Virulence factors profiles and ESBL production in Escherichia coli causing bacteremia in Peruvian children

• Bacteremic E. coli belonged to phylogroups D, 47.7%; A, 26.1%; B1, 21.5%; B2, 4.6%.
• E. coli from neonates had higher number of virulence genes.
• Bacteremic E. coli (n = 65) showed 44.6% ESBL production, 66.2% quinolone resistance.
• Neonatal sepsis isolates tended to be more quinolone-resistant (P = 0.0697).
• Neonatal sepsis isolates tended to be ESBL-producers (P = 0.0776).

The presence of 25 virulence genes (VGs), genetic phylogroups, quinolone-resistance and Extended Spectrum β-lactamase (ESBL)-production was assessed in 65 Escherichia coli isolates from blood cultures in children <5 years in Peru. The most frequent VGs were fimA (89.2%), iutA (83.1%), agn43 (72.3%), iucA (67.7%), and fyuA (49.2%). The isolates belonged to D (47.7%), A (26.1%), B1 (21.5%), and B2 (4.6%) phylogroups. D + B2 isolates presented a high number of fimA, hly, papC, sat, and fyuA genes. Quinolone-susceptible (22 isolates – 33.8%) and ESBL-negative (31 isolates – 47.7%) isolates carried more VGs that their respective counterparts (5.7 vs. 4.7 and 5.3 vs. 4.4 respectively); the frequency of the fyuA, aat, aap, and hly genes significantly differed between quinolone-resistant and quinolone-susceptible isolates. Neonatal sepsis isolates tended to be more quinolone-resistant (P = 0.0697) and ESBL-producers (P = 0.0776). Early-onset neonatal sepsis isolates possessed a high number of VGs (5.2 VGs), especially in neonates of ≤1 day (5.9 VGs).