Emergence of Azithromycin Resistance Mediated by Phosphotransferase-Encoding mph(A) in Diarrheagenic Vibrio fluvialis

Prevalence and molecular characterization of multi-drug and extreme drug resistant Escherichia coli in companion animals in Bangladesh

The study aimed to investigate multi-drug resistant (MDR) Escherichia coli (E. coli) in companion animals in Bangladesh, with a focus on the resistance profiles of isolates from non-food-producing animals. In 2023, the studied samples were from cats, dogs, and environmental sources linked with companion animal hospitals in Dhaka city, Bangladesh. E. coli was isolated using standard techniques and its antimicrobial resistance (AMR) was assessed against 23 antibiotics following the CLSI protocols. Metallo-beta-lactamase genes (blaNDM-1 and blaNDM-5) and mobile genetic elements (class 1 integron) were detected by multiplex PCR. The overall prevalence of E. coli was 70%, 76% in cats, 65.71% in dogs, and 65.71% in the environmental samples. Cefuroxime exhibited the highest resistance at 25%, while imipenem and nitrofurantoin showed the highest sensitivity at 100%, followed by ceftazidime at 95%. MDR strains made up 38.10%, while 11.90% were extremely drug-resistant (XDR). Additionally, 29% of E. coli were extended-spectrum beta-lactamase (ESBL) producers. The prevalence and association among class 1 integron and the resistant genes including blaNDM-1 and blaNDM-5 were also notable. This highlights the complex AMR challenges in these settings, including the presence of class 1 integron-a key element involved in capturing and transferring antimicrobial resistance genes.

Systemic Acetylome Analysis of Evolution in Fluconazole Resistance Candida auris

Candida auris is an opportunistic pathogen and has become a globally clinical concern due to multidrug resistance. In this study, we generated a series of C. auris strains (CF2, -3, -4, -5, and -6) with elevated MIC50 of fluconazole from CF1 by gradually increasing fluconazole concentration. Employing 4D label-free proteomics, we explored the contributions of acetylome alterations to the evolution of fluconazole resistance in C. auris. From 18 samples of six C. auris strains, we identified 2419 acetylated proteins with 7833 sites, quantified 3032 proteins, and 6310 sites. Compared to CF1, differentially acetylated proteins were significantly linked to cytosolic ribosomes, structural molecule activity, hexose and monosaccharide catabolism, glycolysis/gluconeogenesis, and alcohol dehydrogenase GroES-like domain. CF3 (16-32 μg/mL) and CF4 (64 μg/mL) were suggested as the key resistance inflection. CF3 was associated with a significant decrease in ribosomal protein acetylation, while CF4 witnesses a marked upsurge in acetylated proteins and sites. Upregulated proteins in CF3 were notably involved in oxidative stress, detoxification, osmotic stress, and alcohol. We drew a diagram to show acetylated sites on histones in C. auris. To the best of our knowledge, this is the first acetylome study in C. auris, providing insights into the biological and pathogenic roles of post-translational modifications (PTMs) in this organism.

Bacterial community and antibiotic resistance genes assembly processes were shaped by different mechanisms in the deep-sea basins of the Western Pacific Ocean

