Upper respiratory tract infections: Clinical sciences

Upper respiratory tract infections, or URIs, are a common cause of acute illness. They occur when a pathogen causes inflammation in the nasal cavity, sinuses, and throat. Based on their clinical presentation, URIs can be classified as; pharyngitis; acute rhinosinusitis, also known as acute sinusitis; and unspecified URI.

Now, if you suspect a URI, you first should perform an ABCDE assessment to determine if the patient is unstable or stable. If they are unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access, provide supplemental oxygen, and put them on continuous vital sign monitoring, including blood pressure, heart rate, and pulse oximetry. Finally, don’t forget to start IV empiric broad-spectrum antibiotics.

Now, here’s a high-yield fact! If your patient presents with drooling, tender neck swelling, and inspiratory stridor, along with painful and difficult swallowing, you should suspect epiglottitis or retropharyngeal abscess. These conditions can be caused by Streptococcus pneumoniae or pyogenes, as well as Staphylococcus aureus, and can quickly lead to airway compromise. Also consider Lemierre syndrome, which is septic thrombophlebitis of the internal jugular vein and is caused by the anaerobe Fusobacterium necrophorum.

Okay, now that we’ve dealt with unstable patients, let’s return to the ABCDE assessment and focus on stable patients. If your patient is stable, proceed with obtaining a focused history and physical exam. The history will commonly reveal symptoms of fatigue, runny nose, and fever. Additionally, the patient might report a sore throat, as well as cough. The general physical exam will reveal an ill-appearing person.

At this point, you should suspect a URI, so your next step is to classify it clinically as pharyngitis, acute rhinosinusitis, or unspecified URI.

Here’s a clinical pearl! Don’t forget to inquire about a history of allergies, lung disorders, immunosuppression, tobacco use, recent sick contacts, and recent travel history, as these may change not only what pathogens you think are involved, but also the severity of the disease.

Okay, first let’s discuss an individual that has primarily a sore throat. They may also report rigors, night sweats, painful swallowing, or a cough. The physical exam could reveal enlarged tender cervical lymph nodes, a scarlatiniform rash, palatal petechiae, swollen tonsils, and tonsillopharyngeal exudates. Based on these findings, you can diagnose pharyngitis.

Next, you need to assess for Group A Strep using the Centor Criteria, which assigns 1 point to each clinical finding. These findings include the absence of a cough; a fever equal or greater than 38oC or 100.4oF; tender anterior cervical lymphadenopathy; and tonsillar exudates or swelling. Lastly, an additional point is added if the patient is between 3 and 14 years of age since GAS is incredibly rare in patients under 3, and less common in older adults.

Here’s a high-yield fact! EBV-induced infectious mononucleosis should be suspected when an adolescent or young adult complains of sore throat, fever, and malaise, and also has lymphadenopathy and pharyngitis on physical examination.

First, if your patient has 1 or no points, then no further testing is recommended. Diagnose this as viral pharyngitis and provide symptomatic treatment with analgesics and antipyretics like acetaminophen or nonsteroidal anti-inflammatory drugs. Additionally, throat lozenges, salt water gargles, or viscous lidocaine might be helpful. Lastly, provide reassurance that this will resolve on its own and that antibiotics are not necessary.

Now, if your patient has 2 or 3 points, you should perform a rapid strep antigen test. If this is negative, diagnose the patient with unspecified pharyngitis, and provide symptomatic treatment. In the meantime, the swab from the rapid strep antigen test should be sent for Group A Strep culture, which might take a few days. If the culture comes back negative, this confirms the diagnosis of unspecified pharyngitis and you should continue symptomatic treatment. On the other hand, if the culture is positive, then refine your diagnosis to Group A Strep Pharyngitis, and continue with symptomatic treatment and add antibiotics, such as a beta-lactam penicillin, like amoxicillin. If the individual has a penicillin allergy, then consider a macrolide, like azithromycin. This will treat the throat infection and will prevent complications such as abscesses or rheumatic fever.

Okay, let’s go back to the initial rapid strep antigen test. Now, if this test is positive, then diagnose Group A Strep Pharyngitis and treat it symptomatically and with beta-lactam penicillin, primarily amoxicillin.

Lastly, if your patient meets 4 or more points, no additional testing is needed and you can clinically diagnose Group A Strep Pharyngitis. Again, treatment consists of symptom management and amoxicillin. Timely diagnosis and treatment of group A strep is important because this infection can have long-lasting consequences, including rheumatic feve.