Serogroup O1 Research Articles

Characterization of Shiga toxin‐producing Escherichia coli bacteriophages isolated from agricultural environments and examination of their prevalence with bacterial hosts

AbstractIn the natural environment, ruminant livestock, including cattle, are the main reservoir of the outbreak–causing strains of Shiga toxin‐producing Escherichia coli (STEC), where bacteriophages sustainably thrive as well. This study focuses on the characterization of STEC‐specific bacteriophages isolated from cow manure samples in Maine farms and examines their prevalence with STEC hosts. Phenotypic features of representative isolates were characterized by using a transmission electron microscope. Similarly, host range, one‐step growth curve, thermal stability, lytic capability, and genomic analyses were performed to fully characterize selected representative isolates. Results showed that representative bacteriophage isolates belong to Myoviridae (S6P10 and S14P12) and Siphoviridae (S19). The most prevalent and common bacteriophages (46%) were specific to the O26 serogroup. The farm C sampling site had highly heterogenous bacteriophage populations that were specific to six STEC serogroups. The most prevalent bacteriophage isolate (S1P5, Escherichia phage vB_EcoM‐S1P5QW) was verified to have a double‐stranded DNA genome (166,102 bp) with 266 CDs of which 130 have known functions. The majority of the diverse bacteriophage isolates had strong lytic capabilities and a narrow host range that could withstand selected temperature conditions (−20, 37, and 62°C). Results of bacterial screening showed that STEC host strains were not detected in Farms A, C, and E, but were detected on Farms B and D. In conclusion, the highly‐diverse bacteriophage ecology found in cow manure samples may have been an important element in shaping the population of STEC serogroups, specifically in its natural environment, which can provide useful tools for potential antibiotic‐free therapeutics and diagnostic technologies.

Antimicrobial Efficacy of Cinnamon Essential Oil against Avian Pathogenic Escherichia coli from Poultry.

Colibacillosis, caused by E. coli, is responsible for economic losses in the poultry industry due to mortality, decreased production, and the cost of antibiotic treatments. Prevention of colibacillosis is based on improved biosecurity measures and the use of the vaccine performed with O78 E. coli strains, which is responsible for most cases of colibacillosis. Recently, there has been increased interest in other infection control methods, such as the use of natural compounds. The aim of this study was to evaluate the antimicrobial efficacy of cinnamon essential oil (CEO) against E. coli strains isolated from poultry. The MIC50 and MIC90 of CEO were determined by testing 117 strains belonging to serogroups O78, O2, O128, O139, isolated from laying hens (91 strains), broilers (10 strains), and turkeys (16 strains). The bacterial strains were tested at cell densities of 108 and 106 CFU/mL. At the cell density of 108 CFU/mL, MIC50 and MIC90 were 0.4 and 0.5 µL/mL for most of the tested strains, while they corresponded to 0.5 µL/mL for all strains isolated from broilers and for strains belonging to serogroup O139. At the cell density of 106 CFU/mL, MIC50 and MIC90 were 0.3 and 0.4 µL/mL, regardless of bird species of origin and for strains belonging to serogroups O78 and O2. In addition, a concentration of 0.04 µL/mL of CEO corresponded both to MIC50 and MIC90 for strains belonging to serogroups O139 and O128. Based on these results, cinnamon essential oil showed an effective antibacterial activity against E. coli strains from poultry and could find field application for the prevention of colibacillosis.

Preventive efficacy of preparations of vesicles of external membranes of atoxygenic strains of <i>Vibrio cholerae О1</i> serogroup

Purpose: To evaluate the effectiveness and expediency of using vesicles of the outer membranes of atoxygenic strains of Vibrio cholerae O1 serogroup for the prevention of experimental cholera. Materials and methods: atoxigenic strains of V. cholerae O1 El Tor 18950 (ctxAB-tcpA-) and 18780 (ctxAB-tcpA+) isolated from the water of surface reservoirs were used to obtain vesicles. The protective properties of the obtained drugs were evaluated using a model of generalized cholera in white mice and a model of an isolated loop of the small intestine of an adult rabbit. Results: it has been shown that vesicles of the outer membranes isolated from atoxygenic strains of V. cholerae have a protective effect and prevent the development of infection in experimental animals when infected with a virulent strain of cholera. The obtained drugs are most effective when administered parenterally twice, with an interval of seven days, preventing the death of all white mice taken in the experiment and the development of pathogenetic processes in the small intestine of adult rabbits. Summary: the data obtained indicates the formation of pronounced immune protection against the disease in animals, as well as the possibility of using these structures to create preventive anti-cholera drugs.

