United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

Veterinary Services

Centers for Epidemiology and Animal Health May 2011 

_________________________________________________________________________________________________________________________ 

Clostridium difficile on U.S. 

Swine Operations 

Disease caused by Clostridium difficile is linked most 

commonly to nosocomial (hospital-acquired) infections in 

humans, especially after antibiotics are administered that 

alter normal gastrointestinal flora. Humans develop a 

spectrum of disease when infected with some strains of 

C. difficile. Symptoms range from mild diarrhea to lifethreatening toxic megacolon and pseudo-membranous 

colitis (Weese, 2010). Even though C. difficile is typically 

seen as a nosocomial infection, there are increasing 

reports of community acquired infections. 

C. difficile is a spore-forming organism which can survive 

in the environment for long periods and can, therefore, 

be ingested by animals or humans through contaminated 

foodstuffs and water (Yaeger et al., 2002). C. difficile has 

also been associated with clinical disease in young pigs 

and dairy calves (Yaeger et al., 2002; Hammitt et al., 

2008). Shedding of C. difficile bacteria in animal feces 

can occur in the absence of clinical signs (Weese, 

2010). In addition, some strains of C. difficile have been 

isolated from ground beef, ground pork, and ground veal 

purchased from retail markets in Canada which could 

serve as a source of infection in humans (RodriguezPalacios et al., 2007; Weese et al., 2009). To date, there 

has been little information available on the distribution 

and characteristics of C. difficile on various types of 

livestock operations across the United States. 

Swine 2006 study 

The U.S. Department of Agriculture’s National 

Animal Health Monitoring System (NAHMS) conducted 

the Swine 2006 study, which focused on swine health 

and management practices in 17 States.1

 These States 

represented 94.2 percent of U.S. swine operations with 

100 or more pigs and 94.0 percent of U.S. pig inventory 

for operations with more than 100 pigs on December 1, 

2004. One objective of the Swine 2006 study was to 

determine if C. difficile could be found in the feces of 

grower/finisher pigs on U.S. swine operations and, if so, 

to determine the characteristics of the C. difficile

isolates. 

 

1 States/Regions: 

North: Michigan, Minnesota, Pennsylvania, Wisconsin 

West Central: Colorado, Kansas, Missouri, Nebraska, South Dakota 

East Central: Illinois, Indiana, Iowa, Ohio 

South: Arkansas, North Carolina, Oklahoma, Texas

C. difficile prevalence 

 During the Swine 2006 study, testing for C. difficile

was performed on 63 swine operations from 15 of the 17 

participating States. Overall, 867 fecal samples from pen 

floors (up to 10 samples per pen) of grower/finisher pigs 

(20+ weeks of age) were cultured2

 for the presence of C. 

difficile. All pens contained pigs that were presumed to 

be healthy and showing no clinical signs of disease. Of 

the 867 fecal samples tested, C. difficile was isolated 

from 99 (11.4 percent) [table 1]. At least 1 positive 

sample was found on 26 of the 63 operations tested for 

C. difficile (41.3 percent). 

Table 1. Number and percentage of samples and 

operations tested for C. difficile, by test result 

Samples 

Tested 

Operations 

Tested 

Test 

Result No. Pct. No. Pct. 

Positive 99 11.4 26 41.3 

Negative 768 88.6 37 58.7 

Total 867 100 63 100 

 

2

 Culture methods available in Thitaram et al. (2011). 

Technical Brief
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

Sample-level results 

Herd size and region

There was no significant difference by herd size in 

the percentage of samples positive for C. difficile 

(p=0.60) [table 2]. 

Table 2. Number of samples tested and number and 

percentage of samples positive for C. difficile, by 

herd size 

Herd Size (total inventory) 

Fewer 

than 

2,000 

2,000–

4,999 

5,000 or 

More Total 

Number 

samples 

tested 

485 225 157 867 

Number 

samples 

positive 

66 19 14 99 

Percent 

samples 

positive 

13.6 8.4 8.9 11.4 

The percentage of samples positive for C. difficile

did not vary significantly by region (p<0.42) [table 3]. 

