Brook and Gober1 showed that group A β-hemolytic streptococci can survive on toothbrushes and suggested that the failure of treating streptococcal pharyngitis may be due to the persistence of the organism on toothbrushes and orthodontic appliances. This is useful information and not surprising since, as they point out, toothbrushes have been shown to become contaminated with other microorganisms. Considering the price of a toothbrush compared with that of another office visit, it makes sense to follow the suggestion of Glass and Lare2: "We recommend that for the general population, toothbrushes be changed at least once a month and after any illness."
Fischer H. Contaminated Toothbrushes and Pharyngitis. Arch Otolaryngol Head Neck Surg. 1999;125(4):479. doi: