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Urine culture
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A urine culture is the test used to find out which microorganism is causing a urinary tract infection. It is the reference standard, meaning the test the others are measured against, because it identifies the culprit.
The procedure comes down to letting the bacteria grow. In the lab the urine is sampled with calibrated loops, wire loops that always collect the same volume, and spread onto culture media, which are plates with nutrients; the most commonly used are blood agar and MacConkey agar. The plates then go into an incubator at thirty-five to thirty-seven degrees Celsius for twenty-four to forty-eight hours. The bacteria are given food and warmth so they multiply until they are visible.
Two things come out of this. One is a number: the colony-forming units per milliliter, a count of how many bacteria were present. The other is isolated colonies, separate clumps of a single species, which are used to identify the germ and test which antibiotics it is susceptible to.
In brief
A urine culture is the reference standard for identifying the organism causing a urinary tract infection.
The urine is plated with calibrated loops on media such as blood agar and MacConkey agar and incubated for twenty-four to forty-eight hours at 35 to 37 degrees Celsius.
The bacteria are given food and warmth so they multiply until they are visible.
That yields the colony-forming units per milliliter and isolated colonies to identify the germ and test its antibiotic susceptibility.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingUrine Culture, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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