(10-26) Respiratory Infections Flashcards
1. Outline the functions of the upper respiratory tract. 2. Describe the mucociliary escalator. 3. List the parts of the respiratory system that are normally free of bacterial flora. 4. Describe the important opportunistic pathogen that commonly inhabits the nose. 5. List the cause, major characteristics and modes of transmission for the following diseases: Streptococcal pharyngitis, Common cold, Pneumococcal pneumonia, Tuberculosis, Influenza 6. Name the reservoirs for infectious microorga
Which area of the body warms and moistens incoming air?
The Upper Respiratory System
What connects the middle ear, sinuses, eyes, and nasal cavity?
Tubes
Describe the action of the Mucociliary Escalator.
Microorganisms get caught in goblet-formed mucus and moved up by the beating cilia. They can then be disposed of by expulsion or stomach acid.
What is Pneumonitis?
Pneumonitis is inflammation of the lungs.
What is Pneumonia?
Pneumonia is the filling of alveoli with pus and fluid.
List 5 Bacterial Infections of the Upper Respiratory System
- Strep throat
- Diptheria
- Pinkeye
- Otitis media
- Sinus infections
List 4 Bacterial Infections of the Lower Respiratory System.
- Pneumonia (various)
- Whooping cough
- Tuberculosis
- Legionnaires’ Disease
Streptococcal Pharyngitis is also known as what?
Strep Throat
What are the symptoms of Streptococcal Pharyngitis?
- pain
- difficulty swallowing
- fever
- enlarged, tender lymph nodes in neck
Streptococcal Pharyngitis is caused by which bacterium?
Streptococcus pyogenes (Group A)
Which vaccine prevents Streptococcal Pharyngitis?
No vaccine is available.
How can Streptococcal Pharyngitis be prevented?
- Adequate ventilation
2. Avoid crowds
Why should sore throats in the presence of fever be cultured for prompt treatment?
There is a chance of complications of infection.
Name 3 diseases that can be complications of sore throats with fevers.
- Scarlet fever
- Acute rheumatic fever
- Acute glomerulonephritis
What is the treatment for confirmed strep throat?
10 days of antibiotics
~ penicillin or erythromycin
Name 2 viral infections of the upper respiratory system.
- Common cold (rhinoviruses)
2. Sore throat caused by adenoviruses
Name 4 viral infections of the upper respiratory system.
- Influenza
- Viral pneumonia (SARS)
- Respiratory syncytial virus (RSV)
- Hantavirus Pulmonary Syndrome
How many serotypes of rhinovirus are there?
More than 100
How many viruses cause colds and what percentage is caused by rhinovirus?
- Dozen types of virus cause cold
2. 30%-50% caused by rhinovirus
Rhinoviruses attach to specific receptors on ____________ and multiply in cells, releasing ________.
- respiratory epithelial cells
2. large number of viruses
What causes the symptoms associated with the common cold?
Injured cells cause inflammation which stimulates profuse nasal secretion, sneezing and tissue swelling
How is a rhinovirus infection stopped?
Infection is halted by immune response
~ infection can extend to ears or sinuses before stopping
Why isn’t there a vaccine for the common cold?
Too many different types of rhinovirus makes vaccination impractical.
How can rhinovirus infections be prevented?
- No vaccination
- Hand washing
- Keep hands away from face
- Avoid crowds during times when colds are prevalent
How does treatment affect the common cold?
- Antibiotic therapy is ineffectual
2. Treatment with over-the-counter medications may prolong duration due to inhibition of inflammation.
When are high concentrations of rhinovirus found in nasal secretions?
During first 2 or 3 days of a cold
Why do young children transmit cold virus easily?
Lack of good hygiene
What is the source for the common cold, and what is required for its transmission?
- Humans are the only source
2. Close contact with infected person or secretions (usually) necessary for transmission
List 3 types of bacterial pneumonia.
- Pneumococcal pneumonia
- Klebsiella pneumonia
- Mycoplasmal pneumonia (walking pneumonia)
List the symptoms of Pneumococcal Pneumonia.
- Cough with sputum production
- fever
- chest pain
Which bacterium causes Pneumococcal Pneumonia?
Streptococcus pneumoniae
Describe the bacterial attributes of Streptococcus pneumoniae.
- Gram-positive diplococci with thick polysaccharide capsule
- Capsule interferes with phagocytosis
- More than 80 different strains
Name 3 often fatal complications that Pneumococci that enter bloodstream are responsible for.
- Septicemia
- Endocarditis
- Meningitis
What is Septicemia?
