High prevalence of ESBL-producing E. coli phylogroup B2 clinical isolates in northeastern Thailand
Sumontha Chaisaeng, Peechanika Chopjitt, Pachara Kasemsiri, Nuntiput Putthanachote, Parichart Boueroy, Dan Takeuchi, Yukihiro Akeda, Sihigeyuki Hamada, Anusak Kerdsin
Abstract
Production of extended-spectrum β-lactamases (ESBLs) is a common resistance mechanism in Enterobacteriaceae , leading to serious hospital-acquired infections. This study aimed to assess phenotypic, phylogenetic, and antibiotic resistance patterns among ESBL-producing Escherichia coli isolates recovered from two rural tertiary hospitals in Thailand. Among 467 Enterobacteriaceae isolates, E. coli was the most prevalent 356 (76.2%) followed by K. pneumoniae 88 (18.8%), K. aerogenes 8 (1.7%), K. variicola 3 (0.6%), K. quasipneumoniae 1 (0.2%%), K. oxytoca 1 (0.2%), and unidentified 9 (1.9%). Of the 202 cephalosporin-resistant E. coli isolates, 195 (96.5%) were ESBL-producing and 7 (3.5%) were non-ESBL-producing. Clermont typing revealed that phylogroup B2 was predominant (43.3%), followed by phylogroups F (11.3%), D (10.3%), C (9.7%), and A (8.7%). Among the beta-lactamase-encoding genes, bla CTX−M (83.6%) and bla TEM (81.0%) were widely found among the isolates, and bla CTX−M−1 (60.7%) was the most common among the five bla CTX−M subgroups detected. The predominant ESBL was bla CTX−M−15 (58.3%). All isolates were resistant to cefotaxime (100%) and ampicillin (100%), followed by ciprofloxacin (91.3 %), ceftazidime (72.8 %), and tetracycline (64.1%). Our findings show that phylogroup B2 was the most prevalent phylogroup among ESBL-producing E. coli isolates in northeastern Thailand. Notably, the isolates mostly carried the bla CTX−M gene(s).