Recent entries on DB's Medical Rants have called attention to a somewhat obscure cause of sore throat, namely a potentially very serious infection with a bacteria with the appropriately ominous name of Fusibacterium necrophorum. I will admit I was not aware of that issue.He discusses this infection in the important context of the "long tail" of diagnostic possibilities.
There is another, arguably a bit more common, cause of bacterial sore throat-infection with Arcanobacterium haemolyticum,formerly known as corynbacterium hemolyticum. This form of bacterial throat infection may be associated with a rash so that confusion with scarlet fever caused by beta-strep is possible. A CDC report indicates it may account for as many as 2.5 % of sore throat cases in young patients,occasionally cause a "membrane" on the throat as in diphtheria and may be penicillin resistant.
Clearly group A , beta-hemolytic streptococcal (GABHS) infection is the most common etiologic bacterial pathogen in pharyngitis but Arcanobacterium infection is easily missed. Not only is it similar to GABHS, a typical throat culture might miss A.Hemolyticum because the usual culture plate used for throat swabs may only show a small area of hemolysis after 24 hours with Arcanobacterium and the report would indicate only no beta strep present.
The e-Medicine article on Arcanobacterium infection suggests that the macrolide family of antibiotics are preferable to penicillin which is the traditional drug of choice for GABHS.
Neisseria gonorrhoeae and corynebacterium diphtheria have to mentioned as well although diphtheria is basically of historical interest only at least in the U.S. As time goes on,I'll bet we will add more bacterial pathogens to the recognized inhabitants of the long tail of etiologic agents of sore throat.