As the intrinsic property of microorganisms, antibiotic resistance genes (ARGs) are fundamentally coupled to microbially-linked biogeochemical processes within ecosystems. However, human activities often obscure the natural distribution of ARGs through deterministic selective pressures. The deep-sea basin of the western Pacific Ocean is one of the least disturbed areas globally by human activities, providing a natural laboratory to investigate the intrinsic mechanisms governing ARGs in natural environments. In this study, we analyzed bacterial community and ARG diversity in 15 surface sediment samples from three deep-sea basins in the western Pacific Ocean. The relative abundance of ARGs in the surface sediments ranged from 3.10 × 10-3 to 5.37 × 10-2 copies/16S rRNA copies, with multidrug and β-lactam resistance genes dominated in all samples (49.06%-100%). The bacteria were mainly dominated by the Proteobacteria. The principal coordinate analysis (PCoA) showed significant spatial heterogeneity of ARGs and bacteria among the three basins. Null model, neutral community models (NCM), and normalized stochasticity ratio (NST) indicated that bacterial community was dominated by stochastic assembly, driven by geographic barriers leading to independent evolution. Conversely, the NST revealed that the ARGs profile was mainly shaped by deterministic processes. Environmental factors are more crucial than geographical factors and bacterial community for ARG occurrence among the selected factors. Meanwhile, we found that the spread of ARGs was mainly through vertical gene transfer in the pre-antibiotic era. The disparity between the assembly processes of bacterial community and ARGs may be attributed to the fact that ARG hosts were not the dominant bacteria in the community. This study first reported the distribution and assembly processes of ARGs and bacterial community in surface sediments of the western Pacific.

Differential polyvalent passive immune protection of egg yolk antibodies (IgY) against live and inactivated Vibrio fluvialis in fish

Egg yolk antibodies (IgY) can be prepared in large quantities and economically, and have potential value as polyvalent passive vaccines (against multiple bacteria) in aquaculture. This study prepared live and inactivated Vibrio fluvialis IgY and immunized Carassius auratus prior to infection with V. fluvialis and Aeromonas hydrophila. The results showed that the two IgY antibodies hold effective passive protective rates against V. fluvialis and A. hydrophila in C. auratus. Further, the serum of C. auratus recognized the two bacteria in vitro, with a decrease in the bacteria content of the kidney. The phagocytic activity of C. auratus plasma was enhanced, with a decrease in the expression of inflammatory and antioxidant factors. Pathological sections showed that the kidney, spleen, and intestinal tissue structures were intact, and apoptosis and DNA damage decreased in kidney cells. Moreover, the immunoprotection conferred by the live V. fluvialis IgY was higher than that of the inactivated IgY. Addition, live V. fluvialis immunity induced IgY antibodies against outer membrane proteins of V. fluvialis were more than inactivated V. fluvialis immunity. Furthermore, heterologous immune bacteria will not cause infection, so V. fluvialis can be used to immunize chickens to obtain a large amount of IgY antibody. These findings suggest that the passive immunization effect of live bacterial IgY antibody on fish is significantly better than that of inactivated bacterial antibody, and the live V. fluvialis IgY hold potential value as polyvalent passive vaccines in aquaculture.

Virulence, antibiotic resistance phenotypes and molecular characterisation of Vibrio furnissii isolates from patients with diarrhoea

BACKGROUND

Vibrio furnissii is an emerging human pathogen closely related to V. fluvialis that causes acute gastroenteritis. V. furnissii infection has been reported to be rarer than V. fluvialis, but a multi-drug resistance plasmid has recently been discovered in V. furnissii.

METHODS

During daily monitoring at a general hospital in Beijing, China, seven V. furnissii strains were collected from patients aged over 14 years who presented with acute diarrhoea between April and October 2018. Genome analysis and comparison were performed for virulence and antimicrobial resistance genes, plasmids and transposon islands, together with phylogenetic analysis. Antimicrobial resistance to 19 antibiotics was investigated using the microbroth dilution method. Virulence phenotypes were investigated based on type VI secretion system (T6SS) expression and using a bacterial killing assay and a haemolysin assay.

