Respiratory Tract Infections Flashcards
1
Q
How are respiratory infections classifed by?
A
location (upper and lower) & time (acute/chronic)
2
Q
What is part of the upper respiratory tract?
A
- upper airways (nasal passages)
- sinuses
- pharynx
- larynx
3
Q
what is part of the lower respiratory tract?
A
- larynx-trachea
- bronchi
- bronchioles
- alveoli
4
Q
What are the upper RT syndromes?
A
- rhinitis
- sinusitis (rhinosinusitis)
- pharyngitis (w/ or without tonsillitis)
- otitis
- larygnitis
- epiglottitis
5
Q
what are the lower RT syndromes?
A
- croup (laryngotracheobronchitis)
- bronchitis/bronchiolitis
- pneumonia (infection of alveoli)
- TB
6
Q
how to know if it is an upper RT infection?
A
self-limited irritation and swelling of upper airways with associated cough with no proof of pneumonia, lacking a separate condition to account for the pt’s symptoms, or no hx of COPD/emphysema/chronic bronchitis
- involves nose, sinuses, middle ear, pharynx, and larynx –> localized to URT
6
Q
what is acute otitis media caused by?
A
50% d/t respiratory viruses
common bacterial causes:
- streptococcus pneumoniae
- h. influenzae
- moraxella catarrhalis
- group A beta-hemolytic streptococci (staph pyogenes)
- s. aureus (main cause if bacterial)
7
Q
what is acute infectious rhinitis/sinusitis usually caused by?
A
usually caused by viral rather than bacterial agents
8
Q
Most common causes of rhinitis/sinusitis infections?
A
- common cold virus group - rhinoviruses, adenoviruses, coronaviruses, parainfluenza virus, respiratory syncytial virus, enterovirus = acute nasopharyngitis
- influenza virus
9
Q
What are the 3 cardinal symptoms of infectious rhinitis + how long?
A
- 10 days or longer
- clear-to-mucopurulent nasal discharge
- nasal obstruction/congestion
- headache (facial pressure)
fever = 50% sensitive & specific, temp depends on type of bac/virus
10
Q
What increases the likelihood of influenza A infection?
combo of what s/s?
A
combo of high fever, chills, and cough
10
Q
How to know if rhinitis/sinusitis is bacterial?
A
- double sickening (3-5 days after improvement)
- S&S > 10 days with no improvements
- fever
- foul-smelling nasal discharge or breath
11
Q
What suggests a secondary bacterial infection?
A
- persistant facial pain and edema, purulent drainage, fever
11
Q
Common Cold Syndrome - timing?
incubation & duration of s/s
A
- incubation period = 10-12h after inoculation
- average duration s/s = 7-10 days, but can persist for as long as 3 weeks
12
Q
Influenza etiology
incubation, s/s timing, how many types?
A
incubation period = 1-4 days, symptoms resolve 7-10 days
influenza A, B, C
- see influenza A the most, can have antigenic shifts and antigenic drifts = can be pandemic and epidemic
13
Q
What is Pharyngitis?
A
= inflammation of mucous membranes of oropharynx (can have multiple inflammations @ same time)
- mainly bacterial or viral cause, fungal is rare
less common causes = allergies, trauma, cancer, reflux, toxins
14
Q
Pharyngitis - Epidemiology
A
viral: transmission by aerosol and direct contact
bacterial: ~5-10% of population are carriers of streptococcus pyogenes (normal biota) in pharynx (rates higher in children)
15
Q
Where do most cases of pharyngitis occur in?
A
occur in children under age of 5
16
Q
What is the cardinal sign of pharyngitis?
A
Redness of pharyngitis
17
Q
Infectious Pharyngitis - Etiology, Viral
A
- ~50-80% of pharyngitis = viral in origin (predominantly rhinovirus, influenza, adenovirus, coronavirus, parainfluenza)
- less common viral pathogens: herpes, epstein-barr, HIV, coxsackievirus
- more severe cases tend to be bacterial and may develop after initial viral infection (can have complications)
18
Q
Infectious Pharyngitis - Etiology, bacterial
A
most common bacterial infection = Group A B-hemolytic streptococci (5%-36%)
other bacterial etiologies (very rare):
- group B & C streptococci
- chlamydia pneumoniae
- mycoplasma pneumoniae
- haemophilus influenzae
- neisseria meningitidis
- nesseria gonorrhoeae
19
Q
What can untreated bacterial pharyngitis lead to?
