51.   From the start of treatment with the three-drug cocktails, doctors have worried about the spread of resistant strains.

52.   He compared missile defense systems with the overuse of antibiotics, which results in more resistant strains of disease.

53.   Resistant strains are being discovered in China at an alarming rate.

54.   Resistant strains develop when the treatment of a TB patient is inadequate or incomplete, thereby allowing some of the stronger bacilli to survive and multiply.

55.   Stover said it kills all of the drug-resistant forms of TB that have been tested to date, including the strains resistant to more than one drug.

56.   That might make it easier for seed companies to market strains more resistant to the stem rot.

57.   The advance is expected to enable scientists to engineer rice strains resistant to drought, salinity and insects.

58.   The letter warned that the special drugs needed to treat the resistant strains are too expensive for public health care systems even in wealthy countries.

59.   Treating patients with resistant strains is far more expensive, the report said.

60.   Tuberculosis re-emerged with a vengeance after the breakup of the Soviet Union, including new strains resistant to traditional drug treatments.