Resp infections Flashcards
Resp infections in children (5)
Epiglottitis Croup Syndrome (Laryngitis, Laryngotracheitis, Laryngotracheobronchitis) Bronchiolitis Pneumonia Acute Otitis Media
Critical points of airway obstruction:
Junction of tongue and posterior pharynx
Supraglottic area
Subglottic area
Upper airway obstruction gives ______
Lower airway obstruction gives ______
inspiratory stridor
expiratory wheeze
Resp pathogens: Viruses (5) Mycoplasma (1) Chlamydia (3) Bacteria (5)
Viruses RSV Rhinovirus Parainfluenza Adenovirus Influenza
Mycoplasma
M. pneumoniae
Chlamydia
C. trachomatis
C. pneumoniae
C. psittaci
Bacteria S. pneumoniae (Pneumococcus) H. influenzae M. catarrhalis Staphylococcus M. tuberculosis
- Croup syndrome triad
- Caused by ____ (3 classes)
Stridor, cough, hoarseness
Infectious (Epiglottitis, Laryngitis, Laryngeal Diphtheria, Laryngo-tracheitis, L-T-bronchitis, L-T-B-pneumonia), mechanical (foreign body, trauma), allergic (Acute angioneurotic edema)
Epiglottitis:
- usually caused by which pathogen?
- pathogenesis?
- child’s appearance?
- sign on resp exam?
- H. influenzae B (Hib) (rarely seen today due to immuniz’n)
- Colonization of nasopharynx –> bacteremia –> seeding of epiglottis –> supraglottic edema obstruction due to ball-valve effect
- Abrupt onset in < 24 hours; Child insists on sitting, leaning forward, hyperextension of the neck, anxious, drooling, toxic-looking
- Stridor may or may not be present
Laryngotracheitis (Viral Croup):
- ages?
- which viruses? (4)
- pathogenesis?
- Tx?
- Ages 3 months to 3 years
- Parainfluenza 3 (1 or 2), RSV, Influenza, Adenovirus
- Diffuse URTI –> spreads to larynx, trachea, bronchi, vocal cords –> expansion of inflamed tissue inward –> stridor, hoarse voice, and cough
- Tx: Goal is to reduce inflammation: Cool mist; cold air; Hydration; Systemic steroids (dexamethasone); Racemic epinephrine (closely observe for rebound obstruction)
Bacterial tracheitis:
- pathogenesis?
- Sx? (3)
- may resemble _____
- which bacteria? (4)
- Tx?
Sequela of injury to trachea (post-intubation; post- viral URI)
Acute onset of fever, stridor and copious amounts of purulent sputum (adults)
May resemble epiglottitis
Bacterial etiology: S. aureus, Group A strep, Pneumococcus, H. influenza
Medical emergency: ICU admission, probable intubation and antibiotics
Acute bronchitis:
- Sx/findings (3)
- pathogenesis?
- Tx?
- Fever, cough, and rhonchi
- Viral URI with distal spread resulting in inflammation and damage to trachea and bronchi. Mycoplasma rarely implicated, but even so response to therapy is not impressive.
Bronchiolitis:
- ages?
- Sx/findings (3)
- seasons?
- main virus?
- pathogenesis?
- Tx (6)
-Disease of infancy
-rhinorrhea, expiratory wheezes, cough
-Occurs in winter and spring
-RSV is the major cause
-Walls of small bronchi and bronchioles become edematous, occluded with mucous, +/- bronchospasm
-Mortality almost exclusively seen in infants with underlying cardiac/pulmonary disease
Tx: O2, supportive care, fluids, Suctioning as needed, +/- inhaled bronchodilators, epinephrine
High risk infants: monthly Synagis (Palivizumab = monoclonal RSV antibody) during RSV season
Microbial Agents that cause pneumonia (6 categories; incl 3 bacteria)
Viral Bacterial (S. pneumococcus, H. influenzae, M. catarrhalis) Mycoplasma (> 5 years old) Chlamydia TB Fungal
Pneumonia:
- Pathophysiology?
- Clinical manifestations (3)
- Pathophysiology: (1) Aspiration, (2) Contiguous spread, (3) Secondary to poor host defenses (Cystic Fibrosis, smoke inhalation), (4) Hematogenous spread
- Clinical manifestations: usually fever, tachypnea, +/- other findings (e.g. crackles)
- Tx dep on age, distribution of disease, status of child
Acute otitis media pathogenesis
-Viral URTI –> Edema of mucosal surfaces –> obstruction of Eustachian tube –> Stasis of fluid in the middle ear –> Bacterial superinfection
Acute otitis media Dx (3)
- Sudden onset of symptoms
- Signs of inflammation (e.g. pain, bulging tympanic membrane, erythema of TM)
- Signs of effusion (e.g. immobile TM, air-fluid level, loss of the bony landmarks behind the TM—especially the short process of the malleus) - Effusion can persist for weeks to months = OM with effusion/“glue ear”
- Acute otitis media microbiology
- Always Tx with antibiotics?
S. pneumo (36%) No growth (25%) H. flu (22%) M. cat (14%) GAS (3%)
-if minimal Sx, 92% will resolve on their own.
AAP otitis media Tx guidelines
- Treat with antibiotics for children under 6 months
- If 6 - 24 months, not too sick and diagnosis is uncertain, could choose to observe for 48 - 72 hrs
- If older than 24 months and not too sick, could observe for 48 – 72 hrs, even if diagnosis is certain
- Should make sure follow-up available, caregivers reliable
- Should always treat the pain!
CPS otitis media Tx guidelines (wrt observation)
Observe 48 to 72 hrs if :
> 6 months of age
No immunodeficiency, chronic cardiac or pulmonary disease, anatomical abnormalities of head/neck or history of complicated otitis media, or Down sydrome. (? Aboriginal children?)
Illness is mild (mild otalgia, fever < 39)
Parents are capable of recognizing signs of worsening illness and can readily access medical care if child does not improve
Otitis media spontaneous resolution is pathogen-dependent; 3 main pathogens and their % spontaneous resolution?
S. pneumoniae 19% spont. resolution
H. influenzae 48% spont. resolution
M. catarrhalis 79% spont. resolution
- Otitis media antibiotic Tx (first- and second-line)
- Risk factors for resistance? (2)
First-line:
Amoxicillin: excellent middle-ear penetration, well- tolerated, relatively narrow antimicrobial spectrum
-Recommendation now is to start with high dose amoxicillin for everyone (80-100 mg/kg/day); If it fails, likely due to B-lactamase production, so switch to amoxicillin-clavulinic acid (can give high-dose)
Second-line:
Amoxicillin-clavulinic acid: inhibition of B-lactamase
Also 2nd/3rd generation cephalosporins, macrolides
-If fails high dose amoxicillin-clavulinic acid, consider intravenous Ceftriaxone (3rd generation cephalosporin) for 3 days
Risk factors: Day care, recent antibiotic use (past 1 -3 months)
How the 3 main otitis media pathogens each devel resistance
S. pneumoniae: Change in penicillin-binding site
H. influenzae & M. catarrhalis: Production of B-lactamase
Length of antibiotic Tx for otitis media (2 groups)
10 days: Children younger than 2 years old Children with frequent recurrent AOM Children with perforated TM Children who failed their initial treatment
5 days:
Everybody else!
Which common bacterial pathogen does NOT make B-lactamase?
S. pneumoniae
