Question

A broad spectrum antibiotic is (a) penicillin (b) paracetamol (c) chloramphenicol (d) aspirin

Short answer

The broad spectrum antibiotic is (c) chloramphenicol.

Step-by-step solution

Understand What Broad Spectrum Means

Broad spectrum antibiotics are medications that are effective against a wide variety of bacteria, including both Gram-positive and Gram-negative bacteria. This contrasts with narrow spectrum antibiotics, which are only effective against a specific type or group of bacteria.

Identify Each Option

We have four options to consider: (a) penicillin, (b) paracetamol, (c) chloramphenicol, and (d) aspirin. Penicillin is a well-known antibiotic, paracetamol is an analgesic and antipyretic, chloramphenicol is an antibiotic, and aspirin is an analgesic and anti-inflammatory drug.

Evaluate Effectiveness on Bacteria

Among the options, chloramphenicol is a broad spectrum antibiotic, meaning it can act on a range of bacteria including various Gram-positive and Gram-negative bacteria. Penicillin, while an antibiotic, is generally more specific and not considered broad spectrum. Paracetamol and aspirin are not antibiotics and therefore do not fit the definition.

Choose the Correct Option

Given the nature of chloramphenicol as effective against a wide range of bacteria, it fits the definition of a broad spectrum antibiotic within the provided options.

Key concepts

Gram-positive bacteria

Gram-positive bacteria are characterized by their thick peptidoglycan cell walls. This structure makes them stain purple when subjected to the Gram stain technique, a critical identifier in microbiology.
Bacteria such as *Staphylococcus* and *Streptococcus* are common examples.

These bacteria are generally more susceptible to certain antibiotics that target their cell wall composition.

• **Thick Peptidoglycan Layer**: Provides structural support and protection.
• **Vulnerability to Antibiotics**: Many antibiotics, like penicillin, are especially effective against Gram-positive bacteria due to their impact on cell wall synthesis.

Understanding the characteristics of Gram-positive bacteria helps in selecting appropriate antibiotics and confirms the effectiveness of broad spectrum antibiotics like chloramphenicol, which can act on these bacteria.

Gram-negative bacteria

Gram-negative bacteria possess a complex cell wall structure, which includes an outer membrane and a thin peptidoglycan layer. Due to these features, they do not retain the violet stain used in the Gram staining process and instead appear pink.
Common diseases caused by Gram-negative bacteria include infections from *Escherichia coli* and *Salmonella*.

The presence of the outer membrane in these bacteria provides resistance to certain types of antibiotics, making treatment more challenging.

• **Outer Membrane**: Provides an extra layer of protection, making Gram-negative bacteria more resistant to antibodies and antibiotics.
• **Resistance**: The outer membrane contains lipopolysaccharides, which contribute to the enhanced defense against antibiotics.

Broad spectrum antibiotics, such as chloramphenicol, are vital because they can penetrate these sophisticated defense mechanisms, effectively treating infections caused by Gram-negative bacteria.

Antibiotic effectiveness

Antibiotic effectiveness is a crucial consideration in medical treatment and involves the ability of a drug to inhibit or kill bacterial pathogens. It often depends on the specific type of bacteria and the properties of the antibiotic itself.
The spectrum of an antibiotic refers to the range of bacteria it affects.

Narrow spectrum antibiotics are tailored to a specific group, while broad spectrum antibiotics cover a wide array of pathogens.

• **Broad Spectrum Antibiotics**: Effective against both Gram-positive and Gram-negative bacteria, bridging typical barriers that prevent treatment.
• **Narrow Spectrum Antibiotics**: Target a specific type of bacteria, often used when the causative agent is known.

Chloramphenicol's classification as a broad spectrum antibiotic highlights its broad applicability in treating various bacterial infections, which is essential in combating resistant strains.

Chloramphenicol as an antibiotic

Chloramphenicol is noted for its broad spectrum antimicrobial activity. It works by inhibiting bacterial protein synthesis, effectively halting bacterial growth and reproduction.
This mechanism makes it potent against both Gram-positive and Gram-negative bacteria.

However, chloramphenicol's use is often reserved for serious infections due to its potential side effects.

• **Mechanism of Action**: Inhibits protein synthesis by binding to the bacterial ribosome, a crucial component in the protein production process.
• **Applications**: Used to treat serious infections such as typhoid fever, meningitis, and certain eye infections.
• **Side Effects**: Rare yet significant side effects, including bone marrow suppression, necessitate careful monitoring and restricted use.

Despite these concerns, the broad efficacy of chloramphenicol continues to make it an invaluable tool in the antibiotic arsenal, especially when other treatments are ineffective.