Antibiotic resistance mechanisms of Vibrio cholerae

Genomic insights into the dynamic antibiotic resistance landscape of Vibrio cholerae during the Cholera outbreak 2022 in Odisha, India

This research delves into the evolving dynamics of antibiogram trends, the diversity of antibiotic resistance genes and antibiotic efficacy against Vibrio cholerae strains that triggered the cholera outbreak 2022 in Odisha, India. The study will provide valuable insights managing antimicrobial resistance during cholera outbreaks. Eighty V. cholerae strains isolated during the outbreak were analysed for genotypic variations in associated drug resistance genes using PCR assays. Antibiogram profiles and MIC gradient analysis were performed according CLSI guidelines to assess antibiotic effectiveness. Substitution of amino acid position in the QRDR Region was examined to understand the development of Fluoroquinolone resistance. Elevated resistances in V. cholerae strains were observed against doxycycline, azithromycin, ciprofloxacin, and chloramphenicol. The average MARI registered 0.63 value, exceeding the threshold value 0.2. PCR assays revealed higher prevalence of antibiotic resistance genes, and MIC values observed have surpassed the previously registered values during any cholera outbreaks in India. Novel mutations in the parC gene, specifically Tyr-88→Cys and Ser-85→Leu implicated Fluoroquinolone resistance in V. cholerae. This study urges moving beyond on antibiotic reliance to control cholera, emphasizing alternative strategies like OCV, rehydration therapy, probiotics and Water, Sanitation and Hygiene (WASH) interventions as effective tools to combat cholera outbreaks and mitigate antibiotic resistance.

Mathematical modeling of cholera dynamics in the presence of antimicrobial utilization strategy

Antimicrobial resistance poses a significant threat to public health, particularly in cholera treatment. The emergence of antibiotic resistance, coupled with the sharp decline in pharmaceutical companies developing new cholera antibiotics, is a cause for concern. We formulate a multidrug-resistant (MDR) cholera epidemic model that incorporates a stage-switching strategy between two antibiotics to reduce the magnitude of resistance. The model is analyzed mathematically, and sensitivity analysis of the reproduction number is performed using sub-reproduction numbers. Stability analysis of the cholera-sensitive-only and cholera-resistant-only equilibria is investigated using Centre Manifold Theory. The model is calibrated through Markov Chain Monte Carlo simulations in Stan, showing stability at equilibrium points, which is further verified through numerical simulations. The simulations demonstrate an inverse relationship between the number of MDR cholera cases and the number of individuals receiving second-line treatment for cholera. This study suggests that the correct use of antibiotics can effectively manage the emergence of antimicrobial resistance. From a public health policy perspective, these findings emphasize the importance of antibiotic stewardship programs and the need for policies that promote the responsible use of existing antibiotics while encouraging the development of new treatment options. Such measures could help mitigate the global burden of MDR cholera and prevent further escalation of resistance.

Antibacterial and antibiofilm features of mutSMAP-18 against Vibrio cholerae

Cholera continues to be a pointed global health issue, prominently in developing nations, where the disease's severe diarrheal symptoms pose substantial public health risks. With the escalating spread of antibiotic resistance among V. cholerae strains, alternative therapeutic approaches are imperative. Antimicrobial peptides are increasingly recognized for their potential, with research focusing on finding the most effective options. We explored the antibacterial and antibiofilm properties of analogues of sheep myeloid antimicrobial peptide-18 (SMAP-18) against V. cholerae in this investigation. Our prior research demonstrated that substituting glycine with alanine at different positions within SMAP-18 altered its structure and antimicrobial activity. Among these altered analogues, our focus was on a mutant variant (mutSMAP-18), characterized by glycine-to-alanine substitutions at positions 2, 7, and 13. Our results indicated that mutSMAP-18 exhibited heightened antimicrobial and antibiofilm activities against V. cholerae compared to SMAP-18. We conducted several mechanistic investigations to check the membrane integrity using DNA-binding dye, SYTOX Green or measuring calcein dye leakage and analyzing flow cytometry by fluorescence-activated cell sorting (FACScan). From these tests, we elucidated that SMAP-18 primarily functions intracellularly, while mutSMAP-18 targets the bacterial membrane. Additionally, scanning electron microscopy (SEM) images illustrated membrane disruption at lower concentrations for mutSMAP-18. Notably, mutSMAP-18 demonstrated significant antibiofilm properties against V. cholerae. Overall, these findings offer valuable perspectives for developing novel antibacterial therapies targeting the pathogenic V. cholerae.

Vibrio cholerae virulence is blocked by chitosan oligosaccharide-mediated inhibition of ChsR activity

Vibrio cholerae causes cholera, an important cause of death worldwide. A fuller understanding of how virulence is regulated offers the potential for developing virulence inhibitors, regarded as efficient therapeutic alternatives for cholera treatment. Here we show using competitive infections of wild-type and mutant bacteria that the regulator of chitosan utilization, ChsR, increases V. cholerae virulence in vivo. Mechanistically, RNA sequencing, chromatin immunoprecipitation with sequencing and molecular biology approaches revealed that ChsR directly upregulated the expression of the virulence regulator, TcpP, which promoted expression of the cholera toxin and the toxin co-regulated pilus, in response to low O2 levels in the small intestine. We also found that chitosan degradation products inhibit the ChsR-tcpP promoter interaction. Consistently, administration of chitosan oligosaccharide, particularly when delivered via sodium alginate microsphere carriers, reduced V. cholerae intestinal colonization and disease severity in mice by blocking the chsR-mediated pathway. These data reveal the potential of chitosan oligosaccharide as supplemental therapy for cholera treatment and prevention.

Wastewater-based surveillance of Vibrio cholerae: Molecular insights on biofilm regulatory diguanylate cyclases, virulence factors and antibiotic resistance patterns

Vibrio cholerae is an inherent inhabitant of aquatic ecosystems. The Indian state of West Bengal, especially the Gangetic delta region is the highest cholera affected region and is considered as the hub of Asiatic cholera. V. cholerae were isolated from publicly accessible wastewater of Midnapore, West Bengal, India. Serotyping determined all isolates to be of non-O1/non-O139 serogroups. Moderate biofilm-forming abilities were noticed in most of the isolates (74.7 %) while, high biofilm formation was recorded for only 6.3 % isolates and 19 % of isolates exhibited low/non-biofilm-forming abilities. PCR-based screening of crucial diguanylate cyclases (DGCs) involved in cyclic-di-GMP-mediated biofilm signaling was performed. cdgH and cdgM were the most abundant DGCs among 93.7 % and 91.5 % of isolates, respectively. Other important DGCs, i.e., cdgK, cdgA, cdgL, and vpvC were present in 84 %, 75.5 %, 72 % and 68 % of isolates, respectively. Besides, the non-O1/non-O139 isolates were screened for the occurrence of virulence factor encoding genes. Moreover, among these non-O1/non-O139 isolates, two strains (3.17 %) harbored both ctxA and ctxB genes, which encode the cholera toxin associated with epidemic cholera. ompU was the most prevalent virulence factor, present in 24.8 % of isolates. Other virulence factors like, zot and st were found in 4.7 % and 9.5 % of isolates. Genes encoding tcp and ace were found to be PCR-negative for the isolates. Additionally, crucial virulence factor regulators, toxT, toxR and hapR were found to be PCR-positive in all the isolates. Antibiotic resistance patterns displayed further vulnerabilities with decreased sensitivity towards commonly used antibiotics with multiple antibiotic resistance index ranging between 0.37 and 0.62. The presence of cholera toxin-encoding multi-drug resistant (MDR) V. cholerae strains in environmental settings is alarming. High occurrence of DGCs are considered to encourage further investigations to use them as alternative therapeutic targets against MDR cholera pathogen due to their unique presence in bacterial systems.

Public health aspects of Vibrio spp. related to the consumption of seafood in the EU

Vibrio parahaemolyticus, Vibrio vulnificus and non-O1/non-O139 Vibrio cholerae are the Vibrio spp. of highest relevance for public health in the EU through seafood consumption. Infection with V. parahaemolyticus is associated with the haemolysins thermostable direct haemolysin (TDH) and TDH-related haemolysin (TRH) and mainly leads to acute gastroenteritis. V. vulnificus infections can lead to sepsis and death in susceptible individuals. V. cholerae non-O1/non-O139 can cause mild gastroenteritis or lead to severe infections, including sepsis, in susceptible individuals. The pooled prevalence estimate in seafood is 19.6% (95% CI 13.7-27.4), 6.1% (95% CI 3.0-11.8) and 4.1% (95% CI 2.4-6.9) for V. parahaemolyticus, V. vulnificus and non-choleragenic V. cholerae, respectively. Approximately one out of five V. parahaemolyticus-positive samples contain pathogenic strains. A large spectrum of antimicrobial resistances, some of which are intrinsic, has been found in vibrios isolated from seafood or food-borne infections in Europe. Genes conferring resistance to medically important antimicrobials and associated with mobile genetic elements are increasingly detected in vibrios. Temperature and salinity are the most relevant drivers for Vibrio abundance in the aquatic environment. It is anticipated that the occurrence and levels of the relevant Vibrio spp. in seafood will increase in response to coastal warming and extreme weather events, especially in low-salinity/brackish waters. While some measures, like high-pressure processing, irradiation or depuration reduce the levels of Vibrio spp. in seafood, maintaining the cold chain is important to prevent their growth. Available risk assessments addressed V. parahaemolyticus in various types of seafood and V. vulnificus in raw oysters and octopus. A quantitative microbiological risk assessment relevant in an EU context would be V. parahaemolyticus in bivalve molluscs (oysters), evaluating the effect of mitigations, especially in a climate change scenario. Knowledge gaps related to Vibrio spp. in seafood and aquatic environments are identified and future research needs are prioritised.

