RT Pathogens Flashcards
What are the differences in the upper and lower respiratory tract?
Upper is non sterile. Lower is sterile
What are common pathogens in the RT from upper to lower?
Bordetella pertussis Corynebacterium diphtehriae Neisseria meningitidis Strep pyogenes Staph aureus Strep pneumoniae Haemophilus influenzae Mycoplasma pneumoniae Pseudomonas aeruginosa Legionella penumophila Mycobacterium tuberculosis (true pathogen)
What does Legionella pneumophila cuase?
Legionnaire’s disease and pontiac fever
Describe the motility and metabolism of mycobacterium
Non motile, aerobic
What is unique about Mycobacterium?
Lipid-rich cell wall–resists antimicrobials, disinfectants and stainings
What kind of stain identifies Mycobacterium?
Acid fast
What kind of diseases do mycobacteria cause?
Mycobacterium tuberculosis-tuberculosis
Mycobacterium leprae-leprosy
Mycobacterium avium complex (MAC)-pulmonary disease in mostly immunocompromised
Where is trehalose dimycolate found, and what does it do?
in cell wall of mycobacterium tuberculosis
makes caseating granulomas (necrosis, inflammation)
What are the reservoirs for Mycobacterium tuberculosis?
Humans only
How does a healthy person get M. tuberculosis?
From close exposure for long time with someone who has active tuberculosis
HOw is M. tuberculosis transmitted?
inhalation, taken up by phagocytic cells
What makes someone with active TB infectious?
Have lots of TB in their sputum
What are the symptoms of active TB?
Malaise
Weight loss
COUGH
NIGHT SWEATS
What is characteristic of latent TB?
granuloma (area of activated immune cells)
What are the symptoms of latent TB? What do you see on CXRs?
usually none, no signs of lesion on CXR and sputum normal
How can you tell the difference from a primary infection with TB as opposed to that caused by reactivation of latent infection?
Hard to tell
What is the gold standard for ID of M tuberculosis?
Positive culture (however, grows slowly)
What ID tests can you do for M tuberculosis?
PPD Quantiferon assay (using bacterium's secreted antigens, detects IFN released from blood cells)
How is mycobacterium leprae spread?
Inhalation
How can you differentiate the two main types of leprosy?
Tuberculoidal leprosy follows a strong cell mediated immune response and weak humoral response. The opposite is true for lepromatous leprosy
In tuberculoidal, few erythematous plaques; not infectious
In lepromatous, many erythematous plaques, very infectious
What is treatment like in general for Mycobacteria?
Difficult in treating; needs multiple antibiotics and lengthy treatments
Describe the stain and shape, any other features of Legionella
Gram negative (but stain poorly) bacilli, single flagella
Metabolism of Legionella
Obligate aerobes
Where does Legionella infection start?
Lungs
Which of the following are opportunistic pathogens? Pseudomonas aeruginosa, Legionella pneumophila, Mycobacterium tuberculosis
Pseudomonas aeruginosa and Legionella pneumophila
What is unique about the metabolism of Legionella?
gets most energy from breaking down amino acids instead of carbs
What is the major Legionella species causing disease in humans?
Legionella penumophila serogroup I
Where are Legionellea commonly found?
water, living in amoeba
How are Legionella able to infect humans?
inhalation, NOT by drinking water. no transmission between people
Pathogenesis of Legionella
Intracellular pathogen, replicates within phagocytic cells
Makes virulence factors (many-cytotoxins, hemolysins, proteases, endotoxins, lipases)
Type IV secretion system that ejects things into macrophage cytosol
Prevents phagosome-lysosome fusion
What are the symptoms of Legionaire’s disease?
Pneumonia, cough, fever, chest pain
Pontiac fever symptoms
Flu-like (fever, chills, malaise)
Stain and shape of Pseudomonas
gram negative rods, flagella
Where are Pseudomonas commonly found?
water and soil, biofilms on catheters
Metabolism of Pseudomonas aeruginosa
oxidase positive! oxidize various carbs
Hemolysis ability of Pseudomonas aeruginosa?
hemolytic on blood agar plates
What are special pigments made by Pseudomonas aeruginosa?
Pyoverdin and pyocanin–help resist ox stress and give it green color on agar
What is the phenotype of Pseudomonas aeruginosa in CF patients?
mucoid
What enables Pseudomonas aeruginosa to make biofilms and microcolonies?
polysaccharide capsule
What changes do you see in CF patients with age with respect to Psuedomonas aeruginosa infection?
Non-mucoid to mucoid bacteria
Pathogenesis of Pseudomonas aeruginosa
Lots of different virulence factors!
makes adhesins
makes polyshaccharide capsule alginate cover that causes mucoid phenotype
makes endotoxin-can cause shock
pyocyanine and pyochelin cause oxygen radicals to be released from host cells
exotoxins injected into host cells
makes proteases
Where do Pseudomonas live in the host?
extracellular
How can Psuedomonas infect a human?
cystic fibrosis eye (contact lenses for long time) burns UTI wound can cause bacteremia and endocarditis
