Journal of medical microbiology最新文献

Introduction. Our synbiotics (Lacticaseibacillus paracasei strain Shirota, Bifidobacterium breve strain Yakult, and galacto-oligosaccharides: LBG) helps mitigate serious adverse events such as febrile neutropenia (FN) and diarrhoea in oesophageal cancer patients receiving neoadjuvant chemotherapy (NAC). Unfortunately, LBG therapy does not benefit all patients.Hypothesis/Gap Statement. Identification of the gut microbiota species involved in adverse events during chemotherapy could help predict the onset of adverse events. Identification of the gut microbiota that influence the efficacy of LBG could also help establish a diagnostic method to identify patients who will respond to LBG before the initiation of therapy.Aim. To identify the gut microbiota involved in adverse events during NAC and that affect the efficacy of LBG therapy.Methodology. This study was ancillary to a parent randomized controlled trial in which 81 oesophageal cancer patients were recruited and administered either prophylactic antibiotics or LBG combined with enteral nutrition (LBG+EN). The study included 73 of 81 patients from whom faecal samples were collected both before and after NAC. The gut microbiota was analysed using 16S rRNA gene amplicon sequencing and compared based on the degree of NAC-associated adverse events. Furthermore, the association between the counts of identified bacteria and adverse events and the mitigation effect of LBG+EN was also analysed.Results. The abundance of Anaerostipes hadrus and Bifidobacterium pseudocatenulatum in patients with no FN or only mild diarrhoea was significantly higher (P<0.05) compared to those with FN or severe diarrhoea. Moreover, subgroup analyses of patients receiving LBG+EN showed that the faecal A. hadrus count before NAC was significantly associated with a risk of developing FN (OR, 0.11; 95 % CI, 0.01-0.60, P=0.019). The faecal A. hadrus count after NAC was positively correlated with intestinal concentrations of acetic acid (P=0.0007) and butyric acid (P=0.00005).Conclusion. Anaerostipes hadrus and B. pseudocatenulatum may be involved in the ameliorating adverse events and can thus be used to identify beforehand patients that would benefit from LBG+EN during NAC. These results also suggest that LBG+EN would be useful in the development of measures to prevent adverse events during NAC.

Introduction. Hepatocellular carcinoma (HCC) is one of the most common malignant tumours in the world. Due to the characteristics of low early diagnosis rate, high malignancy and rapid progression, the majority of diagnosed patients are in the middle or late stage. Accumulating evidence reveals that intestinal flora imbalance will aggravate HCC by disturbing immune regulation, especially interleukin expression. Therefore, intestinal flora-based methods have the potential to be new diagnostic or therapeutic methods for HCC.Hypothesis. Compositions of intestinal florae were different between HCC patients and healthy people. Further, intestinal florae may alleviate or aggravate HCCs.Methods. To determine which intestinal florae and interleukin aggravate HCCs, we studied the differences in intestinal florae composition and interleukin (IL) indices between HCC patients and healthy people. A total of 64 HCC patients and 24 healthy people were recruited, and their fresh stool samples and serum samples were collected for 16S rRNA sequencing and metabolite index measurement.Results. Data showed that 484 operational taxonomic units (OTUs) and 476 OTUs were detected in the HCC and control groups, respectively. From the phylum level to the species level, 5, 6, 10, 15, 23 and 19 colonies showed differential abundance between the HCC group and healthy people. Moreover, interleukin-6 expression and interleukin-10 expression were significantly different between two groups. Of note, differences of Coriobacterium, Atopobium and Coprococcus at genus level and Veillonella dispar at species level in two groups were significantly related to IL-6 and IL-10.Conclusion. The abundance of intestinal florae in the HCC group was different from the control group. Additionally, combinatorial detection of Coriobacterium, Atopobium and Coprococcus at genus level and V. dispar at species level may be a new method for HCC diagnosis.

