Prevalence and relatedness of Escherichia coli O157:H7 strains in the feces and on the hides and carcasses of U.S. meat goats at slaughter

Antimicrobial Resistance Characteristics of Fecal Escherichia coli and Enterococcus Species in U.S. Goats: 2019 National Animal Health Monitoring System Enteric Study

Escherichia coli and Enterococcus species are normal bacteria of the gastrointestinal tract and serve as indicator organisms for the epidemiology and emergence of antimicrobial resistance in their hosts and the environment. Some E. coli serovars, including E. coli O157:H7, are important human pathogens, although reservoir species such as goats remain asymptomatic. We describe the prevalence and antimicrobial resistance of generic E. coli, E. coli O157:H7, and Enterococcus species collected from a national surveillance study of goat feces as part of the National Animal Health Monitoring System (NAHMS) Goat 2019 study. Fecal samples were collected from 4918 goats on 332 operations across the United States. Expectedly, a high prevalence of E. coli (98.7%, 4850/4915) and Enterococcus species (94.8%, 4662/4918) was found. E. coli O157:H7 prevalence was low (0.2%; 10/4918). E. coli isolates, up to three per operation, were evaluated for antimicrobial susceptibility and 84.7% (571/674) were pansusceptible. Multidrug resistance (MDR; ≥3 classes) was uncommon among E. coli, occurring in 8.2% of isolates (55/674). Resistance toward seven antimicrobial classes was observed in a single isolate. Resistance to tetracycline alone (13.6%, 92/674) or to tetracycline, streptomycin, and sulfisoxazole (7.0% 47/674) was the most common pattern. All E. coli O157:H7 isolates were pansusceptible. Enterococcus isolates, up to four per operation, were prioritized by public health importance, including Enterococcus faecium and Enterococcus faecalis and evaluated. Resistance to lincomycin (93.8%, 1232/1313) was most common, with MDR detected in 29.5% (388/1313) of isolates. The combination of ciprofloxacin, lincomycin, and quinupristin resistance (27.1%, 105/388) was the most common pattern detected. Distribution and characteristics of antimicrobial resistance in E. coli and Enterococcus in the U.S. goat population from this study can inform stewardship considerations and public health efforts surrounding goats and their products.

Antimicrobial Susceptibility Profile of Pathogenic and Commensal Bacteria Recovered from Cattle and Goat Farms

The use of antibiotics in food animals results to antimicrobial resistant bacteria that complicates the ability to treat infections. The purpose of this study was to investigate the prevalence of pathogenic and commensal bacteria in soil, water, manure, and milk from cattle and goat farms. A total of 285 environmental and 81 milk samples were analyzed for Enterobacteriaceae by using biochemical and PCR techniques. Susceptibility to antibiotics was determined by the Kirby-Bauer disk diffusion technique. A total of 15 different Enterobacteriaceae species were identified from goat and cattle farms. Manure had significantly higher (p < 0.05) Enterobacteriaceae (52.0%) than soil (37.2%), trough water (5.4%), and runoff water (5.4%). There was a significant difference (p < 0.05) in Enterobacteriaceae in goat milk (53.9%) and cow milk (46.2%). Enterobacteriaceae from environment showed 100% resistance to novobiocin, erythromycin, and vancomycin E. coli O157:H7, Salmonella spp., Enterococcus spp., and Listeria monocytogenes displayed three, five, six, and ten. AMR patterns, respectively. NOV-TET-ERY-VAN was the most common phenotype observed in all isolates. Our study suggest that cattle and goat farms are reservoirs of multidrug-resistant bacteria. Food animal producers should be informed on the prudent use of antimicrobials, good agricultural practices, and biosecurity measures.

