11.   Drug resistance to the older AIDS medicines like AZT has emerged after long-term use, and has been caused by the tendency of the AIDS virus to undergo mutation.

12.   Drug resistance is estimated to affect only a small percentage of infected individuals now, said Dr. John W. Mellors of the University of Pittsburgh.

13.   Drug resistance and the AIDS epidemic are two contributing factors.

14.   Drug resistance has become a critical factor in the failure of potent drug cocktails in many individuals infected with HIV, the AIDS virus.

15.   Drug resistance may take us back to those days, experts say.

16.   Failing to finish off a round of antibiotics is a problem unto itself, and leaves a child more vulnerable to re-infection and to developing drug resistance.

17.   For many people, the drugs prove too toxic, leading them to miss doses, and possibly promoting drug resistance.

18.   For patients with drug resistance or long-term complications of therapy, that goal may be unattainable.

19.   Fortunately, a new treatment cures normal TB and prevents new drug resistance.

20.   He said the challenge is to balance the need for precautionary medication with the risk of overusing drugs and increasing drug resistance.