Table 3. Number of samples tested and number and 

percentage of samples positive for C. difficile, by 

region 

 Region 

North 

West 

Central 

East 

Central South 

Number 

samples 

tested 

165 247 406 49 

Number 

samples 

positive 

18 40 29 12 

Percent 

samples 

positive 

10.9 16.2 7.1 24.5 

Operation-level results

Herd size and region

 There was no difference by herd size (p=0.8) 

[table 4] or by region (p=0.2) [table 5] in the percentage 

of operations with at least one positive sample. 

Table 4. Number of operations tested and number 

and percentage of operations with at least one 

sample positive for C. difficile, by herd size 

Herd Size (total inventory) 

Fewer 

than 

2,000 

2,000–

4,999 

5,000 or 

More Total 

Number 

operations 

tested 

36 15 12 63 

Number 

operations 

positive 

16 6 4 26 

Percent 

operations 

positive 

44.4 40.0 33.3 41.3 

Table 5. Number and percentage of operations with 

at least one sample positive for C. difficile, by region 

 Region 

North 

West 

Central 

East 

Central South 

Number 

operations 

tested 

11 20 28 4 

Number 

operations 

positive 

6 11 8 1 

Percent 

operations 

positive 

54.5 55.0 28.6 25.0 
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

Summary

 Overall, the prevalence of C. difficile was relatively 

low (11.4 percent of samples positive) but the organism 

was widely distributed (41.3 percent of operations had at 

least one positive sample). 

The recovery of C. difficile from feces on livestock 

operations warrants further investigation. Not all strains 

of C. difficile appear to have the same propensity to 

cause disease. Therefore, isolates from this study will be 

further characterized to determine how related these 

isolates are to those causing human disease. Further 

characterization of C. difficile isolates, including 

molecular typing and additional epidemiological studies, 

is needed to ascertain if a relationship exists between 

food animal isolates and those from humans in order to 

determine the potential for foodborne disease. 

References

Hammitt MC, Bueschel DM, Keel MK, Glock RD, Cuneo 

P, DeYoung DW, Reggiardo C, Trinh HT, Songer 

JG. 2008. A possible role for Clostridium difficile in 

the etiology of calf enteritis. Vet Microbiol.127(3–

4):343–352. 

Rodriguez-Palacios A, Staempfli HR, Duffield T, Weese 

JS. 2007. Clostridium difficile in retail ground meat, 

Canada. Emerg Infect Dis.13(3):485–487. 

Thitaram SN, Frank JF, Lyon SA, Siragusa GR, Bailey 

JS, Lombard JE, Haley CA, Wagner BA, Dargatz 

DA, Fedorka-Cray PJ. 2011. Clostridium difficile

from healthy food animals: optimized isolation and 

prevalence. J Food Prot 74(1):130–133. 

Weese JS. 2010. Clostridium difficile in food—innocent 

bystander or serious treat? Clin Microbiol Infect 16: 

3–10. 

Weese JS, Avery BP, Rousseau J, Reid-Smith RJ. 2009. 

Detection and enumeration of Clostridium difficile

spores in retail beef and pork. Appl Environ 

Microbiol. 75(15):5009-11. 

Yaeger M, Funk N, Hoffman L. 2002. A survey of agents 

associated with neonatal diarrhea in Iowa swine 

including Clostridium difficile and porcine 

reproductive and respiratory syndrome virus. J Vet 

Diagn Invest 14(4):281–287. 

AHPIS acknowledges the contributions of the USDAARS Bacterial Epidemiology and Antimicrobial 

Resistance Research Unit for their participation in the 

Swine 2006 study. 

____________________ 

For more information, contact: 

USDA–APHIS–VS–CEAH 

NRRC Building B, M.S. 2E7 

2150 Centre Avenue 

Fort Collins, CO 80526-8117 

970.494.7000 

Email: NAHMS@aphis.usda.gov 

http://nahms.aphis.usda.gov 

#600.0511 

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