Isolation of New Delhi metallo-β-lactamase 1-producing Vibrio cholerae non-O1, non-O139 strain carrying ctxA, st and hly genes in southern Vietnam

Antibiotic Resistance in Selected Emerging Bacterial Foodborne Pathogens-An Issue of Concern?

Antibiotic resistance (AR) and multidrug resistance (MDR) have been confirmed for all major foodborne pathogens: Campylobacter spp., Salmonella spp., Escherichia coli and Listeria monocytogenes. Of great concern to scientists and physicians are also reports of antibiotic-resistant emerging food pathogens-microorganisms that have not previously been linked to food contamination or were considered epidemiologically insignificant. Since the properties of foodborne pathogens are not always sufficiently recognized, the consequences of the infections are often not easily predictable, and the control of their activity is difficult. The bacteria most commonly identified as emerging foodborne pathogens include Aliarcobacter spp., Aeromonas spp., Cronobacter spp., Vibrio spp., Clostridioides difficile, Escherichia coli, Mycobacterium paratuberculosis, Salmonella enterica, Streptocccus suis, Campylobacter jejuni, Helicobacter pylori, Listeria monocytogenes and Yersinia enterocolitica. The results of our analysis confirm antibiotic resistance and multidrug resistance among the mentioned species. Among the antibiotics whose effectiveness is steadily declining due to expanding resistance among bacteria isolated from food are β-lactams, sulfonamides, tetracyclines and fluoroquinolones. Continuous and thorough monitoring of strains isolated from food is necessary to characterize the existing mechanisms of resistance. In our opinion, this review shows the scale of the problem of microbes related to health, which should not be underestimated.

Direct and Rapid Identification of Vibrio Cholerae Serogroup and Toxigenicity by a Novel Multiplex Real-Time Assay

Molecular diagnostic assays for cholera detection have superior sensitivity to conventional assays and are now being accepted as the new standard method, especially the real-time PCR/RT-PCR. However, limited throughput capacity and long detection duration prevent them from detecting more specimens and more targets in one turnaround time simultaneously. In this study, we utilized nucleic acid extraction-free, direct RT-PCR and high-speed amplification to develop a novel multiplex assay, a quadplex direct one-tube real-time RT-PCR assay, for rapid detection of the serogroup and cholera toxin toxigenicity of Vibrio cholerae targeting the epsM, ctxA, rfb-O1, and rfb-O139 genes. Performance of the multiplex assay was evaluated by comparison with the monoplex real-time PCR assay according to the China Cholera Prevention Manual. Detection data from clinical specimens showed that the new assay had good diagnostic sensitivities for epsM (100%, n = 301), ctxA (100%, n = 125), rfb-O1 (100%, n = 85), and rfb-O139 (97.87%, n = 49). Analysis of the analytical sensitivities with serial dilutions of positive standards showed that the detection limits of the new assay for Vibrio cholerae epsM,ctxA,rfb-O1, and rfb-O139 were up to 200, 590, 115, and 1052 copies per mL lower than the monoplex real-time PCR (910, 345, and 1616 copies/mL respectively, for ctxA,rfb-O1, and rfb-O139). The results indicate that the multiplex assay is a rapid, sensitive, specific, and easy-to-use detection tool for Vibrio cholerae, especially suitable for rapid identification and screening detection of mass specimens.

Aquatic environments: A Potential Source of Antimicrobial-Resistant Vibrio spp

Vibrio spp. are associated with water and seafood-related outbreaks worldwide. They are naturally present in aquatic environments such as seawater, brackish water and freshwater environments. These aquatic environments serve as the main reservoirs of antimicrobial-resistant genes and promote the transfer of antimicrobial-resistant bacterial species to aquatic animals and humans through the aquatic food chain. Vibrio spp. are known as etiological agents of cholera and non-cholera Vibrio infections in humans and animals. Antimicrobial-resistant Vibrio species have become a huge threat in regard to treating Vibrio infections in aquaculture and public health. Most of the Vibrio spp. possess resistance towards the commonly used antimicrobials, including β-lactams, aminoglycosides, tetracyclines, sulfonamides, quinolones and macrolides. The aim of this review is to summarize the antimicrobial resistance properties of Vibrio spp. isolated from aquatic environments to provide awareness about potential health risks related to Vibrio infections in aquaculture and public health.