Vibrio cholerae-An emerging pathogen in Austrian bathing waters?

Vibrio cholerae, an important human pathogen, is naturally occurring in specific aquatic ecosystems. With very few exceptions, only the cholera-toxigenic strains belonging to the serogroups O1 and O139 are responsible for severe cholera outbreaks with epidemic or pandemic potential. All other nontoxigenic, non-O1/non-O139 V.cholerae (NTVC) strains may cause various other diseases, such as mild to severe infections of the ears, of the gastrointestinal and urinary tracts as well as wound and bloodstream infections. Older, immunocompromised people and patients with specific preconditions have an elevated risk. In recent years, worldwide reports demonstrated that NTVC infections are on the rise, caused amongst others by elevated water temperatures due to global warming.The aim of this review is to summarize the knowledge gained during the past two decades on V.cholerae infections and its occurrence in bathing waters in Austria, with aspecial focus on the lake Neusiedler See. We investigated whether NTVC infections have increased and which specific environmental conditions favor the occurrence of NTVC. We present an overview of state of the art methods that are currently available for clinical and environmental diagnostics. Apreliminary public health risk assessment concerning NTVC infections related to the Neusiedler See was established. In order to raise awareness of healthcare professionals for NTVC infections, typical symptoms, possible treatment options and the antibiotic resistance status of Austrian NTVC isolates are discussed.

Detection of high-risk Avian Pathogenic Escherichia coli (APEC) isolated from broilers in São Paulo, Brazil.

Some high-risk Avian Pathogenic Escherichia coli (APEC) clones have been associated with increased economic losses caused by avian colibacillosis. They may represent an additional food consumption concern due to the potential zoonotic role causing urinary tract infections mainly related to E. coli ST73 and ST95 lineages. This study aimed to characterize APEC isolated from slaughterhouse carcasses presenting lesions compatible with avian colibacillosis. We analyzed about 6500 broilers carcasses, and 48 showed lesions consistent with colibacillosis. Forty-four strains of E. coli were isolated, with 77.27% (n = 34/44) classified as APEC. The isolates belonged to the phylogenetic groups B2 (41.17%, n = 14/34), G (20.59%, n = 7/34), A (17.65%, n = 6/34), B1 (8.82%, n = 3/34), and E (5.88%, n = 2/34). Determining the phylogenetic group of 5.88% (n = 2/34) of the strains was impossible. Moreover, 20.59% (n = 7/34) were positive to the clonal groups ST117, 8.82% (n = 3/34) to ST95, and 8.82% (n = 3/34) were classified as belonging to serogroup O78 by PCR screening. Strains of APEC from O78 serogroup and ST117 are considered high-risk clones for poultry, and our data reinforced the need for surveillance of these pathogens in poultry farms and slaughterhouses.

Absolute quantification of viable Vibrio cholerae in seawater samples using multiplex droplet digital PCR combined with propidium monoazide.

