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

Vibrio cholerae O1 and Escherichia coli O157:H7 from drinking water and wastewater in Addis Ababa, Ethiopia

BACKGROUND

In Addis Ababa, Ethiopia, open ditches along innner roads in residential areas serve to convey domestic wastewater and rainwater away from residences. Contamination of drinking water by wastewater through faulty distribution lines could expose households to waterborne illnesses. This prompted the study to assess the microbiological safety of wastewater and drinking water in Addis Ababa, identify the pathogens therein, and determine their antibiotic resistance patterns.

RESULTS VIBRIO CHOLERAE

O1, mainly Hikojima serotype, was isolated from 23 wastewater and 16 drinking water samples. Similarly, 19 wastewater and 10 drinking water samples yielded Escherichia coli O157:H7. V. cholerae O1 were 100% resistant to the penicillins (Amoxacillin and Ampicillin), and 51-82% were resistant to the cephalosporins. About 44% of the V. cholerae O1 isolates in this study were Extended Spectrum Beta-Lactamase (ESBL) producers. Moreover, 26% were resistant to Meropenem. Peperacillin/Tazobactam was the only effective β-lactam antibiotic against V. cholerae O1. V. cholerae O1 isolates showed 37 different patterns of multiple resistance ranging from a minimum of three to a maximum of ten antimicrobials. Of the E. coli O157:H7 isolates, 71% were ESBL producers. About 96% were resistant to Ampicillin. Amikacin and Gentamicin were very effective against E. coli O157:H7 isolates. The isolates from wastewater and drinking water showed multiple antibiotic resistance against three to eight antibiotic drugs.

CONCLUSIONS

Open ditches for wastewater conveyance along innner roads in residence areas and underground faulty municipal water distribution lines could be possible sources for V. cholerae O1 and E. coli O157:H7 infections to surrounding households and for dissemination of multiple drug resistance in humans and, potentially, the environment.

Prevalence and antimicrobial resistance of food safety related Vibrio species in inland saline water shrimp culture farms

This study evaluated the potential pathogenicity and antimicrobial resistance (AMR) of Vibrio species isolated from inland saline shrimp culture farms. Out of 200 Vibrio isolates obtained from 166 shrimp/water samples, 105 isolates were identified as V. parahaemolyticus and 31 isolates were identified as V. alginolyticus and V. cholerae, respectively. During PCR screening of virulence-associated genes, the presence of the tlh gene was confirmed in 70 and 19 isolates of V. parahaemolyticus and V. alginolyticus, respectively. Besides, 10 isolates of V. parahaemolyticus were also found positive for trh gene. During antibiotic susceptibility testing (AST), very high resistance to cefotaxime (93.0%), amoxiclav (90.3%), ampicillin (88.2%), and ceftazidime (73.7%) was observed in all Vibrio species. Multiple antibiotic resistance (MAR) index values of Vibrio isolates ranged from 0.00 to 0.75, with 90.1% of isolates showing resistance to ≥ 3 antibiotics. The AST and MAR patterns did not significantly vary sample-wise or Vibrio species-wise. During the minimum inhibitory concentration (MIC) testing of various antibiotics against Vibrio isolates, the highest MIC values were recorded for amoxiclav followed by kanamycin. These results indicated that multi-drug resistant Vibrio species could act as the reservoirs of antibiotic resistance genes in the shrimp culture environment. The limited host range of 12 previously isolated V. parahaemolyticus phages against V. parahaemolyticus isolates from this study indicated that multiple strains of V. parahaemolyticus were prevalent in inland saline shrimp culture farms. The findings of the current study emphasize that routine monitoring of emerging aquaculture areas is critical for AMR pathogen risk assessment.

