Micro - Respiratory Flashcards
Upper Respiratory Tract Infections
otitis externa, sinusitis, rhinitis, pharyngitis, epiglottitis, laryngitis
Lower Respiratory Tract Infections
bronchitis, bronchiolitis, pneumonia
Respiratory Defenses
- Mucociliary lining of nasal cavity
- Change of direction of airway (pathogens get trapped in mucous layer)
- Ciliary Elevator
- Normal flora competition
- Alveolar macrophages (innate immune system)
- IgA (acquired immune system)
2 Major obstacles organisms must overcome
- Avoid/survive mucus layers
2. Avoid phagocytosis and survive
Turbinate Bones
“Baffle plates”
covered with mucus –> air swirls as it passes over –> pathogens come into contact with mucus covered passages
Mucociliary Elevator
- mucus-producing goblet cells
- ciliated epithelium
* smoking paralyzes the cilia –> smoking cessation can lead to regrowth of cilia
Normal flora of respiratory tract
Upper - lots
Lower - NONE –> considered sterile
Pathogen initiation of disease
- Must be sufficient dose of microorganisms
- infectious particles must be airborne
- airborne particles must be viable in air
- organisms must be deposited on tissue susceptible to infeciton
Rhinitis
Common cold - generally no fever
Nasal stuffiness, sneezing, headache, tiredness, lacrimation, sore throat
Usually seen in winter, spread person-person
- symptoms peak 2-5 days post infection, resolved by 14 days
- supportive therapy
Rhinovirus
#1 cause of rhinitis RNA virus --> icosahedral --> non-enveloped --> ss(+)non-segmented(IV) --> picornaviridae infects nasal passages following attachment to ICAM-1 --> localized inflammation and lytic infection --> ciliated epithelial cells are destroyed - break in barrier may lead to secondary infection by normal flora
Parainfluenza
RNA virus –> helical capsid –> enveloped –> ss(-)non-segmented(V) –> paramyxoviridae
F-protein –> forms multinucleated cells
Hemagglutinin –> interacts with salic acid –> endocytosis
Neuroaminidase –> envelope protein responsible for cleaving HA bound to salic acid –> viral spread
Coronavirus
RNA virus –> helical capsid –> enveloped –> ss(+)non-segmented (IV) –> coronaviridae
Can cause SARS –> rapidly progressive pneumonia
Mastadenovirus
DNA virus –> icosahedreal nucleocapsid –> non-enveloped –> DS linear DNA (I) –> adenoviridae
most common viral cause of conjunctivitis
Rhinosinusitis
inflammation or infection of mucosa of nasal passages and atleast 1 paranasal sinuses
2 most common causes = S. pneumoniae and H. flu
Sx: sneezing, rhinorrhea, congestion, post-nasal drip, aural fullness, facial pressure, headache
Fungal rhinosinusitis –> RARE, aspergillus fumigatus (immunocompromised)
- antibiotic treatment for bacterial causes
Strep pneumoniae
gram (+) diplococci –> catalase (-) –> alpha hemolytic –> bile-esculin negative –> optochin susceptible
Capsule, IgA proteases
Major cause of community acquired pneumonia
H. influenzae
gram (-) –> coccobacilli, pleomorphic –> X & V factors
IgA protease, capsule –> avoids phagocytosis
Pharyngitis
Majority caused by viruses (conjunctivitis, cough, hoarseness)
Strep pyogenes is most common bacterial cause (severe pain with swallowing)
Sx: fever, sore throat, edema, hyperemia of tonsils
Rapid strep test tells if bacterial –> culture takes 1-2 days
needs to be treated within 9 days to prevent glomerulonephritis or rheumatic fever