Researchers say overuse of antibiotics is breeding a stronger strep.
A Harvard School of Public Health study predicts as many as 40 percent of the strains of a dangerous form of strep (Streptococcus pneumoniae) could be resistant to two common antibiotics by next year.
That form of strep causes thousands of cases of meningitis, sinusitis, ear infections and pneumonia every year.
Researchers studied reports from eight states showing steady growth of resistance to penicillin and erythromycin from 1996 to 1999.
One of the researchers says the study adds more proof of the danger of unnecessary antibiotic use.
Many people demand antibiotics for colds -- even though antibiotics can't fight a cold.
Experts say doctors must be sure patients have a bacterial infection -- not a virus with similar symptoms -- before prescribing antibiotics.