Vibrio cholerae non-O1, non-O139 bacteraemia associated with pneumonia, Italy 2016

Vibrio cholerae Bacteremia: An Enigma in Cholera-Endemic African Countries

Cholera is highly endemic in many sub-Saharan African countries. The bacterium Vibrio cholerae is responsible for this severe dehydrating diarrheal disease that accounts for over 100,000 deaths each year globally. In recent years, the pathogen has been found to invade intestinal layers and translocate into the bloodstream of humans. The non-toxigenic strains of V. cholerae (non-O1/O139), also known as NOVC, which do not cause epidemic or pandemic cases of cholera, are the major culprits of V. cholerae bacteremia. In non-cholera-endemic regions, clinical reports on NOVC infection have been noted over the past few decades, particularly in Europe and America. Although low-middle-income countries are most susceptible to cholera infections because of challenges with access to clean water and inappropriate sanitation issues, just a few cases of V. cholerae bloodstream infections have been reported. The lack of evidence-based research and surveillance of V. cholerae bacteremia in Africa may have significant clinical implications. This commentary summarizes the existing knowledge on the host risk factors, pathogenesis, and diagnostics of NOVC bacteremia.

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.

DegS protease regulates the motility, chemotaxis, and colonization of Vibrio cholerae

In bacteria, DegS protease functions as an activating factor of the σ^E envelope stress response system, which ultimately activates the transcription of stress response genes in the cytoplasm. On the basis of high-throughput RNA sequencing, we have previously found that degS knockout inhibits the expression of flagellum synthesis- and chemotaxis-related genes, thereby indicating that DegS may be involved in the regulation of V. cholerae motility. In this study, we examined the relationships between DegS and motility in V. cholerae. Swimming motility and chemotaxis assays revealed that degS or rpoE deletion promotes a substantial reduction in the motility and chemotaxis of V. cholerae, whereas these activities were restored in ΔdegS::degS and ΔdegSΔrseA strains, indicating that DegS is partially dependent on σ^E to positively regulate V. cholerae activity. Gene-act network analysis revealed that the cAMP-CRP-RpoS signaling pathway, which plays an important role in flagellar synthesis, is significantly inhibited in ΔdegS mutants, whereas in response to the overexpression of cyaA/crp and rpoS in the ΔdegS strain, the motility and chemotaxis of the ΔdegS + cyaA/crp and ΔdegS + rpoS strains were partially restored compared with the ΔdegS strain. We further demonstrated that transcription levels of the flagellar regulatory gene flhF are regulated by DegS via the cAMP-CRP-RpoS signaling pathway. Overexpression of the flhF gene in the ΔdegS strain partially restored motility and chemotaxis. In addition, suckling mouse intestinal colonization experiments indicated that the ΔdegS and ΔrpoE strains were characterized by the poor colonization of mouse intestines, whereas colonization efficacy was restored in the ΔdegSΔrseA, ΔdegS + cyaA/crp, ΔdegS + rpoS, and ΔdegS + flhF strains. Collectively, our findings indicate that DegS regulates the motility and chemotaxis of V. cholerae via the cAMP-CRP-RpoS-FlhF pathway, thereby influencing the colonization of suckling mouse intestines.

Heatwave-associated Vibrio infections in Germany, 2018 and 2019

Background

Vibrio spp. are aquatic bacteria that prefer warm seawater with moderate salinity. In humans, they can cause gastroenteritis, wound infections, and ear infections. During the summers of 2018 and 2019, unprecedented high sea surface temperatures were recorded in the German Baltic Sea.

Aim

We aimed to describe the clinical course and microbiological characteristics of Vibrio infections in Germany in 2018 and 2019.

Methods

We performed an observational retrospective multi-centre cohort study of patients diagnosed with domestically-acquired Vibrio infections in Germany in 2018 and 2019. Demographic, clinical, and microbiological data were assessed, and isolates were subjected to whole genome sequencing and antimicrobial susceptibility testing.