The Rise of Bacterial G-Quadruplexes in Current Antimicrobial Discovery

Antimicrobial resistance (AMR) is a silent critical issue that poses several challenges to health systems. While the discovery of novel antibiotics is currently stalled and prevalently focused on chemical variations of the scaffolds of available drugs, novel targets and innovative strategies are urgently needed to face this global threat. In this context, bacterial G-quadruplexes (G4s) are emerging as timely and profitable targets for the design and development of antimicrobial agents. Indeed, they are expressed in regulatory regions of bacterial genomes, and their modulation has been observed to provide antimicrobial effects with translational perspectives in the context of AMR. In this work, we review the current knowledge of bacterial G4s as well as their modulation by small molecules, including tools and techniques suitable for these investigations. Finally, we critically analyze the needs and future directions in the field, with a focus on the development of small molecules as bacterial G4s modulators endowed with remarkable drug-likeness.

Emerging resistome diversity in clinical Vibrio cholerae strains revealing their role as potential reservoirs of antimicrobial resistance

BACKGROUND

This is a unique and novel study delineating the genotyping and subsequent prediction of AMR determinants of Vibrio cholerae revealing the potential of contemporary strains to serve as precursors of severe AMR crisis in cholera.

METHODS AND RESULTS

Genotyping of representative strains, VC1 and VC2 was undertaken to characterize antimicrobial resistance genes (ARGs) against chloramphenicol, SXT, nalidixic acid and streptomycin against which they were found to be resistant by antibiogram analysis in our previous investigation. strAB, sxt, sul2, qace∆1-sul1 were detected by PCR. Genome annotation and identification of ARGs with WGS helped to detect the presence of almG, varG, strA (APH(3'')-Ib), strB (APH(6)-Id), sul2, catB9, floR, CRP, dfrA1 genes. Signatures of resistance determinants and protein domains involved in antimicrobial resistance, primarily, efflux of antibiotics were identified on the basis of 30-100% homology to reference proteins. These domains were predicted to be involved in other metabolic functions on the basis of 100% identity with 100% coverage with reference protein and nucleotide sequences and were predicted to be of a diverse taxonomic origin accentuating the influence of the microbiota on AMR acquisition. Sequence analysis of QRDR (quinolone resistance-determining region) revealed SNPs. Cytoscape v3.8.2 was employed to analyse protein-protein interaction of MDR proteins, MdtA and EmrD-2, with nodes of vital AMR pathways. Vital nodes involved in efflux of different classes of antibiotics were found to be absent in VC1 and VC2 justifying the sensitivity of these strains to most antibiotics.

CONCLUSIONS

The study helped to examine the resistome of VC isolated from recent outbreaks to understand the underlying reason of sensitivity to most antibiotics and also to characterize the ARGs in their genome. It revealed that VC is a reservoir of signatures of resistance determinants and serving as precursors for severe AMR crisis in cholera. This is the first study, to our knowledge, which has scrutinized and presented systematically, information on prospective domains which bear the potential of serving as AMR determinants in VC with the help of bioinformatic tools. This pioneering approach may help in the prediction of AMR landfalls and benefit epidemiological surveillance and early warning systems.

A TetR family regulator of an RND efflux system that directs artemisinin resistance in Vibrio cholerae

Artemisinin (ARS) displayed bactericidal activity against Vibrio cholerae. To assess the mechanistic details of its antibacterial action, we have isolated V. cholerae mutants with enhanced ARS resistance and identified a gene (VCA0767) whose loss-of-function resulted in the ARS resistance phenotypes. This gene (atrR) encodes a TetR family transcriptional regulator, and its deletion mutant displayed the reduction in ARS-induced ROS formation and DNA damage. Transcriptomic analysis revealed that the genes encoding a resistance-nodulation-cell division (RND) efflux pump operon (vexRAB) and the outer membrane component (tolC) were highly upregulated in the artR mutant, suggesting that AtrR might act as a negative regulator of this operon and tolC. Gene deletion of vexR, vexB, or tolC abrogated the ARS resistance of the atrR mutant, and more importantly, the ectopic expression of VexAB-TolC was sufficient for the ARS resistance, indicating that the increased expression of the VexAB-TolC efflux system is necessary and sufficient for the ARS resistance of the atrR mutant. The cytoplasmic accumulation of ARS was compromised in the vexBtolC mutant, suggesting that the VexAB-TolC might be the primary efflux system exporting ARS to reduce its toxicity inside of the bacterial cells. The atrR mutant displayed resistance to erythromycin as well in a VexR-dependent manner. This result suggests that AtrR may act as a global regulator responsible for preventing intracellular accumulation of toxic chemicals by enhancing the RND efflux system.IMPORTANCEDrug efflux protein complexes or efflux pumps are considered as the major determinants of multiple antimicrobial resistance by exporting a wide range of structurally diverse antibiotics in bacterial pathogens. Despite the clinical significance of the increased expression of the efflux pumps, their substrate specificity and regulation mechanisms are poorly understood. Here, we demonstrated that VexAB-TolC, a resistance-nodulation-cell division (RND) efflux pump of V. cholerae, is responsible for the resistance to artemisinin (ARS), an antimalarial drug with bactericidal activity. Furthermore, we newly identified AtrR, a TetR family repressor, as a global regulator for VexRAB and the common outer membrane channel, TolC, where VexR functions as the pathway-specific regulator of the vexAB operon. Our findings will help improve our insight into a broad range of substrate specificity of the VexAB-TolC system and highlight the complex regulatory networks of the multiple RND efflux systems during V. cholerae pathogenesis.

Epidemiological cut-off values for non-O1/ non-O139 Vibrio cholerae disc diffusion data generated by standardised methods

This work generates the data needed to set epidemiological cut-off values for disc-diffusion zone measurements of Vibrio cholerae. The susceptibility of 147 European isolates of non-O1/non-O139 V. cholerae to 19 antibiotics was established using a standardised disc diffusion method which specified incubation of Mueller Hinton agar plates at 35°C. Epidemiological cut-off values were calculated by analysis of the zone size data with the statistically based normalised resistance interpretation method. Cut-off values for 17 agents were calculated by analysis of the aggregated data from all 4 laboratories participating in this study. The cut-off values calculated were ≥18 mm for amoxicillin/clavulanate, ≥18 mm for amikacin, ≥19 mm for ampicillin, ≥27 mm for cefepime, ≥31 mm for cefotaxime, ≥24 mm for ceftazidime, ≥24 mm for chloramphenicol, ≥31 mm for ciprofloxacin, ≥16 mm for erythromycin, ≥ 27 mm for florfenicol, ≥16 mm for gentamicin, ≥23 mm for imipenem, ≥25 mm for meropenem, ≥29 mm for nalidixic acid, ≥28 mm for norfloxacin, ≥13 mm for streptomycin and ≥23 mm for tetracycline. For the other 2 agents the data from 1 laboratory was excluded from the censored aggregation because the data from that laboratory was considered excessively imprecise. The cut-off values for these 2 agents calculated for the aggregation of the data from 3 laboratories were ≥23 mm for trimethoprim and ≥24 mm for trimethoprim/sulfamethoxazole. These zone size data will be submitted to the Clinical Laboratory Standards Institute (CLSI) and European Committee for Antimicrobial Susceptibility Testing (EUCAST) for their consideration in setting international consensus epidemiological cut-off values for non O1/non-O139 V. cholerae.

Dynamics of efflux pumps in antimicrobial resistance, persistence, and community living of Vibrionaceae

The marine bacteria of the Vibrionaceae family are significant from the point of view of their role in the marine geochemical cycle, as well as symbionts and opportunistic pathogens of aquatic animals and humans. The well-known pathogens of this group, Vibrio cholerae, V. parahaemolyticus, and V. vulnificus, are responsible for significant morbidity and mortality associated with a range of infections from gastroenteritis to bacteremia acquired through the consumption of raw or undercooked seafood and exposure to seawater containing these pathogens. Although generally regarded as susceptible to commonly employed antibiotics, the antimicrobial resistance of Vibrio spp. has been on the rise in the last two decades, which has raised concern about future infections by these bacteria becoming increasingly challenging to treat. Diverse mechanisms of antimicrobial resistance have been discovered in pathogenic vibrios, the most important being the membrane efflux pumps, which contribute to antimicrobial resistance and their virulence, environmental fitness, and persistence through biofilm formation and quorum sensing. In this review, we discuss the evolution of antimicrobial resistance in pathogenic vibrios and some of the well-characterized efflux pumps' contributions to the physiology of antimicrobial resistance, host and environment survival, and their pathogenicity.

Pharmacological Management of Cholera: A Century of Expert Opinions in Cecil Textbook of Medicine

BACKGROUND

Cholera is a potentially lethal diarrheal disease produced by Vibrio cholerae serotypes O1 El Tor and O139. Known since antiquity, the condition causes epidemics in many areas, particularly in Asia, Africa, and South America. Left untreated, the mortality may reach 50%. The crucial therapeutic intervention is intravenous or oral rehydration and correction of acidosis, dyselectrolytemia, and renal impairment. Antibiotic use represents the main pharmacological intervention.

