1998, is often used to aid in diagnosis. The original Centor criteria had four major criteria but the modified Centor criteria have five. The five major criteria of the modified Centor score are: Presence of tonsillar exudate Painful neck lymph nodes History of fever Age between five and fifteen years Absence of cough The possibility of GABHS infection increases with increasing score. The probability for getting GABHS is 2 to 23% for the score of 1, and 25 to 85% for the score of 4. The diagnosis of GABHS tonsillitis can be confirmed by culture of samples obtained by swabbing the throat and plating them on blood agar medium. This small percentage of false-negative results are part of the characteristics of the tests used but are also possible if the person has received antibiotics prior to testing. Identification requires 24 to 48 hours by culture but rapid screening tests (10–60 minutes), which have a sensitivity of 85–90%, are available. In 40% of the people without any symptoms, the throat culture can be positive. Therefore, throat culture is not routinely used in clinical practice for the detection of GABHS. Bacterial culture may need to be performed in cases of a negative rapid streptococcal test. An increase in antistreptolysin O (ASO) streptococcal antibody titer following the acute infection can provide retrospective evidence of GABHS infection and is considered definitive proof of GABHS infection, but not necessarily of the tonsils. Epstein Barr virus serology can be tested for those who may have infectious mononucleosis with a typical lymphocyte count in full blood count result. Blood investigations are only required for those with hospital admission requiring intravenous antibiotics. Nasoendoscopy can be used for those with severe neck pain and inability to swallow any fluids to rule out masked epiglotitis and supraglotitis. Routine nasoendscopy is not recommended for children. Treatment Treatments to reduce the discomfort from tonsillitis include: pain and fever reducing medications such as paracetamol (acetaminophen) and ibuprofen warm salt water gargle, lozenges, honey, or warm liquids There are no antiviral medical treatments for virally caused tonsillitis. Antibiotics If the tonsillitis is caused by group A streptococcus, then antibiotics are useful, with penicillin or amoxicillin being primary choices. Cephalosporins and macrolides are considered good alternatives to penicillin in the acute care setting. A macrolide, such as azithromycin or erythromycin, is used for people allergic to penicillin. If penicillin therapy fails, bacterial tonsillitis may respond