Resistance of Vibrio cholera to antibiotics that inhibit cell wall synthesis: A systematic review and meta-analysis

Objective: Cholera is a challenging ancient disease caused by Vibrio cholera (V. cholera). Antibiotics that prevent cell wall synthesis are among the first known antibiotic groups. Due to its high consumption, V. cholera has developed resistance to the majority of antibiotics in this class. Resistance to recommended antibiotics for the treatment of V. cholera has also increased. In light of the decrease in consumption of certain antibiotics in this group that inhibit cell wall synthesis and the implementation of new antibiotics, it is necessary to determine the antibiotic resistance pattern of V. cholera and to employ the most effective treatment antibiotic. Method: An comprehensive systematic search for relevant articles was conducted in PubMed, Web of Science, Scopus, and EMBASE through October 2020. Stata version 17.1 utilized the Metaprop package to execute a Freeman-Tukey double arcsine transformation in order to estimate weighted pooled proportions. Results: A total of 131 articles were included in the meta-analysis. Ampicillin was the most investigated antibiotic. The prevalence of antibiotic resistance was in order aztreonam (0%), cefepime (0%), imipenem (0%), meropenem (3%), fosfomycin (4%), ceftazidime (5%), cephalothin (7%), augmentin (8%), cefalexin (8%), ceftriaxone (9%), cefuroxime (9%), cefotaxime (15%), cefixime (37%), amoxicillin (42%), penicillin (44%), ampicillin (48%), cefoxitin (50%), cefamandole (56%), polymyxin-B (77%), carbenicillin (95%) respectively. Discussion: Aztreonam, cefepime, and imipenem are the most efficient V. cholera cell wall synthesis inhibitors. There has been an increase in resistance to antibiotics such as cephalothin, ceftriaxone, amoxicillin, and meropenem. Over the years, resistance to penicillin, ceftazidime, and cefotaxime, has decreased.

Characterization and Potentiating Effects of the Ethanolic Extracts of the Red Seaweed Gracillaria sp. on the Activity of Carbenicillin against Vibrios

β-lactam-resistant Vibrio strains are a significant clinical problem, and β-lactamase inhibitors are generally coadministered with β-lactam drugs to control drug-resistant bacteria. Seaweed is a rich source of natural bioactive compounds; however, their potential as β-lactamase inhibitors against bacterial pathogens remains unknown. Herein, we evaluated the potential β-lactamase inhibitory effect of the ethanolic extracts of the red seaweed Gracilaria sp. (GE) against four Vibrio strains. The minimum inhibitory concentration, half-maximal inhibitory concentration, checkerboard assay results, and time-kill study results indicate that GE has limited antibacterial activity but can potentiate the activity of the β-lactam antibiotic carbenicillin against Vibrio parahemolyticus and V. cholerae. We overexpressed and purified recombinant metallo-β-lactamase, VarG, from V. cholerae for in vitro studies and observed that adding GE reduced the carbenicillin and nitrocefin degradation by VarG by 20% and 60%, respectively. Angiotensin I-converting enzyme inhibition studies demonstrated that GE did not inhibit VarG via metal chelation. Toxicity assays indicated that GE exhibited mild toxicity against human cells. Through gas chromatography and mass spectrometry, we showed that GE comprises alkaloids, phenolic compounds, terpenoids, terpenes, and halogenated aromatic compounds. This study revealed that extracts of the red seaweed Gracillaria sp. can potentially inhibit β-lactamase activity.

Global status of antimicrobial resistance among environmental isolates of Vibrio cholerae O1/O139: a systematic review and meta-analysis

Background

Vibrio cholerae O1/O139 were the predominant circulating serogroups exhibiting multi-drug resistance (MDR) during the cholera outbreak which led to cholera treatment failures.

Objective

This meta-analysis aimed to evaluate the weighted pooled resistance (WPR) rates in V. cholerae O1/O139 isolates obtained from environmental samples.

Methods

We systematically searched the articles in PubMed, Scopus, and Embase (until January 2020). Subgroup analyses were then employed by publication year, geographic areas, and the quality of studies. Statistical analyses were conducted using STATA software (ver. 14.0).