RESULTS

Phylogenetic analysis based on single-nucleotide polymorphisms revealed a closer relationship between V. furnissii and V. fluvialis than between other Vibrio spp. The seven V. furnissii isolates were in different monophyletic clades in the phylogenetic tree, suggesting that the seven cases of gastroenteritis were independent. High resistance to cefazolin, tetracycline and streptomycin was found in the V. furnissii isolates at respective rates of 100.0%, 57.1% and 42.9%, and intermediate resistance to ampicillin/sulbactam and imipenem was observed at respective rates of 85.7% and 85.7%. Of the tested strains, VFBJ02 was resistant to both imipenem and meropenem, while VFBJ01, VFBJ02, VFBJ05 and VFBJ07 were multi-drug resistant. Transposon islands containing antibiotic resistance genes were found on the multi-drug resistance plasmid in VFBJ05. Such transposon islands also occurred in VFBJ07 but were located on the chromosome. The virulence-related genes T6SS, vfh, hupO, vfp and ilpA were widespread in V. furnissii. The results of the virulence phenotype assays demonstrated that our isolated V. furnissii strains encoded an activated T6SS and grew in large colonies with strong beta-haemolysis on blood agar.

CONCLUSION

This study showed that diarrhoea associated with V. furnissii occurred sporadically and was more common than expected in the summer in Beijing, China. The antibiotic resistance of V. furnissii has unique characteristics compared with that of V. fluvialis. Fluoroquinolones and third-generation cephalosporins, such as ceftazidime and doxycycline, were effective at treating V. furnissii infection. Continua laboratory-based surveillance is needed for the prevention and control of V. furnissii infection, especially the dissemination of the antibiotic resistance genes in this pathogen.

Vibriosis in South Asia: A systematic review and meta-analysis

OBJECTIVES

South Asia remains home to foodborne diseases caused by the Vibrio species. We aimed to compile and update information on the epidemiology of vibriosis in South Asia.

METHODS

For this systematic review and meta-analysis, we searched PubMed, Web of Science, EMBASE, and Google Scholar for studies related to vibriosis in South Asia published up to May 2023. A random-effects meta-analysis was used to estimate the pooled isolation rate of non-cholera-causing Vibrio species.

RESULTS

In total, 38 studies were included. Seven of these were case reports and 22 were included in the meta-analysis. The reported vibriosis cases were caused by non-O1/non-O139 V. cholerae, V. parahaemolyticus, V. fluvialis, and V. vulnificus. The overall pooled isolation rate was 4.0% (95% confidence interval [CI] 3.0-5.0%) in patients with diarrhea. Heterogeneity was high (I2 = 98.0%). The isolation rate of non-O1/non-O139 V. cholerae, V. parahaemolyticus, and V. fluvialis were 9.0 (95% CI 7.0-10.0%), 1.0 (95% CI 1.0-2.0%), and 2.0 (95% CI: 1.0-3.0%), respectively. Regarding V. parahaemolyticus, O3:K6 was the most frequently isolated serotype. Cases peaked during summer. Several studies reported antibiotic-resistant strains and those harboring extended-spectrum beta-lactamases genes.

CONCLUSIONS

This study demonstrates a high burden of infections caused by non-cholera-causing Vibrio species in South Asia.

Molecular characterization of IncFII plasmid carrying blaNDM-5 in a Salmonella enterica serovar Typhimurium ST34 clinical isolate in China

IMPORTANCE

In this study, an IncFII plasmid pIncFII-NDM5 carrying blaNDM-5 was found in carbapenem-resistant Salmonella enterica serovar Typhimurium (S. enterica serovar Typhimurium), which has conjugative transferability and carried blaNDM-5, bleMBL, mph(A), and blaTEM-1 four resistance genes that can mediate resistance to multiple antibiotics including cephalosporins, beta-lactamase inhibitor combinations, carbapenems, and macrolides. Phylogenetic analysis showed that 1104-65 and 1104-75 were closely related to other S. enterica serovar Typhimurium in this area. The above-mentioned S. enterica serovar Typhimurium chromosome carries blaCTX-M-55, qnrS1, and tet(A) genes, so the antibiotic resistance of isolates will be further enhanced after obtaining the pIncFII_NDM5-like plasmid. Meanwhile, we discovered a novel genetic structure of blaNDM-5 mediated by the IS26 composite transposon, which will expand our understanding of the emergence and spread of carbapenem-resistance genes. Altogether, the presence of the IncFII plasmid pIncFII-NDM5 further underscores the need for vigilant surveillance and appropriate infection control measures to mitigate the impact of carbapenem-resistant S. enterica serovar Typhimurium in clinical settings.

