Respiratory Pathogens Flashcards
community acquired respiratory pathogens
-strep pneumoniae
-haemophilus influenza
-moraxella catarrhalis
-legionella pneumonphilia
-bordetella pertussis
-corynebacterium diphtheriae
hospital-acquired (nosocomial) respiratory pathogens
-legionella pneumophilia
-pseudomonas aeruginosa
division point - community vs hospital acquired
in hospital > 72 hrs, it is hospital acquired
upper respiratory tract infections (URIs)
-strep pneumonia
-haemophilus influenza
-moraxella cararrhalis
-corynebacterium diphtheriae
lower respiratory tract infections (LRIs)
-strep pneumoniae
-haemophilus influenza
-bordetella pertussis
-legionella pneumophilia
-pseudomonas aeruginosa
community acquired pneumonia - overview
*common
*risk factors include respiratory tract disease, smoking, alcohol abuse, comorbidities, immunodeficiency, and acid reducing drugs
which 3 community-acquired pneumonias typically follow viral infection (like flu or covid)
- strep pneumoniae
- strep pyogenes
- staph aureus
where does the majority of community-acquired pneumonia come from
aspiration of upper airway bacteria (90%)
*only 10% from hematogenous pneumonia
streptococcus pneumoniae - morphology
*encapsulated gram positive coccus
*Lancet-shaped diplococci
*ALPHA hemolytic (due to pneumolysin)
strep pneumoniae - virulence factors
ANTIPHAGOCYTIC POLYSACCHARIDE CAPSULE
*protein adhesions, IgA protease, pneumolysin
*techoic acid
*phosphorylcholine
strep pneumonia - pathophysiology
-acquired by inhalation of droplet nuclei or direct contact
-spreads to lungs through microaspiration
strep pneumoniae - main host defense
serospecific antibodies
what is the most common / severe infection for people who had a splenectomy
strep pneumoniae
strep pneumoniae - clinical infection
*lobar pneumonia (rust-colored sputum)
*sinusitis
*otitis media
*MENINGITIS
strep pneumonia - diagnosis
-gram stain of sputum (lancet-shaped diplococci; gram +)
-culture of sputum or sterile body fluid
haemophilus influenza
*gram negative coccobacilli
*requires CHOCOLATE agar
*factor X and V required for growth
what agar is necessary to grow haemophilus influenza
chocolate agar
what factors are necessary for haemophilus influenza
factor X and V
what is the most virulent strain of haemophilus influenza
strain B
haemophilus influenza - virulence factors
*antiphagocytic polysaccharide capsule (polyribitol phosphate - PRP)
*PILI
-lipooligosaccharide
-IgA proteases
-beta lactamases
what is the main host defense against haemophilus influenza
serospecific antibodies
haemophilus influenza - clinical infection
*lobar pneumonia
*sinusitis
*otitis media
*MENINGITIS
*EPIGLOTTITIS
*conjunctivitis
haemophilus influenza - diagnosis
*gram stain or culture (chocolate agar)
*PCR of CSF or blood
moracella catarrhalis
*gram negative coccobacillus
*looks like haemophilus influenza
*less virulent that haemophilus influenza
legionella pneumophilia
*gram negative rod
*requires cysteine for growth (BCYE agar)
*serogroup 1 is the most important
*can cause community and hospital acquired pneumonia
legionella pneumophilia - virulence factors
*LPS/lipid A (endotoxin)
*facultative INTRACELLULAR bacteria (not killed by ROS or phagocytosis)
legionella pneumophilia - pathophysiology
*acquired by inhalation of droplets from an infected AEROSOL (water droplets in environment)
*cooling towers, showers, spas, whirlpools, fountains, grocery store and flower show misters
*able to survive in hot water tanks
legionella pneumophilia - clinical infection
*severe pneumonia
*systemic inflammatory response can be quite severe, causing septic shock
*high fatality rate
legionella pneumophilia - pontiac fever
*much less severe, influenza-like illness
*host response causes the majority of symptoms
legionella pneumophilia - risk factors
-older age
-lung disease
-kidney, liver, or heart disease
-immunocompromised
-cigarette smoking
-alcohol abuse
legionella pneumophilia - diagnosis
*detection of serogroup 1 specific lipopolysaccharide antigens in URINE (using ELISA testing)
legionella pneumophilia - prevention
-monitor water sources through periodic culturing
-hyperchlorination or superheating of water
-discontinuing or shutting off problematic water features
pseudomonas aeruginosa
*gram negative rods
*GREEN PIGMENT
*musty GRAPE ODOR
*found in most, warm environmental soils, plant materials, and water
pseudomonas aeruginosa - virulence factors
**ALGINATE (helps biofilms)
*EXOTOXIN A (kills host cells)
*virulence genes controlled by quorum sensing
pseudomonas aeruginosa - pathophysiology
*inhalation of droplets from infected aerosol or other environmental source
*introduced to lung through microaspiration
*can also go into skin
*colonization extremely common in hospitalized and very ill people (including IV drug users)
pseudomonas aeruginosa - clinical presentations
-pneumonia
-UTIs
-hot tub folliculitis
bordetella pertussis (whooping cough)
*gram negative coccobacilli
*many nutritional requirements
bordetella pertussis - virulence factors
- attachment:
*fimbriae
*FHA
*pertussis toxin - ciliary paralysis - evasion of phagocytosis
*adenylate cyclase toxin (inhibits cAMP)
bordetella pertussis - pathogenesis
*inhalation and subsequent adherence to ciliated respiratory epithelial cells
*local tissue damage and loss of protective respiratory cells
*COUGH
*VERY CONTAGIOUS
bordetella pertussis - 3 phases of clinical manifestation
- catarrhal (1-2 weeks): upper airway
- paroxysmal (2-3 months): lower airway
- convalescent (1-2 weeks): recovery
bordetella pertussis - clinical manifestations during paroxysmal phase
*coughing paroxysms
*inspiratory “whoop”
*post-tussive emesis (coughing to the point of throwing up)**
*LYMPHOCYTOSIS is a clue
prevention of bordetella pertussis
*vaccination of children
*macrolide prophylaxis
diagnosis of bordetella pertussis
PCR of nasopharyngeal swab or aspirate (“gold standard”)
