I agree with Ms Sarah Chan Mun Ling that an antibiotics course should not be stopped too soon (Dangerous to stop antibiotics course too soon; July 31).

Antibiotics are prescribed to kill bacteria. When they are used, they should be used in such a way as to kill off all the bacteria, without leaving behind resistant traces.

However, patients often will not think twice about stopping the course when the symptoms subside. They believe that it is their bodies that develop resistance to the antibiotics, so it is all right not to complete the course. But not all the bacteria may be gone.

The problem is compounded, as antibiotics are easily available over the counter and online.

Public awareness campaigns on how antibiotics work are important.

Doctors must also play their part.

Often, patients go to the doctor and want something tangible to show for it, even if their illness is viral and antibiotics will do them no good.

Doctors, too, may prescribe antibiotics if they are not so sure of the cause of the illness.

One solution is to have diagnostic kits that confirm bacterial infection before antibiotics are prescribed.

If doctors can tell whether an infection is viral or bacterial, they would no longer prescribe antibiotics "just in case".

They can also prescribe drugs that are most effective against the infection, further limiting the emergence of resistant strains.

Francis Cheng