Identification of qnrVF in a Multidrug-Resistant Vibrio furnissii Clinical Strain

We found a new qnr gene, qnrVF1, carried by a multidrug resistance plasmid in a clinical Vibrio furnissii isolate. QnrVF1 exhibits 44.6% to 72.5% similarity in identity with other Qnr family proteins. QnrVF alleles are mainly encoded by chromosomes of V. furnissii and Vibrio fluvialis. Phylogenic analysis showed that QnrVF1 and QnrVF2 form a distinct clade in Qnr proteins. Thus, qnrVF represents a new qnr family. In addition, the qnrVF1 gene is often flanked by the mobile element ISCR1. Thus, it is likely that qnrVF1 is mobilized by ISCR1 from chromosome to plasmid in V. furnissii. IMPORTANCE Quinolones are widely used drugs. Bacteria contain a quinolone resistance gene, which mediates resistance to quinolones. Currently, seven families of Qnr proteins, QnrVC, QnrA, QnrB, QnrC, QnrD, QnrE, and QnrS, have been identified. However, it is unclear whether there are any other qnr families. In this study, we identified a new qnr family, qnrVF. We found many V. furnissii and V. fluvialis strains that possess chromosomal qnrVF alleles, suggesting that V. furnissii and V. fluvialis are the reservoirs of qnrVF. We also found that QnrVF1 confers low-level resistance to quinolones. ISCR1 may facilitate the spread of qnrVF1. The emergence and spread of qnrVF may pose a considerable threat to public health.

Antimicrobial Resistance and Mechanisms of Azithromycin Resistance in Nontyphoidal Salmonella Isolates in Taiwan, 2017 to 2018

Antimicrobial resistance was investigated in 2,341 nontyphoidal Salmonella (NTS) isolates recovered from humans in Taiwan from 2017 to 2018 using antimicrobial susceptibility testing. Azithromycin resistance determinants were detected in 175 selected isolates using PCR and confirmed in 81 selected isolates using whole-genome sequencing. Multidrug resistance was found in 47.3% of total isolates and 96.2% of Salmonella enterica serovar Anatum and 81.7% of S. enterica serovar Typhimurium isolates. Resistance to the conventional first-line drugs (ampicillin, chloramphenicol, and cotrimoxazole), cefotaxime and ceftazidime, and ciprofloxacin was found in 32.5 to 49.0%, 20.3 to 20.4%, and 3.2% of isolates, respectively. A total of 76 (3.1%) isolates were resistant to azithromycin, which was associated with mph(A), erm(42), erm(B), and possibly the enhanced expression of efflux pump(s) due to ramAp or defective ramR. mph(A) was found in 53% of the 76 azithromycin-resistant isolates from 11 serovars and located in an IS26-mph(A)-mrx(A)-mphR(A)-IS6100 unit in various incompatibility plasmids and the chromosomes. erm(42) in S. enterica serovar Albany was carried by an integrative and conjugative element, ICE_erm42, and in S. enterica serovar Enteritidis and S. Typhimurium was located in IS26 composite transposons in the chromosomes. erm(B) was carried by IncI1-I(α) plasmids in S. Enteritidis and S. Typhimurium. ramAp was a plasmid-borne ramA, a regulatory activator of efflux pump(s), found in only S. enterica serovar Goldcoast. Since the azithromycin resistance determinants are primarily carried on mobile genetic elements, they could easily be disseminated among human bacterial pathogens. The ramAp-carrying S. Goldcoast isolates displayed azithromycin MICs of 16 to 32 mg/L. Thus, the epidemiological cutoff value of ≤16 mg/L of azithromycin proposed for wild-type NTS should be reconsidered. IMPORTANCE Antimicrobial resistance in NTS isolates is a major public health concern in Taiwan, and the mechanisms of azithromycin resistance are rarely investigated. Azithromycin and carbapenems are the last resort for the treatment of invasive salmonellosis caused by multidrug-resistant (MDR) and extensively drug-resistant Salmonella strains. Our study reports the epidemiological trend of resistance in NTS in Taiwan and the genetic determinants involved in azithromycin resistance. We point out that nearly half of NTS isolates from 2017 to 2018 are MDR, and 20% are resistant to third-generation cephalosporins. The azithromycin resistance rate (3.1%) for the NTS isolates from Taiwan is much higher than those for the NTS isolates from the United States and Europe. Our study also indicates that azithromycin resistance is primarily mediated by mph(A), erm(42), erm(B), and ramAp, which are frequently carried on mobile genetic elements. Thus, the azithromycin resistance determinants could be expected to be disseminated among diverse bacterial pathogens.

