Diagnosis and Management of C. difficile Infection in Primary Care

Introduction to C. difficile Infection

The American College of Physicians recommends testing patients with unexplained diarrhea for C. difficile, regardless of traditional risk factors, as community-acquired disease is increasingly common and cannot be predicted by patient characteristics alone 1

A prospective study demonstrated that 1.5% of unformed stool samples submitted by general practitioners were positive for C. difficile, with 65% of these patients having no healthcare facility admission in the prior year and 42% having no antibiotic use in the prior 6 months 1
Community-acquired C. difficile infection occurs in patients without traditional risk factors in approximately 25-26% of cases, making it impossible to exclude based on patient characteristics alone 1
The age range of community-acquired cases varied from 1 to 92 years, with 18% under age 20, demonstrating that C. difficile infection is not limited to elderly or hospitalized patients 1

The Infectious Diseases Society of America recommends testing patients with ≥3 unformed stools in 24 hours with no obvious alternative explanation, particularly when common enteropathogens have been ruled out 2, 3
Key clinical criteria for testing include diarrhea defined as three or more unformed stools in 24 hours, no reasonable alternative cause for diarrhea, and no laxative use within 24-48 hours 2, 3, 5
Only unformed stool samples should be tested, as testing formed stool results in false positives and unnecessary antibiotic therapy 5, 6

A two-step testing algorithm is preferred, such as GDH screening followed by toxin testing, or NAAT followed by toxin confirmation, to balance sensitivity and specificity 6, 4
Single toxin EIA testing alone is not recommended due to low sensitivity 5, 4

Positive NAAT results may represent colonization rather than active infection, which is why multistep algorithms are preferred 5, 6, 4
Results should be interpreted in the context of recent antibiotic administration, fever, abdominal pain, and leukocytosis as markers of severity 1, 5, 6

Multistep algorithms are superior to single tests, and NAAT alone may overdiagnose by detecting colonization 6, 4
Toxin EIA alone has insufficient sensitivity, and laboratories should use appropriate testing methodology 5, 4