Question

Anaerobes are resistant intrinsically against

• A. Beta lactam antibiotics
• B. Aminoglycosides
• C. Azithromycin
• D. Metronidazole

Answer 1

The Correct Option is B

Anaerobes are microorganisms that do not require oxygen for growth and can even be inhibited or killed by oxygen. These organisms are intrinsically resistant to several types of antibiotics, due to various physiological reasons.

The question asks which antibiotic anaerobes are intrinsically resistant to.

1. Beta lactam antibiotics: While beta-lactam antibiotics are generally effective against many bacteria, certain anaerobic bacteria can produce beta-lactamase enzymes, which give them resistance. However, not all anaerobes are intrinsically resistant.

2. Aminoglycosides: Anaerobes are intrinsically resistant to aminoglycosides. This is because aminoglycosides require oxygen to be transported into the bacterial cell, and in the absence of oxygen, the uptake of these antibiotics is ineffective. Therefore, anaerobic bacteria are resistant to them.

3. Azithromycin: Azithromycin is a macrolide antibiotic that is effective against a variety of aerobic and anaerobic bacteria. It is not known for intrinsic resistance in anaerobes.

4. Metronidazole: Metronidazole is specifically effective against anaerobic bacteria and protozoa, as it causes the production of free radicals that damage cellular components. Anaerobes are typically sensitive to this antibiotic.

Conclusion: Based on the mechanisms of action and level of resistance in anaerobes, it is clear that the correct answer is Aminoglycosides, as anaerobic bacteria are intrinsically resistant to this class of antibiotics.