# Blood Culture

## Overview

This module describes how to draw blood under sterile conditions and inoculate into a culture medium for microbiological investigations, when suspecting bacteraemia or sepsis.

## Indications

## Contraindications

1. Damaged skin, swelling, sclerosed veins, haematomas or skin infection at the drawing site
2. AV fistula or IV cannula site on the same limb

## Patient information and consent

Always verify your patient’s identity and obtain informed consent before proceeding.

### How do I explain this procedure?

“I need to draw blood from you to test for infections.”

### What can my patient expect?

“You may feel a sharp sting when I insert the needle. This blood test may take a little longer than usual blood tests and I may need to take blood from two or three places. Afterwards, the test results can take several days.”

### What is my patient’s role?

“Let me know if you have any allergies or a bleeding tendency, or use blood thinners. Fearing blood or needles is normal, but tell me if you have fainted from it. Everything must stay very clean to do this test. Keep as still as possible, and don’t cough, sneeze or reach over the equipment. Don’t touch the top of the paper I put over the area. Afterwards, press firmly on the area with cotton wool to prevent bleeding.”

## Preparation

Prepare a trolley with equipment.

### Documentation

1. Laboratory request form
2. Patient labels
3. Patient notes

### Equipment

## Site & Positioning

See Venous Blood Sampling, or if no venous sites found, Arterial Blood Sampling.

## Procedure

Follow medical asepsis with sterile gloves.

## Troubleshooting

I broke sterility.

Don’t risk contamination. Dispose of everything except the blood culture bottle, and start over.

Something fell off my sterile field and I’m gloved up.

Call for an assistant to collect the equipment and open it onto your sterile field while you wait. If nobody is available, collect the equipment yourself, then put on a new pair of sterile gloves and continue.

I couldn’t get a full 10 ml of blood.

You need a full 10 ml of blood. Don’t try to take a little more from another site and put it into the same bottle. Start over completely at a new site with a new bottle.

I want to use a femoral site for blood culture.

Only as a last resort, as these sites have a higher risk for contamination than upper limb sites. Be especially meticulous about skin antisepsis when using these sites.

Also see Venous Blood Sampling and Arterial Blood Sampling.

## Risks

See Venous Blood Sampling and Arterial Blood Sampling.

## References

1. Fabre V, Sharara SL, Salinas AB, Carroll KC, Desai S, & Cosgrove SE. Does This Patient Need Blood Cultures? A Scoping Review of Indications for Blood Cultures in Adult Nonneutropenic Inpatients. Clinical infectious diseases: an official publication of the Infectious Diseases Society of America. 2020;71(5):1339–1347.
2. WHO Guidelines on Drawing Blood: Best Practices in Phlebotomy. Geneva: World Health Organization; 2010. Available from: https://www.ncbi.nlm.nih.gov/books/NBK138665/.
3. Ntusi N, Aubin L, Oliver S, Whitelaw A, Mendelson M. Guideline for the optimal use of blood cultures. S Afr Med J. 2010;100(12):839-843. Published 2010 Dec 1. doi:10.7196/samj.4217