Investigation into the Efficacy of Bdellovibrio bacteriovorus as a Novel Preharvest Intervention To Control Escherichia coli O157:H7 and Salmonella in Cattle Using an In Vitro Model

Abstract

Cattle are an important reservoir for the foodborne pathogens Salmonella and Escherichia coli O157:H7; they frequently harbor these microorganisms in their digestive tracts and shed them in their feces. Thus, there is potential for contamination of cattle hides and, subsequently, carcasses. Interventions aimed at reducing or eliminating pathogen shedding preharvest will also reduce the likelihood of beef product contamination by these pathogens. Therefore, this study used an in vitro model to evaluate Bdellovibrio bacteriovorus, a gram-negative microorganism that preys upon other gram-negative microorganisms, as a preharvest intervention to control Salmonella and E. coli O157:H7. Rumen fluid and feces were inoculated with pansusceptible or antimicrobial-resistant strains of one pathogen. Control samples were treated with HEPES buffer, whereas experimental samples were exposed to HEPES buffer plus B. bacteriovorus. Salmonella and E. coli O157:H7 populations were quantified at 0, 24, 48, and 72 h. The most-probable-number (MPN) technique, followed by streaking onto xylose lysine Tergitol 4 agar, was used to determine Salmonella populations, whereas spread plating onto sorbitol MacConkey agar supplemented with cefixime and tellurite was employed to enumerate E. coli O157:H7. B. bacteriovorus reduced pansusceptible Salmonella in cattle feces by 2.02 Log MPN/g (P = 0.0005) and antimicrobial-resistant Salmonella by 3.79 (P < 0.0001) and 2.24 (P = 0.0013) Log MPN/g after 24 and 48 h, respectively, in comparison to control samples. Significant reductions were not observed for E. coli O157:H7 in rumen or feces. These data suggest that further investigation into B. bacteriovorus efficacy as a preharvest intervention to control Salmonella in cattle is warranted.

The Use of Probiotic Megasphaera elsdenii as a Pre-Harvest Intervention to Reduce Salmonella in Finishing Beef Cattle: An In Vitro Model

“…An in vitro challenge model described by Page et al [ 17 ] was utilized to determine if M. elsdenii is effective at reducing Salmonella populations in the rumen and feces of cattle. This study was completed as a completely randomized design.…”

“…Ruminal fluid and feces were enumerated via the most probable number (MPN) as described by Page et al [ 17 ]. Briefly, at each time point, 10 g of each sample were homogenized in 90 mL of PW, serially diluted in 9 mL PW tubes, and used to inoculate a 3 × 7 matrix of Rappaport Vasiliadis (RV) broth.…”

“…The objective of this study is to use an in vitro challenge model previously developed by our team [ 17 ] to determine the efficacy of M. elsdenii at reducing antibiotic susceptible and resistant Salmonella populations in cattle feces and ruminal fluid. The data generated may provide preliminary information to support a larger in vivo cattle feeding trial.…”

Quinolone Signals Related to Pseudomonas Quinolone Signal-Quorum Sensing Inhibits the Predatory Activity of Bdellovibrio bacteriovorus

“…It has been reported that various QS regulatory molecules, such as acyl-homoserine lactones, quinolones, and phenazines, can interact with host cells and thereby affect various responses, including immune regulation (Liu et al, 2015). However, E. coli strains, including E. coli O157:H7 (Page et al, 2015), use indole as one of the signal molecules (Wang et al, 2001), and Dwidar et al (2015) investigated that a high concentration (2 mM) of indole inhibits the predation of E. coli by B. bacteriovorus. Since 0.25-1.1 mM indole was detected in human feces (Karlin et al, 1985;Zuccato et al, 1993), indole may help E. coli to inactivate the predatory activity of B. bacteriovorus if they grow together.…”

Таксономическая И Функциональная Характеристика Микробиоты Рубца Лактирующих Коров Под Влиянием Пробиотика Целлобактерина+

“…Представители рода Bdellovibrio, например B. bacteriovorus, -это хищные микроорганизмы, осуществляющие контроль таких патогенов, как Salmonella sp. и Escherichia coli (48).…”