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Terms | Definitions |
|---|---|
 Lowenstein-Jensen agar | special medium, often supplemented with egg yolk, necessary to culture fastidious mycobacteria. NON-PIGMENTED colonies in 4-6 weeks |
| Kinyoun's "acid-fast" stain | due to high lipid content of mycolic acid cell wall, these organisms (Mycobacteria, Nocardia asteroides) are exposed to carbofuschin (pink) stain along w/ heat or tergitol detergent. tx w/ ethanol-hydrochloric acid mixture. |
| BACTEC broth culture | rapid detection of mycobacteria and better recovery of microorganisms |
| "atypical/walking" pneumonia | causative bacterium cannot be isolated on routine media or does not resemble pneumococcal pneumonia. most common culprit is Mycoplasma pneumoniae, but may be caused by Legionnaire's, Q fever, psittacosis, and viral pneumonias. |
| extrapulmonary manifestations of Mycoplasma pneumoniae | Stevens-Johnson syndrome, erythema multiforme, Raynaud's phenomenon, cardiac arrhythmias, arthralgias, hemolytic anemia, and some Guillan-Barre |
| cold agglutinin test | displays auto-antibodies against RBCs, brain, lung and liver cells. half of Mycoplasma pneumonia pts will be positive, false positives with flu and adenovirus |
| auramine-rhodamine stain | mycobacteria will fluoresce yellow-orange with this stain |
| cord factor | glycolipid trehalose 6',6'dimycolate, causes virulent strains of Mycobacteria to grow in a serpentine cord-like fashion (rods arranged end-to-end to form parallel cords |
| Mycobacterium tuberculosis inhibits... | phagosome-lysosome fusion, oxidative burst, acidification of phagosome, and inflammatory cytokine responses |
| TST/PPD | mixture of mycobacterial proteins given as an intradermal injection. positive test (type IV hypersensitivity) indicates previous exposure to tuberculin antigens or vaccination w/ M. bovis BCG. CXR reccomended for BCG vaccination. |
| induration caused by... | local immune and inflammatory respones at injection site up-regulate expression of adhesion molecules on endothelial cells, promoting the accumulation of leukocytes. 15 mm of this reaction indicates positive test, smaller threshold if individual is immunocompromised, mimics initial stages of granuloma formation |
| granuolma | primary pathologic sign of TB when host defenses become exaggerated as an attempt to wall off infxn. Pathogen is engulfed by macs and monos, presented to antigen specific Th1 cells |
| IFN-y | activates macrophages, secreted by Th1 cells |
| TNF | kills chronically infected macrophages releasing bacilli as well as lysosomal components that damage the lungs |
| IL-2 | induces T-cell proliferation |
| IL-1, IL-6, IL-12, TNF-a and chemotactic factors | proinflammatory cytokines secreted by macrophages |
| giant cells | formed by macrophages |
| caseous necrosis | soft "cheesy" areas of tissue indicative of cell death caused by enzymatic degradation. |
| Ghon complex | combination of a single parenchymal lesion in lung and caseation resulting in calcified bronchial lymph nodes visible on x-ray |
| IL-1, IL-6, TNF-a | increase prostaglandin PGE2 in hypothalamus, inducing fever (TNF-a's contribution also contributes to weight loss) |
| miliary tuberculosis | progressive disseminated hematogenous TB. alcoholism, cirrhosis, neoplasm, pregnancy, rheumatologic dz or immunosuppressed individuals are at high risk |
| reactivation tuberculosis | reactivation of a latent infection, can happen several years or decades following initial infection, assoc'd w/ pts that become immunocompromised |
| treatment for TB | based on sxs, TST/PPD conversion, and/or abnormal CXR: isoniazid (INH), rifampin (RIF), pyrazinamide (PZA), and ethambutol (EMB). if isolate is drug susceptible, discontinue EMB (ocular toxicity). INH and RIF continued until pt becomes culture and smear neg. |
| point mutations | drug resistance in M. tuberculosis results ENTIRELY from... |
| catalase/peroxidase enzyme (KatG) | activates INH (mycobacterial abx) so it can inhibit biosynthesis of mycolic acids. mutations in the gene encoding this protein results in bacterial drug resistance |
| multi-drug resistant TB | resistance to at least isoniazid (INH) and rifampin (RIF). detected by PCR |
| ASO test | titer measured by highest dilution of serum that can neutralize the lysing activity of a measured amt of streptolysin O mixed w/ given quantity of RBCs. Significance indicates preceding acute, suppurative infection: two-well change in Todd units OR single sample titer >240 taken at time of presentation of non-suppurative dz (AFR/APSGN) |
| CAMP test | innoculate GBS perpendicular to streak of beta lysin (toxin-producing) strain of S. aureus and incubation in candle jar. positive test: "arrowhead" of clear/B hemolysis. CAMP factor produced by GBS enhances zone of hemolysis produced by B-lysin |
| Opa protein | recognizes and binds heparin sulfate proteoglycan (HPSG) receptors, triggering signaling cascades that cause ingestion of pathogen. gonococci become enclosed w/in a vacuole and are rapidly transported to basal side of epithelium where they are released. also involved in AGGREGATION (focus of infection) |
