations for improving the current Campylobacter surveillance strategies.Methodology. All diagnostic laboratories in England were encouraged to refer isolates of Campylobacter spp. for WGS over a 3-month period (7 June-31 August 2021).Results. Over 6,000 Campylobacter species isolates were characterized, of which 87.5% were successfully identified as Campylobacter jejuni and 8.1% as Campylobacter coli. Just over half of the isolates were referred from patients who were male (53%), and C. coli isolates tended to be from older patients than C. jejuni, with median ages of 55 and 44 years, respectively. The most common multi-locus sequencing type clonal complex identified was ST-21, and within this, the sequencing type ST6175 was the most frequently identified, of which 96.8% were predicted to carry antimicrobial resistance determinants, inferring reduced susceptibility to both ciprofloxacin and tetracycline. The four largest C. jejuni 5-single nucleotide polymorphism (SNP) clusters, associated with the larger clonal complexes and sequence type groups (ST6175, ST48, ST6175 and ST5136), accounted for 23.8% (n=1,150/4,838) of SNP typable isolates. Conversely, 28.4% and 39.5% of isolates C. jejuni and C. coli, respectively, appeared to be sporadic, with each isolate assigned a unique SNP address at the 5-SNP level.Conclusion. WGS enabled identification of genetically related clusters of Campylobacter isolates in almost real time and shows potential for monitoring of inferred antimicrobial resistance. However, unlocking its full potential requires referral of sufficient and representative isolates for sequencing with parallel epidemiological data collection.

Introduction. The antibiotic trimethoprim has been used to treat urinary tract infection (UTI) since ~1962. Alongside the nitrofurantoin, there are still justified reasons for trimethoprim use, especially in non-pregnant women. Trimethoprim resistance is commonly the result of acquiring the trimethoprim-insensitive dihydrofolate reductase gene: dfrA. Assessment of clinical Escherichia coli isolates from two clinical trials, AnTIC and ALTAR, identified carriage of two copies of dfrA.Hypothesis. The hypothesis tested here was that dual dfrA carriage provided E. coli with a growth advantage.Methodology. Two hundred and seventy-eight clinical isolates from AnTIC/ALTAR were assessed for dfrA carriage. Microplate-based growth assays assessed growth behaviour with and without 64 mg l^-1 trimethoprim. Allelic replacement of dfrA5 with five other alleles was also performed.Results. One hundred and four isolates (37%) were identified to carry a total of 112 dfrA genes. Eight isolates (2.9%) carried two copies of dfrA. Comparison of dfrA ⁺ to dual dfrA carriage could be differentiated by their growth behaviour when exposed to trimethoprim but had comparable MIC (>512 mg l^-1). Analysis of all dfrA ⁺ isolates determined that the growth behaviour exhibited an allelic bias. Allelic replacement of dfrA5 with dfrA1, dfrA7, dfrA8, dfrA14 and dfrA17 demonstrated that the growth behaviour was dfrA specific.Conclusion. This analysis determined that the dual carriage of two dfrA alleles generated a growth advantage to E. coli. However, the growth behaviour was dictated by allele carriage and not specifically dual carriage, as single carriage isolates also possessed the identified phenotype. This data suggests that there is a potential clinical impact dictated by dfrA allele carriage that could improve clinical decisions on management strategies of UTI.

Introduction. Alterations in ocular surface microbiota (OSM) have been noted in both dry eye disease (DED) and glaucoma. However, the combined effects of these conditions on OSM have not been explored.Hypothesis. We hypothesized that patients with both glaucoma and dry eye would exhibit distinct changes in OSM composition and diversity compared to those with only glaucoma, only dry eye or healthy individuals.Aim. We employed amplicon sequencing to investigate OSM profiles in patients with glaucoma and/or dry eye disease.Methods. Swab samples from the conjunctiva of both eyes were collected from 28 glaucomatous patients [13 without dry eye syndrome (G-only) and 15 with dry eye syndrome (G-DED)], 13 DED patients without glaucoma (DED-only) and 31 age-matched healthy controls (HCs). After V3-V4 16S rRNA sequencing, MOTHUR tools and R language were used to elucidate and compare OSM composition and diversity between groups.Results. Our data revealed very diverse bacterial communities with 28 phyla and 785 genera. All the groups shared the three most abundant phyla, Actinobacteria (67.47%), Firmicutes (17.14%) and Proteobacteria (13.73%). Corynebacterium (54.75%), Staphylococcus (10.71%), Cutibacterium (8.77%) and Streptococcus (3.20%) were the most abundant genera. Only the G-DED group showed higher alpha diversity than the HC group (P<0.05). However, significant differences in beta diversity were observed between all three patient groups and the HC group. The Differential Expression for Sequencing 2 (DESeq2) analysis unveiled an increased presence of opportunistic bacteria across all pathological groups, with the G-DED group demonstrating the most pronounced alterations.Conclusions. Our findings confirm the predominance of Gram-positive bacteria in normal OSM and the rise of opportunistic Gram-negative bacteria in glaucoma and dry eye disease. This is the first study to characterize OSM in glaucoma patients with DED.

Introduction. In recent years, with the increase of drug resistance of Candida, the incidence rate and mortality of candidemia have gradually increased, which has brought a huge economic and health burden to people.Gap Statement. The epidemiological characteristics and antifungal drug sensitivity patterns in different regions have varied.Aim. To analyse the distribution and antifungal susceptibility of Candida strains isolated from bloodstreams and provide a basis for the use of antifungal drugs for treatment.Methodology. A total of 115 strains of Candida were collected from the bloodstream, and 28 strains of colonized Candida albicans were collected from the upper respiratory tract. Candida species were identified using matrix-assisted laser desorption/ionization time-of-flight technology. Antifungal susceptibility was assessed using broth microdilution combined with redox methods.Results. There were eight types of Candida strains isolated from the bloodstream; C. albicans was the most common species (36.5%), followed by Candida parapsilosis (24.3%), Candida glabrata (17.4%) and Candida tropicalis (14.8%). There was no significant difference in the resistance of C. albicans to azole drugs between the bloodstream infection group and the upper respiratory tract colonization group, but there was a significant difference in the MIC values of micafungin and fluconazole, with P values of 0.017 and 0.003, respectively. Amphotericin B and echinocandins are the most susceptible drugs for all Candida species, but the MICs of echinocandins against C. parapsilosis are significantly higher than those of other Candida species. Candida (except for C. glabrata) is highly resistant to azoles, with C. parapsilosis showing resistance rates of 89.3% and 82.1% to itraconazole and posaconazole, respectively; the resistance rates of C. tropicalis are 100% and 94.1%, respectively.Conclusion. C. albicans remains the predominant pathogen responsible for candidemia. Although the resistance of Candida to antifungals is relatively stable, there are significant differences in the MICs of antifungal drugs against Candida, indicating the importance of strain identification in the treatment of candidemia. For empirical treatment, the use of echinocandin drugs is recommended.