Objective: The emerging epidemic of extended-spectrum β-lactamase-producing E. coli (ESBL-EC) is a global public health crisis. ESBL-EC infections are increasing worldwide and contribute to morbidity and mortality among newborn infants. However, the antimicrobial resistance characteristics and clonal transmission of maternal and neonatal ESBL-EC isolates need to be further deciphered.
Materials and Methods: We performed phenotypic and genotypic characterization of 33 ESBL-EC isolates from pregnant women and newborn during 2019– 2020.
Results: Minimum inhibitory concentrations of 17 antimicrobial agents showed that all isolates were multidrug-resistant (MDR) and had a resistance rate of 100% to ampicillin, and mild resistance to florfenicol, gentamicin, ceftazidime, and amoxicillin-clavulanate. Additionally, imipenem, meropenem, polymyxin, and tigecycline exhibited good activity against the tested ESBL-EC isolates with low MIC₅₀ (0.06– 1 μg/mL) and MIC₉₀ (0.06– 1 μg/mL). Whole genome sequencing indicated that ESBL-EC isolates contained diverse antimicrobial resistant genes (bla_CTX-M, bla_TEM, bla_SHV, tetA , etc.) and toxin genes (ompA, csg, fimH, hybtA , etc.). bla_CTX-M genes were the main ESBL genotype. ST1193 (18.2%) was the second most abundant ST among the ESBL-EC isolates (ST131 was the most common, with 30.3%), and this is the first report of its mother-to-infant colonization transmission in China.
Conclusion: These findings revealed the occurrence of high-risk ST1193 clone among ESBL-EC isolates from pregnant women and newborn colonization in China. Further national or regional multicenter studies are needed to assess the dissemination and evolution of ESBL-EC ST1193 clone as a nosocomial pathogen in China.
Keywords: ESBL, E. coli , antibiotic resistance, colonization transmission, ST1193 clone