A
- peritonsillar abcesses
- scarlet fever (damage heart + kidney)
- rheumatic fever
- acute glomerulonephritis
19
Q
Pharyngitis - clinical manifestations, bacterial
A
- sore throat & odynophagia (mild to severe)
- high fever > 38 degrees
- tonsillar exudates
- painful cervical adenopathy
- ear pain
- no cough or flu-like symptoms
- might see microhemorrhaging
20
Q
Pharyngitis - clinical manifestations, viral
A
- flu/cold-like symptoms
- erythema associated with pharyngitis
- odynophagia
- low fever (> 38 degrees)
- concurrent conjunctivitis
21
What can untreated viral pharyngitis lead to?
influenze complications:
* respiratory - viral pneumonia, secondary bacterial pneumonia, otitis media, sinusitis
* muscular - rhabdomyolysis, myositis
* neurologic - encephalitis, meningitis, transverse myelitis, guillain-barré syndrome
22
How to diagnose pharyngitis/evaluate
* nasopharyngeal swabs for rapid-antigen detection, or RT-PCR (influenza gold standard)
* rapid antigen detection tests (RADT): specific for group A beta-hemolytic streptococci (sensitivity 70-90%)
* lymphocytosis (greater than 50%) = suggests infectious mononucleosis (epsein-barr)
23
Pharyngitis evaluation - wbc count?
not useful for etiology differentiation
24
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Pharyngitis evaluation - rapid antigen detection test results?
positive = treatment initiated
negative = obtain throat culture and use that to guide treatment (in children)
25
Pharyngitis evaluation - McIsaac score
| what is the score used for and what does a higher score mean?
higher score = more likely to be bacterial
score 0-1 =. no test/treatment, infection risk <10%
score 2 = use rapid antigen test, 11-17% infection risk
score 3 or higher = 100% run RT-PCT test, test or treat empirically
26
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URT Bacterial infections: Streptococcal sequelae
| what is it caused by and what does it lead to?
caused by immune response to bacteria
- antibodies cross-react with host cells in autoimmune reaction, resulting in serious sequelae
- acute rheumatic fever
- glomerulonephritis
27
URT Streptococcal sequelae - acute rheumatic fever
| what happens?
- 4-9 years of age (2-3 weeks after)
- high fever
- damage to heart, joints (migrating), skin or nervous system
- cross reactive M protein antibodies, T cells, and complement
28
URT Streptococcal sequelae - glomerulonephritis
- hematuria and proteinuria
- high BP
29
Pharyngitis - Treatment, Viral
viral: treat s/s
influenza - give antiviral therapy within 48h of symptom onset (or earlier) to reduce risk of complications
- oseltamivir or zanamivir
- vaccination = most effective method of preventing influenza illness/complications
29
Pharyngitis - Treatment, Bacterial
- hydration therapy critical
bacterial:
- 6-10 day course of oral amoxicillin (eradication of bacterial carriage and prevention of rheumatic fever)
- adherence? single IM dose of penicillin G
- corticosteroids not recommended for bacterial infection
- oral cephalosporins, clarithromycin, clindamycin if hypersensitivity to other abx
30
reemerging URT: Diphteria
| cause, s/s + how is it treated?
cause: corynebacterium diphtheriae, gram-positive rod
- abx +antitoxins used simultaneously (has exotoxins)
s/s: sore throat, cervical lymphadenopathy, a low-grade fever, and pseudomembrane (leather-like)
31
reemerging URT: whooping cough
| cause, phases?
cause: gram-negative bacillus Bordetella pertussis, airborne droplet transmission
- incubation 7-21 days
3 stages:
1. catarrhal (upper)
2. paroxysmal (lower) - whooping noise
3. convalescent - paroxysms gradually disappear 2-3 weeks
31
Lower RT viral infection - how to classify?
bronchitis/bronchiolitis = when bronchial tubes/bronchioloes involved
pneumonia = when lungs (alveoli) affected
viral = self-limiting disease
32
Lower RT viral infection - Croup
| what is affected? who is affected? s/s? cause?
