Escherichia coli O104 in Feedlot Cattle Feces: Prevalence, Isolation and Characterization

Abstract

Escherichia coli O104:H4, an hybrid pathotype of Shiga toxigenic and enteroaggregative E. coli, involved in a major foodborne outbreak in Germany in 2011, has not been detected in cattle feces. Serogroup O104 with H type other than H4 has been reported to cause human illnesses, but their prevalence and characteristics in cattle have not been reported. Our objectives were to determine the prevalence of E. coli O104 in feces of feedlot cattle, by culture and PCR detection methods, and characterize the isolated strains. Rectal fecal samples from a total of 757 cattle originating from 29 feedlots were collected at a Midwest commercial slaughter plant. Fecal samples, enriched in E. coli broth, were subjected to culture and PCR methods of detection. The culture method involved immunomagnetic separation with O104-specific beads and plating on a selective chromogenic medium, followed by serogroup confirmation of pooled colonies by PCR. If pooled colonies were positive for the wzxO104 gene, then colonies were tested individually to identify wzxO104-positive serogroup and associated genes of the hybrid strains. Extracted DNA from feces were also tested by a multiplex PCR to detect wzxO104-positive serogroup and associated major genes of the O104 hybrid pathotype. Because wzxO104 has been shown to be present in E. coli O8/O9/O9a, wzxO104-positive isolates and extracted DNA from fecal samples were also tested by a PCR targeting wbdDO8/O9/O9a, a gene specific for E. coli O8/O9/O9a serogroups. Model-adjusted prevalence estimates of E. coli O104 (positive for wzxO104 and negative for wbdDO8/O9/O9a) at the feedlot level were 5.7% and 21.2%, and at the sample level were 0.5% and 25.9% by culture and PCR, respectively. The McNemar’s test indicated that there was a significant difference (P < 0.01) between the proportions of samples that tested positive for wzxO104 and samples that were positive for wzxO104, but negative for wbdDO8/O9/O9a by PCR and culture methods. A total of 143 isolates, positive for the wzxO104, were obtained in pure culture from 146 positive fecal samples. Ninety-two of the 143 isolates (64.3%) also tested positive for the wbdDO8/O9/O9a, indicating that only 51 (35.7%) isolates truly belonged to the O104 serogroup (positive for wzxO104 and negative for wbdDO8/O9/O9a). All 51 isolates tested negative for eae, and 16 tested positive for stx1 gene of the subtype 1c. Thirteen of the 16 stx1-positive O104 isolates were from one feedlot. The predominant serotype was O104:H7. Pulsed-field gel electrophoresis analysis indicated that stx1-positive O104:H7 isolates had 62.4% homology to the German outbreak strain and 67.9% to 77.5% homology to human diarrheagenic O104:H7 strains. The 13 isolates obtained from the same feedlot were of the same PFGE subtype with 100% Dice similarity. Although cattle do not harbor the O104:H4 pathotype, they do harbor and shed Shiga toxigenic O104 in the feces and the predominant serotype was O104:H7.

Draft Genome Sequences of Escherichia coli O104 Strains of Bovine and Human Origin

“…A majority of O104 serotypes were non-Shiga toxigenic, and only a few strains were Shiga toxigenic, possessing stx 1c . All strains of O104 isolated from cattle feces were eae negative, similar to the German outbreak O104:H4 ( 2 ). A stx 2 -carrying O104:H21 serotype, also negative for eae , was involved in an outbreak of hemorrhagic colitis associated with the consumption of raw milk in Helena, MT, in 1994 ( 3 , 4 ).…”

“…Although cattle are a primary reservoir of STEC, E. coli O104:H4 has not been detected in cattle feces. We have reported that cattle harbor and shed O104 serotypes other than those that possess H4 ( 2 ). The predominant serotype in cattle feces was O104:H7, and other serotypes included O104:H2, O104:H11, and O104:H21 ( 2 ).…”

“…We have reported that cattle harbor and shed O104 serotypes other than those that possess H4 ( 2 ). The predominant serotype in cattle feces was O104:H7, and other serotypes included O104:H2, O104:H11, and O104:H21 ( 2 ). A majority of O104 serotypes were non-Shiga toxigenic, and only a few strains were Shiga toxigenic, possessing stx 1c .…”

Effect of pomegranate powder on the heat inactivation of Escherichia coli O104:H4 in ground chicken

“…Recent reports indicate that E. coli O104:H4 strongly adheres to the surfaces of spinach (Nagy, Xu, Bauchan, Shelton, & Nou, 2016) and is present in feedlot cattle feces (Shridhar et al, 2016), suggesting that the pathogen has the potential to contaminate produce and meat derived from food-producing animals. Related studies (Navarro-Garcia, 2014;Tietze et al, 2015) suggest that the virulent pathogen might originate from yet unknown reservoirs.…”

Experimental Infection of Calves with Escherichia coli O104:H4 outbreak strain

“…Although being fairly non-pathogenic for cattle similar to classical STEC strains, EHEC O104:H4 appear to be less well adapted to bovine intestine than classical STEC strains. EHEC O104:H4 was not yet found in cattle herds272844 but the present experimental infection study, as well as epidemiological evidence gathered in the outbreak region30, support the hypothesis that EHEC O104:H4 and probably other EAEC may be or become part of the E. coli microbiome in this livestock species and contribute to and participate in the genome plasticity through uptake and loss of virulence genes45. Future risk assessments must therefore take cattle as an animal reservoir for EHEC/EAEC hybrid strains and a potential source of transmission to humans into account.…”