Blood Culture

Test information:

To identify the causative pathogen in blood culture vials and were applicable to determine antimicrobial susceptibility results. The detection and identification of micro-organisms from blood is essential for microbiological diagnosis of bacteraemia, fungaemia (particularly candidaemia), infective endocarditis and conditions associated with a clinical presentation of pyrexia of unknown origin.

Availability:

Available locally during routine hours: 08:45 - 21:00. Emergency Department (ED) blood culture vials may be given to the POCT laboratory for loading overnight.

Sepsis: recognition, diagnosis and early management NICE guidelines

Turnaround Time:

36 hours (preliminary paediatric), 48 hours (preliminary adult), 5 days (final).

This test is not suitable for Mycobacterial blood culture investigation. Please see Related Tests:

Mycobacterium (Microscopy & Culture)

Specimen Type(s)

• Blood;

Other Acceptable Specimen Type(s)

• Venous Blood;
• Arterial Blood;
• Blood via IV line;

Specimen Container - Adult

• BD BACTEC Lytic Anaerobic medium;
• BD BACTEC Plus Aerobic medium;

Specimen Container - Paediatric

• BD BACTEC Peds Plus medium;

Analytes

• Microscopy Culture & Sensitivity;

Part of a test profile?

No

Volume (min) of sample to be sent to laboratory

• 8-10mL BD BACTEC Plus Aerobic medium.
• 8-10mL BD BACTEC Lytic Anaerobic medium.
• 0.5-5mL BD BACTEC Peds Plus medium.

Patient Preparation, Sample Handling and Transport

• Collect specimens before antimicrobial therapy where possible.
• Clearly indicate any travel history, in particular South and Central America, Africa and South East Asia which is relevant to brucellosis or enteric fever.
• Specimens should be sent to the laboratory without delay at all times of the day/night using the ATTS (pod) or a porter.
• National recommendations indicate there should be less than 4 hours delay from collection to incubation for blood culture samples reflecting their clinical significance.
• If transport is delayed store samples at room temperature; inoculated bottles must NOT be refrigerated.
• Please refer to 'Clinical Guideline for Blood Culture Collection' on RCHT document library.
• Under-filled blood culture vials may result in failure to detect a pathogen present.
• Over-filled blood culture vials may result in a false positive flag on the analyser.
• Time of collection must be added to the request form.
• Samples should be taken as soon as possible after a spike of fever as fevers and rigors occur 30 to 60 minutes after the entry of organisms into the bloodstream.
• If endocarditis is suspected, 3 sets of blood culture bottles (3x2 bottles, 60mL) should be collected as separate draws over a 24h period.
• Other samples should be collected (e.g urine , sputum) on basis of suspected focus of infection.

Maximum add on time

N/A

Units and Reference Ranges / Interpretation

Any positive flagged vial is investigated to determine the identity of the pathogen. The significance of this pathogen is then determined by the medical microbiologists using clinical details provided.

Susceptibility Testing: Each susceptibility category is defined by breakpoints specific for each species and agent. The breakpoints are minimum inhibitory concentrations (MIC) and describe the amount of agent required to inhibit the growth of the organism.

The definitions of (S),(I), and (R) emphasize the close relationship between the susceptibility of the organism and the exposure of the organism at the site of infection.

Susceptible (S): High likelihood of therapeutic success with standard dosing.
Susceptible Increased Exposure (I): High likelihood of therapeutic success with increased dosing.
Resistant (R): High likelihood of therapeutic failure.

UKAS number

8869

UKAS accredited test?

Yes

Comments

Useful Links:

• Adult Antimicrobial Guide
• Paediatric Antimicrobial Guide
• Primary Care Antibiotic Guide

If you have any queries about a test or results interpretation please contact us.