Results

Of the 63 patients with Vibrio infections, most contracted the virus between June and September, primarily in the Baltic Sea: 44 (70%) were male and the median age was 65 years (range: 2–93 years). Thirty-eight patients presented with wound infections, 16 with ear infections, six with gastroenteritis, two with pneumonia (after seawater aspiration) and one with primary septicaemia. The majority of infections were attributed to V. cholerae (non–O1/non-O139) (n = 30; 48%) or V. vulnificus (n = 22; 38%). Phylogenetic analyses of 12 available isolates showed clusters of three identical strains of V. vulnificus, which caused wound infections, suggesting that some clonal lines can spread across the Baltic Sea.

Conclusions

During the summers of 2018 and 2019, severe heatwaves facilitated increased numbers of Vibrio infections in Germany. Since climate change is likely to favour the proliferation of these bacteria, a further increase in Vibrio-associated diseases is expected.

Non-O1/non-O139 Vibrio cholerae bacteraemia in mainland China from 2005 to 2019: clinical, epidemiological and genetic characteristics

In mainland China, the clinical, epidemiological and genetic features of non-O1/non-O139 Vibrio cholerae (NOVC) bacteraemia have been scarcely investigated. Herein, we describe a patient with NOVC bacteraemia diagnosed in our hospital and present a retrospective analysis of literature reports of 32 other cases in China, detailing the clinical epidemiology, antibiotic resistance and molecular characteristics of isolates. Most patients were male (84.8%; median age, 53 years) and had predisposing factors, such as cirrhosis, malignant tumours, blood diseases and diabetes. In addition to fever, gastroenteritis was the most frequent presenting symptom. The mortality rate during hospitalisation was 12.1%. NOVC bacteraemia cases were more common in June–August, with the majority in coastal provinces and the Yangtze River basin. Only 42.4% of cases were attributed to consumption of marine (aquatic) products. Tetracycline, third-generation cephalosporins, and fluoroquinolones were the most effective antimicrobial agents, and the highest frequencies of resistance were recorded for ampicillin/sulbactam (37.5%), amoxicillin/clavulanic acid (33.3%), ampicillin (29.2%) and sulfamethoxazole (20%). Multi-drug resistant isolates were not detected. Limited data indicate that ctxAB and tcpA genes were absent in all NOVC isolates but other putative virulence genes (hlyA, toxR, hap and rtxA) were common. Ten multilocus sequence types were identified with marked genetic heterogeneity between different isolates. As clinical manifestations of NOVC bacteraemia may vary widely, and isolates exhibit genetic diversity, clinicians and public health experts should be alerted to the possibility of infection with this pathogen because of the high prevalence of liver disease in China.

Non-O1, Non-O139 Vibrio cholerae (NOVC) Bacteremia: Case Report and Literature Review, 2015-2019

Non-O1, non-O139 Vibrio cholerae (NOVC) does not agglutinate with O1 and O139 antisera and can cause intestinal and extraintestinal infections in immunocompromised individuals. NOVC bacteremia has the highest mortality among NOVC infections, and the number of reports has increased in recent years. Nevertheless, some clinicians are poorly informed about this disease. Herein, we describe a documented case of NOVC bacteremia in a male patient with impaired liver function. Blood cultures revealed the presence of V. cholerae, but this strain showed self-coagulation on the serum agglutination test. To our knowledge, this phenomenon is unreported among cases of NOVC infections. This pathogen was finally confirmed as NOVC via PCR. Because the patient worked as a garbage transporter, he was likely infected after contact with contaminated water through a foot wound. The patient developed septic shock shortly after admission and ultimately died from the illness. This paper reviews 23 cases of NOVC bacteremia from 2015 to 2019. To improve the accuracy of identifying NOVC and analyze its virulence factors, relevant detection methods were reviewed and analyzed.

Phenotypic and Genotypic Antimicrobial Resistance Traits of Vibrio cholerae Non-O1/Non-O139 Isolated From a Large Austrian Lake Frequently Associated With Cases of Human Infection

