Phenotypic and genotypic characterization of multi- drug-resistant Escherichia coli isolates harboring blaCTX-M group extended-spectrum β-lactamases recovered from pediatric patients in Shenzhen, southern China

Aims and Objectives: The emergence and spread of extended-spectrum β-lactamases (ESBLs) particularly CTX-M producing multi-drug-resistant (MDR) Escherichia coli ( E. coli ) is one of the greatest challenges for community health globally. The study investigated the phenotypic and genotypic characteristics of ESBLs-producing E. coli recovered from pediatric patients from Shenzhen Children’s Hospital, China. Materials and methods: Present study, a total of 2,670 isolates of E . coli were collected from Shenzhen Children’s Hospital, China of which 950 were ESBLs producer. ESBLs production was confirmed by using the combination disc diffusion method, and antimicrobial susceptibility test was detected. In addition, β-lactamase-producing genes and co-existence of carbapenem/colistin resistance genes were determined by PCR assay and sequencing. The diversity and phylogenetic relationship were determined by multi-locus sequence typing method. Results: Thirty-five percent ( n =950) prevalence of ESBLs-producing E . coli we reported in Shenzhen, China of which 50 ESBLs producing E. coli were randomly selected for a further characterization. All 50 ESBLs- producing E. coli isolates revealed MDR phenotype and 100% were resistant to Ampicillin/sulbactam, Ampicillin, Cefazolin, and Ceftriaxone. All 50 ESBLs producers harbored at least one type of β-lactamase gene particular bla CTX-M . The PCR and sequencing revealed the most common CTX-M subtype was blaCTX-M-15 ( n =18), followed by blaCTX-M-14 ( n =16), blaCTX-M-90 ( n =9), blaCTX-M-55 ( n =3), blaCTX-M-27, blaCTX-M-101 , and blaCTX-M-211 each ( n =1). Co-existence of bla CTX-M with bla TEM , bla SHV , bla GES , and bla VEB was detected in few isolates. Among identified sequence types, ST131 (12%) was more dominant in ESBLs-producing E. coli . Phylogenetic group A was the most prominent group among the ESBLs-producing E. coli based on multiplex PCR. Conclusion: Our study shows the prevalence of bla CTX-M gene in ESBLs-producing E. coli in pediatric patients in Shenzhen, China. We highlight the importance to monitor the emergence and trends of ESBLs-producing isolates in a pediatric healthcare setting. Keywords: Antimicrobial resistance, molecular characterization, MLST, ESBLs, Escherichia coli