Antibiotic resistance in uropathogens across northern Australia 2007-20 and impact on treatment guidelines

Abstract

Background: Urinary tract infections are common and are increasingly resistant to antibiotic therapy. Northern Australia is a sparsely populated region with limited access to healthcare, a relatively high burden of disease, a substantial regional and remote population, and high rates of antibiotic resistance in skin pathogens.

Objectives: To explore trends in antibiotic resistance for common uropathogens Escherichia coli and Klebsiella pneumoniae in northern Australia, and how these relate to current treatment guidelines in the community and hospital settings.

Methods: We used data from an antibiotic resistance surveillance system. We calculated the monthly and yearly percentage of isolates that were resistant in each antibiotic class, by bacterium. We analysed resistance proportions geographically and temporally, stratifying by healthcare setting. Using simple linear regression, we investigated longitudinal trends in monthly resistance proportions and correlation between community and hospital isolates.

Results: Our analysis included 177 223 urinary isolates from four pathology providers between 2007 and 2020. Resistance to most studied antibiotics remained <20% (for E. coli and K. pneumoniae, respectively, in 2019: amoxicillin/clavulanate 16%, 5%; cefazolin 17%, 8%; nitrofurantoin 1%, 31%; trimethoprim 36%, 17%; gentamicin 7%, 2%; extended-spectrum cephalosporins 8%, 5%), but many are increasing by 1%-3% (absolute) per year. Patterns of resistance were similar between isolates from community and hospital patients.

Conclusions: Antibiotic resistance in uropathogens is increasing in northern Australia, but treatment guidelines generally remain appropriate for empirical therapy of patients with suspected infection (except trimethoprim in some settings). Our findings demonstrate the importance of local surveillance data (HOTspots) to inform clinical decision making and guidelines.

Figure 1.

Map of northern Australia and regions represented in dataset, and summary of data sources. WA, Western Australia (Kimberley and Pilbara); NT, Northern Territory; QLD, far north Queensland; WD, Western Diagnostic Pathology; PW, PathWest; TP, Territory Pathology; PQ, Pathology Queensland. The following antibiotics were not included in pathology datasets: (WA, community: gentamicin, trimethoprim/sulfamethoxazole; hospital: cefazolin, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, trimethoprim/sulfamethoxazole); (NT, community: nitrofurantoin, trimethoprim, trimethoprim/sulfamethoxazole); (QLD, community: nitrofurantoin, trimethoprim, trimethoprim/sulfamethoxazole; hospital: nitrofurantoin, trimethoprim, trimethoprim/sulfamethoxazole).

Figure 2.

Proportion of isolates resistant to five antibiotics/antibiotic groups in 2019, by region and healthcare setting [community or hospital (displayed as circles)]. ESCs, extended-spectrum cephalosporins (resistance to ceftriaxone or ceftazidime); fluoroquinolones, resistance to ciprofloxacin or norfloxacin (only norfloxacin in WA hospitals). Regions (i.e. community healthcare facilities) with <30 isolates: [WA, all regions (E. coli and K. pneumoniae, cefazolin and ESCs)]; [NT, all regions (E. coli and K. pneumoniae, all antibiotics)]; [QLD, Cairns & Hinterland (E. coli and K. pneumoniae, all antibiotics); North West (K. pneumoniae, all antibiotics); Townsville (E. coli and K. pneumoniae, all antibiotics)]. Hospitals with <30 isolates: [WA, Pilbara (K. pneumoniae, amoxicillin/clavulanate and fluoroquinolones)]; [NT: East Arnhem (K. pneumoniae, all antibiotics); Katherine (E. coli, all antibiotics); Barkly (K. pneumoniae, all antibiotics)].

Figure 3.

Proportion of isolates resistant to five antibiotics/antibiotic groups over time (smoothed using locally weighted regression), by jurisdiction and healthcare setting. ESCs, extended-spectrum cephalosporins (resistance to ceftriaxone or ceftazidime); fluoroquinolones, resistance to ciprofloxacin or norfloxacin (only norfloxacin in WA hospitals). Non-significant changes: Community [(WA: E. coli, amoxicillin/clavulanate and cefazolin and fluoroquinolones and ESCs, K. pneumoniae, fluoroquinolones); (NT: E. coli, amoxicillin/clavulanate; K. pneumoniae, fluoroquinolones); (QLD: E. coli, amoxicillin/clavulanate; K. pneumoniae, amoxicillin/clavulanate and fluoroquinolones)]; Hospital [(WA: E. coli, amoxicillin/clavulanate; K. pneumoniae, amoxicillin/clavulanate and fluoroquinolones); (NT: E. coli, gentamicin; K. pneumoniae, amoxicillin/clavulanate and cefazolin and ESCs); (QLD: K. pneumoniae, amoxicillin/clavulanate and ESCs)]. Significant decreases: Hospital [(NT: E. coli, amoxicillin/clavulanate; K. pneumoniae, fluoroquinolones and gentamicin); (QLD: K. pneumoniae, gentamicin)].