Physical exam and vitals
Virus vs. Bacteria (Clinical)
Mechanism of Infections
Respiratory Infections
Wild Card
100
What is the indicator for normal capillary refill?
Normal capillary refill time in children is ≤2 seconds when measured at room temperature on the sternum or fingertip. A capillary refill time of 3–4 seconds is considered prolonged and abnormal. Prolonged capillary refill in the context of abnormal vital signs, increased work of breathing, low oxygen saturation, and reduced urine output most commonly indicates impaired peripheral perfusion. Prolonged capillary refill is a key early sign of shock, including septic shock, hypovolemic shock, and cardiogenic shock.
100
In which season are viruses most prevalent?
RSV and influenza viruses consistently peak in December and January, causing significant morbidity, especially in children and older adults, and are frequently associated with lower respiratory tract involvement and hypoxemia. SARS-CoV-2 has become a major winter pathogen since 2020, with surges in January and symptom overlap with other respiratory viruses
100
What are three ways that viruses can be transmitted?
Bonus: What is a fourth one? Which one does RSV fall under?
Transmission methods include respiratory droplets/aerosols, contact with bodily fluids (including blood), direct contact, and vertical (mother to child) transmission. RSV spreads through respiratory droplets.
100
Name one anatomical structure affected by Upper Respiratory Tract Infections (URTIs) and one by Lower Respiratory Tract Infections (LRTIs).
URTI: nose, sinus, pharynx, larynx/ include common cold, mostly viral etiologies (influenza, coronavirus, RSV)
LRTI: trachea, bronchi, bronchioles, lungs/ Acute bronchitis (influenza, coronavirus, RSV), Bronchiolitis (RSV), Pneumonia (bacterial, fungal, or viral [influenza, coronavirus, RSV])
Other respiratory tract infections: Tuberculosis, fungal infections, infections in immunocompromised hosts
100
What is the leading cause of antibiotic resistance in respiratory infections?
Overuse and misuse.
This creates selective pressure from antibiotic misuse that promotes the survival and proliferation of resistant bacterial strains. A common mechanism of this that we see in class and clinically is bacteria producing B-lactamase to inhibit the mechanism of Penicillins.
200
What is the acceptable heart rate range for our 8 month old patient?
Bonus: Acceptable respiratory rate
Normal heart rate for infants (birth–1 year) is typically 110–160 bpm, for toddlers (1–2 years) 100–150 bpm, for preschoolers (3–5 years) 95–140 bpm, and for school-age children (6–12 years) 80–120 bpm.
Normal respiratory rate declines with age: for infants (birth–1 year) 30–50 breaths/min, for toddlers 25–40 breaths/min, for preschoolers 20–30 breaths/min, and for school-age children 16–24 breaths/min.
200
List 3 of the most common symptoms of viral infections
200
What are the six steps of viral infection of a cell?
Attachment, penetration, uncoating, replication, assembly, and release.
200
A patient has a URTI presenting with pharyngitis that is determined to not be bacterial. What is the appropriate treatment?
Nothing, or NSAIDs if it is painful. Some also recommend nasal saline if congested.
Antibiotics would NOT be useful for a viral infection, and could cause adverse effects in patients or propagate antibiotic resistance.
Nephrotoxicity is most commonly seen with aminoglycosides (gentamicin, amikacin), vancomycin, and TMP-SMX
200
It is pretty obvious why kids attending daycare are more prone to infections, but can you name 3 other environmental factors that increase the risk of infections in infants?
Bonus: How impactful are environmental factors?
Infections occur more commonly in kids that attend daycare, are not exposed to tobacco, were delivered by c-section, had less breastfeeding, and have older siblings at home.
Environmental factors have only a minor effect on long-term infection rates (~8%).
300
What is the significance of subcostal intercostal and suprasternal retractions?
Subcostal retractions - when the soft tissue just below the rib cage (under the costal margin) pulls inward with each breath, sign of increased work of breathing;
Mild if only subcostal, more concerning if you also see intercostal (between ribs) or suprasternal (above sternum) retractions
300
How can we differentiate viral vs bacterial infection on a chest X-ray?
It is not possible to reliably differentiate between viral and bacterial pneumonia based solely on chest X-ray findings. The American College of Radiology emphasizes that chest radiography is essential for confirming the diagnosis of pneumonia but does not reliably distinguish its etiology. Additional imaging such CT or MRI is required.
300
In a bacterial infection, what are the differences between endotoxins and exotoxins with regard to source, temperature resistance, and antibody response?
Endotoxins:
LPS on outer membrane of gram-negative bacteria, highly heat resistant (fever does not kill), weak antibody response (no immunity/vaccine).
Exotoxins:
Secreted proteins produced by gram positive and negative bacteria. Generally not heat resistant with exceptions. Strong antibody response that allows for immunity
300
What is the difference between Bronchiolitis and Bronchitis?
