51.   Indeed, Takuma Shirasaka of the National Cancer Institute in Bethesda, Md., reported Wednesday that HIV can develop resistance to two drugs at once.

52.   Incomplete antibiotic use can allow various bacteria, residing in harmless amounts in most people, to develop resistance.

53.   It happens when a patient taking one drug becomes resistant to it and at the same time develops resistance to one or more totally separate drugs.

54.   It could also mean that patients will benefit from the current drugs for much longer before the virus develops resistance.

55.   It takes about two weeks to develop resistance to influenza virus after being vaccinated.

56.   It relies heavily on food baited with chemicals that prevent blood clotting, and rats, in particular, are quick to develop resistance to these anticoagulants.

57.   It was also a good sign, they said, that the reemergent virus had not developed resistance to antiviral drugs.

58.   Like Aedes aegypti, the Anopheles mosquito rapidly developed resistance to insecticides like DDT.

59.   Louganis learned about the importance of adherence the hard way, when he developed resistance and had to switch drugs.

60.   Many agents can make a tumor slow down for a while, until its cells develop resistance.