What are quinolone (fluoroquinolone) antibiotics?

From the Guidelines

Quinolone antibiotics should be used with caution due to potential side effects, and their use should be guided by local resistance patterns and susceptibility testing, as recommended by the most recent guidelines 1.

Key Points

• Quinolone antibiotics, such as ciprofloxacin, levofloxacin, moxifloxacin, and ofloxacin, are effective against many gram-negative and some gram-positive bacteria.
• They are useful for treating urinary tract infections, respiratory infections, gastrointestinal infections, and certain skin infections.
• Typical dosing varies by specific medication and infection type, with ciprofloxacin often prescribed at 250-750mg twice daily and levofloxacin at 250-750mg once daily for 5-14 days depending on the infection.
• Quinolones should be used cautiously due to potential side effects including tendon damage, peripheral neuropathy, and QT interval prolongation.
• They are contraindicated in patients with myasthenia gravis and should be used carefully in elderly patients and those with kidney disease.
• Patients should avoid taking quinolones with dairy products, antacids, or supplements containing calcium, magnesium, aluminum, iron, or zinc, as these can reduce absorption.

Recommendations

• For empiric treatment of mild-to-moderate pyelonephritis and prostatitis, ciprofloxacin can be used as a first-choice option if local/national data on antimicrobial resistance patterns allow its use 1.
• For severe cases, amikacin is preferred to gentamicin due to its higher activity against Enterobacterales.
• Ceftriaxone and cefotaxime are also listed for severe infections.

Considerations

• The use of quinolones should be guided by local resistance patterns and susceptibility testing to minimize the risk of resistance development and treatment failure.
• The FDA has warned of serious safety issues with fluoroquinolones, including tendon damage, muscle and joint pain, and nerve damage, and recommends their use only for serious infections where the benefits outweigh the risks 1.

From the FDA Drug Label

The mechanism of action of levofloxacin and other fluoroquinolone antimicrobials involves inhibition of bacterial topoisomerase IV and DNA gyrase (both of which are type II topoisomerases), enzymes required for DNA replication, transcription, repair and recombination The bactericidal action of ciprofloxacin results from inhibition of the enzymes topoisomerase II (DNA gyrase) and topoisomerase IV, which are required for bacterial DNA replication, transcription, repair, and recombination

Quinolone Antibiotics work by inhibiting bacterial topoisomerase IV and DNA gyrase, which are essential for DNA replication, transcription, repair, and recombination.

• Levofloxacin and ciprofloxacin are examples of quinolone antibiotics that exhibit this mechanism of action 2, 3.
• The bactericidal action of these antibiotics results from the inhibition of these enzymes, ultimately leading to the death of the bacterial cells.
• Quinolone antibiotics are effective against a wide range of gram-negative and gram-positive microorganisms.

From the Research

Quinolone Antibiotics

• Quinolone antibiotics are a class of broad-spectrum antibiotics that are active against both gram-positive and gram-negative bacteria 4.
• They are commonly used to treat urinary tract infections, including complicated and nosocomial infections, as well as infections caused by multiresistant strains 4.
• Quinolones have also been shown to be effective against atypical pulmonary pathogens, such as Legionella, and against Chlamydia trachomatis and Ureaplasma urealyticum 4, 5.

Efficacy and Safety

• Studies have demonstrated that quinolones are effective in treating uncomplicated urinary tract infections in women, with ofloxacin being a commonly used option 6.
• However, the use of quinolones has also been associated with adverse events, such as central nervous system side effects and photosensitivity reactions 6, 5.
• The choice of quinolone versus trimethoprim-sulfamethoxazole for outpatient urinary tract infection treatment is influenced by factors such as patient demographics and physician prescribing patterns 7.

Clinical Use

• Quinolones are recommended as first-line treatment for certain infections, including complicated urinary tract infections, bacterial prostatitis, and selected pneumonia cases 8.
• Ciprofloxacin, a synthetic fluoroquinolone, is an oral quinolone that can be used to treat infections with gram-negative pathogens, and its use can help minimize overprescribing and development of resistance 8.
• The selection of quinolones depends on factors such as microbiologic activity, safety profile, and cost, with levofloxacin being preferred for general use due to its low resistance potential and minimal side effects 5.