Term
| what is the species of mycoplasma that causes pulmonary disease? |
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Definition
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Term
| what is unique about mycoplasma in comparison to other bacteria/fungi? what is clinically significant about this? |
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Definition
| mycoplasma is free-living, yet it doesn't have a cell wall - just a cell membrane, therefore mycoplasma needs sterols to make its membrane. b/c of the lack of a cell wall, PCN/cephalosporins do not work and only tetracycline/erythromycin/azithromycin will work |
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Term
| in general, what should you think when you see a fried egg appearance on an agar plate? |
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Definition
| some kind of mycoplasma, *except mycoplasma pneumonia |
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Term
| how will mycoplasma appear on EM? |
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Definition
| fuzzy organisms bunching up around host cells and sticking to them - eventually penetrating and moving intracellularly |
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Term
| what is the natural habitat of mycoplasma? |
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Definition
| unusual environments - hot springs/acid outflows of mining wasts. |
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Term
| what characterizes culturing mycoplasma? |
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Definition
| mycoplasma require special media (sterols in media for culturing) and grow slowly (wks). most except for mycoplasma pneumoniae have a "fried egg" appearance |
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Term
| how is mycoplasma pneumoniae differentiated from mycoplasma hominis/urealyticum? |
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Definition
| mycoplasma pneumoniae can metabolize glucose |
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Term
| where is mycoplasma found? is it contagious? is it a common pathogen? |
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Definition
| in respiratory secretions - often the source of infection is not IDed. mycoplasma is moderately contagious, can be found in home/residential institutions. it is a very common cause of pneumonia in children 5-15 and a common pathogen of lung infections in people 5-35 |
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Term
| who is the reservoir for mycoplasma pneumoniae? |
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Definition
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Term
| where does mycoplasma pneumoniae bind? can antibodies prevent this binding? |
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Definition
| mycoplasma pneumoniae binds to the respiratory epithelium with a specialized terminal attachment structure consisting of P1 (pillin) adherence protiens that bind to *neuraminic acid* on epithelial surfaces. antibodies can inhibit this attachment. |
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Term
| how is a mycoplasma pneumoniae infection differentiated from other pneumonias? |
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Definition
| mycoplasma pneumoniae infections are limited to the respiratory mucosa that lines the airways (in contrasts to strep pneumonia and legionella). the infections do not involve the alveoli. there is an infiltrate of mononuclear cells surrounding the bronchi/bronchioles = *bronchipneumonia* (not a lobar process) |
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Term
| what kind of damage does mycoplasma pneumoniae cause to the lungs? |
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Definition
| the infection is not highly destructive of the tissue, though there is impaired ciliary function due to immune system released tissue-toxic substances (H2O2). |
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Term
| what part of the immune system usually responds to mycoplasma pneumoniae? |
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Definition
| lymphocytes, only a few neutrophils |
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Term
| how does mycoplasma pneumoniae affect the blood? |
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Definition
| mycoplasma pneumoniae can cause hemolytic anemia b/c IgM antibodies are made against RBCs (these are called "cold hemagglutinins" b/c they only form aggregates at cold temps). this is detectable in 50% of severe infections |
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Term
| what are clinical manifestations of mycoplasma pneumoniae infection? how is the dx confirmed? |
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Definition
| primarily respiratory: non-productive cough, ronchi and rales upon auscultation, scanty/non-purulent sputum production, CXR - highly variable (infiltrate, patchy bronchopneumonia in lower lobes), 20% of the time - maculopapular rashes, erythema multiform (target lesions on palm - stevens-johnson syndrome). dx is confirmed by serlogic testing; immuno-assays & PCR |
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Term
| what do the initial symptoms of mycoplasma pneumoniae infection resemble? how severe can it get? |
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Definition
| influenza - malaise, sore throat, dry cough and an increase in severity as the disease progresses. generally it is a mild disease, but some pts can have severe pneumonia, resulting in ARDS. |
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Term
| what are extrapulmonary complications associated with mycoplasma pneumoniae infection? are they common? |
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Definition
| these are common: hemolytic anemia, thromboembolic complications, polyarthritis, and neurologic syndromes: meningoencephalitis, peripheral neurophathis, or cerebellar ataxia |
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Term
| what is the tx for mycoplasma pneumoniae infection? is there a vaccine? |
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Definition
| there is no mycoplasma pneumoniae vaccine. tx for mycoplasma pneumoniae infection is tetracycline/eryhromycin. treated pts can maintain the organism for wks post-therapy, mycoplasma hominis is resistant to erythromycin and beta-lactam antibx are all ineffective against mycoplasma pneumoniae |
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Term
| what characterizes the chlamydiae family? |
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Definition
| chlamydiae were once thought to be viruses, but are now known to be intracellular bacteria (they can go through a very small filter .2 microns). chlamydia trachomatis is the STD, though it has forms that can affect other parts of the body. chlamydia pneumoniae is the organism isolated from human respiratory tracts (community acquired pneumonia), and chlamydia psittaci is a pathogen coming from parrot droppings - which causes a massive inflammatory response and can be fatal |
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Term
| what characterizes chlamydia as a bacteria? |
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Definition
| small chromosome, gram negative (LPS on outer membrane), no murcin (peptidoglycan, the classic cells wall constituent), and chlamydia will parasitize its host |
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Term
| why is chlamydia considered to be an "energy parasite"? |
