Differential Diagnosis
- Single most likely diagnosis
- Acute bacterial pharyngitis (likely caused by a beta-hemolytic streptococcal infection that was not detected by the rapid strep test, or another bacterial pathogen): The patient's symptoms of a persistent sore throat, particularly the recurrence and worsening of symptoms after completing a course of antibiotics, suggest a bacterial infection. The negative rapid strep test does not entirely rule out streptococcal pharyngitis, as these tests can have false negatives.
- Other Likely diagnoses
- Viral pharyngitis: Given the patient's recent history of a cold and the presence of post-nasal drip and nasal congestion, a viral etiology for the sore throat is possible. The improvement and then recurrence of symptoms could be due to a viral infection that was not fully resolved or a secondary viral infection.
- Chronic post-nasal drip: The patient's description of a sensation of a mucus ball in the back of her nasal cavity and frequent clearing of mucus from her throat suggests significant post-nasal drip, which could be causing or exacerbating her sore throat.
- Sinusitis: The patient's symptoms of nasal congestion, post-nasal drip, and sore throat could be indicative of sinusitis, especially if the infection has spread from the nasal passages to the sinuses.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Epiglottitis: Although rare in adults, epiglottitis is a life-threatening condition that requires immediate attention. The patient's sore throat and difficulty could be indicative of this condition, especially if the airway is compromised.
- Peritonsillar abscess: This is a serious complication of tonsillitis that can cause severe throat pain, usually unilateral, and can lead to airway obstruction if not treated promptly.
- Lemierre's syndrome: A rare but potentially life-threatening condition characterized by a bacterial infection of the throat, followed by septic thrombophlebitis of the internal jugular vein. The patient's history of a sore throat and recent antibiotic use could be relevant, although the lack of other symptoms such as fever and neck pain makes this less likely.
- Rare diagnoses
- Infectious mononucleosis (mono): Although the patient's age and lack of specific symptoms such as fever and lymphadenopathy make this less likely, it is a possibility, especially if the sore throat is part of a larger syndrome.
- HIV pharyngitis: In rare cases, an acute HIV infection can present with pharyngitis among other symptoms. However, the patient's recent history of a cold and lack of other symptoms suggestive of an acute retroviral syndrome make this unlikely.
- Tuberculous pharyngitis: This is a rare condition, especially in immunocompetent individuals, but could be considered if the patient has risk factors for tuberculosis or if other diagnoses are ruled out.