Antimicrobial susceptibility patterns of Clostridium difficile strains belonging to different polymerase chain reaction ribotypes isolated in Poland in 2012

• Ten antibiotics were used to define the susceptibility of Polish Clostridium difficile strains.
• Resistance rates to antibiotics depending on the PCR ribotype of C. difficile.
• 85.5% of toxigenic C. difficile strains were multidrug resistance.
• Multidrug resistance was observed in C. difficile PCR ribotypes 027, 176, 012 and 046.

In the beginning of 2012, a study was conducted to obtain an overview of Clostridium difficile infections (CDIs) in Polish hospitals. The collection of 83 toxigenic C. difficile isolates obtained from this hospital-based survey was used to identify antimicrobial susceptibility patterns. Among the C. difficile isolates analyzed, 48 (57.8%) belonged to PCR ribotype 027, 21 (25.3%) to its closely related PCR ribotype 176, and 14 (16.9%) to different PCR ribotypes. Seventy one (85.5%) isolates were resistant to erythromycin, whereas 23 (27.7%) had high-level clindamycin resistance, having minimum inhibitory concentrations (MICs) greater than 256 mg/L. All strains were ciprofloxacin resistant and 69 (83.1%) were moxifloxacin resistant. Seventy-three (87.9%) strains were imipenem resistant, but only 2 (2.4%) strains were resistant to tetracycline. All strains were sensitive to tigecycline. Metronidazole and vancomycin were generally effective against the C. difficile isolates, both having an MIC90 value of 0.75 mg/L. Isolates belonging to PCR ribotype 027 and the closely related PCR ribotype 176, showed higher resistance. All ribotype 027 and 176 C. difficile isolates demonstrated high-level resistance to erythromycin (MIC ≥ 256 mg/L), and 95,2% of ribotype 176 isolates were co-resistant to erythromycin and clindamycin. The MIC of moxifloxacin for this epidemic strain was very high (≥32 mg/L). Resistance to erythromycin, moxifloxacin, and rifampicin was observed in 15 (18%) of the isolates, all of which belonged to PCR ribotype 027. Multidrug resistance (MDR), defined as resistance at least to three classes of antimicrobial agents was observed in 85.5% (n = 71) of toxigenic C. difficile strains.