Introduction. The bla _NDM-1 -positive Enterobacter cloacae has led to limited therapeutic options for clinical treatment.Hypothesis/Gap Statement. Analysing the antimicrobial resistance and molecular typing of bla _NDM-1-positive E. cloacae is of great significance. Meanwhile, the effect of the bla _NDM-1 gene on the virulence and pathogenicity of E. cloacae remains unclear and should be assessed.Aim. To understand bla _NDM-1-positive E. cloacae from different perspectives.Methodology. The PCR was used to screen bla _NDM-1-positive E. cloacae, then, antimicrobial susceptibility tests and multilocus sequence typing (MLST) were performed on them; sixty-nine strains of bla _NDM-1-negative E. cloacae were collected as the controls, 28 pairs of virulence-related genes' carriage and biofilm-forming ability were detected for preliminary evaluation of the virulence phenotype of the strains; to gain insight into the effect of the bla _NDM-1 gene on the virulence and pathogenicity of E. cloacae, the bla _NDM-1-positive E. cloacae T2 (NDM-1), the T2 bla _NDM-1 knockout strain (ΔNDM-1) and ATCC13047 (ST) were studied, compared the motility, anti-serum killing ability, and virulence to cells. Then, the mice intraperitoneal infection model was established, the survival curve, histopathological characteristics, bacterial load in spleen and the contents of cytokines were compared.Results. (1) Thirty-five bla _NDM-1-positive E. cloacae exhibited multidrug resistance. MLST distinguished 12 STs, ST74 was the most common clonal type (11/35), followed by ST114 (10/35). (2) The detection rates of virulence genes clpB, icmf, VasD/Lip and acrA in the bla _NDM-1-positive E. cloacae were significantly higher than those in bla _NDM-1-negative E. cloacae (P<0.05), while there was no significant difference in the amount of biofilm formation between two groups. (3) The presence of bla _NDM-1 gene attenuated the motility diameter of E. cloacae, but had no significant effect on their ability to resist serum killing, and the virulence to cells. The survival rate, histopathological changes, bacterial load in spleen and inflammatory cytokines were not significantly affected.Conclusions. (1) The bla _NDM-1-positive E. cloacae exhibited multidrug resistance, and the MLST typing was mainly ST74 and ST114, with a small-scale clonal spread of the ST114 strain in the hospital NICU ward. (2) The bla _NDM-1 gene did not affect the virulence and pathogenicity of E. cloacae.

Human monkeypox virus (hMpoxV) is of zoonotic origin and is closely related to the once-dreaded smallpox virus. It is largely endemic to the African continent but has moved out of the endemic regions as sporadic clusters in the past 20 years, raising concerns worldwide. Human Mpox is characterized by a mild to severe, self-limiting infection, with mortality ranging from less than 1% to up to 10% during different outbreaks caused by different clades of MpoxV. Bushmeat hunting is one of the primary reasons for its transmission from animals to humans. Various international and national health regulatory bodies are closely monitoring the disease and have laid down guidelines to manage and prevent hMpox cases. Emergency Use Status has been granted to Tecovirimat and Brincidofovir to treat severe cases and vaccination with the smallpox vaccine is recommended for high-risk group individuals. Strategies to repurpose and discover novel therapeutics and vaccines to control the outbreak are being researched. The current Mpox outbreak that has mainly affected men as approximately 96% of all cases are reported in men, is probably the result of a complex intersection of various factors. This necessitates a strong One Health response coordination involving human, animal and environmental health institutions. This review is an attempt to provide an all-inclusive overview of the biology, history, epidemiology, pathophysiology, diagnosis and management of hMpox in context to the recent 2022-2023 multi-country outbreak which is termed by WHO a 'Public Health Emergency of International Concern (PHEIC)'.

