Abstract
The aim of present study is to characterize the resistance and virulence profile of enterococci isolated from aquaculture excavated ponds and masonry tanks (6 samples) in southern Brazil. Samples were cultured in selective medium, 10 colonies were randomly selected from each sample, which were identified by MALDI-TOF and tested against 13 antimicrobials. The presence of resistance (tetL, tetM, tetS, ermB and msrC) and virulence (ace, esp, agg, cylA and gelE) genes were determined by PCR. A total of 79 enterococci were identified, and Entecococcus faecalis (44.3%) and E. casseliflavus (36.7%) were the most prevalent species isolated. Sixty-five strains (82.3%) were resistant to at least one of the antimicrobials tested, whereas 27 (34.2%) strains were multiresistant. The overall percentages of antimicrobial resistant isolates were: 58.2% to rifampicin, 40.5% to fluoroquinolones, 36.7% to erythromycin and 30.4% to tetracycline. The tetL and tetM genes were found in 57.7% of the tetracycline-resistant strains; and msrC in 31.01% of erythromycin-resistant strains. The most frequently detected virulence factors were ace and gelE genes. Although limited to a single farm, these data suggest that aquaculture may be a reservoir of resistant and virulent enterococci. This study is the first step towards enhancing our understandingof distribution, resistance and virulence profile in enterococci isolated from fish farming environments in the south Brazil.
Highlights
Aquaculture is the fastest growing sector of world foodproduction, with a growth rate of over 8.0%
The present study aims to determine the occurrence, the antimicrobial susceptibility profile and the presence of virulence genes in enterococci isolated from a fish farming environment in southern Brazil
The most common species found in our samples were E. faecalis (n = 35; 44.3%) and E. casseliflavus (n = 29; 36.7%), followed by E. faecium (n = 11; 13.9%), E. gallinarum (n = 2; 2.5%) and E. hirae (n = 2; 2.5%)
Summary
Aquaculture is the fastest growing sector of world foodproduction, with a growth rate of over 8.0%. The presence of bacterial species carrying antimicrobial resistance profile has already been detected in fish farming systems, as well as in water effluents (Novais et al, 2018). Enterococcus species are resistant to low levels of aminoglycosides, due to the decreased uptake of this antibiotic class They can transfer and acquire antibiotic resistance genes (through the transfer of plasmids and transposons, chromosomal exchange, or mutation) (Lebreton et al, 2014). This ability to transfer/acquire resistance and/or virulence genes, offer a selective advantage to Enterococcus spp. survival and dispersal in the environment (Savaşan et al, 2016). The present study aims to determine the occurrence, the antimicrobial susceptibility profile and the presence of virulence genes in enterococci isolated from a fish farming environment in southern Brazil
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