Resistance to empirical antibiotics in urinary tract infections caused by Enterobacterales in the East of England

Abstract

Objectives: To characterize resistance rates in urinary tract infections caused by Enterobacterales to first- and second-line antibiotics.

Methods: Positive urine cultures examined by the Eastern Pathology Alliance network from September 2018 to September 2023 were retrospectively analysed. Enterobacterales from non-pregnant adults were included. Resistance to cefalexin, nitrofurantoin, trimethoprim, pivmecillinam and fosfomycin was investigated.

Results: A total of 193 137 samples from 99 635 patients met inclusion criteria. The mean number of episodes per patient was 1.94, with a range of 1-55 episodes over the 5 year period. Patients were predominantly of female sex (76.6%) and of an older age (mean age 66.4 ± 19.5 SD). Escherichia coli was the commonest organism isolated (73%) followed by undifferentiated coliforms (16%), Proteus spp. (6%) and Klebsiella pneumoniae (2%). Across all samples, trimethoprim resistance was high at 27%, with lower cefalexin (8.3%) and nitrofurantoin (8.8%) resistance. Resistance to two or three of the first-line antibiotics-trimethoprim, cefalexin and nitrofurantoin-was 5.5% and 0.6%, respectively. In E. coli there was low fosfomycin resistance at 3.1%. In resistant isolates subject to extended sensitivity testing, moderate pivmecillinam (21%) resistance was demonstrated. Organisms demonstrating AmpC and ESBL resistance were detected in 3.2% and 3.5% of isolates. Trimethoprim resistance was highest at James Paget University Hospital (37%) and surrounding general practices (30%).

Conclusions: This study illustrates resistance rates to commonly prescribed antibiotics for urinary tract infections in Norfolk and Waveney. Adjustments to local empirical antibiotic guidelines have been shaped by the resistance rates demonstrated herein.

Figure 1.

Organisms cultured from positive urine samples.