11.   This condition is usually brought on by prolonged use of antibiotics or the overuse of different antibiotics.

12.   Different antibiotics are needed for different strains of the disease, he said.

13.   Different antibiotics are needed for different strains of anthrax, he said.

14.   He pointed out that different antibiotics are needed for different strains of anthrax.

15.   The tuberculosis bacteria is airborne and must be treated with different antibiotics for as long as six months.