Impact of Raised without Antibiotics Measures on Antimicrobial Resistance and Prevalence of Pathogens in Sow Barns.

The growing concern over the emergence of antimicrobial resistance (AMR) in animal production as a result of extensive and inappropriate antibiotic use has prompted many swine farmers to raise their animals without antibiotics (RWA). In this study, the impact of implementing an RWA production approach in sow barns on actual on-farm antibiotic use, the emergence of AMR, and the abundance of pathogens was investigated. Over a 13-month period, fecal and nasopharynx samples were collected at 3-month intervals from sows raised in RWA barns and sows in conventional barns using antibiotics in accordance with the new regulations (non-RWA).

Piglet Gut and in-Barn Manure from Farms on a Raised without Antibiotics Program Display Reduced Antimicrobial Resistance but an Increased Prevalence of Pathogens.

In response to new stringent regulations in Canada regarding the use of antibiotics in animal production, many farms have implemented practices to produce animals that are raised without antibiotics (RWA) from birth to slaughter. This study aims to assess the impact of RWA production practices on reducing the actual total on-farm use of antibiotics, the occurrence of pathogens, and the prevalence of antimicrobial resistance (AMR). A 28-month longitudinal surveillance of farms that adopted the RWA program and conventional farms using antibiotics in accordance with the new regulations (non-RWA) was conducted by collecting fecal samples from 6-week-old pigs and composite manure from the barn over six time points and applying whole-genome sequencing (WGS) to assess the prevalence of AMR genes as well as the abundance of pathogens.

A health metadata-based management approach for comparative analysis of high-throughput genetic sequences for quantifying antimicrobial resistance reduction in Canadian hog barns.

New Canadian regulations have required that all use of antibiotics in livestock animal production should be under veterinary prescription and oversight, while the prophylactic use and inclusion of these agents in animal feed as growth promoters are also banned. In response to this new rule, many Canadian animal producers have voluntarily implemented production practices aimed at producing animals effectively while avoiding the use of antibiotics. In the swine industry, one such program is the 'raised without antibiotics' (RWA) program.

Microscale and molecular analyses of river biofilm communities treated with microgram levels of cerium oxide nanoparticles indicate limited but significant effects.

Cerium oxide (CeO) nanoparticles are used as in-fuel catalysts and in manufacturing processes, creating a potential for release to aquatic environments. Exposures at 1 and 10 μg/L CeO-nanoparticles were made to assess effects during the development of river biofilm communities. Scanning transmission x-ray microscopy (STXM) indicated extensive sorption of nanoparticles to the community and co-localization with lipid moieties.

Role of CpxR in Biofilm Development: Expression of Key Fimbrial, O-Antigen and Virulence Operons of Enteritidis.

Enteritidis is a non-typhoidal serovar of great public health significance worldwide. The RpoE sigma factor and CpxRA two-component system are the major regulators of the extracytoplasmic stress response. In this study, we found that the CpxR has highly significant, but opposite effects on the auto-aggregation and swarming motility of .

Growth and Virulence of Typhimurium Mutants Deficient in Iron Uptake.

The present study investigated the effects of iron, iron chelators, and mutations of or genes on the growth and virulence of Typhimurium Results indicated that organic iron (ferric citrate and ferrous-l-ascorbate) supported better growth of compared to inorganic iron. Among tested chelators, 2,2'-bipyridyl at 500 μM showed the highest inhibition of growth with 5 μM ferrous sulfate. Deletion of genes ( and ) in the iron uptake system attenuated invasion of Caco-2 cells and its ability to damage the epithelial monolayer.

Regulation of by PhoB during P Starvation Promotes Biofilm Formation by Escherichia coli O157:H7.

In open environments such as water, enterohemorrhagic O157:H7 responds to inorganic phosphate (P) starvation by inducing the Pho regulon controlled by PhoB. This activates the phosphate-specific transport (Pst) system that contains a high-affinity P transporter. In the Δ mutant, PhoB is constitutively activated and regulates the expression of genes in the Pho regulon.

Growth of Salmonella enterica Serovars Typhimurium and Enteritidis in Iron-Poor Media and in Meat: Role of Catecholate and Hydroxamate Siderophore Transporters.

Enteritidis and Typhimurium are among the top Salmonella enterica serovars implicated in human salmonellosis worldwide. This study examined the individual and combined roles of catecholate-iron and hydroxamate-iron transporters in the survival in meat of Salmonella Enteritidis and Typhimurium. Catecholate-iron-III (Fe) and hydroxamate-Fe transporter genes fepA, iroN, and fhuACDB were deleted in isolates of these serovars to generate single, double, and triple mutants.

Staphylococcus aureus Inhibits IL-8 Responses Induced by Pseudomonas aeruginosa in Airway Epithelial Cells.

Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) are major respiratory pathogens and can concurrently colonize the airways of patients with chronic obstructive diseases, such as cystic fibrosis (CF). Airway epithelial cell signalling is critical to the activation of innate immune responses. In the setting of polymicrobial colonization or infection of the respiratory tract, how epithelial cells integrate different bacterial stimuli remains unknown.

Interplay between genetic regulation of phosphate homeostasis and bacterial virulence.

Bacterial pathogens, including those of humans, animals, and plants, encounter phosphate (Pi)-limiting or Pi-rich environments in the host, depending on the site of infection. The environmental Pi-concentration results in modulation of expression of the Pho regulon that allows bacteria to regulate phosphate assimilation pathways accordingly. In many cases, modulation of Pho regulon expression also results in concomitant changes in virulence phenotypes.

PhoB activates Escherichia coli O157:H7 virulence factors in response to inorganic phosphate limitation.

Enterohemorrhagic Escherichia coli (EHEC), an emerging food- and water-borne hazard, is highly pathogenic to humans. In the environment, EHEC must survive phosphate (Pi) limitation. The response to such Pi starvation is an induction of the Pho regulon including the Pst system that senses Pi variation.

Shiga toxins decrease enterohaemorrhagic Escherichia coli survival within Acanthamoeba castellanii.

Enterohaemorrhagic Escherichia coli (EHEC) are zoonotic pathogens transmitted to humans through contaminated water or bovine products. One of the strategies used by pathogenic bacteria to survive in aquatic environments is using free-living amoebae as hosts. Acanthamoeba castellanii is an amoeba known to host several waterborne pathogens.

The ecological habitat and transmission of Escherichia coli O157:H7.

Since its first description in 1982, the zoonotic life-threatening Shiga toxin-producing Escherichia coli O157:H7 has emerged as an important food- and water-borne pathogen that causes diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome in humans. In the last decade, increases in E. coli O157:H7 outbreaks were associated with environmental contamination in water and through fresh produce such as green leaves or vegetables.

Survival of enterohemorrhagic Escherichia coli in the presence of Acanthamoeba castellanii and its dependence on Pho regulon.

Enterohemorrhagic Escherichia coli (EHEC) are involved in outbreaks of food-borne illness and transmitted to humans through bovine products or water contaminated by cattle feces. Microbial interaction is one of the strategies used by pathogenic bacteria to survive in the environment. Among protozoa, the free-living amoebae are known to host and protect several water-borne pathogens.