Toxigenic Vibrio cholerae serogroup O1 and O139 are the pathogens responsible for the global cholera epidemic. V. cholerae can settle in the water and spread via the fecal-oral route. Rapid and accurate monitoring of live V. cholerae in environmental water has become an important strategy to prevent and control cholera transmission. Conventional plate counting is widely used to detect viable bacteria but requires time and effort. This study aims to develop a new assay that combines triplex droplet digital PCR (ddPCR) with propidium monoazide (PMA) treatment for quantitatively detecting live V. cholerae O1/O139 and cholera enterotoxin. Specific primers and probes were designed according to the conserved regions of gene rfb O1, rfb O139, and ctxA. The amplification procedures and PMA treatment conditions were optimized. The specificity, sensitivity, and ability of PMA-ddPCR to detect viable bacteria-derived DNA were evaluated in simulated seawater samples. The results revealed that the optimal primer concentrations of rfb O1, rfb O139, and ctxA were 1 μM, while the concentrations of the three probes were 0.25, 0.25, and 0.4 μM, respectively. The best annealing temperature was 58°C to obtain the most accurate results. The optimal strategy for distinguishing dead and live bacteria from PMA treatment was incubation at the concentration of 20 μM for 15 min, followed by exposure to a 650-W halogen lamp for 20 min. In pure culture solutions, the limit of detection (LODs) of V. cholerae O1 and O139, and ctxA were 127.91, 120.23 CFU/mL, and 1.5 copies/reaction in PMA-triplex ddPCR, respectively, while the LODs of the three targets were 150.66, 147.57 CFU/mL, and 2 copies/reaction in seawater samples. The PMA-ddPCR sensitivity was about 10 times higher than that of PMA-qPCR. When detecting spiked seawater samples with live bacterial concentrations of 1.53 × 102 and 1.53 × 105 CFU/mL, the assay presented a higher sensitivity (100%, 16/16) than qPCR (50.00%, 8/16) and a perfect specificity (100%, 9/9). These results indicate that the developed PMA-triplex ddPCR is superior to the qPCR regarding sensitivity and specificity and can be used to rapidly detect viable toxigenic V. cholerae O1 and O139 in suspicious seawater samples.

Whole-Genome Sequencing of Shiga Toxin-Producing Escherichia coli for Characterization and Outbreak Investigation.

Shiga toxin-producing Escherichia coli (STEC) causes high frequencies of foodborne infections worldwide and has been linked to numerous outbreaks each year. Pulsed-field gel electrophoresis (PFGE) has been the gold standard for surveillance until the recent transition to whole-genome sequencing (WGS). To further understand the genetic diversity and relatedness of outbreak isolates, a retrospective analysis of 510 clinical STEC isolates was conducted. Among the 34 STEC serogroups represented, most (59.6%) belonged to the predominant six non-O157 serogroups. Core genome single nucleotide polymorphism (SNP) analysis differentiated clusters of isolates with similar PFGE patterns and multilocus sequence types (STs). One serogroup O26 outbreak strain and another non-typeable (NT) strain, for instance, were identical by PFGE and clustered together by MLST; however, both were distantly related in the SNP analysis. In contrast, six outbreak-associated serogroup O5 strains clustered with five ST-175 serogroup O5 isolates, which were not part of the same outbreak as determined by PFGE. The use of high-quality SNP analyses enhanced the discrimination of these O5 outbreak strains into a single cluster. In all, this study demonstrates how public health laboratories can more rapidly use WGS and phylogenetics to identify related strains during outbreak investigations while simultaneously uncovering important genetic attributes that can inform treatment practices.

Co-Occurrence of mcr-1 and Carbapenem Resistance in Avian Pathogenic E. coli Serogroup O78 ST95 from Colibacillosis-Infected Broiler Chickens.

Avian pathogenic Escherichia coli (APEC) is responsible for significant economic losses in the poultry industry. This study aimed to molecularly detect carbapenem-resistant co-harboring mcr-1 avian pathogenic E. coli in broiler chickens infected with colibacillosis. A total of 750 samples were collected from colibacillosis-infected broilers, and conventional microbiological techniques were used to isolate and identify APEC. MALDI-TOF and virulence-associated genes (VAGs) were used for further identification. Phenotypic carbapenem resistance profiling was followed by molecular detection of carbapenem resistance genes (CRGs) and other resistance genes through PCR using specific primers. Isolates were also subjected to PCR for O typing, followed by allele-specific PCR to detect sequence type (ST) 95. Results showed that 154 (37%) isolates were confirmed as APEC, with 13 (8.4%) isolates found to be carbapenem-resistant (CR)-APEC. Among CR-APEC isolates, 5 (38%) were observed to co-harbor mcr-1. All CR-APEC showed the presence of five markers (ompT, hylF, iutA, iroN, and iss) APEC VAGs, and 89% of CR-APEC isolates displayed O78 type. Furthermore, 7 (54%) CR-APEC isolates were observed with ST95, all displaying O78 type. These results suggest that the improper use of antibiotics in poultry production systems is contributing to the emergence of pathogens such as CR-APEC co-harboring the mcr-1 gene.

