L19- RTI VII Flashcards
Chlamydiaceae family: describe the components of the cell wall
(resembles gram- wall)
- weakly endotoxic LPS
- lacks peptidoglycan
-*MOMP (major outer membrane protein): major cell wall component, common to all Chlamydia spp. (and unique for each species)
TWAR = (1):
- most commonly affects (2), although (3) are the highest risk groups
- (4) is commonly seen in infected patients
1- Taiwan acute respiratory agent / Chlamydophila pneumoniae
2- middle-aged children (note- 50% are adults)
3- n/a
4- re-infection
Chlamydophila pneumoniae:
- (1) property in relation to its location
- Gram(+/-)
- Diagnosis requires (3) investigations
1- obligate intracellular
2- Gram-
3- PCR, culture (slow; special media required - no standard methods), serology
Chlamydophila pneumoniae infects (1) cells and is present in either the (2) or (3) form
1- epitheliocytes (epithelium)
(chlamydial inclusion bodies- biphasic life cycle)
2- EB, elementary bodies
3- RB, reticulate bodies
Briefly describe the life cycle of chlamydophila pneumoniae
1) EB attaches to cell surface
2) EB endocytosis
3) (no lysosomal fusion) reorganization into RB
4) binary fission replication
5) reorganization into EB
6) inclusion body with EBs and RBs
7) reverse endocytosis
Legionella pneumophila causes (1) and or (2). Most infections are due to the (3) form.
-most infections affect (4) systems and there is usually a history of a contaminated (5)
1- Legionnaire's disease (pneumonia) 2- Pontiac fever (self-limiting) 3- L. pneumophila serotype 1 (of very many) 4- respiratory, GI, CNS 5- water source
Legionella pneumophila:
- Gram(+/-) (coccus/bacillus)
- (non-/motile), (non-/spore forming)
- (5) is the required agar
Gram- bacillus, motile, non-spore forming
5- BCYE agar (buffered charcoal yeast extract)
BCYE agar is used for….
(buffered charcoal yeast extract agar)
-legionella pneumophila
Legionella pneumophila:
- predominately transmitted through (1) to infect (2) cells and replicate because of its (3) property
- most of the damage caused its via (4)
- (3) and (5) are its important virulence factors
1- contaminated aerosols 2- alveolar macrophages 3- facultative intracellular 4- host inflammatory response 5- prevention of phagosome-lysosomal fusion
what are the key exposures that would suggest Legionella pneumophila infection
Water exposure
- recent travel: cruise, hotel
- hospital / nursing home stay
list the signs and symptoms that are suggestive Legionnaires disease
what is the test used when suspecting Legionnaires disease
- GI, CNS sxs
- hematuria, hyponatremia, elevated transaminases (LFTs), CRP >100mg/L
- failure to respond to β-lactam monotherapy
- Urinary Ag test
- if neg., respiratory culture is necessary
- possibly fluorescent staining, Ab staining, PCR, serology
Mycobacterium spp.:
- (1) and (2) are important to its growth and appearance in lab
- (3) are the important species
- (4) is the important virulent factor (indicate location)
1- slow growth 2-8 wks
2- grows as long parallel chains / ‘cords’
3- M. tuberbulosis, M. bovis, M. avis
4- Cord Factor, most abundant glycolipid in cell wall
list the components of Mycobacterium cell wall
- *mycolic acid (gives it the thick waxy protective coat)
- arabinogalactan
- lipoarabinomannan
- peptidoglycan
- cytoplasmic membrane
- *Cord Factor / trehalose dimycolate
Cord Factor, aka (1), is made out of (2)
Trehalose Dimycolate
- 2 mycolic acids
- 1 disaccharide trehalose
M. tuberculosis will be transmitted to the respiratory system by (1). The will then be apart of (2) cells where it directly prevents (3) and (4). Therefore (2) will secrete (5) to induce (6).
1- droplet nuclei / dust
2- alveolar macrophages (intracellular)
3- oxidative burst, phagosome-lysosome fusion (cord factor / mycolic acid)
4- resists lysosomal enzymes and ROS
5- IL-12, TNF-α
6- local inflammation, T-cell/NK cell recruitment –> T cells into Th1 cells for IFN-γ secretion (initiates caseous granuloma)
list the cultures used for M. tuberculosis growth
*why is this important for Tb patients
- Lowenstein-Jensen medium
- Oleic acid - albumin broth
-important for culture growth b/c inc in MDR strains (determines antibiotic sensitivity)
M. tuberculosis undergoes a (1) and (2) stains in laboratory
- Ziehl-Neelsen stain ==> indicates acid fast bacilli
- Rhodamine-Auramine fluorescent stain
PPD test is used to induce a (1) reaction in those with M. tuberculosis exposure. PPD tests are composed of (2), injected ID. The reaction takes (3) amount of time and then (4) is used to determine if it is positive or negative. A positive test does not indicate if the Tb infection is one of the following, (5).
1- type IV hypersensitivity reaction 2- cell-free supernate from old M. tuberculosis cultures 3- 48-72 hrs 4- measure induration diameter 5- active, latent, previous vaccination
what results from a PPD would indicate a positive skin test
1) >15mm induration (w/ no known risk factors for Tb)
2) >10mm induration + one of the following:
- recent immigrants for certain countries (w/in last 5 yrs)
- IV drug users
- residents/employess of congregate settings
- mycobacteriology lab personnel
- <4 y/o
- infants, children, adolescents exposed to high-risk adults
3) >5mm induration + one of the following:
- HIV pts
- close contact with Tb pt
- CXR indicating Tb
- organ transplant recipients
- certain immuno-suppressed pts
list the 1st line Tb drugs
(RIPE drugs)
- rifampin
- isoniazid
- pyrazinamide
- ethambutol
list the 2nd line Tb drugs
- para-aminosalicyclic acid
- cycloserine
- fluoroquinolones
how is Tb prevented
- prophylactic antimycobacterials
- BCG (bacillus calmette-guerin) vaccine (attenuated M. bovis strain)
list the M. tuberculosis drug resistant categories
MDR-TB: isoniazid, rifampin resistance
XDR-TB: MDR + Fluoroquinolone + either (amikacin, capreomycin, kanamycin)
TDR-TB: XDR-TB that is completely resistant to all tested drugs
(1) is a key risk for Tb seen in HIV/AIDS patients, with (2) invasion as a less common risk. (1) occurs often because in HIV patient there are low levels of (3) producing (4), which is a big part of the immune defense system.
1- development of extrapulmonary infection (50-70% compared to 15%)
2- CNS invasion (~10%)
3- Th cells (w/ IFN-γ => caseating granuloma to contain infection)
4- IFN-γ
what are the extrapulmonary manifestations of Tb (indicate which patients they are mostly seen in)
(mostly HIV/AIDS patients)
- lymphdenitis
- meningitis
- pericarditis
- Pott disease (vertebrae, intervertebral arthritis type reaction)
- Tuberculoma (CNS- microbe calcifies to mimic tumor)
- miliary (particular rash disease)
