Definition

Sensitivity analysis determines the effectiveness of antibiotics against microorganisms (germs) such as bacteria that have been isolated from cultures.

Sensitivity analysis may be done along with:

• Blood culture
• Clean catch urine culture or catheterized specimen urine culture
• Sputum culture
• Culture from endocervix (female genital tract)
• Throat culture
• Wound and other cultures

Alternative Names

Antibiotic sensitivity testing; Antimicrobial susceptibility testing

How the Test is Performed

After the sample is collected from you, it is sent to a lab. There, the samples are put in special containers to grow the germs from the collected samples. Colonies of germs are combined with different antibiotics to see how well each antibiotic stops each colony from growing. The test determines how effective each antibiotic is against a given organism.

How to Prepare for the Test

Follow your health care provider's instructions on how to prepare for the method used to obtain the culture.

How the Test will Feel

The way the test feels depends on the method used to obtain the culture.

Why the Test is Performed

The test shows which antibiotic drugs should be used to treat an infection.

Many organisms are resistant to certain antibiotics. Sensitivity tests are important in helping find the right antibiotic for you. Your provider may start you on one antibiotic, but later change you to another because of the results of sensitivity analysis.

What Abnormal Results Mean

If the organism shows resistance to the antibiotics used in the test, those antibiotics will not be an effective treatment.

Risks

Risks depend on the method used to obtain the specific culture.

References

Charnot-Katsikas A, Harrington A. In vitro testing of antimicrobial agents. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 58.