MO_IV_L: Molecular Sciences IV. Lectures
Kinga Tóth1,2, Ákos Tóth2, Dóra Szabó1
1 Institute of Medical Microbiology, Semmelweis University, Budapest
2 National Reference Laboratory for Antimicrobial Resistance, National Public Health Center, Budapest;
Background: The Escherichia coli ST131 is a globally dominant multidrug-resistant clone, especially the C2/H30Rx subclade with blaCTX-M-15 and the C1-M27 subclade is responsible for severe extraintestinal infections, including bloodstream and urinary tract infections. In 2018 44.6% (75/168) of invasive ESBL-producing E. coli isolates investigated at the National Public Health Center belonged to the ST131 clone, where the ratio of C2/H30Rx and C1-M27 was 1 to 0.8. Our study aimed to perform genomic analysis on selected C2/H30Rx and C1-M27 ST131 E. coli invasive isolates to compare their genetic backgrounds.
Methods: Seventeen C1-M27 and 16 C2/H30Rx ESBL-producing invasive E. coli isolates that originated from the entire country between 2007-2018 were selected. The antimicrobial susceptibility testing was performed by gradient MIC tests or broth microdilution and interpreted using EUCAST guidelines. The possible clonal relationships were investigated by core genome (cg)MLST (SeqSphere+ (Ridom)) using WGS data of all isolates obtained from Illumina 251-bp paired-end sequencing. From WGS data acquired antimicrobial resistance and virulence genes were retrieved using ResFinder3.1, Virulence Factor Database.
Results: All the isolates proved resistant to ceftriaxone and ciprofloxacin, but susceptible to ceftazidime/avibactam, amikacin, tigecycline, fosfomycin, and carbapenems. C2/H30Rx isolates showed higher resistance rates than the C1-M27 ones to ceftazidime (87.5% vs 23.5%), tobramycin (81.3% vs 0%) and gentamicin (56.3% vs 0%). The virulome and resistome of the subclades showed high similarities, although differences were found (Fisher’s exact test, p<0.05): some adhesin genes (sfaB, afa, dra), some toxin genes (cnf, astA, hylA) and some antibiotic resistance genes (blaCTX-M-15, qnrB19, aac(6')-Ib-cr, aac(3)-IIa) significantly associated with C2/H30Rx; while traD serum-resistance gene, senB toxin gene and some antibiotic resistance genes (blaCTX-M-27, sul2) significantly associated with C1-M27. According to cgMLST, the isolates within a subclade were more closely related than between.
Conclusions: Despite the similarity of their genetic background, some differences can associate with their phenotype in the case of antibiotic resistance and virulence. The possible link between clone dissemination, antibiotic resistance, and virulence needs further investigation.
Semmelweis University, Doctoral School of Pathological Sciences