STUDY QUESTION

What are the milestones of the antibiotics use recommended by experts for the pharmacological management of cholera in the past century?

STUDY DESIGN

To determine the changes in the experts' approach to the management of cholera and particularly the use of antibiotics as presented in a widely used textbook in the United States.

DATA SOURCES

The chapters describing the management of cholera in the 26 editions of Cecil Textbook of Medicine published from 1927 through 2020.

RESULTS

Sulfonamides were recommended in 1947, followed by the introduction of tetracyclines, chloramphenicol, and furazolidone in 1955. The options were restricted in 2000 to doxycycline. In the past decade, patients infected with strains known to have a degree a resistance to tetracyclines were treated with azithromycin or ciprofloxacin. Antibiotic use decreases the volume of stool and the duration of diarrhea but has not been considered lifesaving. Drugs with antimotility, antiemetic, or antisecretory properties are not useful.

CONCLUSIONS

The utility of antibiotic use in cholera has been endorsed by experts, but only as an adjunct to rapid and complete fluid and electrolyte replacement.

Molecular characterization of Vibrio species isolated from dairy and water samples

Vibrio species can cause foodborne infections and lead to serious gastrointestinal illnesses. The purpose of this research was to detect the Vibrio cholerae and Vibrio parahaemolyticus in raw milk, dairy products, and water samples. Also, it investigated the virulence factors, antibiotic resistance and biofilm formation in isolated bacteria. Conventional and molecular approaches were used to identify the isolates in this study. Vibrio species were detected in 5% of the samples. Vibrio cholerae and Vibrio parahaemolyticus were isolated from 1.25 and 1.5%, respectively, of the total samples. Penicillin resistance was detected in all strains of Vibrio cholerae and Vibrio parahaemolyticus, with a MAR index ranging from 0.16 to 0.5. Four isolates were moderate biofilm producer and three of them were MDR. When Vibrio cholerae was screened for virulence genes, ctxAB, hlyA, and tcpA were found in 80, 60, and 80% of isolates, respectively. However, tdh + /trh + associated-virulence genes were found in 33.3% of Vibrio parahaemolyticus isolates.

Antibiotic-Resistant Vibrio cholerae O1 and Its SXT Elements Associated with Two Cholera Epidemics in Kenya in 2007 to 2010 and 2015 to 2016

Multidrug-resistant Vibrio cholerae O1 strains have long been observed in Africa, and strains exhibiting new resistance phenotypes have emerged during recent epidemics in Kenya. This study aimed to determine the epidemiological aspects, drug resistance patterns, and genetic elements of V. cholerae O1 strains isolated from two cholera epidemics in Kenya between 2007 and 2010 and between 2015 and 2016. A total of 228 V. cholerae O1 strains, including 226 clinical strains isolated from 13 counties in Kenya during the 2007-2010 and 2015-2016 cholera epidemics and two environmental isolates (from shallow well water and spring water isolates) isolated from Pokot and Kwale Counties, respectively, in 2010 were subjected to biotyping, serotyping, and antimicrobial susceptibility testing, including the detection of antibiotic resistance genes and mobile genetic elements. All V. cholerae isolates were identified as El Tor biotypes and susceptible to ceftriaxone, gentamicin, and ciprofloxacin. The majority of isolates were resistant to trimethoprim-sulfamethoxazole (94.6%), streptomycin (92.8%), and nalidixic acid (64.5%), while lower resistance was observed against ampicillin (3.6%), amoxicillin (4.2%), chloramphenicol (3.0%), and doxycycline (1.8%). Concurrently, the integrating conjugative (SXT) element was found in 95.5% of the V. cholerae isolates; conversely, class 1, 2, and 3 integrons were absent. Additionally, 64.5% of the isolates exhibited multidrug resistance patterns. Antibiotic-resistant gene clusters suggest that environmental bacteria may act as cassette reservoirs that favor resistant pathogens. On the other hand, the 2015-2016 epidemic strains were found susceptible to most antibiotics except nalidixic acid. This revealed the replacement of multidrug-resistant strains exhibiting new resistance phenotypes that emerged after Kenya's 2007-2010 epidemic. IMPORTANCE Kenya is a country where cholera is endemic; it has experienced three substantial epidemics over the past few decades, but there are limited data on the drug resistance patterns of V. cholerae at the national level. To the best of our knowledge, this is the first study to investigate the antimicrobial susceptibility profiles of V. cholerae O1 strains isolated from two consecutive epidemics and to examine their associated antimicrobial genetic determinants. Our study results revealed two distinct antibiotic resistance trends in two separate epidemics, particularly trends for multidrug-associated mobile genetic elements and chromosomal mutation-oriented resistant strains from the 2007-2010 epidemic. In contrast, only nalidixic acid-associated chromosomal mutated strains were isolated from the 2015-2016 epidemic. This study also found similar patterns of antibiotic resistance in environmental and clinical strains. Continuous monitoring is needed to control emerging multidrug-resistant isolates in the future.

Vibrio cholerae O1 associated with recent endemic cholera shows temporal changes in serotype, genotype, and drug-resistance patterns in Bangladesh

BACKGROUND

Despite the advancement in our understanding of cholera and its etiological agent, Vibrio cholerae, the prevention and treatment of the disease are often hindered due to rapid changes in drug response pattern, serotype, and the major genomic islands namely, the CTX-prophage, and related genetic characteristics. In the present study, V. cholerae (n = 172) associated with endemic cholera in Dhaka during the years 2015-2021 were analyzed for major phenotypic and genetic characteristics, including drug resistance patterns.

RESULTS

Results revealed that the V. cholerae strains belonged to serogroup O1 biotype El Tor carrying El Tor -specific genes rtxC, tcpA El Tor, and hlyA El Tor, but possessed classical-biotype cholera toxin. Serotypes of V. cholerae strains differed temporally in predominance with Inaba during 2015-2017, and again in 2020-2021, while Ogawa was the predominant serotype in 2018-2019. Also, ctxB1 was predominant in V. cholerae associated with cholera during 2015-2017, while ctxB7 was predominant in 2018, and in the subsequent years, as observed until 2021. V. cholerae strains differed in their antibiotic resistance pattern with a majority (97%) being multi-drug resistant (MDR) and belonging to six sub-groups. Notably, one of these MDR strains was resistant to eleven of the eighteen antibiotics tested, with resistance to fourth-generation cephalosporin (cefepime), and aztreonam. This extreme drug resistant (XDR) strain carried resistance-related genes namely, extended-spectrum β-lactamases (ESBL), blaOXA-1 and blaPER-3.

CONCLUSION

The observed temporal switching of serotypes, as well as the ctxB genotype, and the emergence of MDR/XDR V. cholerae and their association with endemic cholera in Dhaka underscore the need for routine monitoring of the pathogen for proper patient management.

Identification and genomic analysis of a Vibrio cholerae strain isolated from a patient with bloodstream infection

Vibrio cholerae is a bacterium ubiquitous in aquatic environments which can cause widespread infection worldwide. V. cholerae gradually became a rare species of bacteria in clinical microbiology laboratories with the control of the cholera epidemic. In this study, we isolated a V. cholerae strain, named VCHL017, from the blood of an elderly patient without gastrointestinal symptoms. The patient had a history of hookworm infection and multiple myeloma. Furthermore, she was immunocompromised, and received long-term chemotherapy and antimicrobial agents. VCHL017 was inoculated on blood agar and thiosulfate citrate bile salt sucrose plates (TCBS) to observe morphological characteristics. Then this isolate was identified by matrix-assisted laser desorption/ionization time-of-flight spectrometry (MALDI-TOF MS). The minimum inhibitory concentrations (MICs) for cefazolin, ceftazidime, cefepime, meropenem, tetracycline, ciprofloxacin, chloramphenicol, and gentamicin of VCHL017 were determined by the microbroth dilution method. PCR and serum agglutination tests were used to determine whether the serogroups of the isolate belonged to the O1/O139 and cholera toxin encoding genes. Finally, the genomic features and phylogeny of VCHL017 were analyzed by whole genome sequencing (WGS). VCHL017 was a non-O1/O139 V cholerae strain that did not carry the ctxA gene. Antimicrobial susceptibility tests revealed that VCHL017 was susceptive to chloramphenicol and tetracycline. Although it did not carry the genes encoding the cholera toxin, WGS indicated that VCHL017 carried a variety of other virulence factors. By calculating the average nucleotide identity (ANI), we precisely identified the species of VCHL017 as V. cholerae. There are also A171S and A202S missense mutations in gyrA of VCHL017. The phylogenetic analysis indicated that VCHL017 was closely related to V. cholerae strains isolated from aquatic environments. Our results suggest that continuous monitoring is necessary for non-O1/O139 V cholerae strains isolated from outside the digestive tract, which could be pathogenic through multiple virulence factors.

Antimicrobial resistance in Vibrio cholerae O1/O139 clinical isolates: a systematic review and meta-analysis

OBJECTIVES

Vibrio cholerae O1/O139 is responsible for cholera epidemics; that remains a huge public health menace across the globe. Furthermore, an increasing resistance rate among V. cholerae strains has been reported around the world. Therefore, the objective of this meta-analysis was to evaluate the weighted pooled resistance (WPR) rates in clinical V. cholerae O1/O139 isolates based on different years, areas, antimicrobial susceptibility testing, and resistance rates.

