Questions and Answers
What is Nalidixic Acid considered as?
A 1st generation quinolone
What is the main difference between the new fluoroquinolones and ciprofloxacin?
They are more active against G+ve organisms
Why were modifications made to Nalidixic Acid?
To expand the spectrum, improve pharmacokinetics, and increase stability against common mechanisms of resistance
What is a common issue associated with the use of fluoroquinolones?
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What is the mechanism of action of fluoroquinolones?
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Which enzyme is inhibited by fluoroquinolones in Gram-positive bacteria?
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What is the target of fluoroquinolones in Gram-negative bacteria?
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Which of the following is a type of fluoroquinolone?
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What distinguishes 2nd generation Fluoroquinolones from other generations?
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What is unique about the 3rd and 4th generation Fluoroquinolones?
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What is the primary target of Fluoroquinolones in bacterial cells?
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Which of the following is a characteristic of Ciprofloxacin?
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What sets Eukaryotic cells apart from bacterial cells in terms of DNA management?
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What is the primary difference between Nalidixic acid and Norfloxacin?
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Why are Fluoroquinolones ineffective against eukaryotic cells?
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What is unique about the antibacterial spectrum of 2nd generation Fluoroquinolones?
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Which generation of fluoroquinolones has poor activity against Pseudomonas aeruginosa?
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Which fluoroquinolone has excellent activity against Streptococcus pneumoniae respiratory infections?
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Which fluoroquinolone is used as an alternative to more toxic drugs such as aminoglycosides?
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Which of the following is a characteristic of 2nd generation fluoroquinolones?
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Which fluoroquinolone has 100% bioavailability and is dosed once daily?
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Which generation of fluoroquinolones has improved activity against atypical organisms and gram-positive bacteria?
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Which fluoroquinolone is used in the treatment of prostatitis due to E-coli?
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Which of the following is a characteristic of 4th generation fluoroquinolones?
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Study Notes
Fluoroquinolones
- Fluoroquinolones are derivatives of nalidixic acid, with broad antimicrobial activity, effective for treating various infectious diseases.
- Nalidixic acid is considered a 1st generation quinolone.
Mechanism of Action
- Fluoroquinolones block bacterial DNA replication by inhibiting DNA gyrase in Gram (-ve) bacteria and topoisomerase IV in Gram (+ve) bacteria.
Generations of Fluoroquinolones
- 1st generation: Nalidixic acid
- 2nd generation: Norfloxacin, Ciprofloxacin
- 3rd generation: Levofloxacin
- 4th generation: Moxifloxacin, Gemifloxacin
Antibacterial Spectrum of 2nd Generation Fluoroquinolones
- Norfloxacin and Ciprofloxacin have activity against:
- Aerobic Gram (-ve) bacteria (Pseudomonas aeruginosa, Haemophilus influenzae, Neisseria spp.)
- Atypical bacteria (Chlamydia, Mycoplasma)
- Ciprofloxacin is particularly useful in treating:
- Infections caused by Enterobacteriaceae, Gram (-ve) bacilli, and E-coli
- Typhoid fever caused by Salmonella typhi
- Pseudomonal infections associated with cystic fibrosis
- Traveler's diarrhea and urinary tract infections
Antibacterial Spectrum of 3rd Generation Fluoroquinolones
- Levofloxacin has:
- Expanded activity against Gram (-ve) bacteria
- Improved activity against atypical organisms and Gram (+ve) bacteria
- Excellent activity against S. pneumoniae respiratory infections
- 100% bioavailability and is dosed once daily
- Used in treating:
- Skin infections
- Acute sinusitis
- Acute exacerbation of chronic bronchitis
- Nosocomial pneumonia
- Prostatitis due to E-coli and sexually transmitted diseases (except syphilis)
Antibacterial Spectrum of 4th Generation Fluoroquinolones
- Moxifloxacin has:
- Enhanced activity against Gram (+ve) organisms (e.g., S. pneumoniae)
- Excellent activity against many anaerobes, although resistance to Bacteroides fragilis has been reported
- Poor activity against P. aeruginosa
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