Shiga toxin (stx) encoding genes in sheep and goats reared in Trinidad and Tobago

Shiga toxin-producing Escherichia coli (STEC) is estimated to cause over two million cases of human disease annually. Trinidad and Tobago is one of the largest livestock producer and consumer of sheep and goat meat in the Caribbean, however, the potential role of these animals in the epidemiology of STEC infections has not been previously described. To fill this critical gap in knowledge, the prevalence of Shiga toxin genes (stx1 and stx2) shed in the faeces of healthy sheep (n = 204) and goats (n = 105) in Trinidad was investigated. Based on PCR screening, goats had a higher stx prevalence than sheep (46% vs 35%, P = 0.06). Most of the recovered STEC isolates were positive for stx1 only; and only three isolates were positive for the eae gene. None of the recovered isolates belonged to the O157 serogroup. In both species, the prevalence of stx was higher in young animals versus older animals. Sheep reared on deep litter flooring (43%) had a higher prevalence than sheep reared other flooring types, however this was not the same for goats. The presence of cows on the same premise was not an associated predictor for STEC carriage in sheep or goats. This study demonstrates that although sheep and goats in Trinidad are reservoirs for stx-positive E. coli isolates, no fecal samples tested positive for O157 STEC, harbored. Furthermore, it appears that non-O157 stx-positive isolates harbored by these animals do not pose a significant threat to human health.

Investigation of Escherichia coli O157 and Listeria monocytogenes presence and antibiotic susceptibility isolated from ruminant feces and feeds in Balikesir province

In this study, which was conducted for the first time in Balıkesir, it was purposed to determine the existense, virulence factors and antibiotic susceptibility of Escherichia coli O157, which is zoonotic in ruminant feces and feed, and the pathogen Listeria monocytogenes, which causes diseases in humans and animals, and to use these results as epidemiological data in our province, region and country. Feces and animal feed samples were analyzed simultaneously for in order of E. coli O157 and L. Monocytogenes according to ISO 16654: 2001 / Amd 1: 2017 and ISO 11290-1. 38 E.coli O157 was isolated from a total of one hunderd stool samples. 18 L. monocytogenes were isolated from a total of one hunderd stool samples. 6 L. monocytogenes were isolated from 50 silage samples. Three of these isolates were isolated from faeces and silage samples taken from the same farm with L. monocytogenes isolates isolated from sheep feces. E. coli O157 could not be isolated from a total of 100 silage and feed samples. All L. monocytogenes isolates were susceptible to sulfamethoxazole / trimethoprim, tetracycline, streptomycin, meropenem and erythromycin. The highest resistance was detected against Sulbactam / ampicillin. 3 E. coli O157 isolates were found resistant to Gentamicin and 7 isolates to Tobramycin. 21 isolates were resistant to erythromycin, and 12 isolates were intermediate. According to PCR results of fliCH7, Stx1, Stx2, eaeA and EhlyA genes, EhlyA gene was found in 20 E. coli O157 isolates. Of these isolates, 4 were isolated from sheep feces and 16 from calf feces. The stx1 gene was found in a total of 5 E. coli O157 isolates, one from sheep feces and four from calf feces. EhlyA gene was also found in all isolates with stx1 gene. The stx2 gene was found in a total of 3 E. coli O157 isolates, one from sheep dung and two from calf dung. Intimin gene was found in 8 E. coli O157 isolates, two of which are sheep faeces and six calf faecal isolates. EhlyA gene was found in all isolates with intimin gene. In this study, enterohaemolysin is the predominant virulence factor among the isolates. Epidemiologically, silage was thought to be the main source of L. monocytogenes contamination, and recently, silage contamination continued in Balikesir.

Antibacterial effect of silver nanoparticles on antibiotic resistant E. coli O157:H7 isolated from some dairy products

