Journal of Medical Microbiology

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ISSN / EISSN : 0022-2615 / 1473-5644
Published by: Microbiology Society (10.1099)
Total articles ≅ 9,144
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Muireann Fallon, Sarah Kennedy, Stephen Daniels, Hilary Humphreys
Published: 6 October 2022
Journal of medical microbiology, Volume 71; https://doi.org/10.1099/jmm.0.001582

Abstract:
Healthcare-associated infections (HCAIs) are a major challenge and the near patient surface is important in harbouring causes such as methicillin-resistant Staphylococcus aureus (MRSA) and Clostridioides difficile. Current approaches to decontamination are sub-optimal and many studies have demonstrated that microbial causes of HCAIs may persist with onward transmission. This may be due to the capacity of these microbes to survive in biofilms on surfaces. New technologies to enhance hospital decontamination may have a role in addressing this challenge. We have reviewed current technologies such as UV light and hydrogen peroxide and also assessed the potential use of cold atmospheric pressure plasma (CAPP) in surface decontamination. The antimicrobial mechanisms of CAPP are not fully understood but the production of reactive oxygen and other species is believed to be important. CAPP systems have been shown to partially or completely remove a variety of biofilms including those caused by Candida albicans, and multi-drug-resistant bacteria such as MRSA. There are some studies that suggest promise for CAPP in the challenge of surface decontamination in the healthcare setting. However, further work is required to define better the mechanism of action. We need to know what surfaces are most amenable to treatment, how microbial components and the maturity of biofilms may affect successful treatment, and how would CAPP be used in the clinical setting.
, Paschalis Paranos, Marilena Tsala, Spyros Pournaras, Sofia Vourli
Published: 6 October 2022
Journal of medical microbiology, Volume 71; https://doi.org/10.1099/jmm.0.001565

Abstract:
Introduction. The presence of heteroresistant subpopulations and the development of resistance during drug exposure (adaptive resistance) limits colistin’s efficacy against carbapenemase-producing Klebsiella pneumoniae (CP-Kp) isolates. Hypothesis/Gap statement. The pharmacokinetic/pharmacodynamic (PK/PD) characteristics of both types of colistin resistance against CP-Kp are unknown. Aim. We therefore studied the PK/PD characteristics of colistin resistance in an in vitro PK/PD model simulating clinical colistin exposures. Methods. Two K. pneumoniae clinical isolates, one non-CP-Kp and one CP-Kp, with colistin MICs of 0.5–1 mg l−1 at a final inoculum of 107 c.f.u. ml−1 were used in an in vitro PK/PD dialysis/diffusion closed model simulating 4.5 MU q12h and 3 MU q8h clinical dosing regimens. Heteroresistant (HRS, bacteria with stable high-level resistance present before drug exposure) and adaptive resistant (ARS, bacteria with reversible low-level resistance emerging after drug exposure) subpopulations were measured and optimal PK/PD targets for reducing both ARS and HRS were determined. Cumulative fractional response (CFR) was calculated with Monte Carlo simulation for 9 MU q24h, 4.5 MU q12h and 3 MU q8h clinical dosing regimens. Results. A 2–5 log10c.f.u. ml–1 decrease of the total bacterial population was observed within the first 2 h of exposure, followed by regrowth at 12 h. Colistin exposure was positively and negatively correlated with HRS and ARS 24–0 h c.f.u. ml–1 changes, respectively. An optimal PK/PD (~0.5log10 increase) target of 35 fAUC/MIC (the ratio of the area under the unbound concentration–time curve to the MIC) was found for reducing both HRS and ARS of high-level resistance (MIC >16 mg l−1). The 4.5 MU q12h regimen had slightly higher CFR (74 %) compared to the other dosing regimens. Conclusions. High colistin exposures reduced high-level adaptive resistance at the expense of selection of heteroresistant subpopulations.
, Roberto M. La Ragione
Published: 26 September 2022
Journal of medical microbiology, Volume 71; https://doi.org/10.1099/jmm.0.001495

