Exploring the antimicrobial effects of a phenolic-rich extract from jabuticaba depulping waste against enterotoxigenic Escherichia coli.

This study evaluated the effects of a phenolic-rich extract from jabuticaba [Myrciaria jaboticaba (Vell.) Berg] depulping waste (PEJ) on the survival, antibiotic susceptibility, virulence, and cellular functions of various enterotoxigenic Escherichia coli (ETEC) strains. The minimum inhibitory concentration of PEJ against the five tested ETEC strains was 125 mg mL-1. PEJ at 125 and 250 mg mL-1 caused reductions in viable cell counts of ≥ 3 and ≥ 5 log CFU mL-1 in ETEC over 24 h, respectively. PEJ at subinhibitory concentrations (31.25 and 62.5 mg mL-1) reduced the viable cell counts of ETEC when exposed to in vitro gastrointestinal conditions, besides decreasing the biofilm formation, cell surface hydrophobicity, mucin adhesion, and swimming and swarming motility. PEJ (31.25 and 62.5 mg mL-1) increased the susceptibility of the tested ETEC strains to various clinically relevant antibiotics. The exposure to PEJ (62.5 and 125 mg mL-1) impaired the membrane permeability and enzymatic and efflux pump activities in ETEC cells. PEJ effectively reduces survival, increases antibiotic susceptibility, and attenuates virulence in ETEC. These effects could be linked to a PEJ multi-target action disturbing various cellular functions in ETEC cells. PEJ could be a candidate for developing innovative solutions to prevent and treat ETEC infections.

Pig vaccination strategies based on enterotoxigenic Escherichia coli toxins.

Enterotoxigenic Escherichia coli (ETEC) are responsible for diarrhea in humans as well as in farm animals. ETEC infections in newborn, suckling, and especially in post-weaning piglets are associated with reduced growth rate, morbidity, and mortality. ETEC express virulence factors as adhesin and enterotoxins that play a central role in the pathogenic process. Adhesins associated with pigs are of diverse type being either fimbrial or non-fimbrial. Enterotoxins belong to two groups: heat-labile (LT) and heat-stable (ST). Heterogeneity of ETEC strains encompass expression of various fimbriae (F4, F5, F6, F18, and F41) and enterotoxins (LT, STa, STb, and EAST1). In the late years, attempts to immunize animals against neonatal and post-weaning diarrhea were focused on the development of anti-adhesin strategies as this is the initial step of ETEC pathogenesis. Although those vaccines demonstrated some protection against ETEC infections, as enterotoxins are pivotal to the virulence of ETEC, a new generation of vaccinal molecules, which include adhesin and one or more enterotoxins, were recently tested. Some of these newly developed chimeric fusion proteins are intended to control as well human diarrhea as enterotoxins are more or less common with the ones found in pigs. As these could not be tested in the natural host (human), either a mouse or pig model was substituted to evaluate the protection efficacy. For the advancement of pig vaccine, mice were sometimes used for preliminary testing. This review summarizes advances in the anti-enterotoxin immunization strategies considered in the last 10 years.