Coexistence of multiple multilocus variable-number tandem-repeat analysis subtypes of Clostridium difficile PCR ribotype 027 strains within fecal specimens

Abstract

We investigated whether multilocus variable-number tandem-repeat analysis (MLVA) typing could identify different subtypes of Clostridium difficile ribotype 027 within the same feces specimen. Five of 39 specimens yielded at least one isolate with an MLVA profile different (more than five summed tandem repeat differences) from that of other isolates in the same specimen, thereby potentially obscuring epidemiological links between C. difficile infection cases.

FIG. 1.

MLVA profiles and minimum spanning trees for specimens yielding C. difficile PCR ribotype 027 isolates at least one of which had an STRD of five or more from the next most closely related isolate. For minimum spanning trees, circles represent unique MLVA profiles in the tree and are scaled by member count. Thick solid lines represent an STRD of one, thin solid lines represent an STRD of two, thick dashed lines represent an STRD of three, and thinner dashed lines represent an STRD of four or more. STRDs of more than four are indicated by numerals between the circles. Gray shading indicates complexes with a maximum neighbor distance of two tandem repeats and a minimum of two MLVA types.