* infects larynx --> trachea and bronchi = laryngotracheobronchitis (LTB)
* highest risk = children 6 months to 5 years age
- s/s: common cold syndromes, barking cough (laryngitis)
- most common cause: parainfluenza viruses type 1 + type 2, will see steeple sign on xray
33
Lower RT viral infection - RSV (RNA virus)
| what happens? what does it cause?
- fusion of adjacent infected cells into a syncytium (giant cell containing many nuclei)
- inhalation of respiratory droplets - mucous membranes
- most common cause of bronchiolitis and pneumonia among infants + children < 1
34
Pneumonia: classification, definition, transmission
= infection of lung parenchyma; serious infection in which air sacs fill with pus and other liquid
Classified based on: anatomical, etiology (viral, bacterial, fungal), clinical
transmission: inhalation (most common), aspiration, hematogenous spread = 3 main mechanisms
34
Lower RT viral infection - RSV: s/s, dx, tx
s/s: fever, runny nose, cough, sometimes wheezing
dx: RT-PCR + rapid-antigen test
tx: severe cases with ribavirin
34
Pneumonia classification: Anatomical
- localized in one lobe/area, unilateral consolidation = bacterial
- intersitial pneumonia, bilateral consolidation = viral
- spotty = fungal
35
Pneumonia: Risk Factors
impaired lung defenses
- poor cough/gag reflex (e.g., illness, drug-induced)
- impaired mucociliary transport (e.g., smoking, cystic fibrosis)
- immunosuppression (e.g., steroids, chemotherapy, AIDs/HIV, DM, transplant, cancer)
increased risk of aspiration
- impaired swallowing mechanisms (e.g., impaired consciousness, neurologic illness causing dysphagia, mechanical obstruction)
36
Pneumonia - Etiology
CAP: non-hospitalized, or <48h after hospitalization, streptococcus pneumoniae = main cause
HAP: presents clinically >48h after hospitalization (incr chance of resistance, staph/MRSA)
VAP: presents >48h after endotracheal intubation
aspiration pneumonia: results from aspiration of colonized URT secretions
36
Pneumonia: Clinical Features
**- cough/ productive cough, fever**, pleuritic chest pain, dyspnea, tachypnea, tachycardia,
**- changes in xray**
- elderly often presents atypically – altered LOC sometimes only sign, fever unlikely
- evidence of consolidation (dullness to percussion and/or crackles) --> cxr/ct scan
37
Criteria for hospitalization & prediction?
| what tools are used and for what?
PSI = pneumonia severity index, best for predicting; for hospitalized pts (need more time + resources)
CURB 65: for ER, to determine if hospitalization is needed
- the higher the score, the more severe the pt
IDSA-ATS = only for ICU/ ICU admissions, to diagnose severeity of CAP
38
What is used to determine if pt has pneumonia?
- pulse oximetry (respiratory distress)
- CXR + CT chest shoes distribution of pathogen (lobar consolidation or interstitial pattern)
- CBC + differentials (incr neutrophils + immature neutrophils), urea, lytes, Cr, ABG (if resp distress), troponin/CK, LFT, urinalysis
- sputum gram stain/C&S, blood C&S, serology/viral detection, pleural fluid C&S (if effusion >5cm or resp distress)
- bronchoscopy + washings for: 1. severely ill pts refractory to treatment, 2. immunocompromised pts
39
What is the treatment for CAP, HAP, & VAP?
1. antibiotics (most important)
2. o2
3. iv fluids + consider salbultamol
40
When would you give two antibiotics for pts with pneumonia?
For streptococcal pneumonia + for atypical pneumonia
41
What can lead to atypical pneumonia?
1. influenza type A + B (most common [type A])
2. covid-19
3. RSV (common in children)
4. rhinovirus (very unlikely)
5. adenovirus (very unlikely)
42
Atypical bacteria causing atypical pneumonia?
