Broth cultures

A broth culture more accurately represents the growing conditions of bacteria and or fungi. In the broth process the urine is placed into a Trypticase Soy Broth (TSB) for 3-6 days instead of being placed directly onto an agar plate or petri dish for incubation.

Critically, the temperature for the broth mixture is closely controlled which allows the microbes in the urine to evolve as they would in the body.

How does the broth process work?

Urine contains not only bacteria and/or fungi but also body waste products from foods, indigestibles, medications (antibiotics/vitamins) and toxins which need to be cleaned first before testing.

The urine is cleaned, spun for around 20 minutes, so that the residue can be poured away.

The remaining ‘clean’ urine is placed into the broth and incubated at 35 degrees celsius until growth appears. If no growth is found in three days the sample is left for up to another three days.

After the broth process the bacteria are placed onto agar plates and incubated again at 35 degrees Celsius for about 24 hours or until significant bacteria and/or fungal anaerobes emerge on the plate.

Once the infecting bacteria are identified, an ABST (Antibiotic Sensitivity Test) on them is carried out.

The results are provided to the patient so that appropriate treatment can take place.

Broth testing can also provide treatment sensitivities for fungal infections such as candida as well as anaerobes such as lactobacillus.

Please note that United Medical Labs discontinued their broth culture test in May 2019.  This test is now only offered by a couple of UK Chronic UTI specialists.

For more information please see Where to get a UTI Test

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