Vibrio cholerae belonging to serogroups other than O1 and O139 are opportunistic pathogens which cause infections with a variety of clinical symptoms. Due to the increasing number of V. cholerae non-O1/non-O139 infections in association with recreational waters in the past two decades, they have received increasing attention in recent literature and by public health authorities. Since the treatment of choice is the administration of antibiotics, we investigated the distribution of antimicrobial resistance properties in a V. cholerae non-O1/non-O139 population in a large Austrian lake intensively used for recreation and in epidemiologically linked clinical isolates. In total, 82 environmental isolates - selected on the basis of comprehensive phylogenetic information - and nine clinical isolates were analyzed for their phenotypic antimicrobial susceptibility. The genomes of 46 environmental and eight clinical strains were screened for known genetic antimicrobial resistance traits in CARD and ResFinder databases. In general, antimicrobial susceptibility of the investigated V. cholerae population was high. The environmental strains were susceptible against most of the 16 tested antibiotics, except sulfonamides (97.5% resistant strains), streptomycin (39% resistant) and ampicillin (20.7% resistant). Clinical isolates partly showed additional resistance to amoxicillin-clavulanic acid. Genome analysis showed that crp, a regulator of multidrug efflux genes, and the bicyclomycin/multidrug efflux system of V. cholerae were present in all isolates. Nine isolates additionally carried variants of bla _CARB-7 and bla _CARB-9, determinants of beta-lactam resistance and six isolates carried catB9, a determinant of phenicol resistance. Three isolates had both bla _CARB-7 and catB9. In 27 isolates, five out of six subfamilies of the MATE-family were present. For all isolates no genes conferring resistance to aminoglycosides, macrolides and sulfonamides were detected. The apparent lack of either known antimicrobial resistance traits or mobile genetic elements indicates that in cholera non-epidemic regions of the world, V. cholerae non-O1/non-O139 play a minor role as a reservoir of resistance in the environment. The discrepancies between the phenotypic and genome-based antimicrobial resistance assessment show that for V. cholerae non-O1/non-O139, resistance databases are currently inappropriate for an assessment of antimicrobial resistance. Continuous collection of both data over time may solve such discrepancies between genotype and phenotype in the future.

Virulence-associated genes and molecular characteristics of non-O1/non-O139 Vibrio cholerae isolated from hepatitis B cirrhosis patients in China

OBJECTIVES

We aimed to report virulence-associated genes and molecular characteristics of non-O1/non-O139 Vibrio cholerae isolated from hepatitis B cirrhosis patients in China.

METHODS

Patient clinical data including course of disease, laboratory tests, antibiotic treatment and outcomes were collected. Antimicrobial susceptibility testing was performed and virulence-associated genes were detected by PCR. Genetic relatedness among non-O1/non-O139 V. cholerae strains was investigated by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

RESULTS

All three strains in this study harbored pathogenicity related genes like rtxA, rtxC, toxR, hapA, hlyA and ompW whereas they lacked ctxA, ctxB, tcpA, ompU and zot genes. None of them showed resistance to any antibiotic detected. A new allele of gyrB was submitted to the MLST database and designated as 97. Two novel sequence types (ST518 and ST519) and ST271 were identified by multilocus sequence typing (MLST). PFGE indicated considerable diversity among three non-O1/non-O139 V. cholerae strains.

CONCLUSIONS

Three sporadic cases highlight that non-O1/non-O139 V. cholerae can cause opportunistic invasiveness infection in cirrhosis patients. Pathogenicity may be related to virulence-associated genes. Timely detection and antibiotic therapy should be paid more attention to in clinic.

Non-O1/non-O139 Vibrio cholerae septicemia in patients with liver cirrhosis and ascites

AIM

To conduct laboratory identification and drug sensitivity testing of suspected Vibrio cholerae isolated from a patient with liver cirrhosis and ascites.

METHODS

By reviewing the patient's clinical symptoms, primary disease, laboratory results, treatment, and prognosis, the bacteria were identified using the Vitek 2 Compact automatic microbial analysis system, manual micro-tube biochemical reaction, and polymerase chain reaction. Drug susceptibility was determined by the K-B paper method, and serum virulence was determined by the slide agglutination method.

RESULTS

After a series of tests, the bacteria were identified as Vibrio cholerae non-O1 non-O139. Drug sensitivity testing showed that the bacteria were sensitive to many antibiotics such as ampicillin, piperacillin, ceftazidime, cefoperazone, shubatan, ceftriaxone, cefepime, imipenem, amikacin, aztreonam,levofloxacin, gatifloxacin, and compound sulfamethoxazole.

CONCLUSION

The bacteria isolated from the patient with liver cirrhosis and ascites were identified as non-O1 non-O139 Vibrio cholerae, which does not produce cholera toxin and is sensitive to common antibiotics.