Recommendations for a microbiology Diagnostic Stewardship Program for antimicrobial resistance: Pre-analytical phase

Diagnostic Stewardship Programs (DSPs) in microbiology aim to ensure that the right diagnostic test is performed on the right patient at the right time, optimizing resource utilization. To maximize their effectiveness against antimicrobial resistance (AMR), DSPs must be integrated with Infection Prevention and Control (IPC) programs and Antimicrobial Stewardship Programs (ASPs). This article focuses on the pre-analytical phase of DSPs, specifically on test ordering, and additionally, it offers some recommendations for resource-limited settings. It presents a series of algorithms for ordering blood cultures, urine cultures, and respiratory specimens. A crucial concept in this phase is pretest probability, which guides rational test ordering, prevents overutilization and associated costs, and reduces laboratory workload. Regarding blood cultures, it is essential to standardize ordering criteria, prioritizing high-risk populations. Routine use is discouraged in cases of low pretest probability or when results do not alter clinical management. Blood volume and the number of bottles are critical for optimal yield. For urine cultures, it is fundamental to order them only when characteristic urinary symptoms are present, avoiding requests for asymptomatic bacteriuria or nonspecific symptoms. Finally, for respiratory specimens, the choice of diagnostic method should consider the patient's condition and available resources. Molecular techniques enhance pathogen detection, but must be integrated within an ASP for proper interpretation and rational antimicrobial use.