Septicemia is an infection of the blood stream.
What is Endocarditis?
Endocarditis is an infection of the heart valves.
What is Meningitis?
Meningitis is an infection of membranes covering brain and spinal cord.
30% of healthy individuals carry an encapsulated strain of what in their throat? Does it make them sick? Why or why not?
- Streptococcus pneumoniae
- It doesn’t generally make them sick.
- S. pneumoniae rarely reaches the lungs, due to the mucociliary escalator
What can destroy the mucociliary escalator, thus making a person more susceptible to pneumonia?
- old age
2. viral infections
What is the prevention of Pneumococcal Pneumonia?
- Vaccine gives immunity to 23 strains
2. Conjugate vaccine against 7 types is available for infants
How can Pneumococcal Pneumonia be treated?
Antibiotic treatment is generally successful if given early
~ penicillin and erythromycin
What 3 symptoms are Tuberculosis characterized by?
- slight fever
- progressive weight loss
- chronic productive cough
~ sputum often bloody
What was Tuberculosis previously known as?
Consumption
How is Tuberculosis contracted?
Contracted by inhalation of airborne organisms
What happens when Mycobacterium tuberculosis bacteria are taken up by pulmonary macrophages?
The resist destruction within the phagocyte.
Describe the staining and growth properties of Mycobacterium tuberculosis.
- Acid fast due to mycolic acid in cell wall
2. Slow growing (generation time 12 hours or more)
How many global deaths are there each year due to Tuberculosis?
2 Million
When was Tuberculosis a leading cause of death in USA?
early 20th century
Describe what happens during the immense immune reaction to a TB infection.
- Bacilli lodged in tissue are “walled of” creating granulomas.
- Tubercles can persist for years
~ 10 M Americans have them. - Sometimes lysis of macrophages spills enzymes that degrade tissue, creating large cavities in lungs
What is a granuloma, with regards to Mycobacterium tuberculosis.
A granuloma is an organized group of macrophages. They can surround partially digested M. tuberculosis bacteria, forming tubercles.
When does an intense immune reaction to TB occur?
about 2 weeks post-TB infection
How long does drug treatment for TB last?
Over 6 months.
Why are Rifampin and Isoniazid both used to treat TB?
To reduce potential antimicrobial resistance
Why are Rifampin and Isoniazid both used to treat TB?
To reduce potential antimicrobial resistance
What is the flu caused by?
Influenza Type A virus
Describe 3 viral attributes of Influenza A.
- Belong to orthomyxovirus
- Single-stranded RNA genome divided into 8 segments
- Spiked envelope
Describe the structure and action of Influenza A’s H and N spikes.
- H spike – hemagglutinin – attachment to sialic acids
- N spikes – neuraminidase - aids in viral spread by down-regulation of sialic acids
- Influenza A’s virus attaches to ciliated epithelial cells via H spikes and spreads with aid of N spikes
What leads to secondary Influenza A symptoms?
Destruction of ciliated cells (mucociliary escalator)
What is the incubation period for Influenza A?
About 2 days.
What are the symptoms of Influenza A?
- headache
- fever
- muscle pain
- dry cough
How long do the symptoms of Influenza A last?
Symptoms abate within a week, but cough, fatigue and generalized weakness may linger.
Describe the Influenza A vaccine, including strains used in the 2005-2006 flu season.
- Vaccine is effective in preventing disease
- The vaccines produced for the 2005-2006 season use:
~ A/New Caledonia/20/1999-like(H1N1)
A/California/7/2004-like(H3N2) (or the antigenically equivalent strain A/New York/55/2004)
B/Jiangsu/10/2003-like viruses.
How do Amantadine and rimantadine fight the flu?
Amantadine and rimantadine block uncoating of influenza virus after it enters cell.
How do Zanamivir and oseltamivir figt the flu?
Zanamivir and oseltamivir block neuraminidase (N-spikes).
How many people die from the flu in the US every year?
10,000 to 40,000
How often do Influenza A pandemics occur? What explains their widespread nature?
Pandemics occur periodically. Their spread is caused by major antigenic changes.
Explain antigenic drift, with regards to Influenza A.
- Antigenic drift consists of minor changes in spikes (particularly hemagglutinin)
- Changes minimize effectiveness of immunity to previous strains
Explain antigenic shift, with regards to Influenza A.
- Shifts represent more dramatic changes.
- Shifted virus strains are drastically antigenically different from previous strains
- The new virus comes from genetic re-assortment
- It occurs when two different viruses infect a cell at the same time
What is MDRTB?
Multi drug resistant tuberculosis.