Results

A total of 20 studies investigating 648 environmental V. cholerae O1/O139 isolates were analysed. The majority of the studies were originated from Asia (n = 9). In addition, a large number of studies (n = 15 i.e. 71.4%) included in the meta-analysis revealed the resistance to cotrimoxazole and ciprofloxacin. The WPR rates were as follows: cotrimoxazole 59%, erythromycin 28%, tetracycline 14%, doxycycline 5%, and ciprofloxacin 0%. There was increased resistance to nalidixic acid, cotrimoxazole, furazolidone, and tetracycline while a decreased resistance to amoxicillin, ciprofloxacin, erythromycin, chloramphenicol, ampicillin, streptomycin, and ceftriaxone was observed during the years 2000–2020. A significant decrease in the doxycycline and ciprofloxacin-resistance rates in V. cholerae O1/O139 isolates was reported over the years 2011–2020 which represents a decrease in 2001–2010 (p < 0.05).

Conclusions

Fluoroquinolones, gentamicin, ceftriaxone, doxycycline, kanamycin, and cefotaxime showed the highest effectiveness and the lowest resistance rate. However, the main interest is the rise of antimicrobial resistance in V. cholerae strains especially in low-income countries or endemic areas, and therefore, continuous surveillance, careful appropriate AST, and limitation on improper antibiotic usage are crucial.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-022-01100-3.

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.

Diagnosis, Management, and Future Control of Cholera

Cholera, caused by Vibrio cholerae, persists in developing countries due to inadequate access to safe water, sanitation, and hygiene. There are approximately 4 million cases and 143,000 deaths each year due to cholera. The disease is transmitted fecally-orally via contaminated food or water. Severe dehydrating cholera can progress to hypovolemic shock due to the rapid loss of fluids and electrolytes, which requires a rapid infusion of intravenous (i.v.) fluids. The case fatality rate exceeds 50% without proper clinical management but can be less than 1% with prompt rehydration and antibiotics. Oral cholera vaccines (OCVs) serve as a major component of an integrated control package during outbreaks or within zones of endemicity. Water, sanitation, and hygiene (WaSH); health education; and prophylactic antibiotic treatment are additional components of the prevention and control of cholera. The World Health Organization (WHO) and the Global Task Force for Cholera Control (GTFCC) have set an ambitious goal of eliminating cholera by 2030 in high-risk areas.

Cell Wall Biology of Vibrio cholerae

Most bacteria are protected from environmental offenses by a cell wall consisting of strong yet elastic peptidoglycan. The cell wall is essential for preserving bacterial morphology and viability, and thus the enzymes involved in the production and turnover of peptidoglycan have become preferred targets for many of our most successful antibiotics. In the past decades, Vibrio cholerae, the gram-negative pathogen causing the diarrheal disease cholera, has become a major model for understanding cell wall genetics, biochemistry, and physiology. More than 100 articles have shed light on novel cell wall genetic determinants, regulatory links, and adaptive mechanisms. Here we provide the first comprehensive review of V. cholerae's cell wall biology and genetics. Special emphasis is placed on the similarities and differences with Escherichia coli, the paradigm for understanding cell wall metabolism and chemical structure in gram-negative bacteria.

Occurrence of Virulence and Antimicrobial Resistance Determinants in Vibrio harveyi Isolated from Marine Food Fish Cultured in Korea

