Multilocus variable-number tandem-repeat analysis (MLVA) is used for source tracking Escherichia coli O157:H7 in agricultural environments. Tandem repeats were stable after limited replication but changed after exposure to irradiation, elevated temperatures, and starvation conditions. The pO157 plasmid was frequently lost under these stress conditions. Environmental stresses may increase phylog...

Several outbreaks of Escherichia coli O157:H7 infections have been associated with minimally processed leafy vegetables in the United States. Harvesting and processing cause plant tissue damage. In order to assess the role of plant tissue damage in the contamination of leafy greens with E. coli O157:H7, the effect of mechanical, physiological, and plant disease-induced lesions on the growth of ...

The survival of Escherichia coli O157:H7 in feces from steers fed corn (CO) or barley (BA) was evaluated at -10, +4 and +22 degrees C. Fecal pats were inoculated with a four-strain mixture of nalidixic-acid resistant E. coli O157:H7 at two levels: 10(3) CFU g(-1) (low, L) and 105 CFU g(-1) (high, H). At -10 degrees C, duration of survival of E. coli O157:H7 was reduced (p < 0.05) in CO-L (35 da...

Outbreaks of Escherichia coli O157:H7 disease associated with animal exhibits have been reported with increasing frequency. Transmission can occur through contact with contaminated haircoats, bedding, farm structures, or water. We investigated the distribution and survival of E. coli O157:H7 in the immediate environments of individually housed, experimentally inoculated cattle by systematically...

This study was conducted to investigate the effect of free chlorine concentrations in wash water on Escherichia coli O157:H7 reduction, survival, and transference during washing of fresh-cut lettuce. The effectiveness of rewashing for inactivation of E. coli O157:H7 on newly cross-contaminated produce previously washed with solutions containing an insufficient amount of chlorine also was assess...

Enrichment and direct (nonenrichment) rectoanal mucosal swab (RAMS) culture techniques were developed and compared to traditional fecal culture for the detection of Escherichia coli O157:H7 in experimentally infected and naturally infected cattle. Holstein steers (n = 16) orally dosed with E. coli O157:H7 were sampled after bacterial colonization starting 15 days postinoculation. Enrichment RAM...

Rhamnolipid (RL) can inhibit biofilm formation of Escherichia coli O157:H7, but the associated mechanism remains unknown. We here conducted comparative physiological and transcriptomic analyses cultures treated with RL untreated to elucidate a potential by which may in E. O157:H7. Anti-biofilm assays showed that over 70% O157:H7 capacity was inhibited treatment 0.25–1 mg/mL RL. Cellular-level a...

A steam-vacuum sanitizer reduced aerobic plate counts associated with bovine faecal contamination from 5.5 log10 cfu cm-2 to 3.0 +/- 0.21 log10 cfu cm-2 on beef carcass short plates. The same beef carcass short plates inoculated with 7.6 +/- 0.09 log10 cfu cm-2 Escherichia coli O157:H7 in faeces, yielded an average residual level of E. coli O157:H7 of 2.1 +/- 0.21 log10 cfu cm-2, after steam-va...

We have isolated one sorbitol-nonfermenting (SNF) Escherichia coli O157:H7 isolate and five sorbitol-fermenting (SF) E. coli O157:H(-) isolates that do not contain Shiga toxin (Stx) genes (stx). Isolates originated from patients with diarrhea (n = 4) and hemolytic-uremic syndrome (HUS) (n = 2). All isolates harbored a chromosomal eae gene encoding gamma-intimin as well as the plasmid genes E-hl...

Enterohemorrhagic Escherichia coli serotype O157:H7 is a major cause of foodborne outbreaks and hemolytic-uremic syndrome. Here, we report the draft genome sequences of three antibiotic-resistant E. coli O157:H7 strains isolated from feedlot cattle. These draft genome sequences will aid in the development of sequence-based tools for the detection of virulence and antimicrobial resistance genoty...