To determine whether the advice is warranted, the UTMB researchers tried to grow group A Streptococcus (GAS), the bacteria that causes strep throat, on toothbrushes that had been exposed to the bacteria in a laboratory. The bacteria did in fact grow and remained on the toothbrushes for at least 48 hours.
Surprisingly, two new toothbrushes that were not exposed to GAS and served as controls also grew bacteria even though they had been removed from their packaging in a sterile fashion. An adult-size toothbrush grew gram-negative bacilli, and a child-size toothbrush grew gram-positive cocci, which was identified as Staphylococcus. Since this was not the main focus of the study, the researchers did not investigate this finding further.
Next, they investigated whether GAS would grow on toothbrushes used by children who had strep throat. Fourteen patients who were diagnosed with strep throat, 13 patients with sore throats without strep and 27 well patients ages 2 to 20 years were instructed to brush their teeth for one minute with a new toothbrush. Afterwards, the toothbrushes were placed in a sterile cover and taken to a lab where they were tested for GAS bacteria growth.
GAS was recovered from only one toothbrush, which had been used by a patient without strep throat. The other study toothbrushes failed to grow GAS but did grow other bacteria that are common in the mouth.
"This study supports that it is probably unnecessary to throw away your toothbrush after a diagnosis of strep throat," said co-author Judith L. Rowen, MD, associate professor of pediatrics in the Department of Pediatrics at UTMB.
Study co-author Lauren K. Shepard, DO, a resident physician in the Department of Pediatrics at UTMB, noted that the study was small. Larger studies with more subjects need to be conducted to confirm that group A Streptococcus does not grow on toothbrushes used at home by children with strep throat, she said.
The study was recently presented at the Pediatric Academic Societies (PAS) annual meeting in Washington, DC.