Recent emergence of an epidemic clindamycin-resistant clone of Clostridium difficile among Polish patients with C. difficile-associated diarrhea

Abstract

Analysis of both the antibiotic resistance and the virulence characteristics of anaerobic human microbial pathogens is important in order to improve our understanding of a number of clinically significant infectious diseases, including Clostridium difficile-associated diarrhea (CDAD). We determined the presence of the clindamycin resistance-associated gene ermB and the ribotype of 33 C. difficile strains isolated from Polish patients suffering from CDAD. While all strains produced cytotoxin B (TcdB), enterotoxin A (TcdA) was produced by a subset of 15 strains only. The results showed that a single ermB-positive, TcdA(-)B(+) C. difficile strain with ribotype A has disseminated widely in the two Warsaw hospitals under investigation. Although different strains with the same phenotype were detected, the genotype A strain appeared to be the only one with a clear epidemic character. Apparently, enhanced local spread of CDAD-causing C. difficile may be restricted to a limited number of bacterial genotypes only.

FIG. 1.

PCR ribotyping of C. difficile strains. Examples of the DNA fingerprints are shown, and their interpretation codes are listed above the lanes (see also Table 1). The fingerprints were obtained for the strains identified by number beneath the lanes. All strains were toxin TcdA⁻B⁺ except for the four strains for which the toxin A gene could also be detected (A⁺B⁺). Molecular size markers are shown in the leftmost and rightmost lanes; the fragment indicated by the arrows is 600 bp in length.