The Centor criteria are a set of clinical findings that, taken together, may be used as an aid in making the diagnosis of Group A β-haemolytic streptococcus as a cause of a sore throat or tonsillitis.
The Centor criteria are:
- tonsillar exudate
- tender anterior cervical lymph nodes
- absence of cough
- history of fever.
- The presence of at least three of these clinical signs suggests that the chance of the patient having a bacterial (streptococcal) infection is between 40% and 60%, so this supports, (but doesn’t mandate) the use of antibiotics.
- The absence of three or more of these signs suggests that there is an 80% chance that the patient doesn’t have a bacterial infection, and so antibiotics are unlikely to be required.
- In patients with tonsillitis who are unwell, and have three or more criteria, the risk of quinsy is 1:60 compared with 1:400 in those who don’t – which would weight decisions in favour of prescribing in these cases.
When to use it
Sore throat is a very common symptom. It may be part of a complex of symptoms associated with a simple viral upper-respiratory tract infection, acid reflux, globus sensation or simple snoring. But sore throat may also represent a more serious and localised bacterial infection. The most common bacterial organism is a group-B haemolytic streptococcus. These infections can be associated with complications such as dysphagia, dehydration, quinsy (peritonsillar abscess) and even nephritis and rheumatic fever – fortunately such complications are rare.
It is important to bear in mind that antibiotics are unnecessary for most patients with an acute sore throat as it is usually self-limiting – symptoms resolve within about a week in 85% of people, whether the sore throat is because of streptococcal infection or not.
The Centor criteria are easy to use in the practice setting when a patient presents with an acute-onset sore throat, to help you decide whether or not to prescribe antibiotics. If antibiotics are prescribed, penicillin V is probably the optimal first choice in a non-penicillin allergic patient.
Nevertheless, the Centor criteria are not perfect – there is still a need for appropriate clinical acumen. Rigid adherence to the criteria will result in some patients with bacterial pharyngitis not being treated and unnecessary antibiotic treatment for others.
There have been a number of clinical trials, and a Cochrane review showing modest benefit in terms of symptom resolution following the prescription of antibiotics for sore throat.1 These benefits are greater in the presence of a confirmed bacterial (streptococcal) infection.
Mr Andrew McCombe is a consultant ENT surgeon at Frimley Park Hospital in Surrey, and honorary secretary of ENT UK.
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- Del Mar CB, Glasziou PP and Spinks AB. Antibiotics for sore throat (Cochrane Review). The Cochrane Library. Issue 4. John Wiley & Sons, Ltd. 2006
MeReC Bulletin. Sore throat. 2006;17(3):12-14