Introduction. Diphtheria is a potentially life-threatening infection and remains endemic in many low- and middle-income countries (LMICs). A reliable, low-cost method for serosurveys in LMICs is warranted to estimate the accurate population immunity to control diphtheria.Hypothesis/Gap Statement. The correlation between the ELISA results against diphtheria toxoid and the gold standard diphtheria toxin neutralization test (TNT) values is poor when ELISA values are <0.1 IU ml^-1, which results in inaccurate estimates of susceptibility in populations when ELISA is used for measuring antibody levels.Aim. To explore methods to accurately predict population immunity and TNT-derived anti-toxin titres from ELISA anti-toxoid results.Methodology. A total of 96 paired serum and dried blood spot (DBS) samples collected in Vietnam were used for comparison of TNT and ELISA. The diagnostic accuracy of ELISA measurement with reference to TNT was assessed by area under the receiver operating characteristic (ROC) curve (AUC) and other parameters. Optimal ELISA cut-off values corresponding to TNT cut-off values of 0.01 and 0.1 IU ml^-1 were identified by ROC analysis. A method based on the multiple imputation approach was also applied to estimate TNT measurements in a dataset that only included ELISA results. These two approaches were then applied to ELISA results previously generated from 510 subjects in a serosurvey in Vietnam.Results. The ELISA results on DBS samples showed a good diagnostic performance compared to TNT. The cut-off values for ELISA measurement corresponding to the TNT cut-off values of 0.01 IU ml^-1 were 0.060 IU ml^-1 in serum samples, and 0.044 IU ml^-1 in DBS samples. When a cut-off value of 0.06 IU ml^-1 was applied to the 510 subject serosurvey data, 54 % of the population were considered susceptible (<0.01 IU ml^-1). The multiple imputation-based approach estimated that 35 % of the population were susceptible. These proportions were much larger than the susceptible proportion estimated by the original ELISA measurements.Conclusion. Testing a subset of sera by TNT combined with ROC analysis or a multiple imputation approach helps to adjust ELISA thresholds or values to assess population susceptibility more accurately. DBS is an effective low-cost alternative to serum for future serological studies for diphtheria.

Background. Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) has been linked to outbreaks of foodborne gastroenteritis disease, and the emergence of antimicrobial-resistant clones. In Colombia, laboratory surveillance of Salmonella spp. between 1997-2018 revealed that S. Typhimurium was the most ubiquitous serovar (27.6 % of all Salmonella isolates), with increasing levels of resistance to several families of antibiotics.Hypothesis. Resistant isolates of S. Typhimurium recovered from human clinical, food and swine samples carry class 1 integrons that are linked to antimicrobial resistance genes.Aim. Identify class 1 integrons, and investigate their association with other mobile genetic elements, and their relationship to the antimicrobial resistance of Colombian S. Typhimurium isolates.Methods. In this study, 442 isolates of S. Typhimurium were analysed, of which 237 were obtained from blood culture, 151 from other clinical sources, 4 from non-clinical sources and 50 from swine samples. Class 1 integrons and plasmid incompatibility groups were analysed by PCR and whole-genome sequencing (WGS), and regions flanking integrons were identified by WGS. The phylogenetic relationship was established by multilocus sequence typing (MLST) and single-nucleotide polymorphism (SNP) distances for 30 clinical isolates.Results . Overall, 39 % (153/392) of the human clinical isolates and 22 % (11/50) of the swine S. Typhimurium isolates carried complete class 1 integrons. Twelve types of gene cassette arrays were identified, including dfr7-aac-bla _OXA-2 (Int1-Col1), which was the most common one in human clinical isolates (75.2 %, 115/153). Human clinical and swine isolates that carried class 1 integrons were resistant to up to five and up to three antimicrobial families, respectively. The Int1-Col1 integron was most prevalent in stool isolates and was associated with Tn21. The most common plasmid incompatibility group was IncA/C.Conclusions. The widespread presence of the IntI1-Col1 integron in Colombia since 1997 was striking. A possible relationship between integrons, source and mobile elements that favour the spread of antimicrobial resistance determinants in Colombian S. Typhimurium was identified.

