Background
This study aimed to investigate the trends and antimicrobial resistance profile of extended-spectrum β-lactamase-producing
Escherichia coli
(ESBL-EC) clinical isolates.
Methods
A total of 1,303
E. coli
isolates from January 2012 to December 2017 at Fukuoka University Chikushi Hospital, Japan, were analyzed. The rate of resistance to cefmetazole (CMZ), flomoxef (FMOX), imipenem (IPM), meropenem (MEPM), amikacin (AMK), gentamicin (GM), minocycline (MINO), ciprofloxacin (CPFX), and levofloxacin (LVFX) was compared between non-ESBL-producing
E. coli
(non-ESBL-EC) and ESBL-EC.
Results
The proportion of ESBL-EC among all the
E. coli
isolates was 24.6% (320/1,303), and the proportion remained stable throughout the study period. There was no difference in the rate of resistance to CMZ, FMOX, IPM, MEPM, and AMK between non-ESBL-EC and ESBL-EC; however, the rate of resistance to GM, MINO, CPFX, and LVFX was higher in ESBL-EC than in non-ESBL-EC (17.5% vs. 10.0%, 19.1% vs. 7.7%, 87.5% vs. 24.2%, and 87.5% vs. 23.5%, respectively; P < 0.01). The rate of resistance to CPFX and LVFX in ESBL-EC increased throughout the study course. The rate of
E. coli
isolates susceptible to all the antibiotics was significantly higher in non-ESBL-EC than in ESBL-EC (68.2% vs. 7.5%; P < 0.01), and this rate decreased significantly from 10.0% in 2012 to 3.8% in 2017 in ESBL-EC (P < 0.01).
Conclusions
Our findings indicate a changing antimicrobial resistance profile of ESBL-EC, particularly to fluoroquinolones. Determination of the prevalence and antimicrobial resistance of ESBL-EC will help physicians in selecting the initial empirical treatment for patients with ESBL-EC infections.