PCR is used to detect which organism in the given context?

• A. C diff
• B. MRSA
• C. E. coli
• D. Streptococcus pneumoniae

Answer: (A)

PCR in this setting targets the toxin-producing genes of Clostridioides difficile directly in stool. Detecting these toxigenic genes confirms the presence of a strain capable of causing disease, making the test both rapid and highly sensitive for diagnosing C. difficile infection. In symptomatic patients, a positive toxigenic C. difficile result supports active infection rather than mere colonization, which is why this approach is preferred here. Other organisms would be addressed with different targets or tests (MRSA by mecA or S. aureus DNA, E. coli or S. pneumoniae by other organism- or virulence-gene targets), so the context points to C. difficile as the organism detected by the PCR.