OBJECTIVES: To analyse characteristics of Clostridioides difficile PCR ribotype 176 clinical isolates from Poland, the Czech Republic and Slovakia with regard to the differences in its epidemiology. METHODS: Antimicrobial susceptibility testing and whole genome sequencing were performed on a selected group of 22 clonally related isolates as determined by multilocus variable-number tandem repeat analysis (n = 509). Heterologous expression and functional analysis of the newly identified methyltransferase were performed. RESULTS: Core genome multilocus sequence typing found 10-37 allele differences. All isolates were resistant to fluoroquinolones (gyrA_p. T82I), aminoglycosides with aac(6')-Ie-aph(2'')-Ia in six isolates. Erythromycin resistance was detected in 21/22 isolates and 15 were also resistant to clindamycin with ermB gene. Fourteen isolates were resistant to rifampicin with rpoB_p. R505K or p. R505K/H502N, and five to imipenem with pbp1_p. P491L and pbp3_p. N537K. PnimBG together with nimB_p. L155I were detected in all isolates but only five were resistant to metronidazole on chocolate agar. The cfrE, vanZ1 and cat-like genes were not associated with linezolid, teicoplanin and chloramphenicol resistance, respectively. The genome comparison identified six transposons carrying antimicrobial resistance genes. The ermB gene was carried by new Tn7808, Tn6189 and Tn6218-like. The aac(6')-Ie-aph(2'')-Ia were carried by Tn6218-like and new Tn7806 together with cfrE gene. New Tn7807 carried a cat-like gene. Tn6110 and new Tn7806 contained an RlmN-type 23S rRNA methyltransferase, designated MrmA, associated with high-level macrolide resistance in isolates without ermB gene. CONCLUSIONS: Multidrug-resistant C. difficile PCR ribotype 176 isolates carry already described and unique transposons. A novel mechanism for erythromycin resistance in C. difficile was identified.

• Keywords
• Clostridioides difficile infection, epidemiology, macrolide resistance methyltransferase, whole genome sequencing,
• MeSH
• Anti-Bacterial Agents * pharmacology   MeSH
• Drug Resistance, Bacterial * MeSH
• Bacterial Proteins genetics   MeSH
• Clostridioides difficile * genetics   drug effects   isolation & purification   classification   MeSH
• Genomic Islands * MeSH
• Clostridium Infections * microbiology   epidemiology   MeSH
• Humans MeSH
• Methyltransferases genetics   MeSH
• Microbial Sensitivity Tests MeSH
• Drug Resistance, Multiple, Bacterial * genetics   MeSH
• Multilocus Sequence Typing MeSH
• Ribotyping MeSH
• Whole Genome Sequencing MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Poland epidemiology   MeSH
• Names of Substances
• Anti-Bacterial Agents * MeSH
• Bacterial Proteins MeSH
• Methyltransferases MeSH

BackgroundOn 29 January 2024, the European Centre for Disease Prevention and Control distributed an alert about a metronidazole-resistant Clostridioides difficile outbreak of PCR ribotype (RT) 955 in England.AimWe aimed to investigate the presence of RT955 in Czech, Slovak and Polish C. difficile isolates and evaluate different culture media for detecting its metronidazole resistance.MethodsIsolates with binary toxin genes identified as 'unknown' by the WEBRIBO PCR ribotyping database up to 2023 were re-analysed after adding the RT955 profile to the database. The RT955 isolates were characterised by whole genome sequencing and tested for susceptibility to 15 antimicrobials.ResultsWe did not find RT955 in Czech (n = 6,661, 2012-2023) and Slovak (n = 776, 2015-2023) isolates, but identified 13 RT955 cases (n = 303, 2021-2023) in three hospitals in Poland. By whole genome multilocus sequence typing, 10 isolates clustered into one clonal complex including a sequence of United Kingdom strain ERR12670107, and shared similar antimicrobial resistance genes/mutations. All 13 isolates were resistant to ciprofloxacin/moxifloxacin, erythromycin/clindamycin and ceftazidime. All isolates had a mutation in the nimB gene promoter and in NimB (Tyr130Ser and Leu155Ile). The metronidazole resistance was detected in all isolates using brain-heart-infusion agar supplemented with haemin and Chocolate agar. Results were discrepant with the European Committee on Antimicrobial Susceptibility Testing-recommended Fastidious anaerobe agar and Brucella blood agar.ConclusionThe identification of clonally related haem-dependent metronidazole-resistant C. difficile RT955 in multiple hospitals indicates a need for prospective surveillance to estimate its prevalence in Europe.

• Keywords
• Leu155Ile, Surveillance, Tyr130Ser, aac(6')-aph(2”), ermB, fluoroquinolones, heme-dependent, nimB,
• MeSH
• Anti-Bacterial Agents * pharmacology   MeSH
• Drug Resistance, Bacterial * genetics   MeSH
• Clostridioides difficile * genetics   drug effects   isolation & purification   classification   MeSH
• Disease Outbreaks MeSH
• Clostridium Infections * epidemiology   microbiology   drug therapy   MeSH
• Humans MeSH
• Metronidazole * pharmacology   MeSH
• Microbial Sensitivity Tests MeSH
• Multilocus Sequence Typing MeSH
• Polymerase Chain Reaction MeSH
• Ribotyping * MeSH
• Whole Genome Sequencing MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Poland epidemiology   MeSH
• Slovakia epidemiology   MeSH
• Names of Substances
• Anti-Bacterial Agents * MeSH
• Metronidazole * MeSH