Respiratory Infections Flashcards
Location of Respiratory Infections
Trachea, Bronchi, Bronchioles, Alveoli
Barriers to infection
Nasal hair, Mucosillary cells, Coughing, Normal flora, Phagocytic inflammatory cells
Normal flora
- changes with time (due to hospitalization)
- alpha hemolytic colonies in pharyngeal culture
Pathogens
- alpha hemolytic colonies in sputum or bronchial aspirate
Differentiating infection
- look at method and site of infection
- presence of white blood cells
- number of organisms present
- clinical syndrome present
- some pathogens are always present (M.TB)
Respiratory Infections (Risk Factors)
- Imunnologic status
- Age (elderly, young at higher risk)
- Reduced clearance promotes infection
- Airway obstruction (H. flu epiglottitis)
- Seasonal patterns contribute (M. pneumo has none)
Empirical treatment
- antibiotics should be given before ID for ICPs
- infections with hard-to-reach specimens
- infections with known/recurring pathogens
Virulence factors
- adherence, fimbrae (Enterics, Streps)
- toxin elaboration (C. diphtheriae, Pseudomonas, pertussis)
Evasion of host defense
- capsules for preventing phagocytosis (S. pneumo, H. flu, Pseudomonas, Klebsiella)
- intracellular (TB, Chlamydia)
- Proteases (cleave antibodies)
Upper Respiratory Tract Infections
Pharyngitis, Sinusitis, Otitis media, Epiglottitis, Pertussis
Pharyngitis
- commonly Group A strep in kids or viral (with rhinorrhea)
- symptoms of Group A strep
- culture or rapid antigen testing
- person-to-person transmission
- pain, difficulty swallowing, fever with bacterial
- C. diphtheriae: pharyngeal membrane
URT Infections (pathogenesis)
inflammatory effects of bacteria
URT complications
sinusitis, otitis media, pneumonia
URT lab diagnosis
- primary: differentiate between viral and bacterial
- secondary: detect uncommon bacterial causes
URT culture
- streak SBA
- Latex agglutination
- Rapid antigen test
- treat with penicillins and cephalosporins
Sinusitis (causes)
- commonly viruses (rhinovirus, influenza)
- 2% are bacteria (S. pneumo, H. flu, S. pyogenes, M. catarrhalis, S. aureus)
- fungal is uncommon
Sinusitis (pathogenesis)
- swelling and blockage of sinuses
- pain and possible complications
- complications: orbital cellulitis, osteomyelitis, meningitis
Sinusitits (lab diagnosis)
- direct sinus puncture or aspiration
- culture on SBA, MAC, Chocolate
- empirical information
Otitis media
- most common in preschool aged kids
- fever, irritability, ear pain, drainage, red tympanic membrane
Otitis media (pathogenesis)
- due to anatomic immaturity
- causes damage to tympanic membrane
Otitis media (lab diagnosis)
- empirical
- antibiotic treatment in kids < 2 y/o