Laboratory Test Reference Guide

Blood cultures collected from outside the hospital into bottles other than Bactec will be processed manually with the same turn around time. If suspecting Mycobacterial or Fungal bacteraemia special culture media is available (Myco/F Lytic) on request from the laboratory ext. 98646

Blood culture media is available from Onelink via inventory. For urgent supplies out of hours contact Duty Manager. Stocks held in the wards should be kept to a minimum because of the relatively short shelf life of the media. Store in a cool, dry place out of direct sunlight.

Collect prior to antibiotic treatment where possible. The volume of blood collected is the most important factor in the sensitivity of organism detection. High volume blood cultures drawn serially return the best yield.

Adults: Aerobic (blue) and Anaerobic (crimson) BACTEC bottles. In cases of PUO three serial sets are recommended. Optimum blood volume 8-10 mLs. DO NOT overfill bottles (i.e. >10mls) Minimum blood volume 3 mLs.

Children: Paeds Plus (pink) BACTEC bottle Optimum blood volume 1-3 mLs Minimum blood volume 0.5 mlSpecimen Collection Refer to IV and Related Procedures Manual for detailed blood culture collection procedures (B22, C23).

Remember to mark and fill to desired level. Using aseptic technique: Fill with bottle standing upright. Fill aerobic bottle first. Collect before any other required blood tubes are filled. If several sets are collected from different sites on the same patient, remove all bar code labels and stick them to the patient form. Label the bar code labels on the request form and the bottles with the site.

• Avoid blood cultures in patients who are not systemically septic, have a clear source of infection and in whom a direct specimen for culture (e.g. urine, wound swab, sputum, cerebrospinal fluid, or joint aspirate) is possible.

Use the screening and action tool to determine the need for blood cultures as a part of the Sepsis Six care bundle. Screening tools are available on the Sepsis Intranet Page and should be available in your clinical area. Be mindful there are different tools for adults, paediatrics and pregnant/postpartum patients.Further information can be found on the Sepsis Trust New Zealand website

• Do not take blood cultures in patients who do not have red or amber flags for sepsis, unless investigating specifically for endocarditis
• In all patients take 2 sets (4 bottles) of blood cultures simultaneously from a single venepuncture site (this increases diagnostic yield (sensitivity)
• If endocarditis is likely take an additional set (2 bottles) from a separate venepuncture before starting antibiotics (this increases diagnostic accuracy (specificity).
• In neonates that have a positive blood culture, the culture is repeated after at least 24 hours of commencement of antibiotic treatment. A negative result determines the length of treatment. Even if treatment is reduced by a day, this supports antibiotic stewardship

Sepsis follow up care and blood cultures:

• Except in patients with Staphylococcus aureus bacteraemia do not repeat cultures after starting antibiotics just because the fever continues.
• New sets of blood cultures are needed only if there is a clear second episode of suspected sepsis with a different suspected site and organism. (e.g. IV line infection after pneumonia)
• Do not collect repeat blood culture sets less than 48 hr apart.

All positive cultures will be reported by phone to medical staff immediately and results updated on the LIS as they come available.