Bacterial Culture Test

 

A swab can be taken from any area of the body that appears to have an infection. The microbiology laboratory attempt to culture (grow) a wide range of organisms (especially bacteria) from this sample, to determine which ‘germ’ is causing the infection.

A swab can be taken from any area of the body that appears to have an infection. The microbiology laboratory attempt to culture (grow) a wide range of organisms (especially bacteria) from this sample, to determine which ‘germ’ is causing the infection.

How the Test is Performed

Body fluids may be collected into a suitable sterile container. Alternatively a cotton-wool swab, which is like an ear-bud, is used to collect a small amount of fluid from a wound or surface. Some of this sample may then be transferred onto a glass slide at the bedside, for microscopy. The swab is transported in a special medium that encourages growth of bacteria.
It may take 2 to 3 days to actually culture (grow) the relevant bacterium in the laboratory. Small amounts of antibiotics are then applied to determine which antibiotics are most likely to be effective in treating the infection: the antibiotic sensitivity.

Medical Conditions and Symptoms

Bacterial cultures may be taken from any infected (or potentially infected) tissue or fluid, for example:

  • Urine
  • Sputum
  • Blood
  • Wound fluid or pus

Symptoms of infection include pain, swelling, warmth, redness and fever.

Test Results Explained

A negative culture or “no growth” does not necessarily exclude infection, but is relatively reassuring.
An organism may initially be identified by its general group, for example “gram-negative bacillus” and then subsequently identified more accurately: “E coli”. One or two days later the report will often contain the antibiotic sensitivities as a list of antibiotics with “R” (resistant) or “S” (sensitive) next to each drug. This reflects the sensitivity of the organism to the antibiotic in the laboratory dish, “in vitro”. This may not always be exactly the same as the clinically observed sensitivity in the human body, “in vivo”, in real life.

Related Specialists

Related Procedures

  • Blood Test (venesection)
  • Urinary Catheterisation
  • Suprapubic Aspiration
  • Tissue Biopsy
  • Bronchoscopy
  • Joint aspiration
  • Lumbar puncture

Related Tests

  • Viral Cultures
  • Blood Cultures

Also Known As

  • Micrsocopy, Culture and Sensitivity (MC&S or MCS)
  • Wound Swab