THE DEVELOPMENT OF CHOLERA VACCINE PRODUCTION: A LITERATURE REVIEW

Introduction. Cholera is a diarrheal disease that causes dehydration and rapid death due to infection with bacterium Vibrio cholerae that develops in the colon. Cholera generally develops in countries with poor sanitation, poverty, and unavailability of clean water such as Africa and South Asian. One of the efforts to prevent cholera transmission to tourists who will visit the country can be conducted through vaccines. Method. This research was made to find out the development of cholera vaccine using the literature search method through PubMed, Elsevier, Google Scholar databases, and credible websites. Result and Analysis. From the results of several literature searches, there is a monovalent O1 serogroup vaccine that contains killed whole-cell bacteria such as Ducoral and live-attenuated bacteria, called Vaxchora. Discussion. In addition, there are bivalent vaccines O1 and O139 serogroups that contain whole-cell killed bacteria such as Shanchol, Euvichol, mORC-Vax, and Cholvax.

Multicountry cholera outbreak alert in Kenya: Current efforts and recommendations

Multicountry cholera outbreak alert in Kenya: Current efforts and recommendations

Recent surge in cholera outbreaks globally during the COVID-19 pandemic era: a potential threat to the African continent and salient counteracting strategies.

Recent surge in cholera outbreaks globally during the COVID-19 pandemic era: a potential threat to the African continent and salient counteracting strategies.

Drug resistance and genomic characteristics of a strain of O139 Vibrio cholerae isolated from human bloodstream infection

Objective: To analyze the drug resistance and genomic characteristics of a strain of serogroup O139 Vibrio cholerae producing cholera toxin isolated from the bloodstream of a person with bacteremia. Methods: The broth dilution method and automatic drug sensitivity analyzer were used to determine the antibiotic sensitivity of the strain. The complete genome sequence of the strain was obtained by using second-generation gene sequencing and nanopore sequencing. BLAST software was used for comparison and analysis with CARD, Resfinder, ISfinder, VFDB, and other databases. The drug-resistant genes, insertion sequences and virulence genes carried by the strain were identified. MEGA 5.1 software was used to construct a genetic phylogenetic tree based on the core genomic single nucleotide polymorphisms. Results: V. cholerae SH400, as the toxigenic strain, carried multiple virulence-related genes and four virulence islands. The strain was resistant to streptomycin, tetracycline and cotrimoxazole, carrying corresponding drug-resistant genes. The strain also carried IncA/C plasmid with the size of 172914 bp and contained 10 drug-resistant genes. Combined with the genomic evolutionary relationship, this study found that the drug-resistant genes and drug-resistant plasmids carried among strains showed certain aggregation. The traditional ST type of strain SH400 was ST69, and the cgMLST type was a new type highly similar to cgST-252. Conclusion: This strain of serogroup O139 V. cholerae carries the ctxAB gene, multiple drug-resistant genes and IncA/C plasmid, and there are multiple drug-resistant islands.

