Modeling the impact and cost of a culture-dependent molecular test for antimicrobial resistance in resource-limited settings.

Abstract

BACKGROUND Limited diagnostic access in resource-limited settings contributes to poor health outcomes among bacterial sepsis patients and the spread of antimicrobial resistance (AMR). Molecular diagnostic profiling of AMR may enable faster targeting of antibiotic therapies, improving clinical outcomes, reducing AMR development, and saving costs. METHODS We modeled the impact of a culture-dependent molecular diagnostic for pathogen identification and resistance testing among hospitalized bloodstream infection patients to guide effective and cost-efficient implementation of these tools. We evaluated patient mortality, antibiotic use, hospital-associated infections, hospital days, and costs under the standard-of-care (empiric therapy, blood culture, phenotypic susceptibility testing) compared to molecular diagnostics - varying culture and susceptibility testing coverage, culture turnaround time, and AMR prevalence. RESULTS The greatest impact of the molecular diagnostic occurred with 100% diagnostic coverage of all patients, shorter culture turnaround time, and high AMR prevalence, reducing up to 6% of deaths [IQR: 0-12.1%], 5% of hospital days [IQR: 0.1-10.7%], and 21% of days on inappropriate antibiotic therapy [IQR: 18.2-24.4%]. The minimum cost per molecular diagnostic performed, offset by cost savings, ranged from $109 in India to $585 in South Africa across all modeled scenarios. CONCLUSIONS In high AMR burden settings with blood culture infrastructure supporting fast turnaround times, a molecular diagnostic could improve bloodstream infection health outcomes. This impact is limited by delayed turnaround times and the effectiveness of empiric therapy. Molecular diagnostics implemented at $100 or less can generate healthcare system cost savings, supporting their adoption to improve health outcomes and reduce AMR while remaining cost neutral.