Mycology 1.2 Flashcards
acid fast
mycobacteria, bacilli obligate aerobes. high lipid content in cell wall, MYCOLIC ACID. pink staining.binds carbol fuchsin
Mycobacterium tuberculosis complex
MTB, M. africanum, M. bovis, M. bovis (bovine bacillus) bacille calmette-guerin (BCG)–> can be used to treat bladder cancer.
NTM, MOTT or atypical mycobacteria
slow growers: m. kansasii, ,.avium-intracellulare complex, m. marinarium, m. scrofulaceum Rapid growers: m. chelonae-abcessus complex, m. fortuitum complecspecial growers: m. leprae
primary infection
individual’s first exposure
granulomatous inflamation
alveolar macrophages?
Ghon complex
that is the characteristic gross appearance with primary tuberculosis, In most persons, the granulomatous disease will not progress.
caseous necrosis
morphological changes indicative of cell death caused by progressive enzymatic degradation.
latent TB
alive organisms still contained in the body
reactivated infection
10% of people with latent can progress to active.more likely to occur early than laterimmunocompromised more likelysite of reactivation is in the upper apical posterior lobes, due to its obligate aerobe status
what is the most common organ infected by tb
lung, cough is symptom. blood tinged sputum, sweaty
Cavitary TB
infiltrate in upper lung with hollow center
Milliary TB
looks like millet seeds, hematogenous spread indication. be able to see them on X-rays
risk factors of TB
close contact, healthcare workers, congregate settings, intravenous drug users, HIV/AIDS, recent immigrants
WHO global prevalance
most dense in subsaharan africa and southeast asia
TST
mantoux tuberculin skin testtests for delayed hypersensitivity, mounts immune responseNOT antibody mediated, type 4 hypersensitivity
type 4 hypersensitivity
CD4+ helper T cells recognize antigen in a complex with Class 2 major histocompatibility complex. The antigen-presenting cells in this case are macrophages that secrete IL-12, which stimulates the proliferation of further CD4+ T1 cells. CD4+ T cells secrete IL-2 and interferon gamma, further inducing the release of other Th1 cytokines, thus mediating the immune response. Activated CD8+ T cells destroy target cells on contact, whereas activated macrophages produce hydrolytic enzymes and, on presentation with certain intracellular pathogens, transform into multinucleated giant cells.
what is the purpose of two step system ppd?
memory weaning, not much of a reaction. a couple weeks later antigen will create more of a response.
what is a positive TST?
induration of 15 o more mm.induration of 5 or more means HIV or organ transplants.induration of 10 mm or more indicates that they are recent immigrants or drug users
interferon release assay
whole blood tests that a diagnose M. tuberculosis. both latent and and active. but to really know if its active need to do further exams. blood will develop same type 4 reaction.
what can give you a false positive tests?
other mycobacterium infections, BCG vaccination
diagnosis of active infection
respiratory samples, early morning sputa. children-gastric aspirate.sterile tissue/ body fluidusine signs of in UT
AFB stains
Ziehl-neelson and kinyounAuramine-Rhodamine- need fluorescent micro
nucleic acid amplification tests
PCR, can detect as little as 10 bacilli per sample
how is TB identified?
from a cultured isolate using nuclide acid hybridization based on the ability of complimentary nuclidc acid chains.
liquid vs solid agar
faster on liquid, looks like parmesan on specific DNA probe
Runyon classifications
current identification classes, 4 groups. rate of growth, pigment production, dark or light
Runyon 1
photochromogens
Runyon 2
Scotochromogens
Runyon 3
Nonchromogenic
Runyon 4
Rapid growersno pigment, colonies in 5 days.M. fortuitum, m. chelonae-abscessus. <- (foot baths)
M. Kansasii
Runyon 1- photochromogen.chronic pulmonary disease, resembles TB but not a public health concern.more common in men
M. Marinum
Runyon 1- Photochromogen. Sporotrichoid lesion. lymphocutaneous infection from aquarium. skin leasions can be caused by other things too.
M. scrofulaceum
Runyon 2- scotochromogen, slow grower causes cervical LYMPHADENITIS, or scrofula.from swamp water.use MTB or MAC for differential diagnosis.
MAI Complex (MAC)
Runyon 3- non chromogen. ppulmonary infection and opportunistic disseminated disease in AIDS
Hansen’s disease
lepromatous leprosy- more severe and advanced presentation.tuberculoid leprosy- well-demarcated lesions with central hypo pigmentation and hypoesthesia.
leprosy key facts
Leprosy is a chronic disease caused by a bacillus, Mycobacterium leprae.Symptoms can take as long as 20 years to appear.Leprosy is not highly infectious. It is transmitted via droplets, from the nose and mouth, during close and frequent contacts with untreated cases.Untreated, leprosy can cause progressive and permanent damage to the skin, nerves, limbs and eyes.Early diagnosis and treatment with multidrug therapy remain the key elements in eliminating the disease and sequela of infection
