Clinical Pearl: Procalcitonin and Lower Respiratory Tract Infections

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Author: Jordan Kaylor, MD PGY4
Northwestern/McGaw Medical Center

Procalcitonin (PCT) is a serum biomarker that, when paired with clinical judgment, may help guide management of lower respiratory tract infections (LRTIs) in the emergency department (ED). Procalcitonin levels can help clinicians distinguish between bacterial and viral infections and might subsequently guide decisions to initiate or discontinue antibiotics. Procalcitonin is a prohormone of calcitonin. It is an acute-phase reactant synthesized in many tissues and released in response to cytokines such as interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-α.1 Normal serum concentrations are <0.05ng/mL, but in bacterial infections, PCT increases to detectable levels within three to four hours (earlier than ESR or CRP).[1] Elevations are not seen in noninfectious inflammatory conditions or viral infections, but are possible in Addisonian crises, malaria, severe fungal infections and medullary thyroid carcinoma.[1] In viral infections, interferon (INF)-ɣ probably decreases PCT release, leading to lower or undetectable serum levels.[2]

Deep Neck Space Infections

Author: Alexandra Murray, OMSIV
Ohio University Heritage College of Osteopathic Medicine

Since the advent of modern antibiotic use, deep neck space infections have decreased in occurrence; however, when these infections take place, the complications can be life threatening.[1-4] Because of the unique compartments of the cervical fascia, deep neck space infections can range in severity and have the potential to extend into the mediastinum. Based on how the infection propagates, these infections have the potential to cause upper airway edema, airway obstruction, mediastinitis, internal jugular vein septic thrombophlebitis, sepsis and septic embolization.[1,2]

Common Sources
Deep neck space infections can develop from infections of the teeth, salivary glands, nasal cavity, paranasal sinuses, pharynx and adenotonsillar tissues.[1,2] In children, adenoids and tonsillar infections are the most common source as they create a drainage pathway through the retropharyngeal lymph nodes resulting in retropharyngeal, parapharyngeal and peritonisllar space infections.1 In adults, dentoalveolar infections are the most common source of infection. In particular, infections of the lower second and third molars are dangerous because their roots spread directly into the submandibular space.[1] Other causes of deep neck space infections in adults include: pharyngitis, tonsillitis, sialoadenitis, trauma, foreing body ingestion, sinusitis, cervical lymphadenitis, middle ear infections, mastoid infections, and IV drug use.[2]