Respiratory Tract Infections 7 Flashcards
what is the function of lipoarabinomannan in the pathogenesis of M. tb
- helps resist lysosomal enzymes and reactive oxygen species
which pathogen that causes atypical pneumonia is an obligate intracellular organism?
- chlamydophila pneumonia
at what life cycle phase is the chlamydophila pneumonia that we see as inclusion bodies on a histopathological slide?
- reticulate bodies: non infectious but metabolically active
Describe the biology of chlamydophila pneumonia
- gram NEGATIVE
- obligate intracellular
- biphasic life cycle: elementary bodies and reticulate bodies
- present as inclusion bodies in the cell
- no special risk groups
PPD test looks for prior exposure of tb but cannot differentiate between:
- active or latent Tb or previous vaccination
_________ cause of atypical pneumonia is a facultative intracellular pathogen
- legionella pneumophila
how does the elementary body of chlamydophila pneumonia survive living inside the host cell?
by inhibiting the fusion of the endosome and lysosome
______ cause of atypical pneumonia is an obligate intracellular pathogen
- Chlamydophila pneumonia
what are some common clinical manifestations of infection by Legionella pneumophila?
- one of the causes of atypical pneumonia
- look for GI and CNS symptoms along with respiratory disease PLUS: water source and hematuria
when treating tb, what other tests would you do?
check for drug resistance
_____________ exists as elementary bodies in the ______
chlamydophila pneumonia;
exists as elementary bodies outside in the environment and colonize the upper respiratory tract and move down to LRT
buffered charcoal yeast extract is used to culture ________
legionella pneumophila
< ____ mm of the induration in the PPD test is a negative test for everyone
5mm
what are unique features of the cell wall in mycobacterium tuberculosis?
- mycolic acid: waxy coating
- lipoarabinomannan: acts like LPS and is attached to the cytoplasmic membrane
what are the two clinical syndromes that legionella pneumphila can cause and how can you differentiate them?
- legionnaire’s disease
- pontiac fever
pontiac fever is self limiting and does not involve the LRT
Describe the biology fo Mycobacterium tuberculosis
- acid fast bacilli
- aerobic
- non spore forming
- grows in long parallel chains: “cords” and grows very slowly
how does legionella survive in the cell?
- inhibits fusion of lysosome and endosome (like Chlamydophia pneumonia)
what additional symptoms to pneumonia would suspect you to think infection by legionella?
- GI and CNS symptoms
- HYPOnatremia
- elevated hepatic transaminases
describe the life cycle of chlamydophila pneumoniae:
- endocytosed as a elementary body
- inhibition of the endosome and phagosome fusion
- conversion to reticulate bodies and replicates via binary fission
- conversion back to elementary bodies
- elementary bodies leave the cell via reverse endocytosis
__________ bodies are infectious but NOT metabolically active
elementary bodies;
what is a good way to distinguish between the different species of chlamydophila?
the result of the pathogen leaving the host cell:
- C. pneumonia and C. trachomatis does not result in cell lysis
- C. psittaci results in cell lysis
_____ bodies are metabolically active but NON infectious
reticulate
_________ on the cell membrane of mycobacterium tuberculosis gives it a waxy appearance and makes it resistant to drying
mycolic acid
how does mycobacterium tuberculosis survive inside the alveolar macrophage?
- prevents oxidative burst inhibits phagosome-lysosome fusion
- resists lysosomal enzymes and reactive oxygen species
CARDS toxin is a virulence factor of ________
mycoplasma pneumonia
legionella is most commonly acquired from ______
contaminated water
legionella can be cultured on ______
buffered charcoal yeast extract
Ziehl- Neelsen stain is used to stain _________
acid fast bacilli such as Mycobacterium tuberculosis
risks of getting pneumonia from what pathogen is high in people with lung diseases or alcoholic
Klebsiella
> ____mm of the induration in the PPD test is a positive test regardless of the patient’s risk factor
15mm
__________ medium is used to culture and diagnose M. tuberculosis
- lowenstein- Jensen medium
- oliec acid albumin broth
wart like colonies that go from green to blue in color
the majority of the damage in tb is due to ______
host immune response to the pathogen
how does chlamydophila pneumonia eventually leave the host cell?
reverse endocytosis (same with C. trachomatis); NO HOST CELL LYSIS (unlike chlamydophila pstacci which will cause cell lysis )
describe the biology of legionella
- gram negative rod
- motile (polar flagella)
- non spore forming
- facultative intracellular organism that lives in the alveolar macrophages
- culture on buffered charcoal yeast extract agar
_______ vaccine is given to kids in endemic countries for prophylactic treatment of tb
BCG (bacillus Calmette Guerin) which is from live attenuated M. Bovis strains
mainly used to prevent the miliary tb or tb meningitis in children
several people have come to the doctor with symptoms such as pleuritic chest pain, SOB, cough and fever and said that they drank contaminated water. What would you use to strain this most likely pathogen? What would you culture it on?
- methylamine silver stain (NOT GRAM STAIN)
- culture: buffered charcoal yeast extract
what are some extrapulmonary manifestations of tb commonly seen in patients with HIV/AIDS
- lymphadenitis
- pott disease
- tuberculoma (CNS)
- meningitis
- pericarditis
- miliary (m. tb that is spread through blood, like sepsis of m. tb)
resistance to TB is largely dependent on ____________
subset of CD4 Helper T cells that produce gamma interferon
reason why patients with HIV/AIDS and get tb, most will develop extra pulmonary infection
the PPD test is based on a type ____ HS reaction
type 4; looking for prior exposure to mycobacterium tuberculosis
the most commonly used laboratory test for diagnosis of legionella is __________
urinary antigen test (only looks for serogroup 1)
what structure is responsible or the staining property of M. tuberculosis?
mycolic acid