Conservation of cholera vibrios in complex microcosm containing green microalgae

BACKGROUND: In the summer-autumn period, the peak of phytoplankton reproduction and flowering occurs and results in the deterioration of the quality of river water is noted. At the same time, cases of gastrointestinal diseases in humans are recorded, and epidemic complications of cholera may occur in endemic areas. V. cholerae form biofilm on the surface of chitinous hydrobionts and plastic components can lead to the spread of V. cholerae, possibly explaining the autochthonous mechanism of their existence in water bodies.
 AIM: This study determines the duration of Vibrio cholerae preservation on biotic (chitin) and abiotic (plastic) substrates in the presence of green unicellular algae with a change in cultivation temperature under experimental conditions.
 MATERIALS AND METHODS: This study used bacteriological and molecular genetic methods to achieve its goal.
 RESULTS: The preservation of toxigenic and non-toxigenic strains of V. cholerae O1 El Tor and V. cholerae O139 (ctxАВ+tcpА+csh1 and ctxАtcpАcsh1+) for six months, including three months at a low temperature simulating the autumn-winter period, as part of biofilms in microcosms, where one component is green microalgae. We noted an excess of the concentration of V. cholerae O1 and O139 serogroups by two orders of magnitude in samples where one of the components is chitin and the reproduction of green microalgae in the presence of a chitin substrate. This is probably one stage in the food chain in the ecology of water bodies and, accordingly, can be a reservoir for biofilm forms of cholera vibrios. Preservation of V. cholerae O1 El Tor non-toxigenic strain in a viable state in biofilm samples on plastic at decreased temperatures 82C for three months is possibly due to the presence of a cold shock gene in its genome.
 CONCLUSION: Without a substrate for adhesion, colonization, and biofilm formation, vibrios are incapable of long-term persistence at low temperatures.

First report on the occurrence of Vibrio cholerae nonO1/nonO139 in natural and artificial lakes and ponds in Serbia: Evidence for a long-distance transfer of strains and the presence of Vibrio paracholerae.

Vibrio cholerae are natural inhabitants of specific aquatic environments. Strains not belonging to serogroups O1 and O139 are usually unable to produce cholera toxin and cause cholera. However, non-toxigenic V. cholerae (NTVC) are able to cause a variety of mild-to-severe human infections (via seafood consumption or recreational activities). The number of unreported cases is considered substantial, as NTVC infections are not notifiable and physicians are mostly unaware of this pathogen. In the northern hemisphere, NTVC infections have been reported to increase due to global warming. In Eastern Europe, climatic and geological conditions favour the existence of inland water-bodies harbouring NTVC. We thus investigated the occurrence of NTVC in nine Serbian natural and artificial lakes and ponds, many of them used for fishing and bathing. With the exception of one highly saline lake, all investigated water-bodies harboured NTVC, ranging from 5.4× 101 to 1.86 × 104 CFU and 4.5× 102 to 5.6× 106 genomic units per 100 ml. The maximum values observed were in the range of bathing waters in other countries, where infections have been reported. Interestingly, 7 out of 39 fully sequenced presumptive V. cholerae isolates were assigned as V. paracholerae, a recently described sister species of V. cholerae. Some clones and sublineages of both V. cholerae and V. paracholerae were shared by different environments indicating an exchange of strains over long distances. Important pathogenicity factors such as hlyA, toxR, and ompU were present in both species. Seasonal monitoring of ponds/lakes used for recreation in Serbia is thus recommended to be prepared for potential occurrence of infections promoted by climate change-induced rise in water temperatures.

Whole-genome analysis of a Vibrio cholerae O1 biotype classical strain isolated in 1946 in Sasebo city, Nagasaki prefecture, from a returnee from the northeast part of China