Systematic review and meta-analysis of environmental Vibrio species - antibiotic resistance

Adequate comprehension of the genomics of microbial resistance to an antimicrobial agent will advance knowledge on the management of associated pathologies and public health safety. However, continued emergences and reemergence of pathogens, including Vibrio species, hallmarks a potential knowledge gap. A clear understanding of the process and forecast of the next trend should be in place to nip in the bud, microbial acquisition of resistance to antibiotics. Therefore, this two-decade (1 January 2000 to 31 December 2019) systematic review and meta-analytical study articulated the prevalence and incidence of antibiotics resistance genes in Vibrio species isolated from environmental samples. Articles from the Web of Science and PubMed electronic databases was engaged. Heterogeneity of the data and bias were analyzed with random effect model meta-analysis and funnel plot. A total of 1920 Vibrio sp. were reported by the ten selected articles included in this study; out of which 32.39% of identified isolates displayed antimicrobial resistance and associated genes. The distribution of antibiotics resistance genes in Vibrio sp., reported within six countries was 21% tetracycline (tet), and 20% sulphonamide (sul) and β-lactamase (bla) respectively. The quinolone, tetracycline and sulfonamide resistance genes showed 32.97% (95% CI 0.18–0.53) prevalence while chloramphenicol, macrolides and aminoglycoside resistance genes are expressed in percentages as 28.67% (95% CI 0.15–0.47) and β-lactamase resistance genes 27.93% (95% CI 0.11–0.56) respectively. The Vibrio antibiotics resistance genes (V-ARG) distribution depicts no regular trend or pattern from the analyzed data. Consequently, more studies would be required to articulate the structure of cohesion in the distribution of the resistance determinants in microbes.

Phenotypic and genotypic characterization of antimicrobial resistance in clinical isolates of Vibrio cholerae over a decade (2002-2016)

PURPOSE

Emergence and spread of resistance among Vibrio cholerae have become a global public health problem. In India, no consolidated data is available on antimicrobial susceptibility patterns and antibiotic resistance genes.

METHODS

A total of 110 representative isolates obtained over a period of 14 years were included. Antimicrobial susceptibility was tested by disc diffusion and micro broth dilution. Presence of 13 antimicrobial resistance genes was ascertained by using PCR.

RESULTS

Antimicrobial resistance fluctuated for most of the antibiotics. Resistance to cotrimoxazole in our study was 92.72% and the SXT element was present in all isolates. Resistance to nalidixic acid, tetracycline, and cefotaxime was found to be 98.18%, 7.27%, and 10.9% respectively. Resistance to ampicillin saw a fluctuating trend with a recent fall. Resistance to ciprofloxacin and azithromycin was 12.72% and 29% by MIC. bla_TEM was the most common ESBL gene (94.5%). Other were bla_CMY (26.36%) and bla_NDM (2.7%). We report bla_CTX-M-15 and bla_OXA-48 and ermB for the first time in the world. Newer antimicrobials like prulifloxacin and rifaximin were tested for the first time from India.

CONCLUSIONS

Our study has shown very high levels of resistance to older antibiotics and the emergence of resistance to some of the newer classes of antibiotics. There is an urgent need for increased surveillance studies, rational use of the antimicrobials and preventive measures to control the disease.

Sero-evaluation of Immune Responses to Vibrio cholerae in a Postelimination Setting

Cholera remains a significant public health problem worldwide. In settings of declining incidence, serosurveillance may be used to augment clinical surveillance. We utilized dried blood spot sampling and cholera-specific antibody testing to examine the serologic profiles of vaccinated and unvaccinated children in southern Vietnam, where cholera was recently eliminated.

blaNDM-1-producing Vibrio parahaemolyticus and V. vulnificus isolated from recreational beaches in Lagos, Nigeria

