SUN-305 - Hematogenous Seeding of the Thyroid Gland: Suppurative Thyroiditis Due to Escherichia Coli

Suppurative thyroiditis is a rare bacterial infection of the thyroid gland, accounting for less than 1% of thyroid diseases. The thyroid is typically resistant to infection due to its encapsulation, high iodide content, rich vascular supply, and extensive lymphatic drainage. Most reported cases are caused by Staphylococcus and Streptococcus species. We describe a rare case of suppurative thyroiditis caused by Escherichia coli following recent bacteremia in a patient without underlying thyroid disease.

A 74-year-old woman presented with a 5-day history of progressive anterior neck pain and dysphagia. Two weeks earlier, she had been hospitalized for abdominal pain, hyperbilirubinemia, and transaminitis. CT abdomen/pelvis and ERCP did not identify a clear etiology; however, blood cultures grew E. coli, and she completed a 5-day course of ceftriaxone with significant improvement both clinically and laboratory testing.. On re-presentation, she was febrile and tachycardic, with leukocytosis of 16.0 K/uL. Thyroid function testing revealed a suppressed TSH of 0.30 uIU/mL and elevated free T4 of 1.62 ng/dL, consistent with inflammatory thyroid hormone release. Neck ultrasound demonstrated a 6.5 cm heterogeneous fluid collection, and CT soft tissue neck revealed a complex 9.0 × 6.5 cm fluid collection in the right thyroid bed with regional mass effect, concerning for suppurative thyroiditis. She had no prior history of thyroid disease, thyroid nodules, or neck procedures.

The patient underwent surgical incision and drainage of the thyroid abscess. Repeat blood cultures were negative, while wound cultures grew E. coli, confirming a persistent gram-negative infectious focus. She completed a 2-week course of amoxicillin/clavulanate with gradual resolution of neck pain and dysphagia. Follow-up neck ultrasound and CT imaging six weeks later demonstrated near-complete resolution of the abscess and repeat thyroid function tests normalized.

Hematogenous spread leading to suppurative thyroiditis is uncommon, particularly in patients without preexisting thyroid pathology, as most cases occur in the setting of structural abnormalities, prior thyroid surgery, or congenital fistulae. Moreover, E coli is an uncommon causative organism. This rare case demonstrates that even a structurally normal thyroid can become infected via unusual bacteremia, therefore expanding clinical understanding of infection susceptibility.

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