Lecture Notes on Infectious Diseases of the Respiratory System

This set of flashcards covers key terms and concepts from the lecture on infectious diseases of the respiratory system, particularly focusing on ear infections, influenza, whooping cough, and tuberculosis.

Acute Otitis Media

An ear infection often following viral infections of the upper respiratory tract, causing inflammation of the eustachian tubes and fluid buildup in the middle ear.

Streptococcus pneumoniae

A primary causative agent of bacterial ear infections.

Influenza

A viral infection that exhibits a cyclical increase during the winter months and can lead to worldwide pandemics.

Antigenic drift

Gradual mutations in the influenza virus’s glycoproteins, leading to changes in the virus that reduce immune recognition.

Antigenic shift

A more abrupt process of exchanging RNA segments between different influenza viruses, resulting in new viral strains.

RT-PCR

Reverse transcriptase PCR, the best standard for detecting influenza viral RNA.

Bordetella pertussis

The bacterium that causes whooping cough.

Pertussis toxin

An exotoxin produced by Bordetella pertussis that contributes to its virulence.

Tuberculosis (TB)

An infectious disease caused by Mycobacterium tuberculosis, characterized by the presence of mycolic acid in the cell walls.

Granulomas

Structures formed in response to tuberculosis infection that contain bacteria but may also cause tissue destruction.

Directly Observed Therapy (DOT)

A treatment strategy for TB where healthcare providers observe patients taking their medication to improve adherence.

Multidrug-resistant TB (MDR-TB)

A strain of tuberculosis that resists isoniazid and rifampin, requiring prolonged multidrug therapy.

Acute Otitis Media

An ear infection often following viral infections of the upper respiratory tract, causing inflammation of the eustachian tubes and fluid buildup in the middle ear.

Streptococcus pneumoniae

A primary causative agent of bacterial ear infections.

Influenza

A viral infection that exhibits a cyclical increase during the winter months and can lead to worldwide pandemics.

Antigenic drift

Gradual mutations in the influenza virus’s glycoproteins, leading to changes in the virus that reduce immune recognition.

Antigenic shift

A more abrupt process of exchanging RNA segments between different influenza viruses, resulting in new viral strains.

RT-PCR

Reverse transcriptase PCR, the best standard for detecting influenza viral RNA.

Bordetella pertussis

The bacterium that causes whooping cough.

Pertussis toxin

An exotoxin produced by Bordetella pertussis that contributes to its virulence.

Tuberculosis (TB)

An infectious disease caused by Mycobacterium tuberculosis, characterized by the presence of mycolic acid in the cell walls.

Granulomas

Structures formed in response to tuberculosis infection that contain bacteria but may also cause tissue destruction.

Directly Observed Therapy (DOT)

A treatment strategy for TB where healthcare providers observe patients taking their medication to improve adherence.

Multidrug-resistant TB (MDR-TB)

A strain of tuberculosis that resists isoniazid and rifampin, requiring prolonged multidrug therapy.

What are common symptoms of Acute Otitis Media?

Ear pain, fever, irritability, and fluid drainage from the ear.

How is Tuberculosis typically transmitted?

Through airborne droplets when an infected person coughs, sneezes, or speaks.

What are the three stages of whooping cough?

The catarrhal stage (cold-like symptoms), paroxysmal stage (severe coughing fits followed by a 'whoop'), and convalescent stage (gradual recovery).

What are the main types of influenza viruses that infect humans?

Influenza A and B are seasonal epidemics, while Influenza C causes mild respiratory illness.

Which vaccine protects against whooping cough?

The DTaP vaccine for children and Tdap vaccine for adolescents and adults.

Acute Otitis Media

An ear infection often following viral infections of the upper respiratory tract, causing inflammation of the eustachian tubes and fluid buildup in the middle ear.

Streptococcus pneumoniae

A primary causative agent of bacterial ear infections.

Influenza

A viral infection that exhibits a cyclical increase during the winter months and can lead to worldwide pandemics.

Antigenic drift

Gradual mutations in the influenza virus’s glycoproteins, leading to changes in the virus that reduce immune recognition.

Antigenic shift

A more abrupt process of exchanging RNA segments between different influenza viruses, resulting in new viral strains.

RT-PCR

Reverse transcriptase PCR, the best standard for detecting influenza viral RNA.

Bordetella pertussis

The bacterium that causes whooping cough.

Pertussis toxin

An exotoxin produced by Bordetella pertussis that contributes to its virulence.

Tuberculosis (TB)

An infectious disease caused by Mycobacterium tuberculosis, characterized by the presence of mycolic acid in the cell walls.

Granulomas

Structures formed in response to tuberculosis infection that contain bacteria but may also cause tissue destruction.

Directly Observed Therapy (DOT)

A treatment strategy for TB where healthcare providers observe patients taking their medication to improve adherence.

Multidrug-resistant TB (MDR-TB)

A strain of tuberculosis that resists isoniazid and rifampin, requiring prolonged multidrug therapy.

