Prevalence and association of PCR ribotypes of Clostridium difficile isolated from symptomatic patients from Warsaw with macrolide-lincosamide-streptogramin B (MLSB) type resistance.

Isolates (79 in total) of Clostridium difficile obtained over a 2 year period from 785 patients suspected of having C. difficile-associated diarrhoea (CDAD) and being hospitalized in the University Hospital in Warsaw were characterized by toxigenicity profile and PCR ribotyping. Furthermore, their susceptibility to clindamycin and erythromycin was determined. Among the 79 C. difficile isolates, 35 were classified as (A+)B+, 1 as (A+)(B+)CDT+, 36 as (A-)B+ and 7 as (A-)B-. A total of 21 different PCR ribotypes was detected. Two main (A+)B+ strains circulated in our hospital: ribotype 014 and ribotype 046. Unexpectedly, the predominant PCR ribotype was type 017, a known (A-)B+ strain, and this accounted for about 45.5 % of all isolates cultured from patients with CDAD. Isolates belonging to PCR ribotype 017 were found in cases from epidemics of antibiotic-associated diarrhoea in the internal and surgery units. High-level resistance (MIC > or = 256 mg l(-1)) to clindamycin and erythromycin was found in 39 (49 %) of the C. difficile isolates. Interestingly, 34 (94 %) of macrolide-lincosamide-streptogramin B (MLSB) type resistance strains did not produce toxin A, but produced toxin B and were (A-)B+ ribotype 017. Thirty-seven of the high-level resistance strains harboured the erythromycin-resistance methylase gene (ermB). C. difficile isolates (2/29) that had high-level clindamycin and erythromycin resistance, and belonged to PCR ribotype 046, were ermB negative. These investigations revealed that the predominant C. difficile strain isolated from symptomatic patients hospitalized in University Hospital in Warsaw was MLSB-positive clindamycin/erythromycin-resistant PCR ribotype 017.