Evaluation of Microbiology Laboratory Turnaround Time and Its Clinical Impact on Antibiotic Therapy at Lagos University Teaching Hospital

Timely delivery of microbiology results is fundamental to enabling culture-directed antibiotic therapy, reducing unnecessary broad-spectrum antibiotic use, and improving patient outcomes. This operational evaluation study assessed microbiology laboratory turnaround time (TAT) performance and its clinical impact on antibiotic prescribing at Lagos University Teaching Hospital (LUTH), Lagos State, in the South West geopolitical zone of Nigeria. Laboratory information system data for 800 clinical microbiology requests, including blood cultures, urine cultures, wound swabs, and cerebrospinal fluid cultures, processed between January and June 2024 were analyzed. TAT was measured from specimen receipt to validated result release. Corresponding clinical notes were reviewed to assess how results influenced antibiotic prescribing decisions. The median TAT for blood cultures was 72 hours, for urine cultures 36 hours, and for wound swabs 48 hours. Clinicians reported using laboratory results to modify antibiotic therapy in only 52.3 percent of cases where results were available, often citing delayed delivery of results after clinical decision points. Specimen processing backlogs were identified in the afternoon shift due to staffing shortages. TAT improvement of 30 percent was modeled with addition of one afternoon shift medical laboratory scientist. These findings advocate for TAT benchmarking as a quality indicator, shift expansion, and electronic result notification systems to enable real-time result-driven prescribing at LUTH. Keywords: turnaround time, microbiology laboratory, antibiotic therapy, Lagos, culture-directed treatment.