Infections of the ear, nose, and throat (ENT) run the gamut from annoying but relatively harmless otitis externa to life-threatening infections of the airway. Despite the broad array of syndromes, most of these share a common set of pathogens and similar principles of evaluation and treatment. This chapter will discuss these pathogens and diagnostic tests before discussing anatomically distinct syndromes and specific treatments.
Pathogens
The anatomic continuity of the ENT with the outside environment lends it to extensive colonization with a variety of organisms. Inherently, colonization is a nonpathogenic state; however, these organisms may still evolve into an infection, thus making diagnosis challenging. The most common causes of ear and nose infections is Streptococcus pneumoniae , followed by Haemophilus influenzae and Moraxella catarrhalis. Staphylococcus aureus is a common colonizer of the nares but can also cause infections in this area. Group A streptococcus is also found throughout the ENT, although significant disease with this pathogen has become less common in the era of antibiotics.
Viruses can also frequently cause ENT infections, particularly respiratory syncytial virus (RSV), rhinovirus, parainfluenza, adenovirus, coronavirus, herpes viruses (herpes simplex viruses [HSV] 1 and 2, varicella zoster virus [VZV]), and influenza. However, most of these viruses do not cause pure ENT disease but involve the ENT as part of a larger syndrome (e.g., RSV and influenza cause significant lower respiratory tract infections).
Fungal organisms are rare, but can cause critical illness in the correct host. Mucormycosis of the sinuses in immunocompromised (including diabetic) patients is a surgical emergency because it is angioinvasive and has the potential to spread quickly. Aspergillosis can also cause fungal sinus infections whereby fungal “balls” obstruct the sinus outlets. This can occur even more quickly with mucormycosis. Endemic fungi, such as histoplasmosis, blastomycosis, and coccidiomycosis, can also cause infections of the sinuses, but this typically occurs as part of a more systemic syndrome, where the ENT symptoms are secondary considerations.
Diagnostic Testing
Given that similar pathogens infect all anatomic parts of the ENT tract, diagnostic laboratory-based testing is uniform, regardless of the specific anatomy involved. A list of pathogens, syndromes, and recommended diagnostic tests is found in Table 8.1 .
| Organism | Syndrome(s) | Testing | Comments |
|---|---|---|---|
| S. pneumoniae | Otitis, rhinosinusitis | Culture Urine antigen test (disseminated/systemic disease only) | Most common bacterial cause of ENT infections |
| H. influenzae | Otitis, sinusitis, pharyngitis epiglottitis | Culture | Less frequent cause of epiglottis since HiB vaccination became common |
| M. catarrhalis | Otitis, rhinosinusitis, pharyngitis | Culture | More common in children than adults |
| Group A streptococci | Pharyngitis, necrotizing fasciitis of the head and neck | Culture, rapid antigen test | Left untreated, has significant immunologic sequelae (rheumatic fever/heart disease, post-streptococcal glomerulonephritis |
| S. aureus | Otitis externa, otitis media, rhinosinusitis, pharyngitis, deep tissue infections | Culture, PCR | Can cause virtually any infection, but typically is either health care associated or related to antecedent trauma |
| Pseudomonas spp. (and other resistant Gram-negative organisms) | Otitis externa, otitis media, sinusitis, pharyngitis | Culture | Most often seen with health care–associated infection Some increased risk in diabetics |
| Fusarium spp. | Pharyngitis, Lemierre disease | Culture | |
| N. gonorrhoeae | Pharyngitis | Culture, PCR |
Culture-based testing is useful, particularly for bacteria and fungi, but the clinical significance of the results must be interpreted in the context of possible chronic colonization. Rapid diagnostic tests, such as polymerase chain reaction (PCR) testing, are valuable for detecting viruses because viral cultures are laborious and have poor sensitivity and specificity. Additionally, pathology from biopsy specimens may identify the class of pathogen by morphologic features, which suggest identification of the specific organism. Of note, culture remains the primary method for assessing antimicrobial susceptibilities ( Tables 8.2 and 8.3 ).
| Organism | Syndrome(s) | Testing | Comments |
|---|---|---|---|
| Rhinovirus | Acute otitis media, rhinosinusitis, pharyngitis | PCR (rarely needed) | Treatment is supportive, and disease is largely self-limiting |
| Enterovirus spp. | Acute otitis media, rhinosinusitis, pharyngitis | PCR (rarely needed) | Treatment is supportive, and disease is largely self-limiting |
| Coronavirus | Acute otitis media, rhinosinusitis, pharyngitis | PCR (rarely needed) | Treatment is supportive, and disease is largely self-limiting |
| Adenovirus | Acute otitis media, rhinosinusitis, pharyngitis | PCR (rarely needed) | Treatment is supportive, and disease is largely self-limiting |
| Parainfluenza | Acute otitis media, rhinosinusitis, pharyngitis, laryngotracheitis (croup) | PCR (rarely needed) | Treatment is supportive, and disease is largely self-limiting |
| Influenza | Acute otitis media, rhinosinusitis, pharyngitis | PCR | |
| RSV | Acute otitis media, rhinosinusitis, pharyngitis | PCR | |
| HSV | Pharyngitis, skin and soft tissue infection | PCR | |
| VZV | Ramsay Hunt syndrome (otitis mimic), pharyngitis, skin and soft tissue infection | PCR |
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