| Thayer Martin medium | selective for Neisseria |
| Luciferase assay | enzyme isolated from fireflies, produces flashes of light in the presence of ATP. Mixed w/ drug to test Mycobacteria TB. W/in a few days, resistant strains will still be able to make ATP, produce normal amount of light. (Drug sensitive strains will produce less light) |
| Interferon-gamma release assay (IGRA/Quantiferon TB) | blood cells from pt are exposed to Ags from M. TB and amount of IFN-y released from cells is measured. |
| lepromatous leprosy dx | acid-fast stain of skin lesions or nasal scrapings, + test b/c of lipid-laden foam cells |
| Bordet-gengou medium | growth of B. pertussis |
| siderophores | made by P. aeruginosa to compete w/ transferrin for Fe. makes elastase and exotoxin A to chop up your tissue if it still can't get enough |
| elastase and Exotoxin A | produced by P. aeruginosa when it is really desperate for Fe and siderophores aren't cutting it. necrose tissue to get Fe. |
| phospholipase C | produced by P. aeruginosa when it needs phosphate, cuts up your membranes |
| Yad | encodes for adherence for Y. pestis |
| Yops | cytotoxic against phagocytes (Y. pestis) |
| Fra1 | anti-phagocytic capsule (Y. pestis) |
| Pla | Plasminogen activation (degrades clots, C3b and C5a, which inhibits opsonization) Y. pestis |
| Sylvatic plague | accidental encounters w/ rodents (Y. pestis) |
| pneumonic plague | Y. pestis disseminated to lungs |
| type IV hypersensitivity | + TB test is a result of |
| TNF-alpha | promotes diapedesis, Th1 cytokine relevant to granuloma formation |
| TNF | kills chronically infected macrophages releasing bacilli as well as lysosomal components that damage lungs, Th1 cytokine relevant to granuloma formation |
| IL-2 | induces T cell proliferation, Th1 cytokine relevant to granuloma formation |
| granuloma | formed when host defenses become exaggerated trying to wall off TB |
| IFN-y | activates macrophages, secreted by Th1 cells |
| caseous necrosis | poor granuloma formation, soft "cheesy" areas of tissue indicative of cell death caused by enzymatic degradation |
| MDR TB | resistant to AT LEAST INH and RIF, detected by PCR! |
| SP-4 blood agar | contains sterols, NECESSARY FOR mycoPLASMA growth! |
| respiratory tract | most common site for infection by pathogens |
| conjunctivae, middle ear, paranasal sinuses | continuous w/ respiratory tract, lined w/ RESPIRATORY EPITHELIUM |
| T cell INdependent | these kinds of type-2 antigens are immunogenic in adults but not in children under a certain age. e.g. purified PRP capsular proteins (Hib). must be coupled to T cell DEPENDENT carrier protein to activate specific T cells. |
| T cell DEpendent | more effective in inducing immunity in children |
| catarrhal stage | follows incubation of B. pertussis, lasts 1-2 wks, resembles common cold, PEAK #s bacteria produced now, HIGHEST RISK OF SPREAD |
| paroxysmal stage | follows catarrhal stage of B. pertussis, sudden intense coughing and classic inspiratory whoop |
| S. aureus | 2 component regulatory system: regulation of exoprotein production (TSST etc), hemolysins, and proteases. sarA/agr is GROWTH-PHASE DEPENDENT. ^ density -->switch from adherence to toxin production |
| Enteroccus faecalis | 2 component regulatory system: regulation of Vanc resistance by VanS/VanR |
| P. aeruginosa | 2 component regulatory system: regulation of pilus colonization factor by PilS/PilR |
| Salmonella | 2 component regulatory system: regulation of virulence properties associated w/ macrophage survival, invasion of epithelial cells, and resistance to cationic peptides by PhoP/PhoQ |
| B. pertussis | 2 component regulatory system: Bvg (virulence gene transcription is goverened in response to magnesium, sulfate ion concentrations and temp. at 25, expression of 20 genes is turned off and synthesis of toxins etc. is discontinued. W/ correct stimuli, sensor protein (BvgS) w/ kinase activity catalyzes the phosphorylation of BvgA (response activator protein) --> production of pertussis toxin, adenylate cyclase toxin, hemolysin, filamentous hemagluttinin etc. |
| phosphorylation by BvgS | BvgA is activated to produce toxins and virulence factors in B. pertussis by... |
| biofilms | P. aeruginosa in CF pts (produced by glycocalyx) Salmonella typhi in carrier state S. epidermidis |
| Legionella in vacuoles surrounded by... | 15 mins: smooth vesicles 1 hr: mitochondria 4-8 hrs: ribosomes (multiply w/in ribosome-lined vacuole, rupture) |
| neutrophils | Legionella pneumophila infects monos and macs, but NOT: |
| pyocins | used in epidemiologic tracking of P. aeruginosa outbreaks. endogenous vs. exogenous, environmental sources, nosocomial. based on observation that ____ will only inhibit growth of a limited number of other bacterial strains. thus characteristic patterns of growth inhibition of known typing strains |
| gram stain of CSF | rapid presumptive diagnosis of acute bacterial meningitis |
| choroid plexus | most common site of microbe entry into CNS. also may follow olfactory or peripheral nerve pathways, or blood circulation. |
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