BHU NO-2019
Pharmacology
Easy
The drug of choice for methicillin resistant staphylococcus aureus (MRSA) is:
Appeared in: BHU NO-2019
Explanation
- Vancomycin is a glycopeptide antibiotic, established as the most effective and first-line drug for treating serious MRSA infections.
- Its mechanism of action involves inhibiting bacterial cell wall synthesis by binding to the D-Ala-D-Ala terminus of peptidoglycan precursors, which is a different target from beta-lactam antibiotics.
- Clinical guidelines reserve Vancomycin for severe gram-positive infections, including MRSA-caused bacteremia, pneumonia, osteomyelitis, and endocarditis.
Why Other Options Were Wrong
- Option A: Clindamycin is not the primary drug of choice for severe or systemic MRSA infections due to variable susceptibility and the risk of inducible resistance.
- Option C: Gentamycin, an aminoglycoside, lacks reliable activity against MRSA when used alone and is not indicated as a primary monotherapy.
- Option D: Erythromycin is a macrolide antibiotic, and a high percentage of MRSA strains exhibit resistance to it, making it clinically ineffective.
Related Visual
Clinical Relevance
- Nursing practice connection: Knowing Pharmacology: Antimicrobial therapy for Methicillin-Resistant Staphylococcus Aureus (MRSA) helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
- A key nursing responsibility when administering IV Vancomycin is to prevent 'Red Man Syndrome' by ensuring a slow infusion rate, typically over at least 60-90 minutes.
- Nurses must diligently monitor for signs of toxicity, including checking renal function (BUN, creatinine) for nephrotoxicity and assessing for hearing changes or tinnitus for ototoxicity.
- Therapeutic drug monitoring is crucial. Nurses often draw blood for trough levels just before a dose to ensure the concentration is within the therapeutic range (e.g., 15-20 mcg/mL for serious infections) to maximize efficacy and minimize harm.
How to Approach the Question
- First, identify the key term in the question: 'MRSA' (Methicillin-Resistant Staphylococcus aureus). This immediately tells you the infection is caused by a bacterium resistant to standard beta-lactam antibiotics.
- Next, recall the specific classes of antibiotics and their primary uses. The question asks for the 'drug of choice,' which implies the most reliable and standard first-line treatment for serious infections.
- Evaluate each option's role against resistant gram-positive bacteria. Vancomycin is widely recognized in pharmacology as the cornerstone of therapy for severe MRSA infections.
- Eliminate the other options based on their known limitations. Clindamycin is for less severe, susceptible strains. Gentamycin is an add-on therapy, not a primary one. Erythromycin has high resistance rates.
- By this process of elimination and recall of first-line therapies, you can confidently select Vancomycin.
Concept Tested & Keywords
- Concept Tested: Pharmacology: Antimicrobial therapy for Methicillin-Resistant Staphylococcus Aureus (MRSA).
- Stem keywords: drug of choice, methicillin resistant staphylococcus aureus, MRSA
- Lead-in keywords: is
- Negative lead-in flag: false
Question ID
Qp7Z3_qVv53w93WbGVpp9w
Reference Book
E6 Pharmacology KD Tripathi Essentials 9e Part 3 p. 84-86
E6 Microbiology Essentials Sastry 4e Part 2 p. 70-72
E6 Medicine Harrison 22e Part 1 p. 1217-1219
Practise the full BHU NO-2019
Attempt every question from this paper in a timed mock, then review the full solution for each one.
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