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.
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%).
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.