Question

Antibiotics inhibit the growth of:

• A. Bacteria and fungi
• B. Bacteria and viruses
• C. Bacteria, fungi and viruses
• D. Bacteria, algae and viruses

Answer 1

The correct option is D

Explanation of the correct answer:

1. The term antibiotic has been derived from the two terms 'anti' meaning 'against' and 'biotic' meaning 'life' (of bacteria).
2. It means antibiotics are the substances that inhibit the growth of mainly bacterial cells.
3. These either kill the bacterial cells or inhibit their growth.
4. E.g., penicillin, streptomycin, ampicillin, amoxicillin, etc.
5. However, there are few antibiotic that have been found to work against fungi and mainly applied on skin or scalp, for e.g., ketoconazole (used in anti-dandruff shampoos), clotrimazole (often used in anti-fungal ointments), etc.
6. Antibiotics either work by damaging cell wall or inhibiting the cell wall formation, or by hindering the protein formation in the living cells of bacteria or fungal cells.
7. Viruses lack the cell wall and their own protein synthesising machinery.
8. Hence, antibiotics do not work on viruses at all.
9. However, in complicated or prolonged viral infections, bacteria may invade as well, and cause what is known as a “secondary bacterial infection”, such as bacterial pneumonia.
10. In these cases, doctors may prescribe an antibiotic, if one is needed, to kill the specific invading bacteria.

Explanation of the incorrect answers:

Option A:

1. Antibiotics either work by damaging cell wall or inhibiting the cell wall formation, or by hindering the protein formation in the living cells of bacteria or fungal cells.
2. Viruses lack the cell wall and their own protein synthesising machinery.
3. Hence, antibiotics do not work on viruses at all.

4. They are given in some prolonged viral infection to prevent the secondary infection from the invading bacteria that may attack due to weakened immune system.

Option B:

1. Antibiotics do not work on algae, as they have different cell wall composition of cellulose.
2. Antibiotics also do not inhibit the growth of the viruses.

Option C:

1. Since, antibiotics do not inhibit the growth of the viruses.
2. Hence, this option is invalid.

Final answer: Antibiotics inhibit the growth of bacteria and fungi.