Introduction Blood cultures are routinely done in Paediatric practice. We decided to audit the volume of blood inoculated into Paediatric blood culture bottles at Leeds Children's Hospital. 1-3 mls blood was chosen as the standard for the audit based on recommendation from the manufacturer of the blood culture bottles (BD BACTEC, Becton Dickinson).
Method 100 paediatric blood culture bottles (BD/BACTEC) were weighed and marked with an identification number and distributed to paediatric areas. The bottles were re-weighed after inoculation. Volume of blood inoculated was calculated by subtracting pre- from post-inoculation weight.
Results 63 bottles were returned. 3 bottles were excluded due to negative post-inoculation weight. Average blood volume inoculated was 0.88 mls. 83% (50 bottles) had less than 1 ml inoculated. 10% (6) had 1-3 mls. 3% (4) had more than 3 mls.
Discussion Majority of bottles were underfilled. Only 10% met the standard. This could be due to lack of awareness about the recommended volume or the challenging nature of getting enough blood from children. Growth in culture bottles is affected by underfilling and hence the reliability of all under filled negative blood cultures is questionable. This is likely to be a problem in other hospitals as well. As blood culture results play an important part in our decision making process about antibiotics a greater emphasis is needed to get this right.