TssI2-TsiI2 of Vibrio fluvialis VflT6SS2 delivers pesticin domain-containing periplasmic toxin and cognate immunity that modulates bacterial competitiveness

Vibrio fluvialis is a halophilic Gram-negative bacterium regarded as an emerging unusual enteric pathogen of increasing public health concern. Our previous work has identified two type VI secretion systems (T6SSs) in V. fluvialis, VflT6SS1, and VflT6SS2, and the latter is functional in mediating interbacterial competitiveness. However, its antibacterial effectors remain to be clarified. In this work, we focused on a new potential effector/immunity pair TssI2/TsiI2. Bioinformatics analysis revealed that the C-terminal domain of TssI2 belongs to a widespread family of pesticin, and its antibacterial toxicity and corresponding protection by TsiI2 were proved via bacterial killing assays, and their action sites were localized to the periplasm of bacterial cells. The interaction of TssI2 and TsiI2 was demonstrated by the bacterial adenylate cyclase two-hybrid, protein pull-down and isothermal titration calorimetry assays. Site-directed mutagenesis demonstrated that, in addition to Glu-844, Thr-863, and Asp-869, which correspond to three reported residues in pesticin of Yersinia pestis, additional residues including Phe-837, Gly-845, Tyr-851, Gly-867, Gln-963, Trp-975, and Arg-1000 were also proved to be crucial to the bactericidal activity of TssI2. Muramidase/lysozyme-related peptidoglycan (PG) hydrolase activities of TssI2 and its variants were validated with permeabilized Escherichia coli cells and purified PG substrate. Based on sequence homologies at C-terminals in various V. fluvialis isolates, TssI2 was subdivided into five clusters (12-22% identity among them), and the antibacterial activities of representative effectors from other four Clusters were also confirmed through periplasmic over-expression in E. coli host. Two selected cognate immunities were proved to confer protection against the toxicities of their effectors. Additionally, TsiI2, which belongs to Cluster I, exhibited cross-protection to effector from Cluster V. Together, current findings expand our knowledge of the diversity and consistency of evolved VgrG effectors in V. fluvialis and on how VflT6SS2 mediates a competitive advantage to gain a better survival.

Characterization of NDM-5 Carbapenemase-Encoding Gene (bla NDM-5) - Positive Multidrug Resistant Commensal Escherichia coli from Diarrheal Patients

Purpose

The multidrug resistance Enterobacteriaceae cause many serious infections resulting in prolonged hospitalization, increased treatment charges and mortality rate. In this study, we characterized bla _NDM-5-positive multidrug resistance commensal Escherichia coli (CE) isolated from diarrheal patients in Kolkata, India.

Methods

Three CE strains were isolated from diarrheal stools, which were negative for different pathogroups of diarrheagenic E. coli (DEC). The presence of carbapenemases encoding genes and other antimicrobial resistance genes (ARGs) was detected using PCR. The genetic arrangement adjoining bla _NDM-5 was investigated by plasmid genome sequencing. The genetic relatedness of the strains was determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) methods.

