Which of the following is not a broad spectrum antibiotic ?

Options

A. Vancomycin
B. Ampicillin
C. Ofloxacin
D. Penicillin

Answer

To determine which of the following is not a broad spectrum antibiotic, we need to understand the definitions and classifications of antibiotics.

### Step-by-Step Solution:

1. **Understand Antibiotic Classification**:
- Antibiotics are classified into two main categories: broad spectrum and narrow spectrum.
- **Broad Spectrum Antibiotics**: These are effective against a wide range of bacteria, both Gram-positive and Gram-negative.
- **Narrow Spectrum Antibiotics**: These are effective against specific types of bacteria, either Gram-positive or Gram-negative, but not both.

2. **Identify the Given Antibiotics**:
- The antibiotics mentioned are vancomycin, ampicillin, ofloxacin, and penicillin-G.

3. **Classify Each Antibiotic**:
- **Vancomycin**: This is generally considered a narrow spectrum antibiotic, primarily effective against Gram-positive bacteria.
- **Ampicillin**: This is a broad spectrum antibiotic effective against both Gram-positive and some Gram-negative bacteria.
- **Ofloxacin**: This is also a broad spectrum antibiotic, effective against a variety of bacteria.
- **Penicillin-G**: This is a narrow spectrum antibiotic, primarily effective against Gram-positive bacteria.

4. **Determine the Answer**:
- Among the options, vancomycin and penicillin-G are narrow spectrum antibiotics, while ampicillin and ofloxacin are broad spectrum antibiotics.
- Therefore, the antibiotic that is not a broad spectrum antibiotic is **penicillin-G**.

### Final Answer:
Penicillin-G is not a broad spectrum antibiotic.