RESEARCH DESIGN AND METHODS

: We searched the studies in PubMed, Scopus, Embase, and Web of Science (until January 2020). Statistical analyses were conducted using STATA software (ver. 14.0).

RESULTS

: A total of 139 studies investigating 24062 V. cholerae O1/O139 isolates were analyzed. The majority of the studies originated in Asia (n=102). The WPR rates were as follows: azithromycin 1%, erythromycin 36%, ciprofloxacin 3%, cotrimoxazole 79%, doxycycline 7%, tetracycline 20%. There was increased resistance to cotrimoxazole, ciprofloxacin, and tetracycline during the 1980 to 2020 years.

CONCLUSIONS

: Temporal changes in antibiotic resistance rate found in this study demonstrated the critical continuous surveillance of antibiotic resistance. Also, ciprofloxacin, azithromycin, gentamicin, cephalexin, imipenem, ofloxacin, and norfloxacin were found to be the best antibiotics against V. cholera, with the highest and the lowest effectiveness resistance rate.

Prediction of Antibiotic Susceptibility Profiles of Vibrio cholerae Isolates From Whole Genome Illumina and Nanopore Sequencing Data: CholerAegon

During the last decades, antimicrobial resistance (AMR) has become a global public health concern. Nowadays multi-drug resistance is commonly observed in strains of Vibrio cholerae, the etiological agent of cholera. In order to limit the spread of pathogenic drug-resistant bacteria and to maintain treatment options the analysis of clinical samples and their AMR profiles are essential. Particularly, in low-resource settings a timely analysis of AMR profiles is often impaired due to lengthy culturing procedures for antibiotic susceptibility testing or lack of laboratory capacity. In this study, we explore the applicability of whole genome sequencing for the prediction of AMR profiles of V. cholerae. We developed the pipeline CholerAegon for the in silico prediction of AMR profiles of 82 V. cholerae genomes assembled from long and short sequencing reads. By correlating the predicted profiles with results from phenotypic antibiotic susceptibility testing we show that the prediction can replace in vitro susceptibility testing for five of seven antibiotics. Because of the relatively low costs, possibility for real-time data analyses, and portability, the Oxford Nanopore Technologies MinION sequencing platform-especially in light of an upcoming less error-prone technology for the platform-appears to be well suited for pathogen genomic analyses such as the one described here. Together with CholerAegon, it can leverage pathogen genomics to improve disease surveillance and to control further spread of antimicrobial resistance.

Effects of chitosan nanoparticles loaded with mesenchymal stem cell conditioned media on gene expression in Vibrio cholerae and Caco-2 cells

Vibrio (V.) cholerae forms a pellicle for self-defense in the pathological conditions in the intestine, which protects it against antibiotics and adverse conditions. Targeting biofilm genes and Toll-like receptors (TLRs) is one of the new strategies to combat multidrug-resistant bacteria. The objective of this study was to evaluate the effect of mesenchymal stem cell conditioned media (MSC CM; 1000 µg), chitosan nanoparticles incorporated with mesenchymal stem cell conditioned media (MSC CM-CS NPs; 1000 µg + 0.05%), and chitosan nanoparticles (CS NPs; 0.05%) on the expression of bap1 and rbmC biofilm genes in V. cholerae and TLR2 and TLR4 genes in Caco-2 cells. The bacteria were inoculated in the presence or absence of MSC CM, MSC CM-CS NPs, and CS NPs for 24 h at 37 °C to evaluate the expression of biofilm genes. The Caco-2 cells were also exposed to V. cholerae for 1 h and then MSC CM, MSC CM-CS NPs, and CS NPs for 18 h at 37 °C. After these times, RNA was extracted from Caco-2 cells and bacteria exposed to the compounds, and the expression of target genes was evaluated using real-time PCR. Caco-2 cell viability was also assessed by MTT assay. After adding MSC CM, MSC CM-CS NPs, and CS NPs to V. cholerae medium, the percentage reduction in gene expression of bap1 was 96, 91, and 39%, and rbmC was 93, 92, and 32%, respectively. After adding MSC CM, MSC CM-CS NPs, and CS NPs to the Caco-2 cell medium, the percentage reduction in the gene expression of TLR4 was 89, 90, and 82%, and TLR2 was 41, 43, and 32%, respectively. MTT showed that Caco-2 cell viability was high and the compounds had little toxicity on these cells. Finally, it suggests that MSC CM-CS NPs designed may be a therapeutic agent to combat inflammation and biofilm formation in multidrug-resistant V. cholerae. However, further studies in vivo are also recommended.

Prevalence, Antibiotic-Resistance, and Growth Profile of Vibrio spp. Isolated From Fish and Shellfish in Subtropical-Arid Area

The study aimed to determine the prevalence of different species of Vibrio spp. in fish and shellfish sold in subtropical-arid countries (United Arab Emirates). It also examined the antimicrobial resistance of the isolated species and their growth behavior upon in vitro environmental changes concerning temperature, pH, and salinity. The prevalence of Vibrio spp. in fish and shellfish samples, was 64.5 and 92%, respectively. However, Vibrio parahemolyticus were detected in a mere 7.5 and 13.0% of the samples, respectively. On the other hand, Vibrio mimicus was detected in 1.5 and 8.5% of the samples, respectively. None of the six antibiotics studied except for Sulfamethoxazole-trimethoprim were effective against fish Vibrio spp. isolates. On a similar note, three antibiotics, namely Penicillin, Daptomycin, and Vancomycin, were ineffective against the shellfish isolates. The growth of the microorganisms did not show any significant trend with changes in pH and salinity. The optimum temperature for Vibrio spp. growth was observed to be 37°C.

Prevalence and molecular characterization of Vibrio cholerae from fruits and salad vegetables sold in Jakarta, Indonesia, using most probable number and PCR

OBJECTIVE

Cholera is an intestinal infection caused by Vibrio cholerae, it is usually occurs in developing countries that lack of sanitation. In developing country including Indonesia, awareness importance of sanitation is still low. Unfortunately, research related to the detection of V. cholerae from fruit and vegetables in Indonesia is still rare. In this study, MPN method was used to determine the prevalence of V. cholerae followed by single and multiplex PCR to detect virulence genes, including toxR, ctxA, tcpA, hlyA, ace, ompU, and zot.

RESULTS

We found 3 fruits and 2 vegetables positive for toxR gene. Fruit samples which were showed toxR positive found from East Jakarta while for vegetables, it was recovered from West Jakarta and Central Jakarta. Twenty-three isolates were recovered from toxR positive samples. The result of antibiotic resistance analysis showed that 4.35% of the isolates resistant to gentamicin, streptomycin (17.39%), trimethoprim (52.17%), ciprofloxacin (30.43%), ampicillin (13.04%), nalidixic acid (82.61%), and polymyxin B (91.30%). None of these isolates were resistant to kanamycin. Combination of MPN and Multiplex PCR method can be used to detect the prevalence and characterize the virulence properties of V. cholerae.

Identification of Small Molecule Inhibitors of the Pathogen Box against Vibrio cholerae

Antimicrobial resistance (AMR) has become a serious public and economic threat. The rate of bacteria acquiring AMR surpasses the rate of new antibiotics discovery, projecting more deadly AMR infections in the future. The Pathogen Box is an open-source library of drug-like compounds that can be screened for antibiotic activity. We have screened molecules of the Pathogen Box against Vibrio cholerae, the cholera-causing pathogen, and successfully identified two compounds, MMV687807 and MMV675968, that inhibit growth. RNA-seq analyses of V. cholerae after incubation with each compound revealed that both compounds affect cellular functions on multiple levels including carbon metabolism, iron homeostasis, and biofilm formation. In addition, whole-genome sequencing analysis of spontaneous resistance mutants identified an efflux system that confers resistance to MMV687807. We also identified that the dihydrofolate reductase is the likely target of MMV675968 suggesting it acts as an analog of trimethoprim but with a MIC 14-fold lower than trimethoprim in molar concentration. In summary, these two compounds that effectively inhibit V. cholerae and other bacteria may lead to the development of new antibiotics for better treatment of the cholera disease. IMPORTANCE Cholera is a serious infectious disease in tropical regions causing millions of infections annually. Vibrio cholerae, the causative agent of cholera, has gained multi-antibiotic resistance over the years, posing greater threat to public health and current treatment strategies. Here we report two compounds that effectively target the growth of V. cholerae and have the potential to control cholera infection.

Global status of tetracycline resistance among clinical isolates of Vibrio cholerae: a systematic review and meta-analysis

BACKGROUND

There has been an increasing resistance rate to tetracyclines, the first line treatment for cholera disease caused by V. cholera strains, worldwide. The aim of the present study was to determine the global status of resistance to this class of antibiotic among V. cholera isolates.

METHODS

For the study, electronic databases were searched using the appropriate keywords including: 'Vibrio', 'cholera', 'Vibrio cholerae', 'V. cholerae', 'resistance', 'antibiotic resistance', 'antibiotic susceptibility', 'antimicrobial resistance', 'antimicrobial susceptibility', 'tetracycline', and 'doxycycline'. Finally, after some exclusion, 52 studies from different countries were selected and included in the study and meta-analysis was performed on the collected data.