Introduction. Hypervirulent-K. pneumoniae (hvKP) is an evolving pathotype that is more virulent than the classical-K. pneumoniae (cKP) and causes serious fatal illnesses.Hypothesis/Gap Statement. Although there are few reports on hvKP isolated from Egyptian patients, the molecular characteristics and clonal relatedness of MDR-hvKP have not been adequately investigated.Aim. To investigate the microbiological and genetic characteristics as well as the epidemiology of hvKP induced ventilator-associated pneumonia (VAP).Methodology. A retrospective study of 59 K. pneumoniae inducing VAP was conducted at Assiut University Hospitals from November 2017 to January 2019. All K. pneumoniae were tested for resistance phenotype, capsular genotype (K1 and K2), virulence gene profile (c-rmpA, p-rmpA, iucA, kfu, iroB, iroN), and the presence of resistance genes (blaNDM-1, blaCTX-M-3-like, blaCTX-M-14-like). Clonal relatedness was assessed by Pulsed field gel electrophoresis (PFGE).Result. HvKP accounted for 89.8 % (53/59) of K. pneumoniae isolates with ~95 % exhibiting extensively-drug resistant (XDR) phenotype. Hypermucoviscous phenotype was detected in 19 (35.8 %) hvKP and K2 capsular gene was identified in 18 (33.9 %) of hvKP. Regarding the virulence genotype of hvKP strains, iucA was the most prevalent virulence gene (98.1%), while p-rmpA and kfu were detected in 75.4 and 52.8 % of hvKP strains, respectively. Resistance genes were highly prevalent in both cKP and hvKP with blaCTX-M-3-like being more prevalent in hvKP (100 % vs 94.3 % for blaNDM-1, 50 % vs 62.2 % for blaCTX-M-3-like and 83.3 % vs 69.8 % for blaCTX-M-14 _-like, respectively). PFGE typing of 29 representative K. pneumoniae revealed 15 pulsotypes, with identical hvKP pulsotypes isolated from different ICUs at different times and several hvKP and cKP isolates belonged to the same pulsotype.Conclusion. This study highlights the dominance and clonal spread of XDR-hvKP strains at Assiut University Hospital in Egypt. Physicians should be aware of the increased risk of hvKP induced-VAP and support further epidemiologic studies.

Introduction. Combination of PCR and Elek testing to identify toxigenic corynebacteria has revealed organisms described as non-toxigenic toxin-gene bearing (NTTB) Corynebacterium diphtheriae or C. ulcerans (i.e. PCR tox positive; Elek negative). These organisms carry part or all of tox, but are unable to express diphtheria toxin (DT) and present a challenge to clinical and public health case management.Gap analysis/Hypothesis. There are few data on the theoretical risk of NTTB reversion to toxigenicity. This unique cluster and subsequent epidemiologically linked isolates allowed the opportunity to determine any change in DT expression status.Aim. To characterize a cluster of infections due to NTTB in a skin clinic and subsequent cases in two household contacts.Methodology. Epidemiological and microbiological investigations were carried out according to existing national guidance at the time. Susceptibility testing used gradient strips. The tox operon analysis and multi-locus sequence typing (MLST) was derived from whole-genome sequencing. Alignment of the tox operon and phylogenetic analyses were performed using clustalW, mega, the public core-genome MLST (cgMLST) scheme and an in-house bioinformatic single nucleotide polymorphism (SNP) typing pipeline.Results. Isolates of NTTB C. diphtheriae were recovered from four cases (cases 1 to 4) with epidermolysis bullosa attending the clinic. Two further isolates were subsequently recovered from case 4, >18 months later, and from two household contacts (cases 5 and 6) after a further 18 months and 3.5 years, respectively. All eight strains were NTTB C. diphtheriae biovar mitis, belonged to the same sequence type (ST-336) with the same deletion in tox. Phylogenetic analysis showed relatively high diversity between the eight strains with 7-199 SNP and 3-109 cgMLST loci differences between them. The number of SNPs between the three isolates from case 4 and two household contacts (cases 5 and 6) was 44-70 with 28-38 cgMLST loci differences.Conclusions. We report a cluster of NTTB C. diphtheriae cases in a skin clinic and evidence of onward household transmission. We conclude the deletion in the tox was responsible for the non-expression of DT. There was no evidence of reversion to DT expression over the 6.5 year period studied. These data informed revision to guidance in the management of NTTB cases and their contacts in the UK.

