The least broad-spectrum antibiotics are

Options

A. Cyclosporins
B. 4-Quinolones
C. Gentamicins
D. Neomycins

Answer

To determine the least broad-spectrum antibiotics from the given options, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Broad-spectrum antibiotics**: These antibiotics are effective against a wide range of bacteria, including both Gram-positive and Gram-negative bacteria.
- **Narrow-spectrum antibiotics**: These antibiotics are effective against a limited range of bacteria.

2. **Analyze the Options**:
- **Cyclsporins**: This is primarily an immunosuppressant and not classified as an antibiotic.
- **4-quinolones**: These are a class of broad-spectrum antibiotics effective against a variety of bacterial infections.
- **Gentamicins**: This is an aminoglycoside antibiotic that has broad-spectrum activity against many bacteria.
- **Neomycins**: Another aminoglycoside antibiotic with broad-spectrum activity.

3. **Identify the Least Broad-Spectrum Antibiotic**:
- Since cyclosporins are not antibiotics, they do not fit into the category of broad-spectrum or narrow-spectrum antibiotics. The other three options (4-quinolones, gentamicins, and neomycins) are all broad-spectrum antibiotics.

4. **Conclusion**:
- Therefore, the least broad-spectrum antibiotic among the given options is **cyclosporins**.

### Final Answer:
The least broad-spectrum antibiotics are **cyclosporins**.

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