RESUMO
This study investigated resistance determinants and genetic relatedness in extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates. PCR and DNA sequencing were used for screening isolates for blaCTX-M, blaTEM, and blaSHV (qnrA, qnrB, qnrC, qnrD, qnrS, aac(6)-lb-cr, and qepA) resistance genes and the sequence type 131 (ST131) clone. Genetic relatedness of E. coli ST131 isolates was determined by pulsed-field gel electrophoresis. Twelve isolates belonged to the ST131 clonal complex, while 8 were positive for aac(6')-lb-cr with qnrB1 also detected in 1 isolate. This study describes the first occurrence of CTX-M-9, qnrB1+aac(6')-lb-cr and CTX-M-3+qnrS1 among E. coli ST131 isolates from South Africa and illustrates their genetic diversity.