Food safety is a worldwide health goal so foodborne diseases are a main health concern. A total 150 of dairy products samples (locally made yoghurt, ice cream and Talaga cheese) (50 for each type) were examined for E.coli O157:H7 detection and PCR confirmation using fliCH7 gene. E. coli O157:H7 was detected at 18%, 4%, 8% respectively, in samples. The isolates showed broad antibiotic resistance against vancomycin (84.6%), penicillin G (76.9%), cloxacillin (69.2%) and tetracycline (61.5%). Because of increasing number of microorganisms that are resistant to multiple antibiotics causing continuing economic losses in dairy manufacturing, there is an urgent need for development of alternative, cost-effective, and efficient antimicrobial agents to overcome antimicrobial resistance. Here, silver nanoparticle (AgNPs) solution was prepared, identified by transmission electron microscopy (TEM) with an average size 26.5 nm and examined for bactericidal activity against E. coli O157:H7 by using well diffusion assay. The mean inhibition zones of 25 and 50 µg/ml concentrations of Ag-NPs were 15.0±1.2 and 20.9±1.4 mm, respectively. In addition, the statistical analysis showed highly significant differences in the bactericidal effect of different Ag-NPs concentrations on E. coli O157:H7 strains. Bacterial sensitivity to nanoparticles is a key factor in manufacture, so nanoparticles were considered suitable for long life application in food packaging and food safety.

Susceptibility of Escherichia coli O157:H7 to Disinfectants In Vitro and in Simulated Footbaths Amended with Manure

Escherichia coli O157:H7 is a human pathogen associated with gastrointestinal disease and hemolytic uremic syndrome. Direct contact with ruminants and their feces at agritourism or livestock interaction events is a known source of transmission. Footbath use is a pathogen reduction strategy that may decrease the transmission of E. coli O157:H7 at these interactions. The efficacy of chemical disinfectants in footbaths is not well reported. Our objective was to determine the susceptibility of E. coli O157:H7 toward commonly used disinfectants in vitro and within contaminated footbaths. The minimum inhibitory concentration and the minimum bactericidal concentration (MIC and MBC) and the time-to-kill were determined in vitro for seven E. coli O157:H7 strains using five disinfectant compounds (didecyldimethylammonium chloride [DDAC], glutaraldehyde, hydrogen peroxide, phenol, and sodium hypochlorite). Time-kill assays were performed within simulated footbaths at 22°C, 37°C, and 42°C with and without organic contamination using three commercial disinfectants with similar active ingredients (0.26% Clorox^® Bleach, 0.034% Virex^® II 256, and 1% Virkon^™ S). The MBCs of disinfectants toward E. coli O157:H7 were 3.2, 625, 40, 5000, and 320 ppm of DDAC, glutaraldehyde, hydrogen peroxide, phenol, and sodium hypochlorite, respectively. At 2 × MIC, E. coli O157:H7 reached a 3 log₁₀(colony-forming unit [CFU]/mL) reduction on contact with glutaraldehyde, by 20 min with DDAC and sodium hypochlorite, and by 4 h with phenol and hydrogen peroxide. In simulated footbaths, the commercial disinfectants reduced concentrations by 3 log₁₀(CFU/mL) on contact in the absence of organic contamination, but viable E. coli O157:H7 was recovered from organically contaminated Clorox Bleach and Virex II 256 footbaths. No E. coli O157:H7 was recovered from the Virkon S footbaths after 10 min. This study highlights the ability for organic contamination to compromise the efficacy of disinfectants in footbaths and the importance of choosing an appropriate footbath disinfectant to retain the efficacy.

Animal Reservoirs of Shiga Toxin-Producing Escherichia coli

Shiga toxin-producing Escherichia coli (STEC) strains have been detected in a wide diversity of mammals, birds, fish, and several insects. Carriage by most animals is asymptomatic, thus allowing for dissemination of the bacterium in the environment without detection. Replication of the organism may occur in the gastrointestinal tract of some animals, notably ruminants. Carriage may also be passive or transient, without significant amplification of bacterial numbers while in the animal host. Animals may be classified as reservoir species, spillover hosts, or dead-end hosts. This classification is based on the animal's ability to (i) transmit STEC to other animal species and (ii) maintain STEC infection in the absence of continuous exposure. Animal reservoirs are able to maintain STEC infections in the absence of continuous STEC exposure and transmit infection to other species. Spillover hosts, although capable of transmitting STEC to other animals, are unable to maintain infection in the absence of repeated exposure. The large diversity of reservoir and spillover host species and the survival of the organism in environmental niches result in complex pathways of transmission that are difficult to interrupt.