Antimicrobial therapy and adherence to guideline recommendations: Studies on pneumonia and bloodstream infections

• Main Author: Waagsbø, Bjørn
• Format: Dissertation
• Language: English

Effective antimicrobial therapy are a prerequisite for modern medical treatment in all medical specialties. However, overuse of antimicrobial therapy is considered a driver of antimicrobial resistance, which eventually increases the risk of therapy failure and mortality. In general, reasons for overuse are unnecessary, inappropriate or suboptimal antimicrobial prescriptions. In Norway, antimicrobial consumption is generally low compared to European countries, and antimicrobial resistance is among the lowest in the world. Good qualitative studies that emphasize the correct and rational use or possible overuse of antimicrobial therapy are lacking. In this doctoral thesis, I have focused on qualitative studies that can highlight the prescribing of antimicrobial therapy to key infections frequently encountered in hospital settings. We chose community-acquired pneumonia (CAP) and bloodstream infections (BSI) diagnosed and managed in hospital settings as models. Our aim was to establish studies that could provide sufficiently knowledge about qualitative aspects for these infections. We therefore conducted four retrospective, observational studies, of which two on CAP and two on BSI. In the first study, we launched an intervention in the emergency room setting to increase proportions of patients that underwent collection of representative respiratory secretions of expectorate or induced sputum in CAP. The number of patients who completed the test increased significantly. In addition, we observed an increase in diagnostic yield from 41.2 % to 62.0 %. The study showed that relatively modest measures in the emergency room setting could increase the proportions of microbiologically confirmed cases of CAP. In the second study, we investigated whether the proportion of patients prescribed with first-line antimicrobial therapy for CAP could be influenced by a targeted intervention that promoted clinical guideline recommendations. Empiric first-line antimicrobial therapy with narrow-spectrum ϐ-lactams increased significantly from 56.1 % to 74.4 % over the six-year period. The proportion that received broad-spectrum regimens decreased significantly from 34.1 % to 17.1 % in the corresponding period. The study showed that CAP is a suitable model for antimicrobial stewardship measures. In the third study, we retrospectively collected data from 270 patients with culturepositive BSIs in the intensive care setting. In community-acquired BSIs, empirical antimicrobial therapy was