What is the difference between broad-spectrum and narrow-spectrum antibiotics?

Broad-spectrum antibiotics are effective against a wide range of bacteria, while narrow-spectrum antibiotics target specific types or groups of bacteria.

Broad-spectrum antibiotics are designed to combat a wide variety of bacterial infections. They are capable of killing or inhibiting the growth of many different types of bacteria. This makes them particularly useful when the exact cause of an infection is unknown, as they can target a wide range of potential culprits. Examples of broad-spectrum antibiotics include tetracyclines and quinolones.

On the other hand, narrow-spectrum antibiotics are more specialised. They are designed to target specific types or groups of bacteria. This means they are less likely to affect beneficial bacteria in the body, reducing the risk of unwanted side effects such as diarrhoea or yeast infections. However, they require a precise diagnosis to ensure they are targeting the correct bacteria. Penicillin is a well-known example of a narrow-spectrum antibiotic.

The choice between broad and narrow-spectrum antibiotics often depends on the situation. Broad-spectrum antibiotics can be a useful first line of defence when the cause of an infection is unknown. However, their use can lead to antibiotic resistance, as they kill off a wide range of bacteria, including those that are not causing illness. This can allow resistant bacteria to thrive and multiply.

In contrast, narrow-spectrum antibiotics are less likely to contribute to antibiotic resistance, as they target a smaller range of bacteria. However, they require a precise diagnosis to be effective. This can be challenging in situations where the cause of an infection is not immediately clear. Therefore, the choice between broad and narrow-spectrum antibiotics often involves a balance between effectiveness and the risk of promoting antibiotic resistance.