RESULTS

The average resistance rate for serogroup O1 to tetracycline and doxycycline was 50% and 28%, respectively (95% CI). A high level of heterogeneity (I2 > 50%, p-value < 0.05) was observed in the studies representing resistance to tetracycline and doxycycline in O1 and non-O1, non-O139 serogroups. The Begg's tests did not indicate the publication bias (p-value > 0.05). However, the Egger's tests showed some evidence of publication bias in the studies conducted on serogroup O1.

CONCLUSIONS

The results of the present study show that the overall resistance to tetracyclines is relatively high and prevalent among V. cholerae isolates, throughout the world. This highlights the necessity of performing standard antimicrobial susceptibility testing prior to treatment choice along with monitoring and management of antibiotic resistance patterns of V. cholerae strains in order to reduce the emergence and propagation of antibiotic resistant strains as well as the failure of treatment.

Mobile Genetic Elements of Vibrio cholerae and the Evolution of Its Antimicrobial Resistance

Vibrio cholerae (VC) is the causative agent of the severe dehydrating diarrheal disease cholera. The primary treatment for cholera is oral rehydration therapy (ORT). However, in case of moderate to severe dehydration, antibiotics are administered to reduce morbidity. Due to the emergence of multidrug resistant (MDR) strains of VC routinely used antibiotics fail to be effective in cholera patients. Antimicrobial resistance (AMR) is encoded in the genome of bacteria and is usually acquired from other organisms cohabiting in the environment or in the gut with which it interacts in the gut or environmental niche. The antimicrobial resistance genes (ARGs) are usually borne on mobile genetic elements (MGEs) like plasmids, transposons, integrons and SXT constin. Horizontal gene transfer (HGT) helps in the exchange of ARGs among bacteria leading to dissemination of AMR. In VC the acquisition and loss of AMR to many antibiotics have been found to be a dynamic process. This review describes the different AMR determinants and mechanisms of resistance that have been discovered in VC. These ARGs borne usually on MGEs have been recovered from isolates associated with past and present epidemics worldwide. These are responsible for resistance of VC to common antibiotics and are periodically lost and gained contributing to its genetic evolution. These resistance markers can be routinely used for AMR surveillance in VC. The review also presents a precise perspective on the importance of the gut microbiome in the emergence of MDR VC and concludes that the gut microbiome is a potential source of molecular markers and networks which can be manipulated for the interception of AMR in the future.

Mesenchymal Stem Cells as a Cornerstone in a Galaxy of Intercellular Signals: Basis for a New Era of Medicine

Around 40% of the population will suffer at some point in their life a disease involving tissue loss or an inflammatory or autoimmune process that cannot be satisfactorily controlled with current therapies. An alternative for these processes is represented by stem cells and, especially, mesenchymal stem cells (MSC). Numerous preclinical studies have shown MSC to have therapeutic effects in different clinical conditions, probably due to their mesodermal origin. Thereby, MSC appear to play a central role in the control of a galaxy of intercellular signals of anti-inflammatory, regenerative, angiogenic, anti-fibrotic, anti-oxidative stress effects of anti-apoptotic, anti-tumor, or anti-microbial type. This concept forces us to return to the origin of natural physiological processes as a starting point to understand the evolution of MSC therapy in the field of regenerative medicine. These biological effects, demonstrated in countless preclinical studies, justify their first clinical applications, and draw a horizon of new therapeutic strategies. However, several limitations of MSC as cell therapy are recognized, such as safety issues, handling difficulties for therapeutic purposes, and high economic cost. For these reasons, there is an ongoing tendency to consider the use of MSC-derived secretome products as a therapeutic tool, since they reproduce the effects of their parent cells. However, it will be necessary to resolve key aspects, such as the choice of the ideal type of MSC according to their origin for each therapeutic indication and the implementation of new standardized production strategies. Therefore, stem cell science based on an intelligently designed production of MSC and or their derivative products will be able to advance towards an innovative and more personalized medical biotechnology.

Assessment and Antibiotic Resistance Profiling in Vibrio Species Isolated from Wild Birds Captured in Danube Delta Biosphere Reserve, Romania

Antimicrobial and multidrug-resistant bacteria are a major problem worldwide and, consequently, the surveillance of antibiotic-resistant bacteria and assessment of the dissemination routes are essential. We hypothesized that migratory birds, coming from various environments, would carry more numerous Vibrio strains than sedentary species, with increased risk to be passed to their contacts or environment in habitats they transit or nest in. Similarly, we presumed that strains from migratory birds will show multidrug resistance. A total of 170 oral and rectal swabs were collected from wild birds captured in different locations of the Danube Delta (Malic, Sfantu-Gheorghe, Letea Forest) and processed using standardized selective media. V. cholerae strains were confirmed by serology and molecular methods and, subsequently, their susceptibility was evaluated. The prevalence of Vibrio species by host species, habitat type, and location was interpreted. The isolated Vibrio species were identified as Vibrio cholerae 14.33%, V. fluvialis 13.33%, V. alginolyticus 12%, V. mimicus 17.33%, V. vulnificus 10.88%, with V. parahaemolyticus and V. metschnikovii (16%) also being prevalent. Of the 76 Vibrio spp. isolates, 18.42% were resistant towards at least three antimicrobials, and 81.57% demonstrated a multidrug resistance phenotype, including mainly penicillins, aminoglycosides, and macrolides. The results of the present study indicate higher numbers of Vibrio strains in migratory (74.66%) than in sedentary birds (25.33%), confirming our hypothesis. Furthermore, the increased pathogenicity of Vibrio spp. strains, isolated from wild migratory and sedentary birds, was confirmed by their increased multiple antibiotic resistance (MAR) index (0.09–0.81).

Inhibition of growth and virulence of Vibrio cholerae by carvacrol, an essential oil component of Origanum spp

AIMS

In the age where bacterial resistance to conventional antibiotics is increasing at an alarming rate, the use of the traditional plant, herb extracts or other bioactive constituents is gradually becoming popular as an anti-virulence agent to treat pathogenic diseases. Carvacrol, a major essential oil fraction of Oregano, possesses a wide range of bioactivities. Therefore, we aimed to study the effect of sub-inhibitory concentrations of carvacrol on major virulence traits of Vibrio cholerae.

METHODS AND RESULTS

We have used in vitro as well as ex vivo models to access the anti-pathogenic role of carvacrol. We found that the sub-inhibitory concentration of carvacrol significantly repressed bacterial mucin penetrating ability. Carvacrol also reduced the adherence and fluid accumulation in the rabbit ileal loop model. Reduction in virulence is associated with the downregulated expression of tcpA, ctxB, hlyA and toxT. Furthermore, carvacrol inhibits flagellar synthesis by downregulating the expression of flrC and most of the class III genes.

CONCLUSIONS

Carvacrol exhibited anti-virulence activity against V. cholerae, which involved many events including the inhibition of mucin penetration, adhesion, reduced expression of virulence-associated genes culminating in reduced fluid accumulation.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings indicate that carvacrol possesses inhibitory activity against V. cholerae pathogenesis and might be considered as a potential bio-active therapeutic alternative to combat cholera.

Identification of chironomid species as natural reservoirs of toxigenic Vibrio cholerae strains with pandemic potential

Vibrio cholerae causes the fatal cholera diarrhea. Chironomids (Diptera; Chironomidae) are abundant in freshwater aquatic habitats and estuaries and are natural reservoirs of V. cholerae. Until now, only the non-O1/O139 serogroups of V. cholerae were identified in chironomids. Here, we explored whether chironomids are natural reservoirs of V. cholerae O1/O139 serogroups, which are associated with cholera endemics and pandemics. All four life stages of chironomids were sampled from two rivers, and a laboratory culture in Pune, India, and from a pond in Israel. In total, we analyzed 223 chironomid samples. The presence of V. cholerae O1/O139 serogroups was verified using molecular tools. Nine chironomid species were identified; of them, Chironomus circumdatus was the most abundant. The presence of V. cholerae serogroup O1 and the cholera toxin genes were detected in samples from all chironomid species. However, serogroup O139 was detected in only two chironomid species. Besides PCR to detect specific genes, a metagenomic analysis that was performed in three selected C. ramosus larvae, identified a list of virulence genes associated with V. cholerae. The findings provide evidence that chironomids are natural reservoirs of toxigenic V. cholerae O1/O139. Chironomid populations and V. cholerae show biannual peak patterns. A similar pattern is found for cholera epidemics in the Bengal Delta region. Thus, we hypothesize that monitoring chironomids in endemic areas of the disease may provide a novel tool for predicting and preventing cholera epidemics. Moreover, serogroup O139 was detected only in two chironomid species that have a restricted distribution in the Indian subcontinent, possibly explaining why the distribution of the O139 serogroup is limited.

Antimicrobial resistance in enteric bacteria: current state and next-generation solutions

Antimicrobial resistance is one of the largest threats to global health and imposes substantial burdens in terms of morbidity, mortality, and economic costs. The gut is a key conduit for the genesis and spread of antimicrobial resistance in enteric bacterial pathogens. Distinct bacterial species that cause enteric disease can exist as invasive enteropathogens that immediately evoke gastrointestinal distress, or pathobionts that can arise from established bacterial commensals to inflict dysbiosis and disease. Furthermore, various environmental reservoirs and stressors facilitate the evolution and transmission of resistance. In this review, we present a comprehensive discussion on circulating resistance profiles and gene mobilization strategies of the most problematic species of enteric bacterial pathogens. Importantly, we present emerging approaches toward surveillance of pathogens and their resistance elements as well as promising treatment strategies that can circumvent common resistance mechanisms.

