Predominance of FQR1 NAP1/RT027 Clostridioides difficile Among Mexican Children and Adult Patients, and its Resistance to Eleven Antibiotics.

Aims: Clostridioides difficile is a major cause of antibiotic-associated diarrhea. This study investigated the diversity, clonality, and antimicrobial resistance of C. difficile isolates from Mexican children and adults with diarrhea.

Methods: Between 2014 and 2016, we isolated 37 C. difficile strains in three hospitals in Mexico City. C. difficile strains were typed by PCR-ribotyping and pulsed-field gel electrophoresis (PFGE). Antimicrobial susceptibility to eleven antibiotics was determined. Whole-genome sequencing (WGS) was used to investigate the presence of antimicrobial resistance genes (ARG) and perform a pangenome analysis of 53 genomes from Mexico and 137 publicly available C. difficile genomes.

Results: Toxigenic strains comprised six isolates from children and 31 from adults. While NAP1/RT027 isolates were found in three children, they were predominant in adults (n = 31, 90.3%) and showed the 1058 and 008 PFGE macrorestriction patterns. All isolates were susceptible to vancomycin and metronidazole but resistant to ciprofloxacin, and over 90% of the isolates were resistant to linezolid and carried cfr(E). The pangenome of these isolates contained 4,852 genes, of which 3,455 (81.2%) were categorized as core genes and 801 (18.8%) as accessory genes. In addition, our isolates demonstrated a close relationship with strains from the United States, Canada, and France.

Conclusions: Our work provides, for the first time, genomic insights into C. difficile strains present in Mexico. In our hospital setting, the predominant strains were primarily NAP1/RT027 and exhibited resistance to linezolid, a pattern observed in both pediatric and adult populations. This unique combination of characteristics has not been previously reported in Latin America.