Penicillin, an antibiotic, can treat all of the following infections except?

Appeared in: IGNOU Post B. SC. Nursing entrance -2021

Explanation

Herpes is a viral infection caused by the Herpes Simplex Virus (HSV).
Penicillin is a β-lactam antibiotic that functions by inhibiting the synthesis of the bacterial cell wall.
Viruses, including HSV, do not have a cell wall, rendering penicillin and other similar antibiotics ineffective against them.
The appropriate treatment for viral infections like herpes involves antiviral medications, such as acyclovir, which interfere with viral replication.

Option A: This is incorrect because many common types of community-acquired pneumonia are caused by bacteria, most notably Streptococcus pneumoniae, which is highly susceptible to penicillin.
Option B: This is incorrect because many common respiratory tract infections, such as streptococcal pharyngitis (strep throat), are bacterial in origin and are effectively treated with penicillin.
Option C: This is incorrect because scarlet fever is a classic bacterial infection caused by toxin-producing strains of Streptococcus pyogenes. Penicillin is the drug of choice for treating scarlet fever to eradicate the bacteria and prevent complications like rheumatic fever.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Spectrum of Antibiotic Activity as background academic context rather than a clinical decision trigger.
A core nursing responsibility is patient education on appropriate antibiotic use. This helps combat the global health crisis of antibiotic resistance.
Nurses must be able to differentiate between signs of bacterial and viral infections to anticipate appropriate treatments and provide correct patient education.
Understanding the mechanism of action for different drug classes (e.g., antibiotics vs. antivirals) is fundamental to safe medication administration and patient care.

How to Approach the Question

First, identify the keyword 'except' in the question stem. This signals that you are looking for the option that does not fit with the others.
The question asks what penicillin, an antibiotic, can NOT treat. This means three of the options are treatable with penicillin, and one is not.
Recall the primary function of antibiotics: they target and kill bacteria.
Analyze each option to determine its cause: is it bacterial or viral?
Pneumonia, respiratory infections, and scarlet fever are often caused by bacteria. Herpes is caused by a virus.
Conclude that the viral infection (Herpes) is the one that cannot be treated by the antibiotic penicillin, making it the correct answer.

Concept Tested & Keywords

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E6 Pharmacology KD Tripathi Essentials 9e Part 3 pp. 50-52, 51-53

E6 Medicine Harrison 22e Part 1 p. 1249-1251

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