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Oxford University Hospitals NHS Foundation Trust
Microbiology

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Line tip culture

Indwelling catheters are used extensively for both monitoring and intervention in clinical treatment. The vast majority are peripheral lines, but central venous or arterial catheters are also used.

Cannula can become colonised with bacteria, especially skin flora, and these may go on to cause a bloodstream infection requiring clinical intervention and management. This may necessitate the removal of the cannula in order to remove the source of the infection and enable successful treatment.

Intravascular device related bacteraemia is now a significant clinical problem in hospitals and an important source of nosocomial infection.

Vascular line tips for the investigation of potential or proven bacteraemia should only be sent along with a blood culture.

Specimen requirements

Samples should be transported to the laboratory as soon as possible. If specimen transport will be delayed, e.g. from primary care, specimens should be stored in a refrigerator until transported to the laboratory.

Microbiology processes:

  • Venflon
  • Central line
  • CVP line
  • Subclavian line
  • Internal jugular line
  • Hickman line
  • PICC line
  • Long line
  • Vascath
  • Tesio line
  • TPN line
  • Swan Ganz line
  • Arterial line
  • Portacath line
  • Pacemaker wires
  • Pacing wires.

Samples should be sent in a sterile universal container. Send a simultaneous peripheral blood culture.

Send only if infection is suspected. Indications are site inflamed, or unexplained fever with central line in situ.

Indicate site and duration of line in situ before removal. Send line entry site swab if inflamed. Vascular line tips are only processed if the patient has a positive blood culture within days of line removal.

Laboratory turnaround time

The turnaround time for these samples is up to three days.

Focused testing

Vascular line tips are only routinely cultured when the patient has received a positive blood culture. Positive blood cultures should flag within a 14 day window of the line tip being received i.e. seven days before or after line tip removal.

If the patient has not had a positive blood culture in the seven days previous to receipt of the sample, it is fridged and reported as such. Please contact the laboratory to discuss if you would like a line tip processed.

Laboratory method

A semi-quantitative method is used to predict which line tips are infected and likely to cause bloodstream infections. A terminal segment of the line tip is rolled over the surface of a blood agar plate and the number of colonies counted after overnight incubation.

A threshold of >15 colonies of any organism is commonly accepted to predict line related sepsis.

Where to find results of these tests

  • All results are returned electronically where possible (EPR, SunquestICE).
  • Some results may be phoned to clinicians and GPs.
  • Results are never given directly to patients by the laboratory staff.

Further information and contact details

For further information please email:

Confidential patient information should only be sent from nhs.net accounts.