Detection, Prevalence, and Pathogenicity of Non-O157 Shiga Toxin-Producing Escherichia coli from Cattle Hides and Carcasses

Proportions and Serogroups of Enterohemorrhagic Shiga Toxin-producing Escherichia coli in Feces of Fed and Cull Beef and Cull Dairy Cattle at Harvest

Cattle are considered a primary reservoir of Shiga toxin (stx)-producing Escherichia coli that cause enterohemorrhagic disease (EHEC), and contaminated beef products are one vehicle of transmission to humans. However, animals entering the beef harvest process originate from differing production systems: feedlots, dairies, and beef breeding herds. The objective of this study was to determine if fed cattle, cull dairy, and or cull beef cattle carry differing proportions and serogroups of EHEC at harvest. Feces were collected via rectoanal mucosal swabs (RAMSs) from 1,039 fed cattle, 1,058 cull dairy cattle, and 1,018 cull beef cattle at harvest plants in seven U.S. states (CA, GA, NE, PA, TX, WA, and WI). The proportion of the stx gene in feces of fed cattle (99.04%) was not significantly different (P > 0.05) than in the feces of cull dairy (92.06%) and cull beef (91.85%) cattle. When two additional factors predictive of EHEC (intimin and ecf1 genes) were considered, EHEC was significantly greater (P < 0.05) in fed cattle (77.29%) than in cull dairy (47.54%) and cull beef (38.51%) cattle. The presence of E. coli O157:H7 and five common non-O157 EHEC of serogroups O26, O103, O111, O121, and O145 was determined using molecular analysis for single nucleotide polymorphisms (SNPs) followed by culture isolation. SNP analysis identified 23.48%, 17.67%, and 10.81% and culture isolation confirmed 2.98%, 3.31%, and 3.00% of fed, cull dairy, and cull beef cattle feces to contain one of these EHEC, respectively. The most common serogroups confirmed by culture isolation were O157, O103, and O26. Potential EHEC of fourteen other serogroups were isolated as well, from 4.86%, 2.46%, and 2.01% of fed, cull dairy, and cull beef cattle feces, respectively; with the most common being serogroups O177, O74, O98, and O84. The identification of particular EHEC serogroups in different types of cattle at harvest may offer opportunities to improve food safety risk management.

Exploring Survey-Based Water, Sanitation, and Animal Associations With Enteric Pathogen Carriage: Comparing Results in a Cohort of Cases With Moderate-to-Severe Diarrhea to Those in Controls in the Vaccine Impact on Diarrhea in Africa (VIDA) Study, 2015-2018

BACKGROUND

The magnitude of pediatric enteric pathogen exposures in low-income settings necessitates substantive water and sanitation interventions, including animal feces management. We assessed associations between pediatric enteric pathogen detection and survey-based water, sanitation, and animal characteristics within the Vaccine Impact on Diarrhea in Africa case-control study.

METHODS

In The Gambia, Kenya, and Mali, we assessed enteric pathogens in stool of children aged <5 years with moderate-to-severe diarrhea and their matched controls (diarrhea-free in prior 7 days) via the TaqMan Array Card and surveyed caregivers about household drinking water and sanitation conditions and animals living in the compound. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated using modified Poisson regression models, stratified for cases and controls and adjusted for age, sex, site, and demographics.

RESULTS

Bacterial (cases, 93%; controls, 72%), viral (63%, 56%), and protozoal (50%, 38%) pathogens were commonly detected (cycle threshold <35) in the 4840 cases and 6213 controls. In cases, unimproved sanitation (RR, 1.56; 95% CI, 1.12-2.17), as well as cows (RR, 1.61; 95% CI, 1.16-2.24) and sheep (RR, 1.48; 95% CI, 1.11-1.96) living in the compound, were associated with Shiga toxin-producing Escherichia coli. In controls, fowl (RR, 1.30; 95% CI, 1.15-1.47) were associated with Campylobacter spp. In controls, surface water sources were associated with Cryptosporidium spp., Shigella spp., heat-stable toxin-producing enterotoxigenic E. coli, and Giardia spp.

