Enterococcus spp. are opportunistic pathogens that are widely distributed in the natural environment. Two remarkable characteristics of enterococci is their intrinsic resistance against several of the antimicrobial agents routinely prescribed in the treatment of Gram-positive cocci, and their enormous capacity to acquire different genetic markers by conjugation. The aim of this study was to evaluate the prevalence of antimicrobial resistance and the frequency of tet(M) and tet(L) genes in 112 Enterococcus spp. strains isolated from food. Fifty-two strains (64%) of Enterococcus faecalis, 10 (55%) of Enterococcus faecium, 2 (66%) of Enterococcus casseliflavus and 3 (42%) of Enterococcus gallinarum showed multidrug resistance. Tet(M) gene associated with or without the tet(L) gene was the most prevalent genotype found in food. Nine erythromycin-resistant and tetracycline-susceptible enterococci strains harbor silencing tet(M) or tet(L) genes were present in our investigation. In conclusion, antibiotic-resistant enterococci current in food may act as a reservoir of resistant strains creating a potential route of genes transference by horizontal gene transfer.

Studies have highlighted the relevance of extracellular glycine and serine in supporting high growth rates of rapidly proliferating tumours. The present study analysed the role of the specific glycine transporter GLYT1 in supplying glycine to cancer cells and maintaining cell proliferation. GLYT1 knockdown in the rapidly proliferating tumour cell lines A549 and HT29 reduced the number of viable cells by approximately 30% and the replication rate presented a decrease of about 50% when compared to cells transfected with control siRNA. In contrast, when compared to control, GLYT1 siRNA had only a minimal effect on cell number of the slowly proliferating tumour cell line A498, reducing the number of viable cells by 7% and no significant difference was observed when analysing the replication rate between GLYT1 knockdown and control group. When utilising a specific GLYT1 inhibitor, ALX-5407, the doubling time of rapidly proliferating cells increased by about 8 h presenting a significant reduction in the number of viable cells after 96 h treatment when compared to untreated cells. Therefore, these results suggest that GLYT1 is required to maintain high proliferation rates in rapidly proliferating cancer cells and encourage further investigation of GLYT1 as a possible target in a novel therapeutic approach.

The Firmicutes bacteria participate extensively in virulence and pathological processes. Enterococcus faecalis is a commensal microorganism; however, it is also a pathogenic bacterium mainly associated with nosocomial infections in immunocompromised patients. Iron-sulfur [Fe-S] clusters are inorganic prosthetic groups involved in diverse biological processes, whose in vivo formation requires several specific protein machineries. Escherichia coli is one of the most frequently studied microorganisms regarding [Fe-S] cluster biogenesis and encodes the iron-sulfur cluster and sulfur assimilation systems. In Firmicutes species, a unique operon composed of the sufCDSUB genes is responsible for [Fe-S] cluster biogenesis. The aim of this study was to investigate the potential of the E. faecalis sufCDSUB system in the [Fe-S] cluster assembly using oxidative stress and iron depletion as adverse growth conditions. Quantitative real-time polymerase chain reaction demonstrated, for the first time, that Gram-positive bacteria possess an OxyR component responsive to oxidative stress conditions, as fully described for E. coli models. Likewise, strong expression of the sufCDSUB genes was observed in low concentrations of hydrogen peroxide, indicating that the lowest concentration of oxygen free radicals inside cells, known to be highly damaging to [Fe-S] clusters, is sufficient to trigger the transcriptional machinery for prompt replacement of [Fe-S] clusters.