Oct 2023 - Journal Final - Flipbook - Page 19
Products
How LOW should the pH Go?
An E. coli challenge.
Rachel Stika Jensen, DVM
Veterinarian
Pipestone Veterinary Services
Dr. Rachel Jensen grew up near Cresco, Iowa and attended Iowa State
University. In college, she discovered a passion for swine production
and joined PIPESTONE in 2021.
Carly Bates
2023 Veterinary Intern
Pipestone Veterinary Services
Following her veterinary internship with PIPESTONE, Carly Bates was
awarded the 2023 Morrison Swine Innovator Prize for her extraordinary
work on this project. Carly will graduate from Iowa State University in
May of 2025.
Hemolytic Escherichia Coli (E.
coli) is a challenging pathogen
due to its high morbidity and
high mortality in weaned pigs.
It causes severe diarrhea and
sudden death. Our tools to
control and reduce hemolytic E.
coli are limited and unfortunately
becoming less effective due
to antimicrobial resistance.
Acidi昀椀cation of drinking water for
swine has been shown to be an
effective tool in the prevention
and control of hemolytic E. coli.
However, the question remains,
how low should the pH go?
3pH
4pH
RESULTS
What are the results of the
study? All plates at pH of 5, 6 and
7 had noticeable surface growth
This summer our veterinary
intern, Carly Bates, completed a
study to determine the growth
of E. coli at varying pH levels.
The study was completed in two
phases. Phase one to reach the
target pH levels of media without
contamination and phase two
for growing E. coli at varying pH
levels.
After proper pH levels had
been produced in each of the
tryptic soy broth (TSB) containers
(3,4,5,6 and 7pH) one colony of
the E. coli isolate was obtained
on an inoculating loop and
5pH
6pH
of E. coli whereas plates at a pH
of 3 and 4 had no visual surface
growth. Providing evidence that
the growth cut off point is a pH
of 4!
placed in each of the six TSB and
swirled vigorously. TSB without
lactic acid was inoculated and
plated as a control. The E.coli
used was an F18 strain isolated
from a clinical case where pigs
experienced diarrhea and
sudden death. At 24 hours, the
TSB containers were removed
from the incubator and diluted
to 1:10 - 1:100,000 dilutions.
These dilutions and the original
inoculum were plated using .05
mL of the solution spread evenly
over the plate with an inoculation
loop. Plates were then incubated
and evaluated at 12 hours.
7pH
control
When using acidifying products
like citric acid or Activate, make
sure to use a pH meter to ensure
the drinking water at the pig level
is 4-4.5pH.
Fall 2023 | 19