CONCLUSIONS

Findings underscore the importance of enteric pathogen exposure risks from animals alongside more broadly recognized water and sanitation risk factors in children.

Epidemiology of Non-O157 Shiga Toxin-Producing Escherichia coli in the Province of Alberta, Canada, from 2018 to 2021

Non-O157 serogroups contribute significantly to the burden of disease caused by Shiga toxin-producing Escherichia coli (STEC) and have been underrecognized by traditional detection algorithms. We described the epidemiology of non-O157 STEC in Alberta, Canada for the period of 2018 to 2021. All non-O157 STEC isolated from clinical samples were submitted for serotyping and qPCR targeting the stx₁ and stx₂ genes. A total of 729 isolates were identified. Increased detection occurred over the summer months, peaking in July. Patients 18 years and younger made up 42.4% of cases, with 31.1% in those 0–9 years of age. There was a slight female predominance (399/729, 54.7%) A total of 50 different serogroups were detected; the most common were O26 (30.3%), O103 (15.9%), O111 (12.8%), O121 (11.0%), O118 (3.3%) and O71 (2.9%). These six serogroups made up 76.2% of all isolates. In total, 567 (77.8%) were positive for stx₁, 114 (15.6%) were positive for stx₂ and 48 (6.6%) were positive for both stx₁ and stx₂. A wide variety of non-O157 serogroups have been detected in Alberta, with the most frequent serogroups differing from other locations. These results highlight the need for further characterization of their virulence factors and clinical impact.

Characterization of Escherichia coli harboring colibactin genes (clb) isolated from beef production and processing systems

Certain strains of Escherichia coli possess and express the toxin colibactin (Clb) which induces host mutations identical to the signature mutations of colorectal cancer (CRC) that lead to tumorigenic lesions. Since cattle are a known reservoir of several Enterobacteriaceae including E. coli, this study screened for clb amongst E. coli isolated from colons of cattle-at-harvest (entering beef processing facility; n = 1430), across the beef processing continuum (feedlot to finished subprimal beef; n = 232), and in ground beef (n = 1074). Results demonstrated that clb⁺E. coli were present in cattle and beef. Prevalence of clb⁺E. coli from colonic contents of cattle and ground beef was 18.3% and 5.5%, respectively. clb⁺E. coli were found susceptible to commonly used meat processing interventions. Whole genome sequencing of 54 bovine and beef clb⁺ isolates showed clb occurred in diverse genetic backgrounds, most frequently in phylogroup B1 (70.4%), MLST 1079 (42.6%), and serogroup O49 (40.7%).

Molecular detection of Shiga toxin-producing Escherichia coli (STEC) O157 in sheep, goats, cows and buffaloes

BACKGROUND

Shiga toxin-producing E. coli (STEC) are important foodborne pathogens that causing serious public health consequences worldwide. The present study aimed to estimate the prevalence ratio and to identify the zoonotic potential of E. coli O157 isolates in slaughtered adult sheep, goats, cows and buffaloes.

MATERIALS AND METHODS

A total of 400 Recto-anal samples were collected from two targeted sites Rawalpindi and Islamabad. Among them, 200 samples were collected from the slaughterhouse of Rawalpindi included sheep (n = 75) and goats (n = 125). While, 200 samples were collected from the slaughterhouse of Islamabad included cows (n = 120) and buffalos (n = 80). All samples were initially processed in buffered peptone water and then amplified by conventional PCR. Samples positive for E. coli O157 were then streaked onto SMAC media plates. From each positive sample, six different Sorbitol fermented pink-colored colonies were isolated and analyzed again via conventional PCR to confirm the presence of rfbE O157 gene. Isolates positive for rfbE O157 gene were then further analyzed by multiplex PCR for the presence of STEC other virulent genes (sxt1, stx2, eae and ehlyA) simultaneously.

