Question

Which of the following does not belong to broad spectrum antibiotics? (A) Penicilin G (B)Ampicilin (C) Amoxycillin (D) Chloramphenicol

Short answer

The correct answer is (A) Penicillin G, as it is a narrow-spectrum antibiotic, not effective against a wide range of bacterial infections.

Step-by-step solution

Analyze each antibiotic option

Let's briefly look at each antibiotic mentioned in the exercise and understand their properties and effectiveness against bacterial infections. (A) Penicillin G - It is a narrow-spectrum antibiotic, primarily effective against gram-positive bacteria. It is not effective against a wide range of bacterial infections. (B) Ampicillin - It is a broad-spectrum antibiotic, effective against both gram-positive and gram-negative bacteria. (C) Amoxicillin - It is also a broad-spectrum antibiotic, effective against both gram-positive and gram-negative bacteria. (D) Chloramphenicol - It is a broad-spectrum antibiotic, effective against a wide range of bacterial infections, including gram-positive and gram-negative bacteria.

Identify the antibiotic that does not belong to the broad-spectrum category

Based on the analysis above, we can see that Penicillin G (option A) is the only antibiotic among the given options that is not effective against a wide range of bacterial infections, which makes it a narrow-spectrum antibiotic.

Choose the correct answer

Therefore, the answer to the question "Which of the following does not belong to broad-spectrum antibiotics?" is (A) Penicillin G, as it is a narrow-spectrum antibiotic, not effective against a wide range of bacterial infections.

Key concepts

Narrow Spectrum Antibiotics

Narrow spectrum antibiotics are a type of antibiotics that are specifically effective against a limited range of bacteria. They are particularly useful when the specific bacteria causing an infection is known, allowing for targeted treatment.
These antibiotics generally focus on either gram-positive or gram-negative bacteria but not both. The advantage of narrow-spectrum antibiotics is that they minimize the impact on beneficial bacteria in the body, reducing the risk of side effects and resistance.
For example, Penicillin G, a narrow spectrum antibiotic, is tailored to combat primarily gram-positive bacteria. It is not designed to tackle a wide variety of bacterial infections, which is why Penicillin G does not fall under the category of broad-spectrum antibiotics.

Gram-Positive Bacteria

Gram-positive bacteria have a thick cell wall composed primarily of peptidoglycan, which is a key characteristic that distinguishes them from gram-negative bacteria.
They retain the crystal violet stain used in the Gram staining procedure, appearing purple under a microscope.
Because of their thick cell wall, certain antibiotics such as narrow-spectrum Penicillin G are particularly effective against gram-positive bacteria, disrupting cell wall synthesis and leading to bacterial cell death.
Common infections caused by gram-positive bacteria include streptococcal throat infections, staphylococcal skin infections, and certain types of pneumonia.

Gram-Negative Bacteria

Gram-negative bacteria are characterized by a thinner peptidoglycan layer but have an additional outer membrane, making them more resistant to certain antibiotics compared to gram-positive bacteria.
Unlike gram-positive bacteria, they do not retain the violet stain in the Gram procedure and instead appear red or pink.
This structural difference is significant because it affects how antibiotics can penetrate and disrupt these bacteria, making some broad-spectrum antibiotics like ampicillin and amoxicillin effective against them.
Infections caused by gram-negative bacteria can include urinary tract infections, respiratory infections, and infections caused by Salmonella and E. coli.