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Purpose: This study aimed to examine the changes in the characteristics of community-onset fluoroquinolone-resistant (FQ-R) Escherichia coli isolates causing community-acquired acute pyelonephritis (APN) in South Korea., Methods: Blood or urine samples were prospectively collected from patients aged ≥15 years with community-acquired APN who were admitted to one of the eight Korean hospitals included in this study between September 2017 and August 2018. Phylogenetic typing, multilocus sequence typing, and molecular characterization of β-lactamase resistance and plasmid-mediated quinolone resistance (PMQR) determinants were performed. The data were compared with those from a previous study with the same design conducted in 2010-2011., Results: A total of 300 and 346 isolates were identified in 2010-2011 and 2017-2018, respectively. Among them, 76 (22.0%) and 77 (25.7%) FQ-R isolates were identified in 2010-2011 and 2017-2018, respectively. A significantly higher antimicrobial resistance against third-to fourth-generation cephalosporins, including cefotaxime (23.9% vs. 77.9%, P < 0.001), were observed among FQ-R isolates in 2017-2018 than among those in 2010-2011. A higher proportion of ST131 isolates (27.6% vs. 66.2%, P < 0.001), as well as isolates that had extended-spectrum β-lactamase (ESBL)/plasmid-mediated AmpC β-lactamase (PABL) (23.7% vs. 79.2%, P < 0.001), was observed in 2017-2018 than in 2010-2011. Further, more PMQR determinants (11.8% vs. 40.8%, P < 0.001) were observed in 2017-2018 than in 2010-2011., Conclusions: Among uropathogenic FQ-R E. coli isolates in South Korea, the prevalence of ST131 and the proportion of isolates containing ESBL and/or PMQR determinants have increased., Competing Interests: Declaration of competing interest None declared., (Copyright © 2022. Published by Elsevier B.V.)

Background/aims: Efforts to decrease the use of extended-spectrum cephalosporins are required to prevent the selection and transmission of multi-drug resistant pathogens, such as extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. The objectives of this study were to assess the clinical efficacy of intravenous cefuroxime as an empirical antibiotic for the treatment of hospitalized women with acute pyelonephritis (APN) caused by Escherichia coli., Methods: We analyzed the clinical and microbiologic database of 328 hospitalized women with community-onset APN., Results: Of 328 women with APN, 22 patients had cefuroxime-resistant E. coli APN, and 306 patients had cefuroxime-susceptible E. coli APN. The early clinical success rates were significantly higher (p = 0.001) in the cefuroxime-susceptible group (90.8%, 278/306) than in the cefuroxime-resistant group (68.2%, 15/22) at 72 hours. The clinical cure rates at 4 to 14 days after completing antimicrobial therapy were not significantly different in the cefuroxime-resistant or -susceptible groups, with 88.2% (15/17) and 97.8% (223/228; p = 0.078), respectively. The microbiological cure rates were not significantly different and were 90.9% (10/11) and 93.4% (128/137), respectively (p = 0.550). The median duration of hospitalization in the cefuroxime-resistant and -susceptible groups was 10 days (interquartile range [IQR], 8 to 13) and 10 days (IQR, 8 to 14), respectively (p =0.319)., Conclusions: Cefuroxime, a second-generation cephalosporin, can be used for the initial empirical therapy of community-onset APN if tailored according to uropathogen identification and susceptibility results, especially in areas where the prevalence rate of ESBL-producing uropathogens is low.

With increase of multi-drug resistant Escherichia coli in community-acquired urinary tract infections (CA-UTI), other treatment option with a therapeutic efficacy and a low antibiotic selective pressure is necessary. In this study, we evaluated in vitro susceptibility of E. coli isolates from CA-UTI to fosfomycin (FM), nitrofurantoin (NI), temocillin (TMO) as well as trimethoprim-sulfamethoxazole (SMX), ciprofloxacin (CIP) and cefepime (FEP). The minimal inhibitory concentrations were determined by E-test or agar dilution method according to the Clinical and Laboratory Standards Institute guidelines, using 346 E. coli collected in 12 Korean hospitals from March 2010 to February 2011. FM, NI and TMO showed an excellent susceptibility profile; FM 100% (346/346), TMO 96.8% (335/346), and NI 99.4% (344/346). Conversely, resistance rates of CIP and SMX were 22% (76/346) and 29.2% (101/349), respectively. FEP still retained an activity of 98.5%. In Korea, NI and TMO in addition to FM are a good therapeutic option for uncomplicated CA-UTI, especially for lower UTI.

The objectives of this study were to evaluate the clinical effectiveness of gentamicin as an initial empirical antimicrobial agent and to determine the effects of gentamicin resistance on clinical outcomes in women with uncomplicated acute pyelonephritis (APN). We analyzed data of 2,033 women with a diagnosis of APN admitted to Catholic University St. Vincent's Hospital. Of those, we enrolled 274 cases of community-acquired uncomplicated APN due to Escherichia coli who received gentamicin as initial antibiotics. Of these 274 patients, 47 patients had gentamicin-resistant (GM-R) E. coli APN, and 227 patients had gentamicin-susceptible (GM-S) E. coli APN. The early clinical response rates were 55.3% (26/47) versus 81.5% (185/227) at 72 hours; 61.7% (29/47) versus 96.9% (220/227) at 96 hours in the GM-R and GM-S groups, which was significantly higher in the GM-S group (p<0.001). Overall clinical cure rates were 100% (47/47) and 99.6% (226/227) in the GM-R and GM-S groups, respectively. APN patients in the GM-R group had longer hospitalization (9.72 ± 3.46 and 7.89 ± 2.27 days; p<0.001) than those in the GM-S group. Resistance of E. coli to gentamicin, bacteremia, and C-reactive protein level showed independent effects on early clinical failure. Aminoglycoside such as gentamicin can be an alternative antibiotic option for initial empirical therapy of community-acquired uncomplicated APN as the fluoroquinolone-sparing or broad-spectrum cephalosporin-sparing agents in an era of increasing antimicrobial resistance, especially in areas where medical resources are limited or antibiotic resistance rate of the uropathogens is high.