Vibrio harveyi is a significant cause of infection in both marine animals and humans. It has been reported frequently in seafood-borne infections worldwide. This study was conducted to determine the potential health impact of the V. harveyi isolated from marine food fish cultured in Korea concerning their virulence and antimicrobial resistance. A total of 49 V. harveyi samples were isolated by biochemical tests and multiplex PCR. Phenotypic detection of virulence factors resulted DNase activity (81.63%), hemolysis (α = 75.51% and β = 12.25), gelatinase activity (71.43%), protease production (71.43%), phospholipase activity (65.31%), and lipase production (34.69%). Virulence genes, including VPI, tlh, tdh, toxR, VAC, and ctxAB, were detected in 57.14%, 44.90%, 36.73%, 22.45%, 12.24%, and 8.16% of the isolates, respectively. Resistance to ampicillin (77.55%), oxacillin (69.39%), nalidixic acid (53.06%), amoxicillin (46.94%), oxytetracycline (46.94%), colistin sulfate (34.69%), fosfomycin (34.69%), chloramphenicol (32.65%), streptomycin (32.65%), cephalothin (28.57%), oxytetracycline (26.53%), ceftriaxone (20.41%), erythromycin (14.29%), and cefoxitin (12.24%) was detected in disc diffusion assay. Most of the isolates were classified as multidrug resistant as they scored multiple antimicrobial resistance index ≥0.2. Furthermore, antimicrobial resistance genes tetB, qnrA, intI1 (Class 1 integron integrase), aac(6')-Ib, bla_SHV, bla_CTX-M, strA-strB, tetA, aphAI-IAB, qnrC, qnrS, and bla_TEM were found in 81.63%, 67.35%, 61.22%, 46.94%, 44.90%, 44.90%, 36.73%, 18.37%, 10.20%, 10.20%, 8.16% and 6.12% of the isolates, respectively. In conclusion, the development of antimicrobial resistance among V. harveyi will ultimately reduce the efficacy of antimicrobials used for treating and can favor the development of more virulent V. harveyi strains.

Antimicrobial Resistance in endemic enteric infections in Kenya and the region, and efforts towards addressing the challenges

Resistance to commonly available antimicrobials is a major threat to the fight against endemic bacterial diseases in sub-Saharan Africa, with a majority of the population unable to afford alternative effective antimicrobial options for management of these diseases. Diseases such as typhoid, cholera, and invasive nontyphoidal Salmonella are among the key enteric infections endemic in most parts of sub-Saharan Africa, especially in displaced populations and among the urban populations living in overcrowded informal settlements. Here, we explore the prevalence and the genomic epidemiology of these infections and the growing problem of multidrug resistance, including emerging resistance to the last line of treatment for these infections. Prevalence rates to commonly available antimicrobials, including ampicillin, chloramphenicol, cotrimoxazole, and tetracycline, now range between 65% and 80%, while 15%–20% of recently studied isolates show reduced susceptibility to fluoroquinolones and emerging resistance to extended-spectrum β-lactams mediated by the CTX-M-15 gene carried on a highly mobile genetic element. The high prevalence of multidrug-resistant isolates including resistance to reserve antibiotics, calls for enhanced control and management options. It will be important for governments in the region to enhance the implementation of national action plans, as guided by the global action plan championed by the World Health Organization, to combat the threat of antimicrobial resistance. However, to yield meaningful results, these efforts will require a strong commitment and enhancement at all levels of healthcare in order. In addition, the use of World Health Organization–approved vaccines in the short to medium term and improvement of water and sanitation in the long term will reduce the burden of disease and antimicrobial resistance in the region.

Antimicrobial Prescribing during Infant Hospital Admissions in a Birth Cohort in Dhaka, Bangladesh

Empirical antimicrobial use is common in hospitalized infants and may contribute to antimicrobial resistance in low- and middle-income countries. In this observational birth cohort study nested in a randomized controlled trial in Dhaka, Bangladesh, inpatient antimicrobial prescription data were extracted from serious adverse event forms completed for hospitalizations of infants (0-12 months of age). The primary outcome was the proportion of inpatient admissions where systemic antimicrobials were prescribed. Infant and hospitalization-related factors associated with antimicrobial prescriptions were determined. Among 1254 infants, there were 448 admissions to 32 facilities from 2014 to 2016. Antimicrobials were prescribed in 73% of admissions with a mean antimicrobial exposure rate of 0.25 antimicrobials per day of admission [95% confidence intervals (95% CIs): 0.24-0.27]. The most common antibiotics were aminoglycosides (29%), penicillins (26%) and third-generation cephalosporins (25%). In all, 58% of antibiotics were classified as 'access', 38% 'watch' and 1% 'reserve' using the World Health Organization (WHO) Essential Medicines List classification. WHO-recommended antimicrobial regimens were used in 68% of neonatal sepsis and 9% of lower respiratory tract infection (LRTI) admissions. 'Watch' antimicrobials were used in 26% of neonatal sepsis and 76% of LRTI admissions. Compared with private facilities, antimicrobial prescription rates were lower at government [rate ratio (RR) 0.71; 95% CI: 0.61-0.83] and charitable facilities (RR 0.39; 95% CI: 0.28-0.53), after adjustment for household wealth index and parental education. Younger infant age, older maternal age and longer admission were associated with higher prescription rates. These findings highlight the need for paediatric antimicrobial stewardship programs in Bangladesh.

