The rate of blood culture contamination and common organisms isolated in Malaysian public hospitals.

Introduction: Blood culture contamination remains a dilemma issue in the diagnosis of bloodstream infection. However, to date, there is no national data on blood culture contamination and the common organism isolated in Malaysia. This is a pioneer multi-centre study involving public hospitals with medical microbiologists in Malaysia to determine the blood culture contamination rate and the common organism isolated.

Materials and methods: This retrospective cross-sectional study involved record review of all blood culture results over 9 months period from 1st January 2018 until 30th September 2018 in 27 government hospitals in Malaysia. For each positive culture result, the type of isolated organism was classified to represent true bacteraemia or contamination.

Results: We analysed 448,109 blood culture records from the participating hospitals. The blood culture positivity rate was 12.5% (57395 of 448109) and 25.0% (14367 of 57395) of the positive blood culture represents contamination. The national blood culture contamination rate in Malaysia was 3.2%. The contamination rate in the adult population was significantly higher than the paediatric population (3.6% vs. 2.6%; p<0.001). The blood contamination rate by institution ranged from 1.5% to 6.8%. The most frequently isolated microorganisms in the contaminated cultures were coagulase-negative staphylococci (71.0%).

Conclusion: Blood culture contamination is a major issue that warrants priority in recognition, and interventions should be implemented to reduce the blood contamination rate in Malaysia.