Abstract:
The genus Brachyspira includes nine officially recognised species, several of which are pathogenic to mammals and birds. B. pilosicoli, B. intermedia, and B. alvinipulli are the causative agents of avian intestinal spirochaetosis (AIS), a gastrointestinal disease in poultry caused by the colonisation of the caeca and/ or colo-rectum by Brachyspira. AIS primarily affects layer hens and broiler breeders over the age of 15 weeks. The severity of symptoms can vary but typically presents as reduced growth rates, delayed onset of lay, reduced egg production, faecally stained eggs, and diarrhoea. This disease is estimated to cost the UK laying industry £18 million per annum. Brachyspira colonisation in humans is common in populations from developing countries and HIV-positive patients; however, it is rarely investigated as a human pathogen.
Yuhui Chen, Huiyan Si, Baoshi Bao, Songyan Li, Da Teng, Yang Yan, Shidong Hu, Yingxin Xu, Xiaohui Du
Published: 22 September 2022
Journal of medical microbiology, Volume 71; https://doi.org/10.1099/jmm.0.001596

Abstract:
Introduction. Colorectal cancer (CRC) is one of the most common cancers and poses heavy burden on global health. The relationship between mucosal microbiome composition and colorectal gene expression are rarely studied. In this study, we integrated transcriptome data with microbiome data to investigate the relationship between them in colorectal cancer patients. Gap statement. Previous studies have identified the contribution of gut microbiota and DEGs to the pathogenesis of CRC, but the relationship between mucosal microbiome composition and colorectal gene expression are rarely studied. Aim. In this study, we integrated transcriptome data with microbiome data to investigate the relationship between mucosal microbiome composition and colorectal gene expression. Methodology. First, three independent CRC gene expression profiles (GSE184093, GSE156355 and GSE146587) from Gene Expression Omnibus (GEO) were used to identify differentially expressed genes (DEGs). Second, another dataset (GSE163366) was used to analyse gut mucosal microbiome differential abundance. GO (Gene Ontology) function and KEGG (Kyoto Encyclopaedia of Genes and Genomes) pathway enrichment analyses of the DEGs were performed. Protein-protein interactions (PPIs) of the DEGs were constructed. The Spearman correlation analysis was computed between host DEGs and gut microbiome abundance data. Results. A total of 1036 upregulated DEGs and 1194 downregulated DEGs between noncancerous tissues and cancerous tissues were identified based on the analysis. One significant module with a score 37.65 was selected out via MCODE including 41 upregulated DEGs, which are were mostly enriched in two pathways, including microtubule binding and tubulin binding. In particular, significant negative correlations are prevalent between Fusobacterium and the 41 DEGs with the correlation ranging between −0.54 and −0.35, and there commonly exist significant positive correlations between Blautia and the 41 DEGs with the correlation ranging between 0.42 and 0.54, indicating that Fusobacterium and Blautia are two of the most important microbes interacting with the gene regulation. Conclusion. Our results demonstrate significant correlation between some gut microbes and DEGs, providing a comprehensive bioinformatics analysis of them for future investigation into the molecular mechanisms and biomarkers.
Wafa Bouglita, Sameh Rabhi, Natacha Raich, Cyrine Bouabid, Cyrine Belghith, Olfa Slimani, Chaima Hkimi, Kais Ghedira, Roger E. Karess, Lamia Guizani-Tabbane, et al.
Published: 20 September 2022
Journal of medical microbiology, Volume 71; https://doi.org/10.1099/jmm.0.001589

Abstract:
Introduction.Candida spp. may cause opportunistic infections called vulvovaginal candidiasis (VVC), which is estimated to be the second most common cause of vaginitis worldwide. Gap Statement. Under various circumstances, VVC could compromise pregnancy outcomes. Emerging data suggests that VVC during pregnancy may be associated with increased risk of complications and congenital cutaneous candidiasis. Aim. To assess the prevalence of Candida spp. in asymptomatic pregnant women and determine the susceptibility of the isolates to antifungal drugs. Methodology. In a prospective cohort, 65 high vaginal swab samples of consented pregnant women. Candida isolates were identified using both microbiological and molecular tools and drug susceptibilities were profiled. Results. The prevalence of VVC among our study participants was 37 %, 24 of the 65 asymptomatic pregnant women show Candida spp. colonization. C. albicans was the most common species 61 %, followed by C. glabrata 39 %. In addition, a significant fraction of the isolated colonies showed resistance to Fluconazole, with a ratio of 63 % for C. albicans isolates and 16 % for Candida glabrata isolates. Moreover, relative quantification of genes related to resistance to fluconazole, CDR1, ERG11 as well as HWP1, showed a significant change compared to controls. Conclusion. Monitoring of vaginal Candida colonization before the third trimester of pregnancy, that could reduce congenital Candida colonization and risk of pregnancy complications.
Zsolt Bella, Eszter Erdelyi, Ágnes Szalenko-Tőkés, Ágnes Kiricsi, Veronika Gaál, Pálma Benedek, László Rovó,
Published: 14 September 2022
Journal of medical microbiology, Volume 71; https://doi.org/10.1099/jmm.0.001576

