Characterization of Clostridium difficile PCR-ribotype 018: A problematic emerging type

Area of Science:

• Microbiology
• Infectious Diseases
• Epidemiology

Background:

• Toxigenic Clostridium difficile strains vary by PCR-ribotype (RT).
• RT 018 has emerged as predominant in Italy, unlike other European countries focusing on RT 027 or RT 078.
• Previous predominant strains in Italy included RT 126, related to RT 078.

Purpose of the Study:

• To investigate the characteristics of Italian RT 018 Clostridium difficile strains.
• To compare the virulence factors and antibiotic resistance profiles of RT 018 with other prevalent strains (RT 078, RT 126).
• To identify factors contributing to the epidemiological success of RT 018 in Italy.

Main Methods:

• Antimicrobial susceptibility testing (erythromycin, clindamycin, moxifloxacin, rifampicin).
• In vitro adhesion assays using Caco-2 cells.
• In vitro competition assays between different RT strains.
• Toxin production and heat-resistant colony-forming unit (CFU) assays.

Main Results:

• Italian RT 018 strains exhibited resistance to erythromycin, clindamycin, moxifloxacin, and notably, rifampicin.
• RT 018 strains demonstrated significantly higher adhesion to Caco-2 cells compared to RT 078 and RT 126.
• RT 018 strains outcompeted RT 078 and RT 126 in vitro and produced higher levels of toxins.
• Rifampicin resistance in RT 018 may be linked to historical rifamycin antibiotic use in Italy.

Conclusions:

• Italian RT 018 strains possess enhanced virulence traits, including increased adhesion, toxin production, and antibiotic resistance.
• These adaptive advantages likely facilitate the successful spread and dominance of RT 018 in Italian healthcare settings.
• The findings highlight the importance of understanding regional strain dynamics and resistance patterns in Clostridium difficile infections.