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Definition
| chlamydia depends on the host for nutrients and energy, for ex: tryptophan and ATP. |
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Term
| how does chlamydia gain ATP from its host? does it give off anything? |
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Definition
| chlamydia siphons ATP from the host mitochondria (via type III secretion mechanisms, pore-like structures) and cells thus parasitized like this over time will undergo mitochondrial distress due to ROSes and ultimately cell death. chlamydia will also release proteases that can damage the cells as well. |
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Term
| when might chlamydia become latent? |
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Definition
| if the host is malnourished or anemic |
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Term
| what are extrapulmonary diseases associated with disseminated chlamydia infections? |
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Definition
| atherosclerosis, alzheimer's, arthritis, and CTCL |
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Term
| where is chlamydia found globally? what is the general rate of exposure? |
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Definition
| chlamydia is ubiquitous, by 20, half the population shows a detectable antibody, and 3/4 of the elderly show this. |
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Term
| what % of community and nosocomial pneumonias are due to chlamydia? |
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Definition
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Term
| what are the 2 forms of chlamydia? |
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Definition
| extracellular: infectious elementary body (EB) and intracellular: the metabolically active reticulate body (RB) |
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Term
| how does cellular uptake of chlamydia occur? |
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Definition
| chlamydia may mimic nutrients, growth factors, hormones and may bind to specific receptors. it is internalized via receptor-mediated endocytosis |
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Term
| why do you get a TH1 and TH2 response to chlamydia? |
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Definition
| the elementary bodies do have outer membrane proteins, so antigens are produced against it - however chlamydia is mainly harbored intracellularly and thus both kinds of T cells are used in defense against it |
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Term
| how does the chlamydia EB protect itself in endocytic vesicles, once taken intracellularly? |
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Definition
| the chlamydia EB maintains the lysosomal pH above 6.2 and prevents vesicle-lysosomal fusion. it guides the lysosome near the nucleus and eventually can cause the lysosome to burst, killing the cell and enabling it to infect other nearby cells. |
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Term
| what is a common cell for chlamydia EBs to infect and become latent in? how can chlamydia become systemic? |
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Definition
| chlamydia EB commonly infects and remains latent in the alveolar macrophages. if the chlamydia EBs infect the epithelial cells and go far enough into the lung tissue, they will get to blood supplies w/monocytes, which they can infect and travel in to more distal areas of the host. (chlamydia should be in the dx for monocytosis) |
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Term
| what does the chlamydia EB become in the cell? |
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Definition
| the RB (reticular body) which is the metabolically active form, taking ATP and tryptophan from the host via 18-23 feeding tubes that form hexagonal arrays, protrude through the vesicle membrane and communicate with the cytoplasm. the developmental cycle takes 2-3 days |
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Term
| what are the most frequent clinical manifestations of chlamydia infection? |
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Definition
| pneumonia and bronchitis (asymptomatic/mildly symptomatic may be more common) featuring a low grade fever, sub-acute onset, chronic non productive cough and often associated with a sinus infection, sore throat, pharyngitis, and at times - hoarsenes. |
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Term
| what is chlamydia often a co-pathogen with in pneumonia? |
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Definition
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Term
| why do chlamydia infections often go undiagnosed? |
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Definition
| often family doctors will prescribe azithromycin (z-pack) and this will take care of the infection w/o further investigation |
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Term
| what does the damage to the host from chlamydia infections consist of? |
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Definition
| the chlamydial side is not highly damaging - hsp60 (can be some antigenic response to heat shock protien) and LPS but most of the damage is due to the host response via IL-1 beta, TNF alpha and IFN gamma |
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Term
| how are chlamydia infections diagnosed? |
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Definition
| serology (MIF) a 4x rise in IgM, IgG (most common), and IgA is a positive result. tissue cx (slow), PCR for specific primers, IF, and ELISA (enzyme linked immunoassay) are also possibilites |
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Term
| why are tetracyclines, macrolides, sulfonamides, and floroquinolones used for chlamydia infections? |
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Definition
| there are multiple RB cell membranes - host and pathogen that need to be penetrated (host cell membrane, inclusion membrane, chlamydial outer/cytoplasmic membranes). |
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Term
| why does a bactericidal concentration of antibx need to be maintained over an extended period for chlamydia infections? |
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Definition
| chlamydia are slow growing |
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Term
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Definition
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Term
| what is good about treating chlamydia infections with azithromycin (z-pack)? |
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Definition
| azithromycin is long lasting, penetrates cells well and only needs short term dosing |
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Term
| what kind of bacteria is legionella? |
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Definition
| an opportunistic gram negative aerobic bacilli that becomes short coccobacilli in tissue (pleomorphic). they are motile and grow fastidiously (complex nutritional requirements) |
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Term
| how was legionella pneumophila discovered? |
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Definition
| members of an american legion convention in philly 1976 came down with an acute febrile illness |
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Term
| what is the most common form of legionella pneumophila that causes pneumonia in humans? |