BackgroundCholera is a water-borne disease caused by toxigenic Vibrio cholerae serogroups O1 and O139. Not a few studies on the whole-genome analyses of V. cholerae O1 biotype El Tor have been published; however, the number of analyses for biotype classical is limited. The whole-genome analysis was made on a V. cholerae biotype classical strain, Man9, isolated in 1946 in Sasebo city, Nagasaki prefecture, from a returnee from the northeast part of China.MethodsPacBio RSII was used to determine the whole-genome of Man9. De novo assemblies were made with CLC Genomics Workbench 8.5.1 and Canu. 2.0 and annotated by Prokka version 1.12. Upon determining the configuration of the CTX prophage region, combined procedures of PCR, RFLP with Southern blotting, and Sanger sequencing method were used. The phylogenetic tree was constructed by RaxML and visualized by Phandango. The identification of Cas genes and spacer sequences was made by CRISPR-finder and NCBI Blast search. These data were compared with those of V. cholerae serogroup O1 biotype classical O395.ResultsThe Man9 carried the 2.9 Mb (Chr1) and 1.1 Mb (Chr2) chromosomes with 2683 and 1198 CDSs, respectively. The genome similarity between Man9 and O395 was 97.0% when the total genomes were compared. Man9 carried a 380-kb inversion on the Chr1, and 95-kb and 35-kb fragments were not present on the Chr1 and on the Chr2, respectively. Man9 monophyletically clustered with 23 other biotype classical strains on the core gene phylogenetic tree analyses. Man9 carries “CTXcla” and a stretch of “truncated CTXcla-CTXcla” on the Chr1 and the Chr2, respectively, which is the opposite arrangement of O395. Man9 carries CRISPR–Cas system subtype I-E with 33 spacers, 64% of which were identical to those of O395.ConclusionsMan9 differs from O395 by 3% on the total genome comparison; however, genomic analysis of a strain having circulated in the interpandemic period between the 6th and the 7th cholera pandemic is valuable and contributes to understanding the evolution of pathogenic V. cholerae.

Serotype conversion gene rfbT is directly regulated by histone-like nucleoid structuring protein (H-NS) in V. cholerae O1.

Vibrio cholerae serogroup O1 (V. cholerae O1) is closely associated with cholera epidemics and has two main immunologically distinguishable serotypes, Ogawa and Inaba. Isolates serotype as Ogawa if the O-antigen polysaccharide (O-PS) is methylated or as Inaba if the O-PS is not methylated. This methylation is mediated by a methyltransferase encoded by the rfbT gene, and the mutation and low expression of rfbT results in serotype switch from Ogawa to Inaba. Previously, we have shown that cAMP receptor protein (CRP) activates rfbT. In this study, we demonstrated that histone-like nucleoid structuring protein (H-NS) is directly involved in the transcriptional repression of rfbT. This finding is supported by the analyses of rfbT mRNA level, rfbT-lux reporter fusions, electrophoretic mobility shift assay (EMSA), and DNase I footprinting assay. The rfbT mRNA abundances were significantly increased by deleting hns rather than fis which also preferentially associates with AT-rich sequences. A single-copy chromosomal complement of hns partly restored the down-regulation of rfbT. Analysis of rfbT-lux reporter fusions validated the transcriptional repression of hns. Subsequent EMSA and DNase I footprinting assay confirmed the direct binding of H-NS to rfbT promoter and mapped the exact binding site which was further verified by site-directed mutagenesis and promoter functional analysis. Furthermore, we found that in hns deletion mutant, CRP is no longer required for transcriptionally activating rfbT, suggesting that CRP functions as a dedicated transcription factor to relieve H-NS repression at rfbT. Together, this study expanded our understanding of the genetic regulatory mechanism of serotype conversion by global regulators in V. cholerae O1.

Emergence of Multidrug Resistant Vibrio cholerae O139 in Acute Diarrhoea Patients Attending a Tertiary Care Hospital, West Bengal, India

