The term broad-spectrum antibiotic refers to an antibiotic that acts against a wide range of disease-causing bacteria. A broad-spectrum antibiotic acts against both Gram-positive and Gram-negative bacteria, in contrast to a narrow-spectrum antibiotic, which is effective against specific families of bacteria.
Broad-spectrum antibiotics are properly used in the following medical situations:
- Empirically (i.e., based on the experience of the practitioner), prior to the formal identification of the causative bacteria, when there is a wide range of possible illnesses and a potentially serious illness would result if treatment is delayed. This occurs, for example, in meningitis, where the patient can become fatally ill within hours if broad-spectrum antibiotics are not initiated.
- For drug resistant bacteria that do not respond to other, more narrow-spectrum antibiotics.
- In the case of superinfections, where there are multiple types of bacteria causing illness, thus warranting either a broad-spectrum antibiotic or combination antibiotic therapy.