title: Multidrug resistance in European Clostridium difficile clinical isolates.
abstract: OBJECTIVE
  Multidrug resistance and antibiotic resistance mechanisms were investigated in 316 Clostridium difficile clinical isolates collected during the first European surveillance on C. difficile in 2005.
  
  
  METHODS
  MICs of eight different antibiotics were determined using Etest. Reserpine- and carbonyl cyanide m-chlorophenylhydrazone-sensitive efflux was tested using the agar dilution method. Molecular analysis of the resistance mechanisms was performed using PCR assays, PCR mapping and sequencing.
  
  
  RESULTS
  One hundred and forty-eight C. difficile strains were resistant to at least one antibiotic and 82 (55%) were multidrug resistant. In particular, 48% of these isolates were resistant to erythromycin, clindamycin, moxifloxacin and rifampicin. New genetic elements or determinants conferring resistance to erythromycin/clindamycin or tetracycline were identified. Even if most multiresistant strains carried an erm(B) gene, quite a few were erm(B) negative. In-depth analysis of the underlying mechanism in these isolates was carried out, including analysis of 23S rDNA and the ribosomal proteins L4 and L22. Interestingly, resistance to rifampicin was observed in multidrug-resistant strains in association with resistance to fluoroquinolones. Mutations in the rpo(B) and gyrA genes were identified as the cause of resistance to these antibiotics, respectively.
  
  
  CONCLUSIONS
  Characterization of multidrug-resistant C. difficile clinical isolates shows that antibiotic resistance is changing, involving new determinants and mechanisms and providing this pathogen with potential advantages over the co-resident gut flora. The present paper provides, for the first time, a comprehensive picture of the different characteristics of multidrug-resistant C. difficile strains in Europe in 2005 and represents an important source of data for future comparative European studies.
authors.affiliation: Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Spigaglia
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Barbanti
authors.forename: Paola
authors.initials: P
authors.lastname: Mastrantonio
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001372:Aza Compounds / Q000494:pharmacology; D002981:Clindamycin / Q000494:pharmacology; D016360:Clostridioides difficile / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*; D003015:Clostridium Infections / Q000382:microbiology; D004251:DNA Transposable Elements; D004275:DNA, Ribosomal / Q000032:analysis / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004917:Erythromycin / Q000494:pharmacology; D005060:Europe; D024841:Fluoroquinolones; D006801:Humans; D008780:Methyltransferases / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D000077266:Moxifloxacin; D011804:Quinolines / Q000494:pharmacology; D012338:RNA, Ribosomal, 23S / Q000032:analysis / Q000235:genetics; D012269:Ribosomal Proteins / Q000235:genetics; D012293:Rifampin / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001372:Aza Compounds; D004251:DNA Transposable Elements; D004275:DNA, Ribosomal; D024841:Fluoroquinolones; D011804:Quinolines; D012338:RNA, Ribosomal, 23S; D012269:Ribosomal Proteins; D002981:Clindamycin; D004917:Erythromycin; D008780:Methyltransferases; C035181:rRNA (adenosine-O-2'-)methyltransferase; D013752:Tetracycline; D000077266:Moxifloxacin; D012293:Rifampin