RESUMEN
During the ongoing western equine encephalitis virus (WEEV) outbreak in South America, we described three fatal cases in horses from Rio Grande do Sul, Brazil. We sequenced WEEV strains and identified a novel lineage causing these cases. Continued surveillance and horse immunization are needed to mitigate the WEEV burden.
RESUMEN
BACKGROUND: Studies evaluating bacteria in insects can provide information about host-microorganism-environment interactions. The gut microbial community has a profound effect on different physiological functions of insects. Enterococcus spp. are part of the gut community in humans and other animals, as well as in insects. The presence and antimicrobial resistance profile of enterococci are well studied in different animals; however, data for Heliconius erato phyllis (Lepidoptera: Nymphalidae) do not yet exist. Therefore, the aims of this study were to evaluate the distribution of enterococcal species, their antimicrobial resistance profile and virulence genes, and the genetic relationships between enterococci isolated from fecal samples from sibling and non-sibling H. erato phyllis caterpillars collected from different sites in South Brazil. METHODS: Three H. erato phyllis females were captured (two from a forest fragment and one from an urban area), and kept individually in open-air insectaries. Eggs were collected and caterpillars (siblings and non-siblings) were fed daily with Passiflora suberosa leaves. Fecal samples (n = 12) were collected from fifth-instar caterpillars, inoculated in selective medium, and 15 bacterial colonies were randomly selected from each sample. Enterococci were identified by PCR and MALDI-TOF, analyzed by disk diffusion antimicrobial susceptibility tests, and screened for resistance and virulence genes by PCR. The genetic relationships between the strains were determined using pulsed-field gel electrophoresis (PFGE). RESULTS: A total of 178 enterococci strains were identified: E. casseliflavus (74.15%; n = 132), E. mundtii (21.34%; n = 38), E. faecalis (1.12%; n = 2) and Enterococcus sp. (3.37%; n = 6). High rates of resistance to rifampicin (56%) and erythromycin (31%) were observed; 120 (67.41%) of the isolates showed resistance to at least one antibiotic and six (3.37%) were multidrug-resistant.None of the erythromycin-resistant strains was positive for the erm(B) and msrC genes. The virulence genes esp, ace, and gelE were observed in 35%, 7%, and 1% of the strains, respectively. PFGE separated the enterococci into 22 patterns, four being composed of strains from sibling caterpillars. CONCLUSION: Enterococcus casseliflavus was the dominant species in fecal samples of fifth-instar caterpillars. Resistant enterococci strains may be related to environmental pollution or the resistome. The PFGE analysis showed genetic relationships between some strains, suggesting that the enterococci isolated from fecal samples of the sibling caterpillars might have come from common sources, e.g., via diet (herbivory) and/or vertical transmission (through the egg surface). Further studies will be conducted to better understand the role of Enterococcus in the microbial community of the gastrointestinal tract of these insects, and the mechanisms involved in acquisition and maintenance of enterococci.
RESUMEN
Enterococci are ubiquitous microorganisms present in various environments and within the gastrointestinal tracts of humans and other animals. Notably, fecal enterococci are suitable indicators for monitoring antimicrobial resistance dissemination. Resistant bacterial strains recovered from the fecal samples of wild animals can highlight important aspects of environmental disturbances. In this report, we investigated antimicrobial susceptibility as well as resistance and virulence genes in fecal enterococci isolated from wild Pampas foxes (Lycalopex gymnocercus) (n = 5) and Geoffroy's cats (Leopardus geoffroyi) (n = 4) in the Brazilian Pampa biome. Enterococci were isolated from eight out of nine fecal samples and Enterococcus faecalis was identified in both animals. However, E. faecium and E. durans were only detected in Pampas foxes, while E. hirae was only detected in Geoffroy's cats. Antimicrobial susceptibility analysis showed resistance to rifampicin (94%), erythromycin (72.6%), ciprofloxacin/norfloxacin (40%), streptomycin (38%), and tetracycline (26%). The high frequency of multidrug-resistant enterococci (66%) isolated in this study is a matter of concern since these are wild animals with no history of therapeutic antibiotic exposure. The tetM/tetL and msrC/ermB genes were detected in most tetracycline- and erythromycin-resistant enterococci, respectively. The gelE, ace, agg, esp, and clyA virulence genes were also detected in enterococci. In conclusion, our data suggest that habitat fragmentation and anthropogenic activities in the Pampa biome may contribute to high frequencies of multidrug-resistant enterococci in the gut communities of wild Pampas foxes and Geoffroy's cats. To the best of the authors' knowledge, this is the first report of antimicrobial-resistant enterococci in the Pampa biome.