Characterization of the Vibriocidal Activity of Chitosan Microparticles: A Potential Therapeutic Agent for Emerging Multidrug-Resistant Cholera Infections

Due to increasing reports of multidrug-resistant (MDR) Vibrio cholerae O1, the goal of this study was to characterize the in vitro antimicrobial activity of chitosan microparticles (CMs) to evaluate their potential as a novel therapeutic agent for cholera. We examined the antimicrobial activity of CMs against toxigenic V. cholerae O1 using direct enumeration, microscopy, and fluorescence microplate assays. Bacterial viability kinetics were measured with different concentrations of CMs, solution pH, and salt content using a live/dead staining technique. Growth inhibition of CM-exposed V. cholerae strains was conducted using a redox-sensitive stain and compared between wild-type and isogenic outer membrane (OM) mutants. CM concentrations above 0.1 wt % were sufficient to kill V. cholerae O1 suspensions with approximately 10⁸ CFU/mL within 3 h. The nonviable cells demonstrated increased OM permeability that corresponded to gross morphological changes observed through scanning electron microscopy. CMs exhibited dose-dependent bactericidal activity that increased predictably at lower pH and decreased with salt addition. V. cholerae O1 strains lacking O-antigen were twice as susceptible to growth inhibition by CMs, whereas those with glycine modification to lipid A were ten times more resistant. We propose that CMs exert vibriocidal activity via electrostatic surface interactions between their positively charged amine groups and the negatively charged Gram-negative bacterial OM, resulting in disruption, increased permeability, decreased redox metabolism, and subsequent loss of cellular viability. Further research should be conducted in vivo to evaluate the efficacy of CMs as luminal agents to treat infections caused by MDR, toxigenic V. cholerae and other diarrheal pathogens.

Exploring Computational and Biophysical Tools to Study the Presence of G-Quadruplex Structures: A Promising Therapeutic Solution for Drug-Resistant Vibrio cholerae

Vibrio cholerae, a gram-negative bacterium that causes cholera, has already caused seven major pandemics across the world and infects roughly 1.3–4 million people every year. Cholera treatment primarily involves oral rehydration therapy supplemented with antibiotics. But recently, multidrug-resistant strains of V. cholerae have emerged. High genomic plasticity further enhances the pathogenesis of this human pathogen. Guanines in DNA or RNA assemble to form G-quadruplex (GQ) structures which have begun to be seen as potential drug targeting sites for different pathogenic bacteria and viruses. In this perspective, we carried out a genome-wide hunt in V. cholerae using a bio-informatics approach and observed ∼85 G-quadruplex forming motifs (VC-PGQs) in chromosome I and ∼45 putative G-quadruplexs (PGQs) in chromosome II. Ten putative G-quadruplex forming motifs (VC-PGQs) were selected on the basis of conservation throughout the genus and functional analysis displayed their location in the essential genes encoding bacterial proteins, for example, methyl-accepting chemotaxis protein, orotate phosphoribosyl transferase protein, amidase proteins, etc. The predicted VC-PGQs were validated using different bio-physical techniques, including Nuclear Magnetic Resonance spectroscopy, Circular Dichroism spectroscopy, and electrophoretic mobility shift assay, which demonstrated the formation of highly stable GQ structures in the bacteria. The interaction of these VC-PGQs with the known specific GQ ligand, TMPyP4, was analyzed using ITC and molecular dynamics studies that displayed the stabilization of the VC-PGQs by the GQ ligands and thus represents a potential therapeutic strategy against this enteric pathogen by inhibiting the PGQ harboring gene expression, thereby inhibiting the bacterial growth and virulence. In summary, this study reveals the presence of conserved GQ forming motifs in the V. cholerae genome that has the potential to be used to treat the multi-drug resistance problem of the notorious enteric pathogen.

Antibacterial effects of plant extracts with hurdle technology against Vibrio cholerae

Vibrio cholerae is an etiological cause of cholera implicated in several pandemics. Antibacterial activity of plant extracts has been established. However, these extracts exhibit activity at a concentration that may alter organoleptic attributes of water and food, hence limiting their application. In this light, there is need to device ways of reducing plant extracts' effective levels in order to widen their application. Thus, this study was conducted to improve activities of plant ethanolic extracts through combination with other generally recognized as safe antimicrobials. Combination of plant extracts with sodium acetate (NaOAc) 0.4% at pH 7.0 reduced minimum inhibitory concentrations (MICs) of clove, lemon eucalyptus, rosemary and sage from 0.2 to 0.025%. At pH 6.4, combinations were more effective reducing MICs of clove, lemon eucalyptus, rosemary and sage from 0.2 to 0.0125% with NaOAc at 0.2%. At pH 7.0, the combination resulted in additive effect. Nevertheless, at pH 6.4, synergic effect was established. No interactive effect was observed with combinations involving glycine. Combination of plant extracts with NaOAc at mildly acidic pH creates a hurdle effect that may have potential application to control the growth of V. cholerae.

Phenotypic and Genotypic Properties of Vibrio cholerae non-O1, non-O139 Isolates Recovered from Domestic Ducks in Germany

Vibrio cholerae non-O1, non-O139 bacteria are natural inhabitants of aquatic ecosystems and have been sporadically associated with human infections. They mostly lack the two major virulence factors of toxigenic V. cholerae serogroups O1 and O139 strains, which are the causative agent of cholera. Non-O1, non-O139 strains are found in water bodies, sediments, and in association with other aquatic organisms. Occurrence of these bacteria in fecal specimens of waterfowl were reported, and migratory birds likely contribute to the long-distance transfer of strains. We investigated four V. cholerae non-O1, non-O139 isolates for phenotypic traits and by whole genome sequencing (WGS). The isolates were recovered from organs of domestic ducks with serious disease symptoms. WGS data revealed only a distant genetic relationship between all isolates. The isolates harbored a number of virulence factors found in most V. cholerae strains. Specific virulence factors of non-O1, non-O139 strains, such as the type III secretion system (TTSS) or cholix toxin, were observed. An interesting observation is that all isolates possess multifunctional autoprocessing repeats-in-toxin toxins (MARTX) closely related to the MARTX of toxigenic El Tor O1 strains. Different primary sequences of the abundant OmpU proteins could indicate a significant role of this virulence factor. Phenotypic characteristics such as hemolysis and antimicrobial resistance (AMR) were studied. Three isolates showed susceptibility to a number of tested antimicrobials, and one strain possessed AMR genes located in an integron. Knowledge of the environmental occurrence of V. cholerae non-O1, non-O139 in Germany is limited. The source of the infection of the ducks is currently unknown. In the context of the ‘One Health’ concept, it is desirable to study the ecology of V. cholerae non-O1, non-O139, as it cannot be excluded that the isolates possess zoonotic potential and could cause infections in humans.

Evaluation of the Antimicrobial and Antibiofilm Effect of Chitosan Nanoparticles as Carrier for Supernatant of Mesenchymal Stem Cells on Multidrug-Resistant Vibrio cholerae

AIM

The aim of the present study was to evaluate the in vitro antimicrobial and antibiofilm activity of chitosan nanoparticles (CS NPs) incorporated with mesenchymal stem cells-derived conditioned media (MSCs CM) on MDR Vibrio cholerae strains.

MATERIALS AND METHODS

Chitosan NPs were prepared and characterized by dynamic light scattering (DLS), scanning electron microscope (SEM) and zeta potential measurement. MSCs CM were prepared and entrapped into MSCs CM-CS NPs composite and its release efficiency was measured. Antibacterial efficacy of nano structures was determined by disk diffusion and broth microdilution methods. Antibiofilm activity was assessed by crystal violet assay.

RESULTS

BM-MSCs were characterized to be negative for CD34 and CD45 markers, positive for CD73 and CD44 markers, and able to differentiate into osteoblast and adipocyte cells. The mean particle size of 96.6% of chitosan NPs was 414.9 nm with a suitable zeta potential and SEM morphology. Entrapment efficiency of MSCs CM-CS NPs was 76.9%. Unstimulated MSCs CM-CS NPs composite as a novel and proficient therapeutic nanostructure against MDR V. cholerae strains showed the synergistic activity of the two components of MSCs CM and CS NPs, leading to greater bacterial killing compared to control groups. MSCs CM more efficiently inhibited biofilm formation, although MSCs CM-CS NPs was also appeared to be effective in inhibiting biofilm formation compared to CS NPs and control group.

CONCLUSION

The designed nanodrug composite showed the best release in conditions mimicking the physiological conditions of the intestinal lumen. Given the fact that no overuse or genetic event would cause the emergence of antimicrobial resistance against the MSCs CM-CS NPs nanodrug, it could be considered as a promising alternative for the treatment of MDR V. cholerae infections in clinical settings.

