## **Core Concept**
Penicillin G, also known as benzylpenicillin, is a narrow-spectrum β-lactam antibiotic of the penicillin class. It is effective against Gram-positive bacteria, some Gram-negative bacteria, and certain anaerobic bacteria. Its mechanism of action involves inhibiting bacterial cell wall synthesis.

## **Why the Correct Answer is Right**
The correct answer, , highlights a key characteristic of penicillin G: it has a narrow spectrum of activity and is primarily effective against Gram-positive bacteria and certain Gram-negative cocci. It is also notable for its relatively short half-life, requiring frequent dosing unless a repository form (like benzathine penicillin) is used.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Incorrect because while penicillin G does have a role in treating certain infections caused by susceptible organisms, stating it without specific context can be misleading.
- **Option B:** Incorrect because, although penicillin G can be administered parenterally (intravenously or intramuscularly), the statement lacks specificity regarding its unique characteristics compared to other options.
- **Option C:** Incorrect as it does not accurately represent a distinguishing feature of penicillin G compared to other penicillins or antibiotics.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that penicillin G is the drug of choice for infections caused by susceptible strains of *Streptococcus pyogenes* (Group A beta-hemolytic streptococci), *Streptococcus pneumoniae*, and *Neisseria meningitidis*. It is also used in the treatment of syphilis.

## **Correct Answer:** .