Abstract:
Introduction. Peritonsillar abscess (PTA) is a common infection which requires surgical intervention and suitable antibiotic therapy. Hypotheses/Gap Statement. Beside Streptococcus pyogenes and Fusobacterium necrophorum several other mostly anaerobic bacteria can be cultured from the properly taken pus samples of PTA, the clinical significance of which is still not fully understood. Aim. This study focused on the culture-based microbiological evaluation of PTA cases, compared to surgical intervention and empirical antibiotic management. Methodology. A retrospective analysis of PTA cases was performed between 2012 and 2019. Data about the aerobic and anaerobic culture results of the samples taken during different surgical interventions were summarized and the coverage of the empirically selected antibiotics was evaluated. The patient’s history, the development of complications and the recurrence rate were also evaluated. Results. The microbiological culture results were available for 208 of 320 patients with clinically diagnosed PTA. Incision and drainage (I and D) and immediate tonsillectomy were the leading surgical interventions. Ninety-five Fusobacterium species (including 44 Fusobacterium necrophorum), 52 Actinomyces species and 47 Streptococcus pyogenes were obtained from PTA samples alone or together with polymicrobial flora. S. pyogenes (33.7 %, n=28) and F. necrophorum (22.9 %, n=19) were the dominating pathogens in the 83 monobacterial PTA samples. In >60 % of the patients polymicrobial infection was demonstrated, involving a great variety of anaerobic bacteria. In 22 out of 42 cases where intravenous cefuroxime was empirically started, the therapy should be changed to properly cover the culture-proven anaerobic flora. There were no serious complications, abscess recurrence was detected in two cases (0.96 %). Conclusion. PTAs are often polymicrobial infections including a great variety of anaerobes. Targeted antibiotic therapy, in conjunction with adequate surgical drainage eliminating the anaerobic milieu, can accelerate the healing process and radically reduce the complication and recurrence rate.
Published: 13 September 2022
Journal of medical microbiology, Volume 71; https://doi.org/10.1099/jmm.0.001575

Abstract:
Introduction. Plants have been used as medicines for centuries to treat human diseases. Studies with plants are extremely important for the development of future drugs that can benefit the human population. Hypothesis/Gap Statement. With the emergence of pathogens resistant to antimicrobial agents, there is an urgent need to direct research towards the discovery of new antimicrobials. Aim. In this study, Spondias purpurea L. (Anacardiaceae) was evaluated for its antimicrobial activity, antioxidant activity and cytotoxicity. Methodology. Antimicrobial activity was evaluated by the MIC using the 96-well plate microdilution technique of ethanolic, hexanic and dicloromethanic extracts of dried S. purpurea leaves against bacteria, yeast and filamentous fungi. The antioxidant activity of extracts was evaluated by the 2,2-diphenyl-1-picrylhydrazine (DPPH) method. To evaluate the safety of extracts, a cytotoxicity study against HaCat, J774 and HepG2 cells was performed. Results. The extracts had no activity against the bacteria at the maximum concentration of 5.0 mg ml−1, but showed fungistatic action against Candida species and dermatophytes. The ethanolic extract showed 88 % antioxidant activity and showed no significant cytotoxicity against the previously mentioned cells. Conclusion. This study showed that the 100 % ethanolic (EtOH) extract was favourable for antifungal and antioxidant activities and did not present significant cytotoxicity against the three studied cell lines, indicating that S. purpurea leaves are promising for the development of new antimicrobials.
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