Asymptomatic carriers are a potential source for transmission of epidemic and nonepidemic Clostridium difficile strains among long-term care facility residents.
BACKGROUND
Asymptomatic fecal carriage of Clostridium difficile is common in patients staying in health care facilities, but the importance of asymptomatic carriers with regard to disease transmission is unclear.


METHODS
We prospectively examined the prevalence of asymptomatic carriage of epidemic North American pulsed-field gel electrophoresis type 1 and nonepidemic toxigenic C. difficile strains among long-term care patients in the context of an outbreak of C. difficile-associated disease and evaluated the frequency of skin and environmental contamination. Molecular typing was performed by pulsed-field gel electrophoresis. Logistic regression was used to assess factors associated with asymptomatic carriage, and a sensitive and specific prediction rule was developed to identify high-risk patients.


RESULTS
Thirty-five (51%) of 68 asymptomatic patients were carriers of toxigenic C. difficile, and 13 (37%) of these patients carried epidemic strains. Compared with noncarriers, asymptomatic carriers had higher percentages of skin (61% vs. 19%; P=.001) and environmental contamination (59% vs. 24%; P=.004). Eighty-seven percent of isolates found in skin samples and 58% of isolates found in environmental samples were identical to concurrent isolates found in stool samples. Spores on the skin of asymptomatic patients were easily transferred to investigators' hands. Previous C. difficile-associated disease (P<.001) and previous antibiotic use (P=.017) were associated with asymptomatic carriage, and the combination of these 2 variables was predictive of asymptomatic carriage (sensitivity, 77%; specificity, 58%; positive predictive value, 66%; negative predictive value, 70%).


CONCLUSIONS
Our findings suggest that asymptomatic carriers of epidemic and nonepidemic C. difficile strains have the potential to contribute significantly to disease transmission in long-term care facilities. Clinical factors, such as previous C. difficile-associated disease and recent antibiotic use, may be predictive of asymptomatic carriage.
Riggs
Michelle M
MM
Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA.
Sethi
Ajay K
AK
Zabarsky
Trina F
TF
Eckstein
Elizabeth C
EC
Jump
Robin L P
RL
Donskey
Curtis J
CJ
D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001427:Bacterial Toxins / Q000096:biosynthesis; D015373:Bacterial Typing Techniques; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology*; D016360:Clostridioides difficile / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D003428:Cross Infection / Q000453:epidemiology / Q000635:transmission*; D004269:DNA, Bacterial / Q000235:genetics; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D004761:Enterocolitis, Pseudomembranous / Q000453:epidemiology / Q000635:transmission*; D004783:Environmental Microbiology; D005243:Feces / Q000382:microbiology; D006801:Humans; D017758:Infectious Disease Transmission, Patient-to-Professional; D016015:Logistic Models; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012867:Skin / Q000382:microbiology; D013171:Spores, Bacterial / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D004269:DNA, Bacterial