Lung infections Flashcards
(45 cards)
what do surfactants do in the lungs
stop lungs sticking together and release opsonins that help phagocytosis
how many alveoli are there and what is their approximate total surface area
approximately 300 million alveoli and their total surface area is about 140 m2
what important clearance mechanisms are present in the lung
– the mucociliary escalator,
– coughing
– phagocytosis by alveolar macrophages.
what are the two parts biphasic particle clearance
– fast (half life of minutes to hours) - tracheobronchial mucociliary clearance
– slow (half life days to thousands of days) - alveolar clearance
the site of particle deposition determines……
…..the mechanism and rate of particle clearance
particles of what size are able travel down to the alveoli
<5 microns
what are the differences in the mucocilliary escalator in non CF and CF airways
in non cf airway - the depth of periciliary fluid is normal, islands of mucus float on top and are propelled towards to mouth by coordinated beating of cilia
in cf airway - decreased depth of periciliary fluid, the mucus is poorly hydrated and hypoxic. the compacted mucus inhibits cilia beating stopping the escalator. lower mucosal oxygens levels are good for some bacterial growth.
what are some features of the cystic fibrosis lung
More fatty deposits, tissue disruption and redder colour
give examples of the early and later colonisers of the CF lung
Early colonisers: Staphylococcus aureus, Haemophilus influenzae
Later colonisers: Pseudomonas aeruginosa, Burkholderia cepacia
what bacterium appears to exacerbate lung infections
Burkholderia cepacia
give four examples of bacterial pathogens that cause progression of pulmonary disease
Bulkholderia cepacia, Haemophilus influenzae, Pseudomonas aeruginosa, Staphylococcus aureus
give some features of Pseudomonas aeruginosa
aerobic, motile, Gram-negative rod.
Able to grow and survive in almost any environment: lives primarily in water, soil, and vegetation.
Noted for its environmental versatility, ability to cause disease in susceptible individuals, and its resistance to antibiotics.
what is the most serious complication of cystic fibrosis
respiratory tract infection with an Extracellular pathogen (goes into the body and doesn’t invade cells, reaping havoc) (eg Pseudomonas aeruginosa)
what types of infections can be caused by Pseudomonas aeruginosa
ventilator-associated pneumonia, urinary and peritoneal dialysis catheter infections, bacterial keratitis, otitis externa, burn wound infections
give examples of P. aeruginosa Virulence factors:
elastase, phospholipase C, protease A, exotoxins and cytotoxins, flagella and pili, pigment production, and QS regulatory system proteins
– biofilm structure & dynamics: aliginate, rhamnolipids
– immune evasion: elastase, alkaline protease
– antibiotic resistance: efflux pumps, modifying enzymes
– cytotoxicity: pyocyanin, T3SS, exotoxin A, HCN
– iron scavenging: proteases, siderophores
– Cell-associated/ motility (flagellum, pilus, non-pilus adhesins, lipopolysaccharide endotoxin [LPS])
what is aliginate
alginate is an eps, helps form thick masses of biofilm, resides for long periods, and can trigger a big response. has the ability to scavenge host innate-immune reactive specie
how are particles cleared in alveoli
there is no mucociliary clearance so particles are cleared by phagocytosis by alveolar macrophages
what cells do intracellular pathogens commonly live and replicate in
– macrophages, dendritic cells, neutrophils,
– fibroblasts, epithelial or endothelial cells or erythrocytes.
when was the first Legionnaires outbreak
21 July 1976 in Philidelphia (among american servicemen who attended a conference) - 221 people developed pneumonia and 34 died
what are the Legionella-associated diseases
Legionnaires’ disease - acute fulminating pneumonia, low attack rate (>12% fatalities)
Pontiac fever - mild, non-pneumonic, febrile infection, high attack rate (resolves spontaneously and often goes undiagnosed.)
what are most cases of legionella caused by
- 85% due to L. pneumophila sg 1
what feature of Legionellaceae aids its waterborne spread
it remains motile at low temperatures
what is the main outbreak source of Legionella
man made water distribution systems
give some examples of other sources of legionella
– Circulating water droplets in air-conditioning and cooling systems.
– Showers (even baths as water splashes up)
– Whirlpool spas and other warm-water baths.
– Decorative fountains.
– Cooling towers. -specifically
– Nebulizers and humidifiers if topped up with contaminated tap water.
– Potting compost was the source of several outbreaks in Australia (L. longbeachae).
