High-risk clonal lineages among extended-spectrum β-lactamase producing Escherichia coli and Klebsiella pneumoniae from urban and rural stagnant water samples in Tunisia

Abstract This study sought to investigate the occurrence and subsequently to characterize extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae from urban and rural stagnant water samples during the wet season (December to February) in several regions of northern Tunisia. From 56 stagnant water samples, 14 ESBL-producing Enterobacteriaceae were recovered, including 9 Escherichia coli , 3 Klebsiella pneumoniae , and 2 K. oxytoca . Most isolates were multidrug-resistant, with ESBL production primarily encoded by bla CTX-M-15 ( n = 8) and bla CTX-M-1 ( n = 4) followed by bla CTX-M-55 ( n = 1) and bla TEM-26 ( n = 1). One K. pneumoniae isolate co-harbored bla KPC and bla CTX-M-15 genes. Class 1 integrons were detected in 4 isolates, however, sul1 , sul2 , and aac(6′)-Ib - cr genes were detected in eleven, two, and four isolates, respectively. The nine E. coli isolates belonged to seven sequence types namely, B2/ST131 (3 isolates), A/ST164, A/ST10, A/ST224, A/ST38, A/ST155, and A/ST69 (each of them one isolate). The three K. pneumoniae isolates were assigned to three sequence types: ST101, ST405 (harboring CTX-M-15 and KPC), and ST1564. Overall, the phenotypic and genotypic traits of collected isolates mirror the molecular epidemiology of ESBL-producing enterobacteria in Tunisia and highlight the potential role of stagnant water in both urban and rural areas as a reservoir of ESBL-producing Enterobacteriaceae .