Pneumonias Flashcards
Typical Pneumonia, Causes
*Strep. pneumoniae
Staph. aureus
Haemophilus influenzae
Gm– enterics
Atypical Pneumonia, Causes
*Mycoplasma pneumoniae Chlamydophila pneumoniae/psittaci Bordetella pertussis Legionella pneumophila Coxiella burnetii Viruses - parainfluenza, adenovirus, EBV, RSV (neonates)
Streptococcus Pneumoniae - Characteristics
Gm+ cocci, often diplococci
catalase –
alpha-hemolytic (green hemolysis)
bile/optochin sensitive/soluble
Streptococcus Pneumoniae - Virulence
capsule prevents depositions of C3b on surface
~90 serotypes, anti-capsular Ab provide serotype specific immunity. Type 3 serotype is the most common cause of disease.
Streptococcus Pneumoniae - Clinical Presentation
Pneumonia
Otitis Media
Meningitis
Complications - abscesses, hearing loss, neurologic problems and learning disabilities.
Streptococcus Pneumoniae - Vaccine
PCV13 (13-valent, conjugated)
PPSV23 (23-valent, polysaccharide only)
Mycoplasma Pneumoniae - Pathogenesis
Tight adhesion (via P1 adhesin) disturbs function of cilia but no cell invasion. CARDS toxin causes cell vacuolation and deterioration of cilia. Immune response causes disease.
Mycoplasma Pneumoniae - Characteristics, Detection
no cell wall, small
“fried-egg” colonies; culture not recommended
test for cold agglutinins (nonspecific)
Chlamydia - Characteristics, Pathogenesis
obligate intracellular pathogen
causes both cytopathic and immune responses
Chlamydophila Pneumonia
diagnose via serology; culture not recommended
present in > 60% of adults
Chlamydia psittaci
zoonotic infection - parrot fever, spontaneous abortion in sheep; transmitted to humans via direct contact or aerosolization of feces; clinical - confusion/altered mental state
Bordetella Pertussis
short Gm– rod
whooping cough, resembles pneumonia
Legionella - Characteristics
Gm– but difficult to gram stain
culture in buffered charcoal yeast extract agar + IRON
sequestered in macrophages (coiling phagocytosis)
Legionella - Environmental Source
iron-rich soil and water (natural and domestic)
water towers, indoor fountains, etc
tolerates temp up to 65C and chlorination
survive in amebas (coiling phagocytosis)
Legionella - Clinical Presentation
Legionnaire’s Disease
-acute ATYPICAL or TYPICAL pneumonia w/ GI SYMPTOMS; occurs in elderly persons with underlying disease
Pontiac Fever
-influenza-like disease; self-limiting more mild form of disease in healthier individuals
Pseudomonas Aeruginosa - Characteristics
flagellated Gm– bacilli, oxidase +, strict aerobe
artificial grape-like smell
Pseudomonas Aeruginosa - Environmental Source
ubiquitous in the environment; soil and water
fresh fruits and vegetables; whirlpools, sinks, respiratory therapy equipment, hospitals/nosocomial
Pseudomonas Aeruginosa - Virulence
LPS (septic shock), capsule (impedes clearance), toxins, biofilm formation.
Pseudomonas Aeruginosa - Clinical Presentation
healthy persons - folliculitis, swimmer’s ear
immunocompromised - pneumonia (esp. in cystic fibrosis, ASPIRATION PNEUMONIA), nosocomial infections
Legionella - Virulence
survival in macrophages, LPS, biofilm formation
Patient presents w/ pneumonia. Lab has trouble w/ gram stain. What organism(s) can this be? If applicable, what further tests would you run?
Legionella pneumophila (Gm– but difficult to stain) Mycoplasma pneumoniae (no cell wall) - test for cold agglutinins
How are endemic mycoses acquired?
inhalation of SPORES, typically aerosolized from disturbed soil
Histoplasma capsulatum
Histoplasmosis
dimorphic fungi, intracellular (macrophages), thin wall
soil + bird/bat feces in Ohio/Mississippi river valleys
caseating granulomas + calcification, consider TB?
pulmonary, mediastinal, disseminated disease
Blastomyces dermatitidis
Blastomycosis
dimorphic fungi, thick wall + broad-base budding
soil of south central US, dogs particularly susceptible
pulmonary, skin, bone, and GU disease