Introduction: India is a developing country with many poor sanitation areas. Cholera, a water borne disease is rampant in areas of poor sanitation and is mainly due to Vibrio cholera of O1 and O139 serogroups causing acute cases of rice watery diarrhoea and high mortality. Infection due to Multidrug Resistant (MDR) Vibrio is on the rise. It is endemic in over 50 countries including India leading to a number of epidemics and pandemics. Till date, about seven pandemics have been identified due to cholera infection. Aim: To isolate Vibrio cholerae from acute diarrhoea cases with their antibiotic susceptibility and identify MDR strains, if any. Materials and Methods: A hospital-based, cross-sectional study was conducted in the Department of Microbiology, Burdwan Medical College, Purba Burdwan, West Bengal, India, from January 2021 to December 2021. Rectal swabs/faeces collected in Cary-Blair Transport Media were brought to the laboratory and incubated at 37°C for six hours; a loopful was inoculated in nutrient agar, MacConkey agar and selective media Thiosulphate-Citrate-Bile Salts-Sucrose agar (TCBS). Gram stain, motility, colony characteristics, oxidase test, cholera-red reaction and slide agglutination test was done. Diagnosis was confirmed; antibiotic susceptibility done and interpreted as per Clinical and Laboratory Standard Institute (CLSI) guidelines. The data was collected and entered into Microsoft Excel software and presented as frequency and percentages. Results: Total 60 samples were collected and tested, out of which 24 (40%) were positive for Vibrio cholerae and nine in 24 (37.5%) samples were MDR strains. Twelve samples were from femlaes and 12 were from males, majority {5 (41.67%) females, 9 (75%) males} belonged to the age group of 0-5 years. Serotyping revealed that Vibrio cholerae O1 serogroup was identified in 8 (33.33%) cases and O-139 serotype in 16 (66.67%) samples. Rest were Escherichia coli (n=10, 25%), Klebsiella pneumoniae (n=5, 12.5%) and Staphylococcus aureus (n=1, 25%). Conclusion: There is a rise of infections due to MDR strains of Vibrio O139 sero group in the community which needs early diagnosis and treatment for control. Vibrio cholerae strains were more resistant to fluoroquinolones, macrolides, tetracycline and Ampicillin.

Detection of hydrolases of different subclasses in cell-free fractions of Vibrio cholerae O1 and O139 serogroups using radial enzymatic diffusion in agarose gel

Cholera remains an actual infection worldwide, which dictates the need for a comprehensive study of its pathogens and, in particular, their hydrolytic enzymes that interact with the cells of the macroorganism. We determined the presence of hydrolases from different subclasses in preparations of cell-free fractions obtained from 58 strains of Vibrio cholerae O1 and O139 serogroups of different epidemic significance and origins using radial enzyme diffusion in agarose gels with various substrates. The analysis revealed statistically significant differences in enzyme activity depending on the origin and epidemiological significance of the original strain. We found that preparations obtained from non-toxigenic strains had increased activity of proteases and chitinolytic enzymes, while those from toxigenic strains showed high activity of mucinases, lipolytic enzymes, and nucleases. These data can be applied in the microbiological diagnosis of cholera as an additional biochemical characterization of Vibrio cholerae strains, as well as contribute to the understanding of the role of enzymes in the pathogenesis and adaptation of cholera pathogens.

Cholera Dynamics and the Emergence of Pandemic Vibrio cholerae.

Cholera is a severe diarrheal disease caused by the aquatic bacterium Vibrio cholerae. Interestingly, to date, only one major clade has emerged to cause pandemic disease in humans: the clade that encompasses the strains from the O1 and O139 serogroups. In this chapter, we provide a comprehensive perspective on the virulence factors and mobile genetic elements (MGEs) associated with the emergence of pandemic V. cholerae strains and highlight novel findings such as specific genomic background or interactions between MGEs that explain their confined distribution. Finally, we discuss pandemic cholera dynamics contextualizing them within the evolution of the bacterium.

Гены и белки холодового шока у Vibrio cholerae различных серогрупп

553 whole genome sequences of Vibrio cholerae strains O1, O139 and nonO1/nonO139 serogroups were studied for the presence of cold-shock genes cspA, cspV and csh1. The cspA and cspV genes were present in almost all strains. The csh1 gene was present in 99/449 strains of the serogroup O1 and in 21/86 cultures of nonO1/nonO139 taken in the study. The absence of the csh1 gene was revealed in strains of the O139 serogroup and strains of the O1 serogroup with ctxAB and tcpA genes. The study of the nucleotide composition identified 13 different variants of the csh1 gene which cause structural differences in the cold-shock protein Csh1. The two main types of Csh1 protein were represented by the reference type (68 genomes) and the major type (35 genomes), 11 minor variants included single genomes. According to the NCBI database, mainly representatives of minor types of Csh1 protein circulate abroad. The reference type Csh1 was mainly detected in O1 serogroup strains, while 10 strains with the reference type Csh1 protein were identified before 2000, then in 2001-2022 their number reached 55 strains. It is assumed that the new cold shock gene csh1 gives vibrions a selective advantage by ensuring survival at low temperatures in reservoirs.