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Volume 2

Journal of Microbiology and Biotechnology Reports

Microbial Biotechnology 2018

September 17-18, 2018

Microbial Biotechnology & Vaccine Design

September 17-18, 2018 Lisbon, Portugal

5

th

World Congress on

Shiga toxin-producing

Escherichia coli

distribution and characterization in a pasture-based cow-calf

production system

Patricia Baltasar, François Elvinger, Monica Ponder, William Swecker and Korine Kolivras

Virginia Tech, USA

Escherichia coli

is part of the normal gastrointestinal microbiota of many animals, especially cattle. While most strains are commensal,

Shiga toxin-producing

E. coli

(STEC) can cause severe human illness. Persistent carriers and environmental contamination may be

responsible for maintenance of STEC in cattle. Prevalence and distribution of

E. coli

virulence genes (stx1, stx2, hlyA and eaeA) were

assessed in a cow-calf pasture-based system. Angus cows (n=90) and their calves (n=90) were kept in three on-farm locations and

fecal samples were collected at three consecutive time-points (July through September, 2011). After enrichment, sample detection of

stx1, stx2, eaeA and hlyA was done by multiplex PCR (mPCR). Fecal samples positive for stx genes were obtained from 93.3% (84/90)

of dams and 95.6% (86/90) of calves. Age class (dam, calf) and spatial distribution of cattle and sampling time-point influenced

prevalence and distribution of virulence genes. Of 293 stx-positive fecal samples, 744

E. coli

colonies were isolated. Virulence patterns

of isolates were determined through mPCR: stx1 was present in 41.9% (312/744) of isolates, stx2 in 6.5% (48/744), eaeA in 4.2%

(31/744) and hlyA in 2.4% (18/744). Prevalence of non-O157 STEC was high among isolates: 33.8% (112/331) were O121, 3.6%

(12/331) were O103, 1.8% (6/331) were O113. One isolate (0.3%) was identified as serotype O157. Repetitive element sequence

based-PCR (rep-PCR) fingerprinting was used to study genetic diversity of stx-positive isolates. Rep-PCR fingerprints were highly

similar, supporting the hypothesis that strains are transmitted between animals, but not necessarily from a dam to its calf. Highly

similar STEC isolates were obtained at each sampling time-point, but isolates from dams were more diverse than those from calves,

suggesting that strain-to-strain differences in transfer may exist. Furthermore, fingerprints from O121 isolates closely resembled

those of test isolates from in human outbreaks.

Biography

Patricia Baltasar has an impressive background in veterinary medicine, public health and research. Her excellent analytical, communication, people skills, coupled

with a strong command of epidemiology have been critical in consistently reflecting the highest academic standards. She has a solid record of publications and

presentations and has established a sound trajectory towards a career focused in the “One Health” concept.

patbaltasar@gmail.com

Patricia Baltasar et al., J Microbio and Biotech Rept 2018, Volume 2