- Fluoroquinolones are a class of broad-spectrum antibiotics used to treat bacterial infections by targeting DNA replication. They inhibit bacterial DNA topoisomerases, specifically DNA gyrase and topoisomerase IV, enzymes essential for DNA supercoiling and cell survival.
- Due to their efficacy against both Gram-positive and Gram-negative bacteria, fluoroquinolones have been widely used in medicine, particularly for respiratory, urinary tract, and gastrointestinal infections.
- Fluoroquinolones are synthetic antibiotics derived from quinolone compounds, characterized by a fluorine atom at the C-6 position, which enhances bacterial penetration and antimicrobial potency. Their core structure includes a bicyclic quinolone scaffold, allowing them to interact with bacterial DNA enzymes.
- Examples of fluoroquinolones include:
- Ciprofloxacin – Effective against Gram-negative bacteria, commonly used for urinary tract infections and anthrax treatment.
- Levofloxacin – A respiratory fluoroquinolone used for pneumonia, bronchitis, and sinus infections.
- Moxifloxacin – A fourth-generation fluoroquinolone with enhanced Gram-positive activity, used for respiratory and intra-abdominal infections.
- Ofloxacin – Used for bacterial conjunctivitis and systemic infections.
- Fluoroquinolones work by inhibiting DNA gyrase (in Gram-negative bacteria) and topoisomerase IV (in Gram-positive bacteria). These enzymes regulate DNA supercoiling and segregation during replication. The antibiotics stabilize the DNA-enzyme complex after cleavage, preventing the re-ligation of DNA strands and leading to lethal double-strand breaks.
- Their bactericidal effect makes them highly effective against actively dividing bacteria, reducing the likelihood of resistance compared to bacteriostatic antibiotics. However, mutations in DNA gyrase or efflux pump mechanisms can lead to fluoroquinolone resistance, posing challenges in antimicrobial therapy.
- Fluoroquinolones are used to treat a variety of infections, including:
- Respiratory tract infections (pneumonia, chronic bronchitis exacerbations).
- Urinary tract infections (pyelonephritis, cystitis).
- Gastrointestinal infections (bacterial diarrhea, typhoid fever).
- Soft tissue and bone infections (osteomyelitis, cellulitis).
- Despite their effectiveness, fluoroquinolones are associated with potential adverse effects, including tendon rupture, QT interval prolongation, and central nervous system disturbances. Due to these risks, their use is often reserved for cases where alternative antibiotics are ineffective or unsuitable.