RESULTS

Of 400 RAJ samples only 2 (0.5%) showed positive results for E. coli O157 gene, included sheep 1/75 (1.33%) and buffalo 1/80 (1.25%). However, goats (n = 125) and cows (n = 120) found negative for E. coli O157. Only 2 isolates from each positive sample of sheep (1/6) and buffalo (1/6) harbored rfbE O157 genes, while five isolates could not. The rfbE O157 isolate (01) of sheep sample did not carry any of STEC genes, while the rfbE O157 isolate (01) of buffalo sample carried sxt1, stx2, eae and ehlyA genes simultaneously.

CONCLUSION

It was concluded that healthy adult sheep and buffalo are possibly essential carriers of STEC O157. However, rfbE O157 isolate of buffalo RAJ sample carried 4 STEC virulent genes, hence considered an important source of STEC infection to humans and environment which should need to devise proper control systems.

Differential Survival of Non-O157 Shiga Toxigenic Escherichia coli in Simulated Cattle Feedlot Runoff

Environmental survival time is important when evaluating adverse health outcomes from foodborne pathogens. Although outbreaks associated with manure-impacted irrigation or runoff water are relatively infrequent, their broad scope, regulatory importance, and severe health outcomes highlight the need to better understand the environmental survival of manure-borne pathogens. Shiga toxigenic Escherichia coli (STEC) are excreted in feces and persist in the environment until they die or recolonize a new host. Surface waters contaminated with manure-borne STEC can infect humans through drinking and recreational water use or irrigated crops that are minimally cooked. In this study, manure-impacted water microcosms mimicking beef cattle feedlot runoff were used to assess survival of STEC strains representing seven STEC serotypes (O26, O45, O103, O111, O121, O145, and O157) and persistence of target O antigen genes. Microcosms were sampled over the course of 1 year, and the entire experiment was repeated in a second year. Culture and polymerase chain reaction (PCR)-based techniques were used for detection and enumeration. Serotype-specific survival results were observed. Both STEC O26 and O45 declined slowly and remained culturable at 24 months. In contrast, STEC O121 and O145 decreased rapidly (-0.84 and -1.99 log10 abundance per month, respectively) and were unculturable by months 4 and 5, but detectable by PCR for a mean of 4.5 and 8.3 months, respectively. STEC O103, O111, and O157 remained culturable for a mean of 11.6, 5.5, and 15 months and detectable by PCR for a mean of 12, 13.8, and 18.6 months after inoculation, respectively. Results document that some STEC serotypes have the biological potential to survive in manure-impacted waters for extended periods of time when competing microflora are eliminated. Serotype-specific differences in survival of target bacteria and persistence of target genes were observed in this sample set, with STEC O26 and O45 strains appearing the most robust in these microcosm studies.

Effects of Beef Juice on Biofilm Formation by Shiga Toxin-Producing Escherichia coli on Stainless Steel

Shiga toxin-producing Escherichia coli (STEC) are a leading cause of foodborne illnesses worldwide, with beef and beef products as a common food reservoir. STEC strains may be present in beef-processing environments in the form of biofilms. The exudate of raw beef, also referred to as beef juice, has been identified as an important source of bacterial contamination on food-processing surfaces. This study applied beef juice as a food-based model to study its effects on biofilm formation of six STEC isolates on stainless steel. Crystal violet staining and cell enumeration demonstrated that beef juice inhibited the biofilm formation of strains O113, O145, and O91 up to 24 h at 22°C, but that biofilm increased (p < 0.05) thereafter over 72 h. Biofilms formed by O157, O111, and O45 were not affected by the addition of beef juice over the whole incubation period. Electron microscopy showed that the morphology of biofilm cells was altered and more extracellular matrix was produced with beef juice than with M9 medium. The present study demonstrated that beef juice residues on stainless steel can enhance biofilm formation of some STEC strains. Thorough and frequent cleaning of meat residues and exudate during meat production and handling is critical to reduce STEC biofilm formation even at 13°C.