Blood cultures in sick children.

Background: Blood cultures (BCs) are frequently performed in sick children. A recent audit of BCs among adult patients documented high rates of contamination by coagulase-negative staphylococci (CoNS).

Objectives: To describe BC contamination rates and common pathogenic organisms causing bloodstream infection in children at a tertiary- level children's hospital.

Methods: BC results for children admitted to Red Cross War Memorial Children's Hospital from 2008 to 2012 were extracted from the National Health Laboratory Service database. Pathogenic and non-pathogenic (contaminated) growth on BCs in children <1 year of age and >1 year of age, were analysed. Data analysis was performed using Epi Info version 3.5.1.

Results: A total of 47 677 BCs were performed in the 5-year period. The proportion of contaminated specimens ranged between 5.9% and 7.2% per year (p=0.4). CoNS was the predominant isolate in 53.8% of all contaminated BCs. Children <1 year of age experienced higher contamination rates than children >1 year of age (8.7% v. 4.7%; relative risk 1.84; 95% confidence interval (CI) 1.71 - 1.97). Pathogenic organisms were isolated in 6.2% (95% CI 6.0 - 6.4) of all BC specimens. Among Gram-positive organisms, the proportion of Streptococcus pneumoniae isolates declined from 14.3% to 4.7% (p<0.00001), while there was a significant increase in Gram-negative organisms (51.8% - 57.9%; p=0.04) over the 5-year period. Klebsiella pneumoniae, the predominant Enterobacteriaceae isolated, decreased from 45.8% to 31.7% (p=0.004).

Conclusion: This study identified unacceptably high BC contamination rates, emphasising the importance of collecting BC specimens under sterile conditions.