Results

In addition to colistin, the bla _NDM-5-positive CE strains showed resistance to most of the antibiotics. Higher MICs were detected for ciprofloxacin (>32 mg/L) and imipenem (8 mg/L). Molecular typing revealed that three CE strains belonged to two different STs (ST 101 and ST 648) but they were 95% similar in the PFGE analysis. Screening for ARGs revealed that CE strains harbored Int-1, bla _TEM, bla_{C TX-M3}, bla _OXA-1, bla _OXA-7, bla _OXA-9, tetA, strA, aadA1, aadB, sul2, floR, mph(A), and aac(6´)-Ib-cr. In conjugation experiment, transfer frequencies ranged from 2.5×10^-3 to 8.4x10^-5. The bla _NDM-5 gene was located on a 94-kb pNDM-TC-CE-89 type plasmid, which is highly similar to the IncFII plasmid harboring an IS26-IS30-bla _NDM-5-ble _MBL-trpF-dsbd-IS91-dhps structure.

Conclusion

To the best of our knowledge, this is the first report on carbapenem resistance involving the bla _NDM-5 gene in CE from diarrheal patients. The circulation of bla _NDM-5 gene in CE is worrisome, since it has the potential to transfer bla _NDM-5 gene to other enteric pathogens.

Emergence of bla OXA-1- and mph(A)-Producing Vibrio furnissii Isolated from Hospital Sewage

Cephalosporins and azithromycin are clinical antibiotics used to treat infections. Co-resistance to cephalosporins and azithromycin has been observed in some Enterobacterales, but it has only rarely been reported in Vibrio species. In this study, we isolated a cephalosporin- and azithromycin-resistant V. furnissii strain, VFN3, from hospital sewage. Whole-genome sequencing results showed that the strain VFN3 possesses an IncA/C2 plasmid, pVFN3-blaOXA-193K. This conjugative plasmid carries several clinically relevant drug resistance genes, including mph(A) and bla _OXA-1. We also found that in the strain VFN3, mph(A) and bla _OXA-1 are surrounded by insertion sequences and class I integrons, respectively. These data suggest that mobile elements mediate the transfer of mph(A) and bla _OXA-1. This is the first reported Vibrio species that possesses an mph(A)- and bla _OXA-1-bearing conjugative plasmid. The emergence of this conjugative multi-drug-resistance plasmid is of great concern to public health.

VfqI-VfqR quorum sensing circuit modulates type VI secretion system VflT6SS2 in Vibrio fluvialis

V. fluvialis is an emerging foodborne pathogen and could cause cholera-like gastroenteritis syndrome and poses a potential threat to public health. VflT6SS2 is a functionally active type VI secretion system (T6SS) in V. fluvialis which confers bactericidal activity. VflT6SS2 is composed of one major cluster and three hcp-vgrG orphan clusters. Previously, we identified two quorum sensing (QS) systems CqsA/LuxS-HapR and VfqI-VfqR in V. fluvialis and demonstrated that the former regulates VflT6SS2. However, whether VfqI-VfqR QS regulates VflT6SS2 is unknown. In this study, we showed that the mRNA abundances of VflT6SS2 tssD2 (hcp), tssI2 (vgrG) and tssB2 (vipA) were all significantly decreased in VfqI or/and VfqR deletion mutant(s). Consistently, Hcp expression/secretion was reduced too in these mutants. Complementation assay with VfqR mutant further confirmed that the reduced Hcp expression/secretion and impaired antibacterial virulence are restored by introducing VfqR-expressing plasmid. Reporter fusion analyses revealed that VfqR modulates the promoter activities of VflT6SS2. Bioinformatical prediction and further reporter fusion assay in E. coli supported that VfqR acts as a transcriptional factor to bind and regulate the gene expression of the VflT6SS2 major cluster. However, VfqR seems to promote transcription of hcp (tssD2) in the orphan clusters through elevating the expression of vasH which is encoded by the VflT6SS2 major cluster. Additionally, we found that the regulation intensity of VfqR on VflT6SS2 is weaker than that of HapR. In conclusion, our current study disclosed that in V. fluvialis, VfqI-VfqR circuit upregulates the expression and function of VflT6SS2 by directly or indirectly activating its transcription. These findings will enhance our understanding of the complicated regulatory network between QS and T6SS in V. fluvialis.

