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 bla_CTX-M-15  (n =18), followed by bla_CTX-M-14  (n =16), bla_CTX-M-90  (n =9), bla_CTX-M-55 (n =3), bla_CTX-M-27 , bla_CTX-M-101 , and bla_CTX-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