Across 1,513,882 non-duplicate (30-day) E. coli urine culture isolates, 856,918 isolates with ≥ 1 resistance phenotype were analyzed (of which 44.8, 37.3, 11.2, and 6.6% were SXT NS, FQ NS, ESBL+/3GC NS, and NTF NS, respectively; Fig. 1).

Proportion of urine culture isolates with ≥ 1 resistance phenotype demonstrating specific individual resistance. 856,918 non-duplicate (30-day) E. coli isolates (with ≥ 1 resistance phenotype) and 187,459 non-duplicate (30-day) K. pneumoniae isolates (with ≥ 1 resistance phenotype) were evaluated for co-resistance. AMR antimicrobial resistance, E. coli Escherichia coli, ESBL+/3GC extended-spectrum β-lactamase-producing/third-generation cephalosporin, FQ fluoroquinolone, K. pneumoniae Klebsiella pneumoniae, NS not susceptible, NTF nitrofurantoin, SXT trimethoprim/sulfamethoxazole

The following co-resistance phenotype combinations were observed among E. coli isolates (Fig. 2a): of 96,306 ESBL+/3GC NS isolates, 72.4% were co-resistant to FQs, 56.7% to SXT, and 11.9% to NTF; 46.6% of ESBL+/3GC NS isolates were co-resistant to FQ + SXT, 9.4% to FQ + NTF, and 8.0% to SXT + NTF, while 6.8% had all four resistance phenotypes. Of 319,354 FQ NS isolates, 21.8% were also ESBL+/3GC NS, 51.6% were co-resistant to SXT, and 8.0% to NTF; 4.9% of FQ NS isolates were co-resistant to SXT + NTF, and 2.0% had all four resistance phenotypes. Of 384,304 SXT NS isolates, 14.2% were also ESBL+/3GC NS, 42.9% were co-resistant to FQs, and 6.8% to NTF; 4.1% of SXT NS isolates were co-resistant to FQ + NTF and 1.7% had all four resistance phenotypes. Of NTF NS isolates (n = 56,954), 20.1% were also ESBL+/3GC NS, 44.7% were co-resistant to FQs, and 46.0% to SXT; 27.4% of NTF NS isolates were co-resistant to FQ + SXT, and 11.5% had all four resistance phenotypes.

Co-resistance phenotype combinations observed among E. coli (a) and K. pneumoniae (b) urine culture isolates. 856,918 non-duplicate (30-day) E. coli isolates (with ≥ 1 resistance phenotype) and 187,459 non-duplicate (30-day) K. pneumoniae isolates (with ≥ 1 resistance phenotype) were evaluated for co-resistance from female outpatients with UTI (2011–2019). Some isolates had overlapping susceptibilities/antimicrobial resistance types, hence individual phenotype totals do not reflect the total number of isolates evaluated. The categories are not mutually exclusive as the isolates are grouped based on the initial phenotype observed. E. coli Escherichia coli, ESBL+/3GC extended-spectrum β-lactamase-producing/third-generation cephalosporin, FQ fluoroquinolone, K. pneumoniae Klebsiella pneumoniae, NS not susceptible, NTF nitrofurantoin, SXT trimethoprim/sulfamethoxazole, UTI urinary tract infection

Across 250,719 non-duplicate (30-day) K. pneumoniae urine culture isolates, 187,459 isolates with ≥ 1 resistance phenotype were analyzed (of which 12.7, 5.8, 5.9, and 75.5% were SXT NS, FQ NS, ESBL+/3GC NS, and NTF NS, respectively; Fig. 1).

The following co-resistance phenotype combinations were observed among K. pneumoniae isolates (Fig. 2b): of 11,065 ESBL+/3GC NS isolates, 54.9% were co-resistant to FQs, 65.7% to SXT, and 75.5% to NTF; 45.7% of ESBL+/3GC NS isolates were co-resistant to FQ + SXT, 45.1% to FQ + NTF, 52.2% to SXT + NTF, and 38.2% had all four resistance phenotypes. Of 10,962 FQ NS isolates, 55.4% were ESBL+/3GC NS, 65.7% were co-resistant to SXT, and 79.6% to NTF; 54.0% of FQ NS isolates were co-resistant to SXT + NTF and 38.6% had all four resistance phenotypes. Of 23,887 SXT NS isolates, 30.4% were ESBL+/3GC NS, 30.1% were co-resistant to FQs, and 69.7% to NTF; 24.8% of SXT NS isolates were co-resistant to FQ + NTF and 17.7% had all four resistance phenotypes. Of 141,545 NTF NS isolates, 5.9% were ESBL+/3GC NS, 6.2% were co-resistant to FQs, and 11.8% to SXT; 4.2% of NTF NS isolates were co-resistant to FQ + SXT and 3.0% had all four resistance phenotypes.