Blood Cultures

Avoiding blood culture contamination when sampling reduces harm to patients from unnecessary investigations and treatment. It also reduces laboratory work and hospitalization costs. The following standard operating procedures should always be followed to minimize this risk:

When taking blood cultures observe universal precautions to reduce any potential infection risks through needle stick injuries. Wear gloves when obtaining blood samples to protect yourself.

For adolescents and adults 10 - 20 mL of blood is the minimum volume per set (i.e. aerobic and anaerobic bottle) and 1 -2 mL for neonates and young children (use the Paediatric blood culture bottle please).

Blood culture samples needed for suspected diagnosis:

Severe bacteraemia or sepsis: take before commencing empirical antibiotic therapy. Minimum one set of cultures but ideally peripheral and central paired cultures if line is present. If clinically permissible collect samples 10 - 20 mins apart.
Severe septicaemia (meningitis, osteomyelitis, arthritis, pneumonia) 2 sets of cultures before antibiotic therapy commences.
Infective endocarditis: 3 sets of cultures before therapy commences, if antibiotic therapy for infective endocarditis is delayed for 24 hrs collect another 3 sets the next day.
Low grade intravascular infection: 3 sets within 24hrs best taken at the start of febrile episodes. Best taken before antibiotic therapy.
Febrile episodes: no more than 3 sets cultures over 24hrs. Bacteraemia may be present 1 hr before febrile episodes.
Fever of unknown origin: 4 - 6 sets over 48 hrs.

Labelling

Follow the Pathology Sample Labelling Policy to prevent delays from rejection of samples due to insufficient details.
The request form should indicate the test requested, and clinical information (e.g. "?Enteric fever after returning from 2 weeks in Mexico". "To start on iv cefotaxime." or "Purpuric rash, shock, ?meningococcaemia. To start cefotaxime" or "Fever of unknown origin. Not on antibiotic therapy").
It is essential to indicate if this is a high risk sample and indicate so with Danger of infection stickers.

Which Container does it go in?

This sample should be sent to us in Bactec blood culture bottles.

For adult blood cultures use a set of 2 culture bottles (anaerobic and aerobic) for each collected blood sample. Red BUFALO blood culture collecting packs available.

For paediatric blood cultures please use a single paediatric blood culture bottle.

Transport

Blood culture bottles should be transported to the laboratory with minimum delay. NICE guidelines recommends 4 hours from venipuncture to incubation within the laboratory.
Blood culture incubators are only present on LGI site so it is essential to transport cultures as soon as they are taken.
The bottles can be sent via the air tube system (bottles for mycobacteria SHOULD NOT be sent via the air tube system).
If the Air tube system is not working porters should be contacted to transport Blood Cultures to specimen reception as soon as possible
If insufficient Pods are available contact 22622 (LGI) or 65100 (SJH) to request additional carriers.

Reporting

Positive blood culture bottles will be reported to you electronically, followed by telephone notification when we can inform you about the presence of presence of potential organisms via a Gram stain.
During this phone call we will enquire about the clinical condition of the patient, antibiotics used and we will give advice on antibiotic therapy where appropriate.
In most cases positive blood cultures will be followed up with susceptibility and identification results the following day.