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VfqI-VfqR quorum sensing (QS) circuit positively modulates VflT6SS2 in V. fluvialis.

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VfqR directly activates VflT6SS2 major cluster while indirectly activates hcp orphan clusters.

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VfqR functions as a secondary QS regulator manipulating VflT6SS2 comparing with HapR.

Population genomics of the food-borne pathogen Vibrio fluvialis reveals lineage associated pathogenicity-related genetic elements

Vibrio fluvialis is a food-borne pathogen with epidemic potential that causes cholera-like acute gastroenteritis and sometimes extraintestinal infections in humans. However, research on its genetic diversity and pathogenicity-related genetic elements based on whole genome sequences is lacking. In this study, we collected and sequenced 130 strains of V. fluvialis from 14 provinces of China, and also determined the susceptibility of 35 of the strains to 30 different antibiotics. Combined with 52 publicly available V. fluvialis genomes, we inferred the population structure and investigated the characteristics of pathogenicity-related factors. The V. fluvialis strains exhibited high levels of homologous recombination and were assigned to two major populations, VflPop1 and VflPop2, according to the different compositions of their gene pools. VflPop2 was subdivided into groups 2.1 and 2.2. Except for VflPop2.2, which consisted only of Asian strains, the strains in VflPop1 and VflPop2.1 were distributed in the Americas, Asia and Europe. Analysis of the pathogenicity potential of V. fluvialis showed that most of the identified virulence-related genes or gene clusters showed high prevalence in V. fluvialis, except for three mobile genetic elements: pBD146, ICEVflInd1 and MGIVflInd1, which were scattered in only a few strains. A total of 21 antimicrobial resistance genes were identified in the genomes of the 182 strains analysed in this study, and 19 (90%) of them were exclusively present in VflPop2. Notably, the tetracycline resistance-related gene tet(35) was present in 150 (95%) of the strains in VflPop2, and in only one (4%) strain in VflPop1, indicating it was population-specific. In total, 91% of the 35 selected strains showed resistance to cefazolin, indicating V. fluvialis has a high resistance rate to cefazolin. Among the 15 genomes that carried the previously reported drug resistance-related plasmid pBD146, 11 (73%) showed resistance to trimethoprim-sulfamethoxazole, which we inferred was related to the presence of the dfr6 gene in the plasmid. On the basis of the population genomics analysis, the genetic diversity, population structure and distribution of pathogenicity-related factors of V. fluvialis were delineated in this study. The results will provide further clues regarding the evolution and pathogenic mechanisms of V. fluvialis, and improve our knowledge for the prevention and control of this pathogen.

Eight years of antibiotic consumption at a primary care outpatient facility in Trinidad and Tobago 2011-18: a synopsis of consumption trends

OBJECTIVES

To explore antibiotic consumption and surveillance patterns in Trinidad and Tobago.

METHODS

A retrospective observational study was conducted. Stock requisition and logbooks from a District Health Facility in Trinidad were examined for the period 2011-18. Daily Defined Doses (DDDs) for each antibiotic were computed and extrapolated to represent the antibiotic consumption per 1000 residents within the population.

RESULTS

The mean consumption across the years was 2.917 DDD per 1000 residents per day. The most consumed antibiotics were cefuroxime, amoxicillin/clavulanic acid, and azithromycin, with mean DDDs of 0.879, 0.695 and 0.373 respectively. The least consumed antibiotics were cefaclor and clarithromycin, with DDDs of 0.0006 and 0.0005, respectively.

