Rate of blood culture contamination in a teaching hospital: A single center study

Abstract

Objectives Contamination of blood samples can lead to serious problems in patient management. The administration of unnecessary antibiotics, wastage of hospital resources, and risks to patient life are some of the known hazards. This study aimed to calculate the rate of blood culture contamination and associated factors at King Khalid University Hospital (KKUH), Riyadh, KSA. Methods This is a retrospective cross-sectional study. The total study population was calculated based on a review of all of the request sheets for blood cultures submitted to the microbiology laboratory from 1st of January to 31st of December, 2012, at KKUH, Riyadh, KSA. Results The rate of blood culture contamination (false positive) was 1.9%, while 8.71% of the blood culture samples had true infections (true positive). Coagulase negative staphylococcus (CoNS) was the most predominant isolate (87%). The rate of blood culture contamination was significantly higher during the summer season of June (1.38%), July (3.97%) and August (3.72%) compared to other months of the year (p value < 0.05). The surgical units in this study had the highest rate of blood culture contamination (3.92%), followed by intensive care (2.61%) and medical units (2.48%). Conclusion The rate of blood culture contamination at KKUH is within the acceptable international range. The highest rates of blood culture contamination occurred during the summer season and in the surgical units.