This works against staphylococcal and streptococcal infections. Guttate psoriasis is often triggered by a streptococcal infection, typically streptococcal pharyngitis. Untreated streptococcal pharyngitis usually resolves within a few days. Spreading of infection through blood has been suggested for those with streptococcal pharyngitis. Air sacculitis is similar to streptococcal infection, e.g. strep throat in "Homo sapiens". A streptococci had to await the development of Lancefield's streptococcal grouping scheme in the 1920s. Sydenham's chorea occurs as a complication of streptococcal infection. The ASO titer is high in cases associated with a streptococcal throat infection. Bacterial culture may need to be performed in cases of a negative rapid streptococcal test. Antibiotics to combat the streptococcal infection are the mainstay of treatment for scarlet fever. The antibiotic treatment of choice for streptococcal and enteroccal infections differs by species. Agglutination techniques are also used in definitive diagnosis of group A streptococcal infection. Rarely it is also caused by a skin infection surrounding the anus (perianal streptococcal dermatitis). The disease typically develops two to four weeks after a streptococcal throat infection. Both conditions appear several weeks following the initial streptococcal infection.