PRE-ANALYTICAL FACTORS IMPACTING BLOOD CULTURE POSITIVITY OUTCOMES: A CROSS SECTIONAL STUDY AT SULTAN AHMAD SHAH MEDICAL CENTRE, IIUM

Abstract

Blood culture (BC) is a crucial test for diagnosing bloodstream infections (BSIs) and can be significantly influenced by pre-analytical factors. Despite its importance, concerns persist regarding the reliability of BC results, often due to contamination and variability in positivity outcomes. This study addresses the research gap concerning the impact of specific pre-analytical factors such as location, transportation time, site of collection, and sample volume on BC positivity rates at Sultan Ahmad Shah Medical Centre @ IIUM. A cross-sectional analysis of 276 BC vials from 138 patients revealed that 58% were male, with a mean age of 61.8 years. Samples for the BC analysis were collected from emergency wards (35.5%) and peripheral veins (84.8%). The overall positivity rate was 29.0%, with 34 (24.6%) positive aerobic vials and 24 (17.4%) positive anaerobic vials. Optimal blood volume (8-10 ml) was achieved in only 17.4% of cases. The mean blood volume was 6.3 ± 3.7 ml for aerobic vials and 5.9 ± 3.0 ml for anaerobic vials, both of which are considered suboptimal based on the literature review (<8 ml). The mean time to positivity (TTP) was significantly different in anaerobic cultures when comparing varying blood volumes (p = 0.009). Although demographics and other pre-analytical factors did not significantly predict true or false positives (p > 0.05), the observed trends underscore the need for improved diagnostic practices. This study provides valuable insights into the pre-analytical factors affecting BC outcomes, emphasizing the importance of refining protocols to enhance diagnostic accuracy and patient management for suspected BSIs.