Differential effects of chromosome and plasmid bla genes on antibiotic susceptibilities in extended-spectrum beta-lactamase-producing Escherichia coli isolates from patients with urinary tract infection.

Objectives: To compare antibiotic susceptibilities between chromosomal and plasmid bla locations in urinary tract infection-causing extended-spectrum β-lactamases-producing Escherichia coli bla isolated in Indonesia.

Methods: A total of 84 strains identified as extended-spectrum β-lactamases-producing E. coli were isolated from patients with urinary tract infection in Indonesia in 2015. Antimicrobial susceptibility tests were performed on these strains using 18 antibiotics, and extended-spectrum β-lactamase bla genes were detected by polymerase chain reaction. Gene localization of bla -positive strains was confirmed by Southern blot hybridization, and epidemiological typing was conducted using multilocus sequence typing.

Results: Of 54 strains harboring the bla gene, 27 showed localization on chromosome, 20 on plasmid, and seven on chromosome and plasmid. Most multilocus sequence typing sequence types of the 27 strains with chromosomal bla were ST405 (25.9%) and ST131 (22.2%) strains, whereas the 20 strains with plasmid-bla were mostly ST410 (55.0%).

Conclusions: Extended-spectrum β-lactamases-producing E. coli bla with plasmid genes show significantly higher resistant rates against piperacillin-tazobactam but lower resistant rates against chloramphenicol compared to chromosomal strains in Indonesian patients with urinary tract infection. Mechanistic investigations will be necessary to advance our knowledge of antimicrobial resistance in urinary tract infection.