UTI caused by multidrug-resistant gram-negative bacteria
Australian Commission on Safety and Quality in Health Care (ACSQHC), 2023Australian Group on Antimicrobial Resistance (AGAR), 2024CDC, 2019Osthoff, 2015
There is worldwide emergence of multidrug-resistant Escherichia coli, particularly extended-spectrum beta-lactamase (ESBL)-producing strains, causing urinary tract infections (UTIs) and associated bacteraemias. Data from 2023 suggest that the rate of ESBL-producing E. coli strains among isolates from blood samples varies significantly across Australia (eg from 6% in Tasmania to 25% in the Northern Territory)Australian Group on Antimicrobial Resistance (AGAR), 2024.
For risk factors for infection caused by multidrug-resistant (MDR) gram-negative bacteria, see Risk factors for infection with a multidrug-resistant gram-negative bacterium. An additional risk factor for resistant bacteria that has been described for UTIs is antibiotic exposure within the previous 1 to 6 months, with the magnitude of risk being relative to the recency of the antibiotic exposureBryce, 2016Duffy, 2013Osthoff, 2015Steinke, 2001. However, patients with risk factors for infection with multidrug-resistant gram-negative bacteria will not necessarily be infected or colonised with a resistant bacterium. The need for input from an infectious diseases physician or clinical microbiologist to determine the appropriate empirical treatment for patients at increased risk of infections with multidrug-resistant gram-negative bacteria depends on infection severity – see Patients with risk factors for infection with multidrug-resistant gram-negative bacteria.
Of the oral treatment options for cystitis, nitrofurantoin, fosfomycin and pivmecillinam1 are active against the majority of ESBL-producing E. coli isolates. For patients with pyelonephritis, caused by ESBL-producing E. coli isolates, oral options may include amoxicillin+clavulanate, trimethoprim+sulfamethoxazole or ciprofloxacin, if susceptible. Intravenous options include aminoglycosides (eg gentamicin, tobramycin); however, susceptibility is variable. ESBL-producing E. coli are resistant to broad-spectrum cephalosporins (eg ceftriaxone, cefotaxime). For general information on the likely activity of various antimicrobials against bacteria that produce ESBLs, see AmpC and extended-spectrum beta-lactamases.
Carbapenemase-producing Enterobacterales (eg E. coli) remain uncommon in Australia but are a growing concern internationallyAustralian Group on Antimicrobial Resistance (AGAR), 2024CDC, 2019. For a summary of the enzymes most commonly responsible for carbapenem resistance in Enterobacterales, and the effectiveness of various antimicrobials against bacteria that produce these enzymes, see Antimicrobials with and without activity against carbapenemase-producing Enterobacterales.