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. An example of a commonly used broad-spectrum antibiotic is ampicillin.
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.
- For prophylaxis within one hour before incision, for an operation, in order to prevent bacterial infections occurring.
As a side-effect, antibiotics can change the body's normal microbial content by attacking indiscriminately both the pathological and naturally occurring, beneficial or harmless bacteria found in the intestines, lungs and bladder. The destruction of the body's normal bacterial flora provides an opportunity for drug-resistant microorganisms to grow vigorously and can lead to a secondary infection such as Clostridium difficile (also known as "C. diff") or Candidiasis (also known as "thrush"). This side-effect is more likely with the use of broad-spectrum antibiotics.
- Aminoglycosides (except for streptomycin)
- Amoxicillin/clavulanic acid (Augmentin)
- Carbapenems (e.g. imipenem)
- Quinolones (e.g. ciprofloxacin)
- Clayton L. Thomas, ed. (1993). Taber's Cyclopedic Medical Dictionary (17th ed.). F. A. Davis Co. ISBN 0-8036-8313-8.
- S. J. Hopkins (1997). Drugs and Pharmacology for Nurses (12th ed.). Churchill Livingstone. ISBN 0-443-05249-2.
- E. A. Martin (2003). Oxford Concise Medical Dictionary (6th ed.). Oxford University Press. ISBN 0-19-860753-9.