Clinical and socio-environmental determinants of multidrug-resistant vibrio cholerae 01 in older children and adults in Bangladesh

Objectives:

Few studies have evaluated determinants of multidrug-resistant (MDR) Vibrio cholerae O1 in older children and adults. This study aimed to characterize the prevalence of MDR V. cholerae O1 and associated risk factors among patients over five years of age in Bangladesh.

Methods:

Stool culture and antimicrobial susceptibility testing were performed as a part of a larger study at Dhaka Hospital in Bangladesh from March 2019–March 2020. Univariate statistics and multiple logistic regression were used to assess the association between a range of variables and MDR V. cholerae O1.

Results:

MDR was found in 175 of 623 (28.1%) V. cholerae O1 isolates. High levels of resistance were found to erythromycin (99.2%), trimethoprim-sulfamethoxazole (99.7%), and ampicillin (88.9%), while susceptibility was high to tetracyclines (99.7%), azithromycin (99.2%), ciprofloxacin (99.8%), and cephalosporins (98.6%). MDR was associated with prior antibiotic use, longer transport time to hospital, higher income, non-flush toilet use, greater stool frequency, lower blood pressure, lower mid-upper arm circumference, and lower percent dehydration.

Conclusions:

MDR V. cholerae O1 was common among patients over five in an urban hospital in Bangladesh. Significant factors associated with MDR may be actionable in identifying patients with a high likelihood of MDR.

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.

High genetic diversity of Vibrio parahaemolyticus isolated from tidal water and mud of southern coast of South Korea

A horizontal, fluorophore-enhanced, repetitive extragenic palindromic-polymerase chain reaction (rep-PCR) DNA fingerprinting technique was adapted to examine the genotypic richness and source differentiation of Vibrio parahaemolyticus (n = 1749) isolated from tidal water and mud of southern coast of South Korea. The number of unique genotypes observed from June (163, 51.9%), September (307, 63.9%), December (205, 73.8%) and February (136, 74.7%), indicating a high degree of genetic diversity. Contrary, lower genetic diversity was detected in April (99, 46.8%), including predominant genotypes comprised >30 V. parahaemolyticus isolates. Jackknife analysis indicated that 65.1% tidal water isolates and 87.1% mud isolates were correctly assigned to their source groups. Sixty-nine isolates of pathogenic V. parahaemolyticus were clustered into two groups, separated by sampling month, source of isolation and serogroups. Serotypes O1, O4, O5, O10/O12 and O11 were the dominant serovariants, while serotypes O3/O13 were highly detected in April where there were no pathogenic V. parahaemolyticus isolates. Most of the V. parahaemolyticus isolates were resistant to ampicillin, ceftazidime and sulfamethoxazole. Interestingly, four V. parahaemolyticus isolates resistant to carbepenem did not contain the known carbapenemase-encoding gene, but possess an extended-spectrum β-lactamase blaTEM.

