Selective reporting of antibiotic susceptibility testing results: less is more

Impact of selective reporting of antibiotic susceptibility testing results for urinary tract infections in the outpatient setting: A prospective controlled before-after intervention study

OBJECTIVES

The use of selective reporting of antibiotic susceptibility testing (AST) results is a recommended antimicrobial stewardship strategy to improve the appropriateness of antibiotic prescriptions. We conducted a large, pragmatic, prospective, multicentre, controlled (selective reporting versus complete reporting) before-after intervention study to assess the impact of selective reporting of AST results for Escherichia coli-positive urine cultures on the prescription of broad-spectrum antibiotics carrying a higher risk of selection of resistance (i.e., amoxicillin-clavulanate, third-generation cephalosporins, and quinolones) in the outpatient setting. We also looked for possible unintended clinical consequences of the intervention leading to consultations and/or hospitalisations.

METHODS

We compared two groups of laboratories located in a French region. We collected data from the health insurance databases before (2017) and after the implementation of the intervention (2019). The primary outcome was the prescription proportions of broad-spectrum antibiotics.

RESULTS

We included 42,956 Escherichia coli-positive urine cultures with AST. The decrease of the proportion of broad-spectrum antibiotic prescriptions between 2017 and 2019 was significantly higher for selective reporting of AST, attributable to a decrease in the prescription proportion of third-generation cephalosporins (- 8.5% for selective reporting versus - 0.1% for complete reporting, p < 0.001). This impact was more marked for targeted therapy and female patients. Requests from clinicians for the complete reporting of AST results were infrequent (1.2% of all the selective AST results reported in 2019). No unintended consequences were observed.

CONCLUSION

The results showed a positive impact of the selective reporting of AST results, but room for improvement is still important.

REGISTRATION AT CLINICAL TRIALS

NCT03612297.

Oral ciprofloxacin activity against ceftriaxone-resistant Escherichia coli in an in vitro bladder infection model

OBJECTIVES

Pharmacodynamic profiling of oral ciprofloxacin dosing for urinary tract infections caused by ceftriaxone-resistant Escherichia coli isolates with ciprofloxacin MIC ≥ 0.25 mg/L.

BACKGROUND

Urine-specific breakpoints for ciprofloxacin do not exist. However, high urinary concentrations may promote efficacy in isolates with low-level resistance.

METHODS

Ceftriaxone-resistant E. coli urinary isolates were screened for ciprofloxacin susceptibility. Fifteen representative strains were selected and tested using a dynamic bladder infection model. Oral ciprofloxacin dosing was simulated over 3 days (250 mg daily, 500 mg daily, 250 mg 12 hourly, 500 mg 12 hourly and 750 mg 12 hourly). The model was run for 96 h. Primary endpoint was change in bacterial density at 72 h. Secondary endpoints were follow-up change in bacterial density at 96 h and area-under-bacterial-kill-curve. Bacterial response was related to exposure (AUC0-24/MIC; Cmax/MIC). PTA was determined using Monte-Carlo simulation.

RESULTS

Ninety-three clinical isolates demonstrated a trimodal ciprofloxacin MIC distribution (modal MICs at 0.016, 0.25 and 32 mg/L). Fifteen selected clinical isolates (ciprofloxacin MIC 0.25-512 mg/L) had a broad range of quinolone-resistance genes. Following ciprofloxacin exposure, E. coli ATCC 25922 (MIC 0.008 mg/L) was killed in all dosing experiments. Six isolates (MIC ≥ 16 mg/L) regrew in all experiments. Remaining isolates (MIC 0.25-8 mg/L) regrew variably after an initial period of killing, depending on simulated ciprofloxacin dose. A >95% PTA, using AUC0-24/MIC targets, supported 250 mg 12 hourly for susceptible isolates (MIC ≤ 0.25 mg/L). For isolates with MIC ≤ 1 mg/L, 750 mg 12 hourly promoted 3 log10 kill at the end of treatment (72 h), 1 log10 kill at follow-up (96 h) and 90% maximal activity (AUBKC0-96).

CONCLUSIONS

Bladder infection modelling supports oral ciprofloxacin activity against E. coli with low-level resistance (ciprofloxacin MIC ≤ 1 mg/L) when using high dose therapy (750 mg 12 hourly).

Establishment of RCPA national guidelines for selective reporting of antimicrobials: processes, challenges and measuring the impact

OBJECTIVES

In 2016, The Royal College of Pathologists of Australasia (RCPA) initiated the formation of a working group comprising medical microbiologists to establish guidelines to assist Australian laboratories to implement selective and cascade reporting of antimicrobials-the first guidelines of this type in the world.

METHODS

A 2017 audit of antimicrobial reporting in Australian and New Zealand laboratories identified significant opportunities for improvement and standardization of selective reporting.

RESULTS

The first draft of the RCPA Selective Reporting Guidelines was circulated to all RCPA Microbiology fellows for feedback in August 2018 and the first version was published in February 2019. Subsequently, version two of the guidelines has recently been published in Australia, and New Zealand adapted these guidelines for formulation of their own national guidelines to accommodate local needs.

CONCLUSIONS

Here we describe the processes, acceptance and challenges associated with the establishment of these guidelines and measurement of their impact.