Changing Susceptibility Pattern of Vibrio cholerae O1 Isolates to Commonly Used Antibiotics in the Largest Diarrheal Disease Hospital in Bangladesh during 2000-2018

The efficacy of commonly used antibiotics for treating severe cholera has been compromised over time because of the reduced antibiotic susceptibility. This study aimed to describe the rate of detection of Vibrio cholerae O1 from fecal samples and antimicrobial susceptibility profiles of V. cholerae O1 serotypes to commonly used antibiotics. During January 2000-December 2018, V. cholerae O1 was detected in fecal samples of 7,472 patients. Vibrio cholerae O1 Inaba serotype was predominant, ranging from 60% to 86% during the period 2000-2006 except for 2003 and 2005 when the Ogawa serotype was predominant. Later on, the Ogawa serotype became predominant from 2007 to 2015, fluctuating between 52% and 100%. However, in 2016 and 2017, isolation rates declined to 2% and 1%, respectively, but surged again to 75% in 2018. Nearly 100% of V. cholerae O1 strains were sensitive to tetracycline during 2000-2004. Thereafter, a declining trend of sensitivity was observed to be continued and dropped down to < 6% during 2012-2017 and again increased to 76% in 2018. Susceptibility to azithromycin and ciprofloxacin was nearly 100%, and susceptibility to cotrimoxazole and furazolidone was 01% throughout the study period. We also found the emergence of resistance to erythromycin in 2005 and sensitivity to cotrimoxazole in 2018. Thus, the rapid decline of the sensitivity of V. cholerae O1 to tetracycline and a reversed peak after 6 years need continued monitoring and reporting.

Current and future perspectives for controlling Vibrio biofilms in the seafood industry: a comprehensive review

The contamination of seafood with Vibrio species can have severe repercussions in the seafood industry. Vibrio species can form mature biofilms and persist on the surface of several seafoods such as crabs, oysters, mussels, and shrimp, for extended duration. Several conventional approaches have been employed to inhibit the growth of planktonic cells and prevent the formation of Vibrio biofilms. Since Vibrio biofilms are mostly resistant to these control measures, novel alternative methods need to be urgently developed. In this review, we propose environmentally friendly approaches to suppress Vibrio biofilm formation using a hypothesized mechanism of action.

Identification of Widespread Antibiotic Exposure in Patients With Cholera Correlates With Clinically Relevant Microbiota Changes

BACKGROUND

A first step to combating antimicrobial resistance in enteric pathogens is to establish an objective assessment of antibiotic exposure. Our goal was to develop and evaluate a liquid chromatography-ion trap mass spectrometry (LC/MS) method to determine antibiotic exposure in patients with cholera.

METHODS

A priority list for targeted LC/MS was generated from medication-vendor surveys in Bangladesh. A study of patients with and those without cholera was conducted to collect and analyze paired urine and stool samples.

RESULTS

Among 845 patients, 11% (90) were Vibrio cholerae positive; among these 90 patients, analysis of stool specimens revealed ≥1 antibiotic in 86% and ≥2 antibiotics in 52%. Among 44 patients with cholera and paired urine and stool specimens, ≥1 antibiotic was detected in 98% and ≥2 antibiotics were detected in 84%, despite 55% self-reporting medication use. Compared with LC/MS, a low-cost antimicrobial detection bioassay lacked a sufficient negative predictive value (10%; 95% confidence interval, 6%-16%). Detection of guideline-recommended antibiotics in stool specimens did (for azithromycin; P = .040) and did not (for ciprofloxacin) correlate with V. cholerae suppression. A nonrecommended antibiotic (metronidazole) was associated with decreases in anaerobes (ie, Prevotella organisms; P < .001).

CONCLUSION

These findings suggest that there may be no true negative control group when attempting to account for antibiotic exposure in settings like those in this study.

Phenotypic and Genotypic Characterization of Veterinary Vibrio cincinnatiensis Isolates

Vibrio cincinnatiensis is a halophilic species which has been found in marine and estuarine environments worldwide. The species is considered a rare pathogen for which the significance for humans is unclear. In this study, nine veterinary isolates were investigated that were obtained from domestic animals in Germany. The isolates were mostly recovered from abortion material of pigs, cattle, and horse (amnion or fetuses). One isolate was from a goose. A human clinical strain from a case of enteritis in Germany described in the literature was also included in the study. Whole-genome sequencing (WGS) of all isolates and MALDI-TOF MS (matrix-assisted-laser-desorption/ionization time-of-flight mass spectrometry) were performed to verify the species assignment. All strains were investigated for phenotypic traits including antimicrobial resistance (AMR), biochemical properties, and two virulence-associated phenotypes (hemolytic activity and resistance to human serum). WGS data and MS spectra confirmed that all veterinary isolates are closely related to the type strain V. cincinnatiensis NCTC12012. An exception was the human isolate from Germany which is related to the other isolates but could belong to another species. The isolates were similar in most biochemical phenotypes. Only one strain showed a very weak hemolytic activity against sheep erythrocytes, and serum resistance was intermediate in two strains. AMR phenotypes were more variable between the isolates. Resistances were observed against ß-lactams ampicillin and cefoxitin and against tetracycline and the sulfonamide antibiotics trimethoprim and sulfamethoxazole. Some acquired AMR genes were identified by bioinformatics analyses. WGS and MALDI-TOF MS data reveal a close relationship of the veterinary isolates and the type strain V. cincinnatiensis NCTC12012, which is a clinical human isolate. As the veterinary isolates of this study were mostly recovered from abortion material (amnions and fetuses), a zoonotic potential of the veterinary isolates seems possible.

Novel Indole-Based Hydrazones as Potent Inhibitors of the α-class Carbonic Anhydrase from Pathogenic Bacterium Vibrio cholerae

Due to the increasing resistance of currently used antimicrobial drugs, there is an urgent problem for the treatment of cholera disease, selective inhibition of the α-class carbonic anhydrases (CA, EC 4.2.1.1) from the pathogenic bacterium Vibrio cholerae (VcCA) presents an alternative therapeutic target. In this study, a series of hydrazone derivatives, carrying the 2-(hydrazinocarbonyl)-3-phenyl-1H-indole-5-sulfonamide scaffold, have been evaluated as inhibitors of the VcCA with molecular modeling studies. The results suggest that these compounds may bind to the active site of VcCA. To verify this, VcCA enzyme inhibition studies were performed and as predicted most of the tested compounds displayed potent inhibitory activities against VcCA with three compounds showing K_I values lower than 30 nM. In addition, all these compounds showed selectivity for VcCA and the off-targets hCA I and II.

Genomic characterization of antibiotic resistance-encoding genes in clinical isolates of Vibrio cholerae non-O1/non-O139 strains from Kolkata, India: generation of novel types of genomic islands containing plural antibiotic resistance genes

Non-O1/non-O139 nontoxigenic Vibrio cholerae associated with cholera-like diarrhea has been reported in Kolkata, India. However, the property involved in the pathogenicity of these strains has remained unclear. The character of 25 non-O1/non-O139 nontoxigenic V. cholerae isolated during 8 years from 2007 to 2014 in Kolkata was examined. Determination of the serogroup showed that the serogroups O6, O10, O35, O36, O39, and O70 were represented by two strains in each serogroup, and the remaining isolates belonged to different serogroups. To clarify the character of antibiotic resistance of these isolates, an antibiotic resistance test and the gene analysis were performed. According to antimicrobial drug susceptibility testing, 13 strains were classified as drug resistant. Among them, 10 strains were quinolone resistant and 6 of the 13 strains were resistant to more than three antibiotics. To define the genetic background of the antibiotic character of these strains, whole-genome sequences of these strains were determined. From the analysis of these sequences, it becomes clear that all quinolone resistance isolates have mutations in quinolone resistance-determining regions. Further research on the genome sequence showed that four strains possess Class 1 integrons in their genomes, and that three of the four integrons are found to be located in their genomic islands. These genomic islands are novel types. This indicates that various integrons containing drug resistance genes are spreading among V. cholerae non-O1/non-O139 strains through the action of newly generated genomic islands.

Mapping cholera outbreaks and antibiotic resistant Vibrio cholerae in India: An assessment of existing data and a scoping review of the literature

Although fluid and electrolyte replenishment remains the mainstay of clinical management of cholera, antibiotics are an important component of the strategy for clinical management of moderate to severe cases of cholera. The emergence of antibiotic resistance (ABR) in Vibrio cholerae has led to difficulties in case management. The past decade has also seen the development of cheap and effective oral cholera vaccines (OCVs). In addition to the two-dose strategy for widespread immunization, OCVs have also been shown to be effective in containing outbreaks using a single-dose schedule. In this scoping review we map the states and union territories (SUTs) of India which are prone to cholera outbreaks followed by a scoping review of peer-reviewed publications about ABR outbreaks of cholera employing the Arksey and O'Malley framework. Using the data reported by the Integrated Disease Surveillance Program (IDSP), we identified 559 outbreaks of cholera between 2009 and 2017, affecting 27 SUTs. We defined SUTs which had reported outbreaks in at least three out of the last five years (2012-2016) or had experienced two or more outbreaks in the same year in at least two of the last five years to be outbreak-prone. The scoping review identified 62 ABR outbreaks, with four SUTs accounting for two-thirds of them: West Bengal (14), Maharashtra (10), Odisha (10) and Delhi (7). Overall, this scoping review suggests that there is an increasing trend of ABR in Vibrio cholerae isolated from outbreaks in India. This opens up avenues for exploring the role of antibiotic stewardship in the clinical management of diarrhea, the institution of vaccination as an infection prevention intervention to reduce selection pressure, and the deployment of high quality surveillance systems which report accurate, real-time data allowing appropriate and timely public health responses. It is crucial to counter the issue of ABR in cholera before it assumes a menacing magnitude.