What are common symptoms of Acute Otitis Media?

Ear pain, fever, irritability, and fluid drainage from the ear.

How is Tuberculosis typically transmitted?

Through airborne droplets when an infected person coughs, sneezes, or speaks.

What are the three stages of whooping cough?

The catarrhal stage (cold-like symptoms), paroxysmal stage (severe coughing fits followed by a 'whoop'), and convalescent stage (gradual recovery).

What are the main types of influenza viruses that infect humans?

Influenza A and B are seasonal epidemics, while Influenza C causes mild respiratory illness.

Which vaccine protects against whooping cough?

The DTaP vaccine for children and Tdap vaccine for adolescents and adults.

What is the primary cause of fluid accumulation in the middle ear during Acute Otitis Media?

Inflammation and swelling of the Eustachian tubes, preventing proper drainage and leading to fluid buildup.

How does antigenic drift impact influenza vaccine effectiveness?

Gradual mutations in the virus's surface proteins (hemagglutinin and neuraminidase) reduce the effectiveness of existing vaccines, necessitating annual vaccine updates.

In what stage of pertussis is the characteristic 'whoop' sound most prominent?

The paroxysmal stage, characterized by severe, uncontrolled coughing fits followed by a gasp for air that produces the 'whooping' sound.

What is the role of mycolic acid in the cell wall of Mycobacterium tuberculosis?

Mycolic acid provides a waxy, hydrophobic barrier that contributes to the bacterium's virulence, resistance to host defenses, and resistance to many antibiotics and disinfectants.

What is the key distinction between latent tuberculosis infection (LTBI) and active TB disease?

In LTBI, the bacteria are present but inactive, causing no symptoms and not spreadable, while in active TB disease, the bacteria are multiplying, causing symptoms, and are contagious.

Why are young children more susceptible to Acute Otitis Media?

Because their Eustachian tubes are narrower, more horizontal, and less effective at drainage, making them more prone to fluid accumulation and infection.

What are the primary surface proteins of the influenza virus responsible for antigenic variation?

Hemagglutinin (HA) and Neuraminidase (NA) glycoproteins, which are targets for the immune system and determinants of vaccine effectiveness.

How does Pertussis toxin contribute to the symptoms of whooping cough?

It acts as an exotoxin that inactivates G proteins, leading to increased cyclic AMP (cAMP) levels, which impairs immune cell function and damages respiratory epithelial cells.

What are the four first-line drugs commonly used in a standard treatment regimen for active Tuberculosis?

Isoniazid, Rifampin, Pyrazinamide, and Ethambutol (often referred to as the RIPE regimen).

What is the primary diagnostic method for latent tuberculosis infection (LTBI)?

The Tuberculin Skin Test (TST) or Interferon-Gamma Release Assays (IGRAs), which detect immune responses to M. tuberculosis without confirming active disease.

What is the primary treatment for bacterial Acute Otitis Media?

Antibiotics are typically prescribed to treat bacterial AOM.

What is the role of Hemagglutinin (HA) in the influenza virus life cycle?

Hemagglutinin is responsible for the influenza virus attaching to and entering host cells by binding to sialic acid receptors on the host cell surface.

What is the role of Neuraminidase (NA) in the influenza virus life cycle?

Neuraminidase facilitates the release of new influenza viral particles from infected cells by cleaving sialic acid receptors on the host cell surface, preventing self-aggregation and improving viral spread.

How is whooping cough (pertussis) primarily diagnosed in a clinical setting?

Typically diagnosed through nasopharyngeal swab for PCR (Polymerase Chain Reaction) testing or bacterial culture, which can detect Bordetella pertussis.

What are some severe consequences of untreated active Tuberculosis?

Untreated active TB can lead to severe and irreversible lung damage, extrapulmonary spread to other organs (e.g., brain, bones, kidneys), and ultimately, death.

Why is Multidrug-resistant TB (MDR-TB) a significant public health

Why is Multidrug-resistant TB (MDR-TB) a significant public health issue?

Because it is resistant to at least isoniazid and rifampin, requiring longer, more toxic, and more expensive treatments, and has a higher mortality rate, making it harder to control its spread and posing a major threat to global TB control efforts.

What are common risk factors for Acute Otitis Media in children?

Childcare attendance, exposure to secondhand smoke, pacifier use, and bottle feeding while lying down.

What are the primary antiviral medications used to treat influenza?

Oseltamivir (Tamiflu), Zanamivir (Relenza), Peramivir (Rapivab), and Baloxavir marboxil (Xofluza), which work best when administered early in the infection.

How does the DTaP vaccine protect against whooping cough?

The DTaP vaccine contains inactivated pertussis toxin and other bacterial components, stimulating antibody production to neutralize the toxin and protect against infection.

What are some key diagnostic methods for active Tuberculosis?

Sputum smear microscopy (for acid-fast bacilli), mycobacterial culture (gold standard), and molecular tests like Xpert MTB/RIF which can detect M. tuberculosis DNA and rifampin resistance.