Bronchiolitis is an infection of the small airways in infants, presenting with wheezing and respiratory distress.
Bronchitis affects the larger airways in all ages of patients, presenting primarily with coughing.
Both of these are treated by managing symptoms, because again, antibiotics are NOT used for viral infections.
300
What are 3 factors that contribute to natural immunity? Which factor is the most important?
Natural immunity is based on age, genetic factors, maternal antibodies, microbiome composition, etc. Age is the most important; very young and very old are the weakest (bell curve).
400
What causes clear vs green mucous?
Can you use it to diagnose a viral infection?
Clear mucus is typical early in viral infections and allergic rhinitis, while green or yellow mucus reflects the presence of neutrophils and cellular debris, which can occur in both viral and bacterial infections as the immune response progresses.
Mucus color alone does not reliably distinguish viral from bacterial etiology. The American Academy of Pediatrics specifically states that thick, colored, or cloudy mucus is common in viral infections and does not by itself indicate bacterial sinusitis.
400
Which medication would you use to treat this virus?
Bonus: How does it work?
Ribavirin
It is a Guanosine Nucleotide Analog that inhibits nucleic acid synthesis in RNA viruses.
400
Define tropism in virology and give one example.
Tropism is the specific set of tissues a virus can target, mostly caused by target receptor availability.
Examples include HSV-1 binding to epithelial tissue, hepatitis B and C binding to hepatocytes, or neuron lysis in cytolytic viral encephalitis.
400
What is the preferred testing for respiratory tract infections? What type of sample is obtained for the test?
PCR testing. Nasal Aspirate.
PCR detects and differentiates a broad range of viruses with high sensitivity and specificity. They typically provide results within 1-5 hours.
To obtain the nasal aspirate, nasal saline is typically administered to loosen respiratory secretions (mucus) before a syringe or bulb is used to draw mucus out for testing.
In the virtual disclosure, Joseph’s nasal aspirate was tested via PCR and tested positive for RSV.
400
Name one implication of antibiotic resistance in healthcare.
Reduced efficacy of standard treatments
Increased risk of complications
Higher healthcare costs
Use of broad-spectrum antibiotics, which are more toxic
500
These patient presented with these signs and symptoms in the disease progression. List the cause of each of them
Decreased urine output and no tear production
Blue lips / fingernails
Course breath sounds
Mottled skin
Grunting and nasal flaring
Decreased urine output and no tear production : Dehydration
Blue lips / fingernails : inadequate oxygenation (hypoxemia) or poor circulation, urgent sign
Course breath sounds: Low-pitched, harsh, “gurgly” sounds (often described as rhonchi) heard across both lungs, Usually due to mucus or secretions in the larger airways
Mottled skin: poor perfusion from infection, blood being shunted away from skin to vital organs, unstable circulation
Grunting and nasal flaring: low, short, forced sound a child makes at the end of expiration; usually when a child is trying to keep alveoli open by creating back-pressure, sign of significant respiratory distress
500
The patients mother wants you to prescribe an antibiotic. Will you prescribe one?
If yes, which one?
If no, imagine Anuj is the mother and explain to her why you can't do so.
Bacteria and viruses are both germs that can make people sick, but they are very different. Bacteria are living organisms that can grow on their own, while viruses are much smaller and need to infect your body’s cells to multiply. Some bacteria are helpful, but some can cause infections like strep throat or certain types of pneumonia. Viruses cause illnesses like the common cold, flu, COVID-19, and most sore throats and runny noses. Antibiotics only work against bacteria, not viruses. Taking antibiotics when you have a viral infection will not help you get better faster. In fact, using antibiotics when they are not needed can cause side effects like diarrhea, rashes, or allergic reactions, and can make bacteria in your body stronger and harder to treat in the future
500
Clinically significant osmotic changes due to viral infections occur on a per-virus basis. What is the impact of RSV on osmolarity and the mechanism through which it occurs?
Specific inflammatory response causes the hypothalamus to release excessive ADH, causing hyponatremia (33% of cases). In severe cases, it can progress to seizures (4%).
500
If an infant developed a respiratory tract infection and PCR determined it to be RSV, which antiviral would be used to treat the infant?
Aerosolized Ribavirin.
In the case of RSV, Ribavirin is primarily used in infants, young children or immunocompromised patients that are at high risk for complications.
Ribavirin is a guanosine nucleotide analog which inhibits nucleic acid synthesis in RNA viruses, such as RSV.
500
What is a mechanism of resistance that could occur to an anti-viral nucleotide analog such as Ribavirin?
AA substitutions that increase polymerase fidelity.
These work by decreasing the incorporation of Ribavirin into the viral genome, which decreases the drug’s antiviral effect.
In nucleoside analogs, including Acyclovir, Penciclovir, and Ganciclovir, there are AA substitutions in viral kinase genes, which due not allow the kinases to activate the drug. Examples of these are thymidine kinase (HSV) and UL97 kinase (CMV).