Dispersion of the Vancomycin Resistance Genes vanA and vanC of Enterococcus Isolated from Nile Tilapia on Retail Sale: A Public Health Hazard

Abstract

Although normally regarded harmless commensals, enterococci may cause a range of different infections in humans, including urinary tract infections, sepsis, and endocarditis. The acquisition of vancomycin resistance by enterococci (VRE) has seriously affected the treatment and infection control of these organisms. VRE are frequently resistant to all antibiotics that are effective treatment for vancomycin-susceptible enterococci, which leaves clinicians treating VRE infections with limited therapeutic options. With VRE emerging as a global threat to public health, we aimed to isolate, identify enterococci species from tilapia and their resistance to van-mediated glycopeptide (vanA and vanC) as well as the presence of enterococcal surface protein (esp) using conventional and molecular methods. The cultural, biochemical (Vitek 2 system) and polymerase chain reaction results revealed eight Enterococcus isolates from the 80 fish samples (10%) to be further identified as E. faecalis (6/8, 75%) and E gallinarum (2/8, 25%). Intraperitoneal injection of healthy Nile tilapia with the eight Enterococcus isolates caused significant morbidity (70%) within 3 days and 100% mortality at 6 days post-injection with general signs of septicemia. All of the eight Enterococcus isolates were found to be resistant to tetracycline. The 6/6 E. faecalis isolates were susceptible for penicillin, nitrofurantoin, gentamicin, and streptomycin. On the other hand 5/6 were susceptible for ampicillin, vancomycin, chloramphenicol, and ciprofloxacin. The two isolates of E. gallinarum were sensitive to rifampicin and ciprofloxacin and resistant to vancomycin, chloramphenicol, and erythromycin. Molecular characterization proved that they all presented the prototypic vanC element. On the whole, one of the two vancomycin resistance gene was present in 3/8 of the enterococci isolates, while the esp virulence gene was present in 1/8 of the enterococci isolates. The results in this study emphasize the potential role that aquatic environments are correlated to proximity to anthropogenic activities in determining the antimicrobial resistance patterns of Enterococcus spp. recovered from fish in the river Nile in Giza, Elmounib, Egypt as a continuation of our larger study on the reservoirs of antibiotic resistance in the environment.

Bacteriological, molecular, and pathological studies on the Gram‐positive bacteria Aerococcus viridans and Enterococcus faecalis and their effects on Oreochromis niloticus in Egyptian fish farms

“…With regard to the pathogenicity test, the clinical signs in our results appeared within 14 days after intraperitoneal injection of O. niloticus by E. faecalis , which resulted in 91.66% morbidity and 83.33% mortality. This finding was nearly identical to the results of Osman et al (2016), who recorded 100% mortality in O. niloticus 6 days of injection with E. faecalis . In our study, fish injected with A. viridans showed a mortality of 91.66%, which is in close agreement with the study by Ke et al (2012), who recorded 85% mortality within 14 days postinjection with the same bacteria.…”

Molecular epidemiology and mechanisms of antibiotic resistance inEnterococcusspp.,Staphylococcusspp., andStreptococcusspp. in Africa: a systematic review from a One Health perspective

“…isolated from chicken, ducks, pigs, fish, and raw milk cheese. VanA ( n = 23), vanB ( n = 27), vanC ( n = 38), and tet (M) ( n = 6) were the dominant resistance genes; Tn 916 ( n = 7) was the MGE detected.…”

Molecular Identification of Vancomycin Resistance and Virulence Genes in Foodborne Enterococci

“…Chajecka-Wierzchowska et al (2016) also reported the presence of vanC2/3 genes in E. casseliflavus isolates from ready-to-eat meat products but not vanC1 gene. Moreover, a study in Egypt demonstrated vanC gene carrying E. gallinarum and E. faecalis strains from fish samples (Osman et al, 2016). Conversely, lack of vanC gene in animal originated food was recently reported by Yilmaz et al (2016) in Turkey and by Gousia et al (2015) in Greece.…”

“…Another work revealed the presence of vanA gene in three vancomycin-susceptible E. faecalis isolates and one E. hirae isolate (Perin et al 2014). Osman et al (2016) and Harada et al (2012) detected vanA gene in one E. faecalis strain from fish and one E. cecorum strain from poultry samples, respectively. Contrary results were reported by Kasımoğlu-Doğru et al (2010) and Chajecka-Wierzchowska et al (2016).…”