Suppurative infection of the chain of lymph nodes between the posterior pharyngeal wall and the prevertebral fascia leads to retropharyngeal abscesses. The most common causative organisms are S aureus, group A b-hemolytic streptococci, and oral anaerobes. Presenting signs and symptoms include a history of pharyngitis, abrupt onset of fever with severe sore throat, refusal of food, drooling, and muffled or noisy breathing. A bulge in the posterior pharyngeal wall is diagnostic, as are radiographs of the lateral neck that reveal the retropharyngeal mass (the radiograph in the question demonstrates thickening of the prevertebral space). Palpation (with adequate provision for emergency control of the airway in case of rupture) reveals a fluctuant mass. Treatment should include incision and drainage if fluctuance is present. The other answers listed would delay definitive treatment and/or might be life threatening.