Role of clinical features in distinguishing between viral and streptococcal pharyngitis and tonsillitis

Distinguishing between viral and streptococcal pharyngitis and tonsillitis based on clinical features can be challenging.

Viral pharyngitis and tonsillitis are strongly suggested by the presence of any one of the following clinical features: cough, hoarse voice, conjunctivitis, nasal congestion, anterior stomatitis, viral exanthema and diarrhoeaShulman, 2012.

Streptococcal pharyngitis and tonsillitis are difficult to diagnose based on clinical features alone. The clinical features traditionally associated with streptococcal infection are abrupt onset of symptoms, fever (above 38°C), tender cervical lymphadenopathy, tonsillar exudate, and the absence of cough, rhinorrhoea or nasal congestionCentor, 1981Shulman, 2012. Clinical scoring systems that use these or similar features to indicate risk of streptococcal infection have not been validated for use in an Australian context or considered in the context of acute rheumatic fever risk, but international studies have shown that even if several of these features are present, the likelihood of having a streptococcal infection is less than 60%National Institute for Clinical Excellence (NICE), 2018RHDAustralia (ARF/RHD writing group), 2020Shulman, 2012. These clinical features are even less predictive in children than in adults.

Pharyngitis caused by particular toxin-producing strains of S. pyogenes can be associated with scarlet fever, particularly in children between the ages of 5 and 15 years. Clinical features of scarlet fever include a sudden high fever (above 38.5°C) followed by a distinctive rash (red initially, becoming dry and rough with a sandpaper feel), facial flushing with circumoral pallor, and tongue discolouration (white initially, becoming red and bumpy [strawberry tongue]). In a patient with acute sore throat, a scarlet fever–type rash increases the likelihood of a streptococcal cause of pharyngitisThe Royal Children's Hospital Melbourne (RCH), Last updated May 2019.