Abstract
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 blaCARB–7 and blaCARB–9, determinants of beta-lactam resistance and six isolates carried catB9, a determinant of phenicol resistance. Three isolates had both blaCARB–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.
Highlights
Antibiotics are supposed to be one of the most effective drugs to treat infectious diseases transmitted by bacteria (Martinez, 2009)
No gene conferring sulfonamide resistance and streptomycin for V. cholerae was found using either Comprehensive Antibiotic Resistance Database (CARD) or ResFinder databases, most of our strains were tested phenotypically resistant to these two antibiotics. These findings indicate that current databases are partly incomplete for assessing antimicrobial resistance properties of V. cholerae non-O1/non-O139 strains on genotypic characterization alone
The large Austrian lake Neusiedler See is an important bathing water with several hundred thousand visitors each year. As it is harboring an abundant and diverse natural V. cholerae non-O1/non-O139 community associated with several cases of human infection each year, the comprehensive assessment of the antimicrobial resistance properties of this pathogen is of public health concern
Summary
Antibiotics are supposed to be one of the most effective drugs to treat infectious diseases transmitted by bacteria (Martinez, 2009). Infections due to V. cholerae nonO1/non-O139 have been increasingly reported for countries of the Northern hemisphere (Newton et al, 2012; Baker-Austin et al, 2013), primarily acquired through contact by swimming in seawater (Baker-Austin et al, 2016b; Marinello et al, 2017) or freshwater lakes (Dalsgaard et al, 2000a; Ninin et al, 2000; Andersson and Ekdahl, 2006; Ottaviani et al, 2011; Dobrovic et al, 2016; Hirk et al, 2016; Kechker et al, 2017) This significant increase in the number of infections has been linked to global warming and associated increase in water temperatures (Baker-Austin et al, 2016a,b; ECDC, 2019). The Neusiedler See may serve as a bioreactor for the appearance of new strains with new (pathogenic) properties, including antibiotic resistance
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