THE COMPUTATION OF REPRODUCTION NUMBERS FOR THE ENVIRONMENT-HOST-ENVIRONMENT CHOLERA TRANSMISSION DYNAMICS

This study presents a new model for the environment-host-environment transmission dynamics of V. cholerae in a community with an interconnected aquatic pond–river water network. For the case when the human host is the sole target of anti-cholera control and the volume of water in the pond is maximum, the disease-free equilibrium of the model is shown to be globally asymptotically stable whenever a certain epidemiological threshold, known as the basic reproduction number [Formula: see text], is less than unity. The epidemiological implication of this result is that cholera can be eliminated from the community if the control strategies implemented can bring (and maintain) [Formula: see text] to a value less than unity. Four scenarios, that represent different interpretations of the role of the V. cholerea pathogen within the environment, were studied. The corresponding basic reproduction numbers were shown to exhibit the same threshold property with respect to the value unity (i.e., if one is less (equal, greater) than unity, then the three others are also less (equal, greater) than unity. Further, it was shown that for the case where anti-cholera control is focused on the human host population, the associated type reproduction number of the model (corresponding to each of the four transmission scenarios considered) is unique. The implication of this result is that the estimate of the effort needed for disease elimination (i.e., the required herd immunity threshold) is unique, regardless of which of the four transmission scenarios is considered. However, when any of the other two bacterial population types in the aquatic environment (i.e., bacterial in the pond or river) is the focus of the control efforts, this study shows that the associated type reproduction number is not unique. Extensive numerical simulations of the model, using a realistic set of parameters from the published literature, show that the community-wide implementation of a strategy that focus on improved water quality, sanitation, and hygiene (known as WASH-only strategy), using the current estimated coverage of 50% and efficacy of 60%, is unable to lead to the elimination of the disease. Such elimination is attainable if the coverage and efficacy are increased (e.g., to 80% and 90%, respectively). Further, elimination can be achieved using a strategy that focuses on oral rehydration therapy and the use of antibiotics to treat the infected humans (i.e., treatment-only strategy) for moderate effectiveness and coverage levels. The combined hybrid WASH-treatment strategy provides far better population-level impact vis a vis disease elimination. This study ranks the three interventions in the following order of population-level effectiveness: combined WASH-treatment, followed by treatment-only and then WASH-only strategy.

Characterisation of Vibrio cholerae isolates from the 2009, 2010 and 2016 cholera outbreaks in Lusaka province, Zambia

Introduction

In 2009 and 2010, more than 6,000 cholera cases were recorded during these outbreaks with more than 80% of cases recorded in Lusaka province. After a five-year break, in 2016 an outbreak occurred in Lusaka, causing more than 1,000 cases of cholera. This study will strengthen the epidemiological information on the changing characteristics of the cholera outbreaks, for treatment, prevention and control of the disease.

Methods

This was a laboratory-based descriptive cross-sectional study conducted at the University Teaching Hospital in Lusaka, Zambia. A total of 83 V. cholerae O1 isolates were characterised by biochemical testing, serotyping, antimicrobial susceptibility testing, and macrorestriction analysis using Pulsed-Field Gel Electrophoresis.

Results

Macrorestriction analysis of the isolates demonstrated high genetic diversity among the isolates with 16 different patterns. The largest pattern comprised 9 isolates while the smallest one had 1 isolate. 2009 and 2010 isolates were highly resistant to nalidixic acid and cotrimoxazole, but highly sensitive to azithromycin and ampicillin. Of the fifty-two isolates from the 2016 cholera outbreak, 90% (47) were sensitive to cotrimoxazole, 94% (49) to tetracycline, and 98% (51) to azithromycin, while 98% (51) were resistant to nalidixic acid and 31(60%) to ampicillin.

Conclusion

macrorestriction analysis demonstrated high genetic diversity among the V. cholerae O1 strains, suggesting that these isolates were probably not from a similar source. This study also revealed the emergence of multidrug resistance among the 2016 V. cholerae outbreak isolates but were susceptible to cotrimoxazole, tetracycline, and azithromycin, which can be used for treatment of the cholera cases.

Synthesis, Characterization, Antibacterial Activity, and Computer-Aided Design of Novel Quinazolin-2,4-dione Derivatives as Potential Inhibitors Against Vibrio cholerae

Cholera is a bacterial disease featured by dehydration and severe diarrhea. It is mainly caused by alimentary infection with Vibrio cholerae. Due to the wide applicability of quinazolin-2,4-dione compounds in medicinal and pharmaceutical chemistry, a new series of N-containing heterocyclic compounds was synthesized. We used the in silico docking method to test the efficacy of quinazolin-2,4-dione compounds in the prevention of cholera in humans. The newly synthesized compounds showed strong interactions and good binding affinity to outer membrane protein OmpU. Moreover, the pharmacokinetic properties of the newly synthesized compounds, such as absorption, distribution, metabolic, excretion, and toxicity (ADMET), were predicted through in silico methods. Compounds with acceptable pharmacokinetic properties were tested as novel ligand molecules. The synthesized compounds were evaluated in vitro for their antibacterial activity properties against Gram-negative Escherichia coli O78 strain using the minimum inhibition concentration (MIC) method. Compounds 2 and 6 showed reproducible, effective antibacterial activity. Hence, our study concludes that the quinazolin-2,4-dione derivatives 1 to 8 may be used as promising drug candidates with potential value for the treatment of cholera disease.

Burden of typhoid fever and cholera: similarities and differences. Prevention strategies for European travelers to endemic/epidemic areas

The burden of diarrheal diseases is very high, accounting for 1.7 to 5 billion cases per year worldwide. Typhoid fever (TF) and cholera are potentially life-threatening infectious diseases, and are mainly transmitted through the consumption of food, drink or water that have been contaminated by the feces or urine of subjects excreting the pathogen. TF is mainly caused by Salmonella typhi, whereas cholera is caused by intestinal infection by the toxin-producing bacterium Vibrio cholerae. These diseases typically affect low- and middle-income countries where housing is overcrowded and water and sanitation are poor, or where conflicts or natural disasters have led to the collapse of the water, sanitation and healthcare systems. Mortality is higher in children under 5 years of age. Regarding their geographical distribution, TF has a high incidence in sub-Saharan Africa, India and south-east Asia, while cholera has a high incidence in a few African countries, particularly in the Horn of Africa and the Arabian Peninsula. In the fight against these diseases, preventive measures are fundamental. With modern air travel, transmissible diseases can spread across continents and oceans in a few days, constituting a threat to global public health. Nowadays, people travel for many reasons, such as tourism and business. Several surveys have shown that a high proportion of travelers lack adequate information on safety issues, such as timely vaccination and prophylactic medications. The main objective of this overview is to provide information to help European travelers to stay healthy while abroad, and thus also to reduce the potential importation of these diseases and their consequent implications for public health and society. The preventive measures to be implemented in the case of travel to countries where these diseases are still endemic are well known: the adoption of safe practices and vaccinations. It is important to stress that an effective preventive strategy should be based both on vaccinations and on hygiene travel guidelines. Furthermore, the emergence of multidrug-resistant strains is becoming a serious problem in the clinical treatment of these diseases. For this reason, vaccination is the main solution.

FtsA-FtsZ interaction in Vibrio cholerae causes conformational change of FtsA resulting in inhibition of ATP hydrolysis and polymerization

Proper interaction between the divisome proteins FtsA and FtsZ is important for the bacterial cell division which is not well characterized till date. In this study, the objective was to understand the mechanism of FtsA-FtsZ interaction using full-length recombinant proteins. We cloned, over-expressed, purified and subsequently characterized FtsA of Vibrio cholerae (VcFtsA). We found that VcFtsA polymerization assembly was dependent on Ca²⁺ ions, which is unique among FtsA proteins reported until now. VcFtsA also showed ATPase activity and its assembly was ATP dependent. Binding parameters of the interaction between the two full-length proteins, VcFtsA, and VcFtsZ determined by fluorescence spectrophotometry yielded a K_d value of around 38 μM. The K_d value of the interaction was 3 μM when VcFtsA was in ATP bound state. We found that VcFtsZ after interacting with VcFtsA causes a change of secondary structure in the later one leading to loss of its ability to hydrolyze ATP, subsequently halting the VcFtsA polymerization. On the other hand, a double-mutant of VcFtsA (VcFtsA-D242E,R300E), that does not bind to VcFtsZ, polymerized in the presence of VcFtsZ. Though FtsA proteins among different organisms show 70-80% homology in their sequences, assembly of VcFtsA showed a difference in its regulatory processes.

Environmental Reservoirs of Vibrio cholerae: Challenges and Opportunities for Ocean-Color Remote Sensing

The World Health Organization has estimated the burden of the on-going pandemic of cholera at 1.3 to 4 million cases per year worldwide in 2016, and a doubling of case-fatality-rate to 1.8% in 2016 from 0.8% in 2015. The disease cholera is caused by the bacterium Vibrio cholerae that can be found in environmental reservoirs, living either in free planktonic form or in association with host organisms, non-living particulate matter or in the sediment, and participating in various biogeochemical cycles. An increasing number of epidemiological studies are using land- and water-based remote-sensing observations for monitoring, surveillance, or risk mapping of Vibrio pathogens and cholera outbreaks. Although the Vibrio pathogens cannot be sensed directly by satellite sensors, remotely-sensed data can be used to infer their presence. Here, we review the use of ocean-color remote-sensing data, in conjunction with information on the ecology of the pathogen, to map its distribution and forecast risk of disease occurrence. Finally, we assess how satellite-based information on cholera may help support the Sustainable Development Goals and targets on Health (Goal 3), Water Quality (Goal 6), Climate (Goal 13), and Life Below Water (Goal 14).