BIOL 232: Respiratory Infection

transmission of respiratory infections

droplet, airborne, contact

droplet respiratory infections

- over 5 microns

- influenca, S. pneumonia

- surgical mask and eye protection

airborne respiratory infections

- less then 5 microns

- TB, measles

- N95, negative pressure room

ways to classify respiratory symptoms

location (URTI, LRTI) and time

what does the epiglottis do

serves as the divider between the two regions

URTI

- affects nose, pharynx, sinuses, +/- conjunctiva or ear mucosa

- most URTI are viral so they DO NOT require antibiotics

- self limiting

MRTI

- epiglottis is the only structure

- division between upper and lower

LRTI affects?

trachea, bronchioles, bronchi, alveoli

URTI includes

- rhinitis, pharyngitis, tonsilitis, sinusitis, laryngitis

- Common cold viruses such as = adenovirus, coronavirus, RSV

common s/s URTI

- runny nose

- sore throat

- sneezing

- mild cough

LRTI involve

- deeper lung structures

- trachea, bronchi, bronchioles, alveoli

most important LRTI

- pneumonia = infection and inflammation of the lung parenchyma (alveoli)

- air sacs fill with pus and liquid

- productive cough + focal indicate bacterial pneumonia

Pneumonia clinical prevalance

typical = bacterial

atypical = viral, fungi

Pneumonia anatomical classifications (areas affected)

bronchopneumonia = more viral

lobar = more commonly seen in bacterial

interstitial = more commonly seen in viral like influenza

Pneumonia location

- CAP (community acquired pneumonia) = non hospitalized or more than 48 hours after hospitalization

- HAP (hospital acquired pneumonia) = presents less than 48 hours after hospitalization

- VAP (ventilator associated pneumonia) = presents less than 48 hurs after endotracheal intubation

- Aspiration pneumonia = from aspiration of colonized URTI or GI secretions

Pneumonia pathogens

- bacterial

- viral

- fungal/opportunistic

- chemical

Pneumonia s/s

- early cases = productive cough/ acute changes, high fever, changes in xrays

- geri might only show LOC as the immune system is not able to trigger fever and there nervous system is not adequate to trigger cough reflex

dx of CAP in adults without immunocompromising conditions

1st = newly recognized pulmonary infiltrates on chest imaging

2nd = one resp symtoms (new or worsening cough or sputum production, dyspnea, chest pain)

3rd = at least one symtom/findings (abnormal lung sounds, fever, leukocytosis or unexplained bandemia, hypoxia)

common organisms in Pneumonia (bacterial, viral, nosocomial)

Streptococcus pneumoniae (typical)

GAS (atypical bacteria)

- Mycoplasma pneumoniae

- Chlamydophila pneumoniae

- Legionella pneumophila

Viral

- Influenza

- Adenovirus

Nosocomial

- Pseudomonas aeruginosa

- S. aureus (including MRSA)

Which class of pneumonia pts need to be hospitalized

Class IV and V (medium to high risk)

3 main mechanisms by which bacteria reach the lungs

- aspiration

- inhalation

- hematogenous spread

common s/s of LRTI

- productive cough

- dyspnea

- pleuritic chest pain

- focal lung findings

- lung infiltration on CXR

cause of infectious sinusitis

- acute infectious rhinitis/sinusitis is usually caused by viral organisms

- common cold viruses and influenza

3 cardinal signs of infectious rhinitis

- for 10 days or longer

- clear to mucopurulent nasal discharge

- nasal obstruction/congestion

- headache (facial pressure)

fever is 50% sensitive and specific = dont need to cosnider that much (do consider how high the fever is, with a cold it should be low grade, but if bacterial infection it should be high grade)

how to know if infectious rhinitis is caused by bacteria

- s/s with no improvement after 10 days

- double sickening (pt initially improves but then develops worsening symptoms several days later = indicates a secondary bacterial infection)

- high fever

- foul smelling nasal discharge

common cold with infectious rhinitis

- gradual onset and mild s/s (depends on the viral tropism for URTI)

- runny nose

- fever not common/low grade

- sneezing

- dysphagia

- mild cough

- stuffy nose, sore throat

- headache is rare/mild

flu with infectious rhinitis

- sudden onset of systemic symtoms

- fever, chills, fatigue, weakness

- aches

- headache is common

- influenzas virus is the only cause of the flu

- rapid progression and abrupt (short incubation period)

infectious pharyngitis microorganisms are

viral or bacterial

viral infectious pharyngitis

- most common etiologic agent is viruses in adults and kids (50-80%)

bacterial infectious pharyngitis

- more common in children

- most common causative organism is group A streptococci aka streptococcus pyogenes = strep throat

viral vs bacterial respiratory infections

viral: diffuse spread, non-productive cough, mild fever, gradual symptoms

bacterial: localized spread, productive cough, high fever, severe symptoms

pharyngitis evaluation/ dx tools

- WBC is not very useful

- RADT is specific for group A beta-hemolytic streptococci

- throat swab = more sensitive

RADT

- fast and cheap

- detect viral bacterial proteins (antigens expressed on the surface of the bacteria)

- if positive can be trusted

- if negative cannot be trusted (false negatives), do throat culture

throat culture

- sensitive

- used if RADT is negative to confirm negative result

streptococci sequelae

- Untreated strep throat can lead to serious complications

- Scarlet fever, acute rheumatic fever

scarlet fever

Rash, strawberry tongue

rheumatic fever

- 4-9 year of age (2-3 weeks after)

- High fever

- Higher risk for developing endocarditis later

- Affected organs: heart valves, joints, skin, nervous system

- Untreated strep leads to rheumatic heart disease

- Antibodies against streptococcus cross-react with host cells in an autoimmune reaction, resulting in serious sequalae (attack our own tissues)

tx for bacterial pharyngitis

- 6-10 day course of oral amoxicillin

tx for viral pharyngitis

- antiviral therapy within 48 hours

- oseltamivir or zanamivir

- vaccination

whooping cough causative organism

Gram negative bacillus Bordetella pertussis

whooping cough characteristics

- Airborne droplets transmission

- Incubation period of 7-21 days

- Progressive phases

LRTI main infections

CROUP and pneumonia

CROUP infects

Infects the larynx - the trachea and even bronchi = laryngotracheobronchitis (LBT)

CROUP main target populations

children 6 months - 5 years

s/s of CROUP

- Barking or seal cough (laryngitis), caused by inflammation of larynx or trachea

organisms responsible for CROUP

Parainfluenza viruses types 1 and 2

dx of CROUP

- neck/chest xray for steeple sign (narrowing of the airway)

- tx is symptomatic and it should be carefully selected to avoid airway obstruction

- when this is present, we can start seeing the STEEPLE sign in x-rays (narrowing of the airway)

Curb 65 Score - Pneumonia Clinical Prediction Tool

More sensitive for treatment decisions and mortality risk prediction