Broad-spectrum antibiotic

Broad-spectrum antibiotics are a class of antibiotics that are capable of acting against a wide range of bacteria, including both Gram-positive and Gram-negative strains. They are often contrasted with narrow-spectrum antibiotics, which are effective against a smaller range of bacterial species.

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Usage

Broad-spectrum antibiotics are often prescribed when the exact cause of an infection is unknown, as they can be effective against a variety of bacteria. They are also commonly used in cases of severe infections, when it is important to quickly reduce the bacterial load, and in cases where specific pathogens are resistant to narrow-spectrum antibiotics.

Beta-Lactams

Some beta-lactam antibiotics, such as amoxicillin and piperacillin, have a broad spectrum of activity. These antibiotics work by inhibiting bacterial cell wall synthesis.

Fluoroquinolones

Fluoroquinolones, such as ciprofloxacin and levofloxacin, are a class of synthetic antibiotics that inhibit the bacterial enzymes DNA gyrase and topoisomerase IV, thereby preventing DNA replication and transcription.

Tetracyclines

Tetracyclines, including doxycycline and tetracycline, are broad-spectrum antibiotics that inhibit bacterial protein synthesis by binding to the 30S ribosomal subunit.

Macrolides

Macrolides, such as erythromycin, azithromycin, and clarithromycin, also inhibit bacterial protein synthesis, but they do so by binding to the 50S ribosomal subunit.

Side Effects and Considerations

The use of broad-spectrum antibiotics can have unintended side effects, such as disrupting the normal microbiota of the human body. This can lead to secondary infections like Clostridioides difficile infection, which is associated with diarrhea and more severe intestinal conditions.

Resistance

Overuse or inappropriate use of broad-spectrum antibiotics can contribute to the development of antibiotic resistance, whereby bacteria evolve mechanisms to survive the effects of antibiotics. This is a significant global health concern.

Clinical Decision-Making

It's important for healthcare professionals to make judicious decisions regarding the prescription of broad-spectrum antibiotics. The decision should take into account the patient's health status, the suspected causative agent of infection, and the potential development of antibiotic resistance. In some cases, it may be preferable to use narrow-spectrum antibiotics if the bacterial cause is known.

See Also

• Narrow-spectrum antibiotic
• Antibiotic stewardship
• Pharmacology
• Antibiotic resistance

References

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• Goodman & Gilman's The Pharmacological Basis of Therapeutics, 13th Edition. Brunton, L.L., Hilal-Dandan, R., & Knollmann, B.C. (Eds.). McGraw-Hill Education, 2017. ISBN 978-1-259-64119-5.
• Principles and Practice of Infectious Diseases, 8th Edition. Mandell, G.L., Bennett, J.E., & Dolin, R. (Eds.). Elsevier, 2014. ISBN 978-1-4557-4801-3.

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