CONCLUSIONS

Trinidad and Tobago is not mentioned in the WHO surveillance report on antibiotic consumption. Our most recent (2018) estimate of total antibiotic consumption was 3.224 DDD per 1000 habitants per day. This figure is an underestimate, as data was derived solely from the public sector. Notwithstanding, this data is novel and can provide a baseline for future comparison and development of national surveillance programmes.

CqsA/LuxS-HapR Quorum sensing circuit modulates type VI secretion system VflT6SS2 in Vibrio fluvialis

Vibrio fluvialis is an emerging enteric pathogen of increasing public health threat. Two quorum sensing (QS) systems, VfqI-VfqR and CqsA/LuxS-HapR, and two type VI secretion systems (T6SSs), VflT6SS1 and VflT6SS2, have been identified in V. fluvialis. Whether there exists any correlation between the two systems is unclear. In this study, we found that CqsA/LuxS-HapR circuit regulator LuxO represses while HapR activates VflT6SS2. The effect of LuxO is more pronounced at low cell density and is HapR-dependent. Deletion of hapR abolished Hcp expression and alleviated antibacterial virulence. However, these effects were rescued by HapR-expressing plasmid. Reporter fusion analyses showed that HapR is required for the promoter activities of VflT6SS2. Sequence inspection of the major cluster promoter revealed two potential Motif 1 HapR binding sites, and their bindings to HapR were confirmed by both electrophoretic mobility shift assay (EMSA) and DNase I footprinting assay. Meanwhile, two single Motif 2 sites were identified in tssD2_a (hcpA) and tssD2_b (hcpB) promoter regions of the orphan cluster which are less conserved and displayed lower affinities to HapR. Together, our study demonstrated that CqsA/LuxS-HapR QS manipulate VflT6SS2 in V. fluvialis, and this finding will enhance our understanding of possible crosstalk between T6SS and QS in microbes.

In hot water: effects of climate change on Vibrio-human interactions

Sea level rise and the anthropogenic warming of the world's oceans is not only an environmental tragedy, but these changes also result in a significant threat to public health. Along with coastal flooding and the encroachment of saltwater farther inland comes an increased risk of human interaction with pathogenic Vibrio species, such as Vibrio cholerae, V. vulnificus and V. parahaemolyticus. This minireview examines the current literature for updates on the climatic changes and practices that impact the location and duration of the presence of Vibrio spp., as well as the infection routes, trends and virulence factors of these highly successful pathogens. Finally, an overview of current treatments and methods for the mitigation of both oral and cutaneous exposures are presented.

Molecular detection of Vibrio cholerae from human stool collected from SK Hospital, Mymensingh, and their antibiogram

Objective:

Vibrio spp., particularly, Vibrio cholerae is a major etiology of diarrhea in humans worldwide. In this study, we isolated and identified V. cholerae from the human stool of suspected cases along with antibiogram.

Materials and Methods:

In total, 25 stool samples from cholera suspected patients were analyzed. Isolation and molecular detection of Vibrio species were performed based on staining, motility, cultural and biochemical characteristics followed by polymerase chain reaction (PCR) using groEL gene-specific primers.

Results:

Among the 25 samples, seven showed growth of yellow color colonies on Thiosulfate-Citrate-Bile salts-Sucrose agar plates. The isolates were Gram-negative, curved shaped, and motile. Biochemically, they were found positive for indole and Methyl Red tests and negative for Voges–Proskauer test. Out of the seven positive samples, only three isolates were confirmed as Vibrio spp. using genus-specific primers. Subsequently, these three isolates were confirmed as V. cholerae by PCR using V. cholerae groEL gene-specific primers. Antibiotic sensitivity test revealed these three isolates as highly sensitive to azithromycin, chloramphenicol, gentamicin, and norfloxacillin while resistant to streptomycin, tetracycline, and oxacillin.

Conclusion:

Vibrio cholerae were isolated from the stool of diarrheic human patients and confirmed by PCR targeting the groEL gene. The isolates were found resistant to streptomycin, tetracycline and oxacillin, and need further characterization to reveal the molecular basis of their origin and resistance.