- mycoplasma
- legionella
- chlamydia
won't have cell wall or are intracellular pathogens
43
How to identify atypical pneumonia?
- RT-PCR – esp if it's a RNA virus
- will see bilateral multilobular ground-glass opacities and interstitial inflammation (look @ location)
- clinical findings overlap overall with typical pneumonia, challenging to confirm without labs
44
Pneumonia tx
| medications?
- neuroaminidase inhibitors (Oseltamivir) or endonuclease inhibitor (Baloxavir marboxil)
- corticosteroids (lack of robust evidence for viral pneumonia
- supportive care
45
Pulmonary Tuberculosis - definition + epidemiology
- infection by bacillus M. tuberculosis (gram +, has mycolic acid = hard to see with gram stain)
- 1/3 of population infected with M. tuberculosis –> only 10% of infected will cause s/s
- incr in incidence related to poverty, population displacement, HIV, and drug resistance
46
Pulmonary Tuberculosis - Etiology
- M. tuberculosis grows slowly = culture apepar around 1-12 weeks
- infections spread usually by inhalation of "droplet nuclei") rarely by ingestion
- incubation period = 4-16 weeks
47
How to classify TB?
| how to classify + what are the types?
by location
- pulmonary TB
- extrapulmonary TB (GI, brain, GU, abdomen of immunocompromised)
- have primary TB, miliary TB, tuberculosis pleurisy, cavitary TB
48
How does primary TB lead to secondary TB?
1. primary lesions (Ghon complex) heal or calcifies, or bacilli become dormant
2. bacteria reinfect, or latent infection is reactivated
3. bacilli may enter bloodstream and infect other organs
49
What do cavity formations look like in TB?
- "cheese" like lung
- cough with blood and "cottage cheese" like consistency
50
Pulmonary TB - Clinical Features, Active TB
- chronic cough (> 3 weeks)
- hemoptysis
- weight loss/anorexia
- malaise
- night sweats
- fever/chills
- chest pain
- apical shadowing in chest radiograph, often with cavities (uncommon in typcial pneumonia)
50
Pulmonary TB - Labratory Diagnosis
- microscopy of relevant specimens
- acid-fast (ZN) stain or fluorescent rhodamine-auramine dye
- PCR
- culture on special media for up to 12 weeks
51
How to measure immune response of TB
1. skin test
2. in vitro blood test
measurement of induration and erythema
51
How to determine positive TB test?
- >5 mm = positive in high-risk individuals (unhoused, super young/old, travel to endemic areas)
- >10 mm = positive in low-risk populations
51
Treatment of Pulmonary TB
- combo of up to 4 anti-mycobacterial drugs (to preevnt emergence of resistance)
- TB hard to treat in certain areas, like granulomas and bac can be hard to kill
initial phase for 2 months:
- **isoniazid** (for mycobacterium TB, inhbits mycolic acid + synthesis of cell wall)
- rifampicin
- pyrazinamide
- ethambutol
continuous phase: followed by 4 months of rifampicin and isoniazid
52
Fungal infections: Coccidiodomycosis / Valley Fever
- atypical s/s
- caused by Coccidioides immitis
- endemic in US + some regions in Canada
52
Fungal infections - portal of entry + common etiologies
- portal of entry = respiratory tract
- usually associated with occupation + recreational activities in wooded areas along waterways (moist soil + spores)
- infections acquired from environment, not person to person
- most common in immunocompromised
53
Fungal Infections: Blastomycosis
- caused by Blastomyces dermatitidis
- found mostly in **Ohio + Mississippi river valleys & Eastern US (soil)**
53
Fungal infections: Histoplasmosis
- caused by Histoplasma capsulatum
- flu-like illness, erythema nodosum, arthritis, arthralgia
- in US, found mostly in **Ohio + Mississippi** river valleys, **grows in soil enriched with bird + bat droppings (caves)**
- check for SpO2 + ct/cxr
54
Fungal Infections: Cryptococcosis
- caused by cryptococcus neoformans
- **associated with pigeon and other bird droppings** (farms, interactions w/ birds)
- most prevalent clinical form = meningoencephalitis in AIDs pts (immunocompromised)