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Definition
| legionella pneumophila serotype 1 |
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Term
| what is the spectrum of disease due to legionella pneumophila? |
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Definition
| 1) asymptomatic seroconversion 2) self-limited flu-like illness w/o pneumonia called *pontiac fever 3)legionaires' disease - the most serious/commonly recognized form characterized by pneumonia 4)finally a rare localized soft tissue infection |
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Term
| what % of community acquired pneumonias resulting in hospitalization is legionella pneumophila responsible for? what % of lethal nosocomial pneumonias? |
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Definition
| 1-8% community acquired pneumonias requiring hospitalization, ~4% of lethal nosocomial pneumonias |
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Term
| does legionella pneumophila have a predilection for a time of year in which it transmits more commonly? |
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Definition
| late summer/early fall (condensate from A/C units is a common place for legionella pneumophila to be found) |
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Term
| is legionella pneumophila transmitted person - person? |
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Definition
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Term
| what is the natural legionella pneumophila habitat? does it have specialized nutritional requirements? what is their metabolism? |
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Definition
| legionella pneumophila is found in aquatic environments and requires the addition of iron and L-cysteine to be grown in media. legionella pneumophila are non-fermentable and derive energyc from aminio acid metabolism |
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Term
| where is legionella pneumophila seen as a commonly infective agent? |
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Definition
| legionella pneumophila colonizes plumbing systems, tap water, faucets, shower heads, and sediments in hot water tanks |
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Term
| how does legionella pneumophila enter its host? what is the effect of complement binding? |
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Definition
| legionella pneumophila's entry is airborne and occurs on contact with alveolar macrophages/monocytes which it invades intracellularly via resistance to lysis. complement binding will initiate the replicative cycle. |
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Term
| how does legionella pneumophila multiply and spread? |
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Definition
| legionella pneumophila is ingested into the phagosome, inhibits lysosomal fusion and will associated with other organelles (has been seen to have SER encircling it). it makes the *DOT gene (defect in organelle trafficking) which allows it to move from organelle to organelle. |
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Term
| what role does TNF alpha play in legionella pneumophila infection? |
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Definition
| this is made to combat the infection, but will ultimately cause collateral damage |
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Term
| what is part of the cell-mediated immune response that directly affects legionella pneumophila? |
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Definition
| the cell-mediated immune response which includes cytokine/IFN gamma release induces macrophages to limit iron availability (a nutrient necessary to legionella pneumophila) *bleeding in medieval time had a similar effect* |
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Term
| how is damage incurred to the hose in a legionella pneumophila infection? |
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Definition
| vigorous inflammatory response, LPS, and proteolytic enzymes (phosphatases, lipases, and nucleases) |
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Term
| what are the symptoms and signs of a pt infected with legionella pneumophila? |
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Definition
| incubation period (2-10 days) then prodromal phase (most pts, resembles influenza) then development of a non-productive cough leading to the a productive cough w/mucoid sputum. then -> *characteristic feature: high fever, bradycardia, and diarrhea |
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Term
| what is seen on a CXR over time of a legionella pneumophila infection? |
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Definition
| early course: unilateral/patchy segmental/lobular alveolar infiltrate. after disease progression: bilateral involvement and pleural effusions are common |
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Term
| can legionella pneumophila cause lung abscesses? |
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Definition
| yes, these are occasionally observed with rounded densities suggestive of septic emboli |
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Term
| can legionella pneumophila infections cause altered mental status and diarrhea? |
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Definition
| yes, and legionella pneumophila is something to consider if a pt has altered mental status but their CSF is normal or if a pt has diarrhea and their stool is negative for WBCs/RBCs |
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Term
| does legionella pneumophila cause leukocytosis? |
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Definition
| yes most pts have moderate leukocytosis - 10,000 - 15,000 |
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Term
| what are common lab findings associated with legionella pneumophila? |
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Definition
| hypoatremia, hypophosphatemia, and abnormal LFTs. rarely: microhematuria |
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Term
| what are the four diagnostic methods of detecting legionella pneumophila? |
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Definition
| 1) cx of organism 2) direct fluorescent aby label of exudate 3) serology using indirect flourescent aby assay 4) urinary antigen assays (aby=antibody) |
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Term
| what is the rate of mortality with legionella pneumophila? |
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Definition
| >15% in community acquired cases, and higher among immunosuppressed or hospitalized pts |
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Term
| what is the rate of convalescence in legionella pneumophila pts responsive to therapy? |
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Definition
| slow - x-rays may be abnormal for >1 mo |
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Term
| what antibx are used for legionella pneumophila? |
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Definition
| those that penetrate cell walls, erythromycin, azithromycin and or ciprofloaxin for >3 wks (IV for seriously ill) |
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Term
| what is prevention for legionella pneumophila? |
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Definition
| superheating water, UV, Cu++ and AG++ ions. vaccines do not yet exist |
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