Most sore throats are caused by infections. Bacterial infections can also cause sore throats. The most common bacteria infection is Group A Streptococcus, is cause of an infection of the throat and tonsils. Streptococcal infection causes nearly 40 percent of sore throat cases in children. Tonsillitis, and sexually transmitted infections like N.gonorrhea can also cause a sore throat.

Any microorganism found where no resident flora is present is considered significant and is reported. For specimens contaminated with the usual bacterial flora, bacteria that are potentially pathogenic are identified.