TITLE:
Quantitative Microbiological Evaluation of Salmonella Typhimurium Shed in Diarrhea, Loose, and Normal Stools of Infected Pigs
AUTHORS:
Tsuyoshi Tanaka, Yasuo Imai, Naosuke Kumagae, Takashi Sasaki, Narutoshi Ochiai, Katsuyoshi Uruno, Haruki Kitazawa, Tadao Saito, Shizuo Sato
KEYWORDS:
Fecal Shedding, Quantitative Evaluation, Salmonella Typhimurium, Swine, Transmission
JOURNAL NAME:
Open Journal of Veterinary Medicine,
Vol.4 No.4,
April
29,
2014
ABSTRACT:
Control
of within-herd transmission of Salmonella is important for reducing the prevalence of this organism on pig farms and for preventing Salmonella-contamination of pork. At the
farm level, understanding the within-herd transmission of Salmonella can lead to more effective control. Salmonella infection is dependent on the inoculation dose; hence,
quantitative evaluation of Salmonella shed in feces would provide useful information for developing effective
measures. In this study, to reproduce and evaluate the number of Salmonella shed in diarrhea, loose
stools, and normal feces, weaned pigs were inoculated with 3.2 × 109,
3.2 × 107, and 3.2 × 105 cfu of Salmonella Typhimurium, respectively. The number of S. Typhimurium
shed in the feces peaked within 1 week post-inoculation in every group and the
most amount of diarrhea and loose stools were observed within 2 weeks
post-inoculation. Diarrhea occurred 10 times (six pigs), and loose stools were
observed 25 times (11 pigs). The average concentration of S. Typhimurium shed in diarrhea, loose stools, and normal feces was
1.0 × 108, 1.6 × 104, and 7.1 × 101 cfu/g
feces, respectively. These data suggest that diarrhea and loose stools are
significant sources of within-herd transmission of Salmonella. Moreover, as some of the normal feces contained >1.0
× 106 cfu/g of S.
Typhimurium, even normal feces could be a source of within-herd transmission of Salmonella. At Salmonella-positive farms, reduction of the amount of Salmonella shed even in normal feces
would lead to better control of within-herd transmission of Salmonella. These data can contribute to
the control of within-herd transmission of Salmonella, particularly during the weaning period.