Prevalence of Vibrio cholerae in Coastal Alternative Supplies of Drinking Water and Association with Bacillus-Like Spore Formers

The scarcity of hygienic drinking water is a normal phenomenon in the coastal areas of Bangladesh due to the high salinity of ground water. The inhabitants of this locality, therefore, live on alternative supplies of water including rain-fed pond water, and rainwater with persistent complex microbial interactions therein, often contaminated with life-threatening pathogens. Hence, this study was aimed at analyzing the prevalence of Vibrio cholerae (Vc) in the alternative drinking waters of Mathbaria, a coastal subdistrict neighboring the Bay of Bengal, the efficacy of pond sand filter (PSF) and the co-association among Bacillus-like spore formers (Sf) and Vc. Vc presumably entrapped into the membrane filter was enriched in alkaline peptone water medium and was isolated on selective thiosulfate-citrate-bile salts-sucrose and taurocholate-tellurite-gelatin agar media. They were finally identified by immunochromatographic one step rapid test and serology test. A total of 26% Vc positive samples were obtained out of 100 [ponds—48, household (HH)—29, and PSFs—23] where 13% cases were pathogenic (Vc O1) and 13% were non-pathogenic (Vc non-O1/non-O139). The distribution of Vc as observed was 33, 26, and 13.8% in waters derived from pond surface, PSF, and HH reservoirs, respectively, and for pathogenic type, it was 62.5%, 50%, and nil, respectively. Although none of the samples was identified with pathogenic Vc O139, the statistics represents a significant and augmentative risk of cholera outbreak in the focused area. The antibiotic sensitivity pattern in this study resembled the trend observed during last few years for Vc. The PSF demonstrated its inability to remove Vc from any of the samples and in addition, the filter itself was evidenced to be the source of pathogens and spores in further contamination and transmission. The development of biofilm in the PSF could be hypothesized as the reservoir in contaminating pathogen-free water samples. From the test of homogeneity, the risk levels of alternative water sources were estimated equal regarding Vc. Simultaneously, it was determined statistically that the prevalence of Vc, by no means, is influenced by Bacillus-like Sf be it for pond surface, HH, or PSF derived water.

Genomic history of the seventh pandemic of cholera in Africa

The seventh cholera pandemic has heavily affected Africa, although the origin and continental spread of the disease remain undefined. We used genomic data from 1070 Vibrio cholerae O1 isolates, across 45 African countries and over a 49-year period, to show that past epidemics were attributable to a single expanded lineage. This lineage was introduced at least 11 times since 1970, into two main regions, West Africa and East/Southern Africa, causing epidemics that lasted up to 28 years. The last five introductions into Africa, all from Asia, involved multidrug-resistant sublineages that replaced antibiotic-susceptible sublineages after 2000. This phylogenetic framework describes the periodicity of lineage introduction and the stable routes of cholera spread, which should inform the rational design of control measures for cholera in Africa.

Antimicrobial Susceptibility among Urban Wastewater and Wild Shellfish Isolates of Non-O1/Non-O139 Vibrio cholerae from La Rance Estuary (Brittany, France)

The early 2000s marked the end of the Golden age of the antibiotics and the beginning of the awareness on the potential threat to human health due to the dissemination of antimicrobial resistance. As a base-line study, we investigated the antimicrobial susceptibility of 99 strains of non-O1/non-O139 Vibrio cholerae isolated from wastewater and shellfish in 2000/2001 within La Rance estuary (Brittany, France). All isolates were susceptible to amoxicillin-clavulanic acid, cefotaxime, imipenem, chloramphenicol, nalidixic acid, ciprofloxacin, norfloxacin, amikacin, gentamicin, tetracycline, doxycycline, trimethoprim-sulfamethoxazole, and erythromycin. The only resistances were to streptomycin, sulfonamides and ampicillin: 54.6% of the isolates had acquired resistance to at least one antimicrobial agent among them and only six isolates from cockles were multidrug resistant. On the basis of the distribution of a limited selection of resistance associated genes, our study shows that V. cholerae can constitute an environmental reservoir for these genes. However, none of our isolates harbored integron. This result casts doubt on the capacity of non-O1/non-O139 V. cholerae to acquire resistance-associated genes in such context, and on its potential role of indicator of the dissemination of antimicrobial resistance in the aquatic environment.