<Li> <P> A set of large tonsils in the back of the throat, covered in white exudate . A culture positive case of streptococcal pharyngitis with typical tonsillar exudate in an 8 - year - old . </P> </Li> <P> A set of large tonsils in the back of the throat, covered in white exudate . A culture positive case of streptococcal pharyngitis with typical tonsillar exudate in an 8 - year - old . </P> <P> Strep throat is caused by group A beta - hemolytic streptococcus (GAS or S. pyogenes). Other bacteria such as non--group A beta - hemolytic streptococci and fusobacterium may also cause pharyngitis . It is spread by direct, close contact with an infected person; thus crowding, as may be found in the military and schools, increases the rate of transmission . Dried bacteria in dust are not infectious, although moist bacteria on toothbrushes or similar items can persist for up to fifteen days . Contaminated food can result in outbreaks, but this is rare . Of children with no signs or symptoms, 12% carry GAS in their pharynx, and, after treatment, approximately 15% of those remain positive, and are true "carriers". </P> <Table> Modified Centor score <Tr> <Th> Points </Th> <Th> Probability of Strep </Th> <Th> Management </Th> </Tr> <Tr> <Td> 1 or fewer </Td> <Td> <10% </Td> <Td> No antibiotic or culture needed </Td> </Tr> <Tr> <Td> </Td> <Td> 11--17% </Td> <Td> Antibiotic based on culture or RADT </Td> </Tr> <Tr> <Td> </Td> <Td> 28--35% </Td> </Tr> <Tr> <Td> 4 or 5 </Td> <Td> 52% </Td> <Td> Empiric antibiotics </Td> </Tr> </Table>

Where does the bacteria that causes strep throat come from
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