Differential diagnosis of strep A and C

Background: Sore throat caused by Streptococcus pyogenes group A (Strep A) may warrant antibiotic treatment due to risk of complications. Other Streptococci (group C) have been associated with sore throat but there is insufficient evidence that they cause complications.Weevaluateddisease severity inpatientswith streptococcal and non-streptococcal sore throat, and the effect of flurbiprofen 8.75mg lozenge on symptoms prior to any antibiotic administration. Methods & Materials: Adults with sore throat <4 days were evaluated for findings of pharyngitis using the Tonsillo-Pharyngitis Assessment (TPA) and pharyngeal inflammation using the Practitioner’s Assessment of Inflammation and randomly assigned flurbiprofen or placebo lozenges under double-blind conditions. They rated their sore throat pain on the Throat Pain Scale and pain on swallowing (odynophagia) on the Sore Throat Pain Intensity Scale (STPIS) at baseline and over 7 days. Antibiotics could be administrated at the investigator’s discretion once a diagnosis was made by throat culture (at ∼48hours). Results: Of 204 patients, 32 (16%) had Strep A and 52 (25%) had Strep C. Both types of Strep patients had similar physical features, although pharyngeal inflammation was slightly more severe for Strep A (18.8%) than Strep C and non-Strep patients (11.5% and 11.7%, respectively, bothp=NS). 62.5%of StrepApatients described relativelymore severeodynophagia comparedwith34.6%of StrepC (p<0.05) and 44.2% of non-Strep patients (p =0.064). Themean TPA scores were similar irrespective of cause, indicating the difficulty in making a diagnosis based on physical findings. Irrespective of cause, patients taking flurbiprofen lozenges reported -473.7 mm*h decrease in STPIS scores over the first (pre-antibiotic) 24hours compared with -322.3 mm*h on placebo (i.e. 47% more relief with flurbiprofen versus placebo, p <0.05). By 48hours, mean lozenge consumption per day had decreased in both treatment groups regardless of etiology, indicating the natural resolution of symptoms with time. Conclusion: Patients with Strep A appear to have more severe pain and inflammation than those with Strep C or nonstreptococcal infection, although their clinical features are not distinct on physical examination. Sore throat, irrespective of cause, is a self-limiting condition but symptoms benefit from treatment with flurbiprofen lozenge.