Speed of detection of Burkholderia pseudomallei in blood cultures and its correlation with the clinical outcome

Abstract

Burkholderia pseudomallei is a major cause of fatalities from nonhospital-acquired, gram-negative bacterial septicemia in northeastern part of Thailand. Rapid isolation of the bacterium is critical for diagnosis and treatment. Bacterial culture is currently the gold standard method for laboratory diagnosis of melioidosis. The present study describes the time to detection of B. pseudomallei in blood cultures using a BacT/Alert® automated blood culture system, and the correlation between the speed of detection and the clinical outcome of the patients. Of 813 consecutive positive blood cultures, 75 blood cultures from 71 patients were positive for B. pseudomallei. The mean ± SD time to detection of growth of B. pseudomallei was 23.9 ± 14.9 hr (95% confidence interval = 20.4-27.5 hr). A total of 62.5% of the B. pseudomallei-positive cultures was detected within 24 hr of incubation, and 93.1% within 48 hr. Interestingly, fatalities occurred in 73.7% of those in which the bacterial growth was detected within the first 24 hr, as compared with only 40.9% in those with a time to detection of culture more than 24 hr (P = 0.012). The shorter time of detection of the bacterial growth in blood cultures may reflect a higher bacterial level in the patient at the time blood was taken, and may be responsible for the poor clinical outcome.