Twenty-six strains of Vibrio parahaemolyticus and 14 strains of V. vulnificus isolated from selected beaches in Lagos State, Nigeria, were examined for virulence and antimicrobial resistance genes. The V. parahaemolyticus isolates were further serotyped and subjected to pulsed field gel electrophoresis (PFGE). Five strains of V. vulnificus and one of V. parahaemolyticus carried the New Delhi-metallo-beta-lactamase gene bla_NDM-1, seven strains carried bla_TEM, and four strains of V. vulnificus and one of V. parahaemolyticus carried bla_CMY. Real-time PCR assay for detection of virulence genes tdh and trh in the V. parahaemolyticus isolates showed that five isolates were positive for tdh, two for trh, and one isolate carried both genes. Ten V. parahaemolyticus serogroups and 23 pulsotypes were identified from 26 isolates based on O and K antigens typing and PFGE. Five of the isolates belong to the pandemic strains O1:Kut and O3:K6, and three belonged to the highly virulent O4:Kut serotype. Nineteen of the isolates showed distinct PFGE banding patterns. These results highlighted the importance of Nigerian recreational beaches as reservoirs of antimicrobial resistance genes of global public health interest, such as bla_NDM-1.

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.

Expression of Hemolysin Is Regulated Under the Collective Actions of HapR, Fur, and HlyU in Vibrio cholerae El Tor Serogroup O1

The biotype El Tor of serogroup O1 and most of the non-O1/non-O139 strains of Vibrio cholerae can produce an extracellular pore-forming toxin known as cholera hemolysin (HlyA). Expression of HlyA has been previously reported to be regulated by the quorum sensing (QS) and the regulatory proteins HlyU and Fur, but lacks the direct evidence for their binding to the promoter of hlyA. In the present work, we showed that the QS regulator HapR, along with Fur and HlyU, regulates the transcription of hlyA in V. cholerae El Tor biotype. At the late mid-logarithmic growth phase, HapR binds to the three promoters of fur, hlyU, and hlyA to repress their transcription. At the early mid-logarithmic growth phase, Fur binds to the promoters of hlyU and hlyA to repress their transcription; meanwhile, HlyU binds to the promoter of hlyA to activate its transcription, but it manifests direct inhibition of its own gene. The highest transcriptional level of hlyA occurs at an OD₆₀₀ value of around 0.6–0.7, which may be due to the subtle regulation of HapR, Fur, and HlyU. The complex regulation of HapR, Fur, and HlyU on hlyA would be beneficial to the invasion and pathogenesis of V. cholerae during the different infection stages.

Carbapenem Resistance in Clonally Distinct Clinical Strains of Vibrio fluvialis Isolated from Diarrheal Samples

These strains might acquire the bla_NDM-1 gene without exposure to antimicrobial drugs.

Carbapenems have been used for many years to treat severe nosocomial Enterobacteriaceae infections. The spread of resistance to these drugs among other bacterial families is an emerging problem worldwide, mostly caused by New Delhi metallo-β-lactamase (NDM-1). We screened for the prevalence of NDM-1–expressing enteric pathogens from hospitalized patients with acute diarrhea in Kolkata, India, and identified 27 Vibrio fluvialis–harboring bla_NDM-1 (NDM-VF) strains. These isolates were also resistant to all the tested antimicrobial drugs except doxycycline. The large plasmid of V. fluvialis harboring bla_NDM-1 could be easily transferred to other enteric pathogens. Genes flanking the bla_NDM-1 were found to be identical to the reported sequence from an Escherichia coli isolate. Analyses showed that the V. fluvialis possessing the NDM-VF region belonged to different clones. The pathogenicity of V. fluvialis to humans and its ubiquitous presence in the environment call for constant monitoring of this species for emerging antimicrobial drug resistance.

