Molecular characteristics of Clostridium difficile strains from patients with a first recurrence more than 8 weeks...

Nearly all published studies of recurrent Clostridium difficile infections (CDI) report recurrent CDI within 8 weeks after the primary infection. This study explored the molecular characteristics of C. difficile isolates from the first recurrent CDI more than 8 weeks after the primary infection.

Consecutive hospitalized patients with a recurrent CDI more than 8 weeks after a primary infection were enrolled prospectively from January 2008 to February 2011. All C. difficile isolates of the primary and recurrent infections were collected and subjected to polymerase chain reaction ribotyping and antimicrobial susceptibility testing.

There were 62 cases of CDI in this study, which included 32 cases (51.6%) of recurrence due to the same ribotype of C. difficile, 26 (41.9%) cases due to a different ribotype, and four (6.5%) cases with 2-4 recurrences due to the same or different strains. One hundred and forty C. difficile isolates were obtained, which included 62 primary CDI isolates and 78 recurrent isolates. Ribotype 020 was the most common C. difficile strain in primary and recurrent infections. Ribotype 001 accounted for 15.4% (10/78) of recurrent infections and 3.2% (2/62) of primary infections (p = 0.0447). The minimum inhibitory concentration at 90% (MIC₉₀) values of linezolid, moxifloxacin, and clindamycin against type 001 strains were much higher, compared to the three other common ribotypes.

Recurrent CDI more than 8 weeks after a primary infection can be caused by the same or different C. difficile ribotype at similar percentages. Ribotype 001 C. difficile strains, which have a lower susceptibility to antimicrobials, were isolated more frequently in patients with a recurrent CDI.