Introduction. Increasing evidence suggests a correlation between gut microbiota and colorectal cancer (CRC).Hypothesis/Gap Statement. However, few studies have used gut microbiota as a diagnostic biomarker for CRC.Aim. The objective of this study was to explore whether a machine learning (ML) model based on gut microbiota could be used to diagnose CRC and identify key biomarkers in the model.Methodology. We sequenced the 16S rRNA gene from faecal samples of 38 participants, including 17 healthy subjects and 21 CRC patients. Eight supervised ML algorithms were used to diagnose CRC based on faecal microbiota operational taxonomic units (OTUs), and the models were evaluated in terms of identification, calibration and clinical practicality for optimal modelling parameters. Finally, the key gut microbiota was identified using the random forest (RF) algorithm.Results. We found that CRC was associated with the dysregulation of gut microbiota. Through a comprehensive evaluation of supervised ML algorithms, we found that different algorithms had significantly different prediction performance using faecal microbiomes. Different data screening methods played an important role in optimization of the prediction models. We found that naïve Bayes algorithms [NB, accuracy=0.917, area under the curve (AUC)=0.926], RF (accuracy=0.750, AUC=0.926) and logistic regression (LR, accuracy=0.750, AUC=0.889) had high predictive potential for CRC. Furthermore, important features in the model, namely s__metagenome_g__Lachnospiraceae_ND3007_group (AUC=0.814), s__Escherichia_coli_g__Escherichia-Shigella (AUC=0.784) and s__unclassified_g__Prevotella (AUC=0.750), could each be used as diagnostic biomarkers of CRC.Conclusions. Our results suggested an association between gut microbiota dysregulation and CRC, and demonstrated the feasibility of the gut microbiota to diagnose cancer. The bacteria s__metagenome_g__Lachnospiraceae_ND3007_group, s__Escherichia_coli_g__Escherichia-Shigella and s__unclassified_g__Prevotella were key biomarkers for CRC.

Introduction. C-type lectin receptors (CLRs) are prominently expressed on myeloid cells where they perform multiple functions including serving as pattern recognition receptors (PRRs) to drive innate as well as adaptive immunity to pathogens. Depending on the presence of a tyrosine-based signalling motif, CLR-microbial pathogen engagement may result in either anti- or pro-inflammatory signalling.Impact statement. In this manuscript, we report our laboratory study of two novel CLRs that recognize Pneumocystis murina cell wall homogenates (CWH) and a purified Pneumocystis carinii cell wall fraction (CWF).Aim. To study the potential of newly generated hFc-CLR fusions on binding to Pneumocystis murina CWHs and P. carinii CWFs and subsequent downstream inflammatory signalling analysis.Methods. Newly generated hFc-CLR fusion CLEC4A and CLEC12B were screened against P. murina CWHs and P. carinii CWFs preparations via modified ELISA. Immunofluorescence assay (IFA) was utilized to visualize hFc-CLR fusion binding against intact fixed fungal life forms to verify results. Quantitative PCR (q-PCR) analysis of lung mRNA from the mouse immunosuppressed Pneumocystis pneumonia (PCP) model versus uninfected mice was employed to detect possible changes in the respective Clec4a and Clec12b transcripts. Lastly, siRNA technology of both CLRs was conducted to determine effects on downstream inflammatory events in mouse macrophages stimulated in the presence of P. carinii CWFs.Results. We determined that both CLEC4A and CLEC12B hFc-CLRs displayed significant binding with P. murina CWHs and P. carinii CWFs. Binding events showed significant binding to both curdlan and laminarin, both polysaccharides containing β-(1,3) glucans as well as N-acetylglucosamine (GlcNAc) residues and modest yet non-significant binding to the negative control carbohydrate dextran. IFA with both CLR hFc-fusions against whole P. murina life forms corroborated these findings. Lastly, we surveyed the mRNA expression profiles of both CLRs tested above in the mouse immunosuppressed Pneumocystis pneumonia (PCP) model and determined that both CLRs were significantly up regulated during infection. Lastly, siRNA of both CLRs in the mouse RAW macrophage cell line was conducted and results demonstrated that silencing of Clec4a resulted in no significant changes in TNF-alpha generation in P. carinii CWF stimulated macrophages. On the contrary, silencing of Clec12b CLR resulted in significant decreases in TNF-alpha in RAW cells stimulated with the same CWF.Conclusion. The data presented here provide new members of the CLRs family recognizing Pneumocystis. Future studies using CLEC4A and/or CLEC12B deficient mice in the PCP mouse model should provide further insights into the host immunological response to Pneumocystis.