Vibriosis, not cholera: toxigenic Vibrio cholerae non-O1, non-O139 infections in the United States, 1984-2014

Toxigenic strains of Vibrio cholerae serogroups O1 and O139 have caused cholera epidemics, but other serogroups - such as O75 or O141 - can also produce cholera toxin and cause severe watery diarrhoea similar to cholera. We describe 31 years of surveillance for toxigenic non-O1, non-O139 infections in the United States and map these infections to the state where the exposure probably originated. While serogroups O75 and O141 are closely related pathogens, they differ in how and where they infect people. Oysters were the main vehicle for O75 infection. The vehicles for O141 infection include oysters, clams, and freshwater in lakes and rivers. The patients infected with serogroup O75 who had food traceback information available ate raw oysters from Florida. Patients infected with O141 ate oysters from Florida and clams from New Jersey, and those who only reported being exposed to freshwater were exposed in Arizona, Michigan, Missouri, and Texas. Improving the safety of oysters, specifically, should help prevent future illnesses from these toxigenic strains and similar pathogenic Vibrio species. Post-harvest processing of raw oysters, such as individual quick freezing, heat-cool pasteurization, and high hydrostatic pressurization, should be considered.

Reduced Susceptibility to Extended-Spectrum β-Lactams in Vibrio cholerae Isolated in Bangladesh

β-lactams are antibiotic molecules able to inhibit cell wall biosynthesis. Among other mechanisms, resistance in Gram-negative bacteria is mostly associated with production of β-lactamase enzymes able to bind and hydrolyze the β-lactam ring. Extended-spectrum β-lactamases extend this ability also to third- and fourth-generation cephalosporins, as well as to carbapenems and monobactams. Vibrio cholerae is the causative agent of epidemic cholera and a public health burden for developing countries like Bangladesh. Although appropriate oral or intravenous rehydration is the therapy of choice for cholera, severe infections and V. cholerae-associated septicemia are treated with antimicrobial drugs, including doxycycline, erythromycin, azithromycin, ciprofloxacin, and/or third-generation cephalosporins. In the years after the introduction of antibiotics in clinical practice, V. cholerae developed resistance to commonly used drugs worldwide mostly through gene acquisition via horizontal gene transfer. Reduced susceptibility of V. cholerae to third-generation cephalosporins has been occasionally documented. However, carbapenemase-producing V. cholerae has been reported at higher rates than resistance to extended-spectrum β-lactams, mainly associated with bla_NDM-1 emergence and successful plasmid dissemination. Recent findings suggest limited β-lactam resistance is present in V. cholerae O1 isolates collected during ecological and epidemiological surveillance in Bangladesh. However, a trend to intermediate-susceptibility insurgence was observed. Horizontal gene transfer of β-lactam resistance from enteric pathogens to environmental microorganisms should not be underrated, given the ability of V. cholerae to acquire new genetic information.

Comparison of isolates and antibiotic sensitivity pattern in pediatric and adult cancer patients; is it different?

BACKGROUND

Infection is a common cause of mortality and morbidity in cancer patients. Organisms are becoming resistant to antibiotics; age appears to be one of the factors responsible. We analyzed common organisms and their antibiotic sensitivity pattern in the correlation with age.

METHODS

This is a single institutional, retrospective analysis of all culture positive adult and pediatric cancer patients from January 2007 to December 2007. For statistical analysis, Chi-square test for trend was used and P values were obtained. Of 1251 isolates, 262 were from children <12 years of age and 989 were from adolescents and adults (>12 years of age). Gram-negative organisms were predominant (64.95) while Gram-positive constituted 35.09% of isolates.

RESULTS

The most common source in all age groups was peripheral-blood, accounting to 47.8% of all samples. The most common organisms in adults were Pseudomonas aeruginosa (15.3%) while in children it was coagulase negative Staphylococcus aureus (19.8%). Antibiotic sensitivity was different in both groups. In pediatric group higher sensitivity was seen for Cefoparazone-sulbactum, Cefipime, Amikacin, and Tobramycin. No resistance was found for Linezolid.

CONCLUSIONS

The isolates in both children and adults were predominantly Gram-negative though children had proportionately higher Gram-positive organisms. High-dose cytarabine use, cotrimoxazole prophylaxis, and frequent use of central lines in children especially in hematological malignancies could explain this observation. Children harbor less antibiotic resistance than adults; Uncontrolled, cumulative exposure to antibiotics in our community with increasing age, age-related immune factors and variable bacterial flora in different wards might explain the higher antibiotic resistance in adults. Thus age is an important factor to be considered while deciding empirical antibiotic therapy.