This question is a rather interesting one. While pharyngitis with viral or bacterial etiologies have very similar clinical presentations, there are a few subtle hints that make Throat Culture the more likely answer regardless of the CENTOR score in this Vignette.

September. The seasonality of Group A Strep (GAS) pharyngitis is usually between winter & early spring. Viral pharyngitis, although all year round, is more common in the colder months.

The main objective of a primary care physician is distinguishing which patients have a higher likelihood of GAS infection vs. viral and because there is a significant overlap between the 2 etiologies, clinical judgment alone is not accurate in diagnosing GAS infections often leading to overtreatment with antimicrobial therapy.

Throat culture is the gold standard in diagnosing GAS. This is done in this scenario, despite the negative rapid test (Sensitivity 70% - 90%), because of the suspicion of viral etiology as well as the avoidance of overtreatment. Throat culture is the most appropriate next step in this case.

As per UWorld : Adults : Centor Criteria : 0-1 : viral,No test reqd; 2-3 : RSAT, if positive antibiotics, if negative, we assume it to be viral so nothing; 4 : penicillin/amoxiciliin whereas for kids, we always need to follow up a negative RSAT with a throat culture. In adults, there is no need

For Sore throat most important thing to remember - Adults & Children are different

Etiologically : Adults more prone to bacterial. Chldren Viral

Diagnostic: Centor is for adults not kids.

Treatment Wise: Adults can be given Empiric antibiotics. Children NEVER

Prognosis wise: Adults has less chance of RF. And its the RF which we mainly target with antibiotics in children.

So in this question u cant use centor criteria. Next u look out for viral prodome..if present u treat it as viral cause. this kiddo don't have viral prodrome.

This is One of the indication for rapid strep test. Others are - presence of tonsilar exudate, palatal petechiae, edema. Any one of them present u do rapid strep test.

strep test positive u stati antibiotics. If negative y do throat culture.

Throat culture positive y start ABX. If neg bact cause definitively ruled out and u treat symptomatically for viral cause.

• Pharyngitis and fever without viral URI symptoms in a young child always concerning for Strep throat, which requires rapid strep test followed by throat culture if negative [NO EMPIRIC TREATMENT IN KIDS]
• Key idea: In adults, patients risk of Strep throat is stratified based on Centor criteria [(1) Fever by history (2) Tender anterior cervical lymphadenopathy (3) Tonsillar exudates (4) Absence of cough], and with patients receiving no testing (scores 0-1), rapid strep test followed by throat culture if negative (2-3) or empiric antibiotics (4+)

https://www.aafp.org/afp/2009/0301/p383.html