Lab tests
How to read a culture and sensitivity report
A culture report says whether anything grew from a sample of urine, blood, a wound or a swab, and a sensitivity table lists which antibiotics worked against it in the laboratory. Add your report below to see both parts laid out and the abbreviations explained.
Explain your culture and sensitivity report
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What you get
- The sample type and the organism or organisms reported.
- Colony counts and phrases such as no growth or mixed growth explained.
- The antibiotic table restated, with S, I and R written out.
- Questions to ask the clinician who requested the culture.
Terms you may see
- No growthNothing grew from the sample in the time it was incubated
- Mixed growthSeveral kinds of organism grew together
- Normal floraOrganisms that usually live at that site
- CFU/mLColony-forming units per millilitre, a measure of how much grew
- S, I and RSusceptible, intermediate and resistant
- MICThe lowest concentration of an antibiotic that stopped the organism growing in the test
What this tool cannot tell you
A sensitivity table shows what happened in a laboratory dish. Choosing an antibiotic also depends on where the infection is, your allergies, other medicines, kidney function and more, and some organisms that grow are not causing illness at all. MedicDecode explains the report. It does not recommend an antibiotic.
Common questions
What is a culture and sensitivity report?
It shows whether bacteria grew from a sample (urine, a wound swab, blood) and, if so, which antibiotics they are sensitive (S) or resistant (R) to in the laboratory.
How long does a culture and sensitivity take?
Usually two to three days, sometimes longer, because the bacteria have to grow before they can be identified and tested.
What do S, I and R mean?
Susceptible means the antibiotic stopped the organism in the laboratory test. Resistant means it did not. Intermediate falls between the two.
What does mixed growth mean?
Several organisms grew at once. Laboratories often report this when a sample may have been contaminated during collection, and may suggest a repeat sample.
The report lists antibiotics I was not given. Why?
Laboratories test a standard set of antibiotics for each type of organism. The list is not a prescription.
Words you may see on this report
Tap a word for its plain-English meaning, an example line and what it does not mean.
- Culture and Sensitivity
A culture and sensitivity test grows germs from a sample to identify them, then checks which antibiotics can stop them.
- ALT (Alanine Aminotransferase)
ALT is an enzyme found mainly in the liver; when liver cells are irritated or damaged, more ALT leaks into the blood.
- AST (Aspartate Aminotransferase)
AST is an enzyme found in the liver, muscles, heart and other tissues; raised levels can signal stress or damage in one of these.
- Bilirubin
Bilirubin is a yellow substance made when old red blood cells break down; the liver processes it so it can leave the body.
- Creatinine
Creatinine is a waste product from normal muscle activity that the kidneys filter out, so its blood level helps show how well the kidneys work.
- CRP (C-Reactive Protein)
CRP is a protein made by the liver that rises quickly when there is inflammation or infection in the body.
- eGFR (Estimated Glomerular Filtration Rate)
eGFR is an estimate of how well your kidneys filter waste from your blood, calculated from a creatinine blood test plus details like age.
- Electrolytes
Electrolytes are minerals in the blood, such as sodium, potassium and chloride, that carry an electric charge and help the body work.
- ESR (Erythrocyte Sedimentation Rate)
ESR measures how fast red blood cells sink in a tube of blood over an hour; a faster rate can be a general sign of inflammation.
- Fasting Sample
A fasting sample is blood taken after you have had nothing to eat or drink except water for a set number of hours.
- Ferritin
Ferritin is a protein that stores iron; its blood level gives a good idea of how much iron the body has in reserve.
- HbA1c
HbA1c shows your average blood sugar over roughly the past two to three months by measuring how much sugar is attached to red blood cells.
Medicines connected to this test
Their official labels mention this kind of test. Each is explained in plain English.
- Albendazole
an anthelmintic drug, a medicine used to treat infections caused by parasitic worms
- Amoxicillin
a penicillin-class antibacterial medicine that works against bacteria
- Amoxicillin and Clavulanate Potassium
A penicillin-class antibacterial combined with a beta-lactamase inhibitor, as the label describes it
- Ampicillin Sodium
a penicillin-type antibacterial medicine
- Azithromycin
a macrolide antibacterial (antibiotic) medicine
- Ceftriaxone
A broad-spectrum cephalosporin antibiotic, as described on the official FDA label
- Cephalexin
a cephalosporin antibacterial medicine (an antibiotic that treats bacterial infections)
- Ciprofloxacin
a fluoroquinolone antibacterial medicine