AssessmentsUpper respiratory tract infection
Upper respiratory tract infection
USMLE® Step 1 style questions USMLE
USMLE® Step 2 style questions USMLE
A 5-year-old girl is brought to the emergency department by her parents because of a sore throat and difficulty swallowing that began 3 days ago. Her temperature is 39.2 °C (102.7 °F), pulse is 92/minute, respiration rate 22/minute, and blood pressure is 100/73 mm Hg. Her O2 saturation of 98% on room air. Physical examination shows an erythematous oropharynx, bilateral tonisillar exudates, and cervical lymphadenopathy. During the examination, the patient resists moving her head and begins drooling. A lateral cervical spine X-ray shows a widened pre-vertebral space. Which of the following is the most likely diagnosis?
Content Reviewers:Rishi Desai, MD, MPH
Contributors:Tanner Marshall, MS
That mucus is salty, sticky, and contains lysozymes, which are enzymes that help kill bacteria.
The paranasal sinuses help the inspired air to circulate for a bit so it has time to get warm and moist.
The paranasal sinuses also act like tiny echo-chambers that help amplify the sound of your voice, which is why you sound so different when they’re clogged with mucus during a cold!
At each side of the back of the throat, there is the pair of tonsils, which are small are clumps of lymphoid tissue that act as the body's first line of defense that swallow viruses and bacteria that enter through the mouth or nose.
Αt the top of the larynx sits a spoon- shaped flap of cartilage called the epiglottis which acts like a lid that seals the airway off when you’re eating, so that the food can only go one way - down the esophagus and towards the stomach.
Now, in addition to air, you’re constantly breathing in other stuff like viruses or bacteria.
For example, when an infected person sneezes or coughs, they spread thousands of droplets containing these pathogens into the local area, up to about two meters or six and a half feet away.
These droplets can then land in the mouths or noses of people nearby, or get inhaled into the upper airways.
Most of these viruses or bacteria can also survive on surfaces for a few hours, so it’s possible to get them by touching a surface, like a contaminated doorknob, and then touching your own eyes, nose, or mouth.
Usually, even when a pathogen gets in, we’re good at protecting ourselves, but sometimes, a particularly nasty pathogen succeeds in colonizing our upper airways and when that happens - Congratulations! You’ve got an infection!
These infectious little pathogens typically jump inside the cells lining the airways, multiply and cross over to the underlying tissue, creating an inflammatory response.
When that happens, goblet cells and submucosal glands in the airways start to produce a lot of mucus in order to try to trap and eventually expel these pathogens.
In severe situations, the pathogens might result in lots of white blood cells coming over to fight off these pathogens.
The battle ensues with the result being pus - a mixture of pathogens, immune cells, and dead tissue and a whole lot of inflammatory signaling molecules, called cytokines.
Alright now, there are many different types of upper respiratory tract infections, depending on the part of the tract that’s involved.
Usually it’s caused by viruses responsible for the common cold or flu, and the most common is rhinovirus, influenza virus, respiratory syncytial virus- or RSV for short, parainfluenza virus, and adenovirus.