Micro - Acid Fast and Bacteria Without Cell Walls Flashcards
tuberculosis
mycobacterium tuberculosis
leprosy
mycobacterium leprae
rods with acid-fast staining
mycobacteria
acid-fast organism
mycobacteria
nocardia
acid-fast stain
smear of sputum covered with red carbolfuchsin and heated
- acid alcohol poured over
- methylene blue counterstained
- cell wall lipids don’t dissolve - so red stain holds
- not acid fast - turn blue
1/3 of HIV patients
also harbor mycobacterium tuberculoid
mycosides
class of lipid in acid-fast organisms
mycolic acid bound to carbohydrate
cord factor
mycoside formed by union of two mycolic acids with a disaccharide
inhibits neutrophil migration and damages mitochondria
tuberculosis
chronic disease - associated with weight loss
-can be confused with cancer
sulfatide
mycoside that resemebles cord factor with sulfates attached to disaccharide
wax D
complicated mycoside
caseous necrosis
in tuberculosis
-due to cell-mediated immunity destroying infected lung tissue
PPD skin test
for mycobacterium tuberculosis
-reveal whether individual has been infected
-positive test - latent TB
> 5mm - HIV positive or immunosuppressed
10mm - common risk factors for exposures
15mm - all other individuals
false positive PPD test
if individual had BCG vaccine
false negative PPD test
some patients do not react to PPD even if infected
asymptomatic primary tuberculosis
bacteria walled off in caseous granulomas
calcified tubercle in middle or lower lung zone - ghon focus
symptomatic primary tuberculosis
children, elderly, immunocompromised
- enlarged mediastinal or hilar lymph nodes
- untreated - leads to cavities in lung (necrosis)
cavitary lesions with air-fluid levels
secondary tuberculosis
-pulmonary - most common site - chronic low grade fever, night sweats, weight loss, productive cough
pleural/pericardial - fluid collection around lung or heart
lymph node - cervical common - swollen, mat together, and drain - scrofula
kidney - sterile pyuria - red and white blood cells in urine
skeletal - potts disease
joints - chronic arthritis of one joint
CNS - subacute meningitis - granulomas in brain
miliary - granulomas all over body
potts disease
IV discs and vertebral bodies destroyed in secondary tuberculosis
Gene Xpert MTB/RIF
easy, fast, reliable diagnosis of tuberculosis
but expensive
MDR and XDR tuberculosis
multi-drug and extremely-drug resistant
TB rule of fives
5 % risk of reactivation
high five (HIV) 5 + 5% risk of reactivation per year
droplet nuclei - 5 micrometers
hansens disease
leprosy
caused by mycobacterium leprae
grows in cool areas of body - damages skin, nerves, eyes, nose, testes
lepromatous leprosy
severest form
- skin lesions cover entire body
- leonine facies - thickened skin of face
- saddle nose deformity
- testicular damage
- blindness
- loss of sensation in extremities in glove distribution
tuberculoid leprosy
can mount cell-mediated response
-contain skin damage
-localized superficial, unilateral skin, and nerve involvement
1 or 2 skin lesions
-well-defined hypopigmented elevated blotches
single skin lesion, no hair growth on lesions, loss of sensation or extremities, no acid fast bacilli in skin scraping, positive lepromin skin test
tuberculoid leprosy
lepromin skin test
measures ability of host to mount delayed hypersensitivity response against myocbacterium leprae
nontuberculous mycobacterium
AIDs patient with disseminated MAC disease
-unexplained fever, weight loss, diarrhea, malaise, elevation fo alkaline phosphatase
most common cause of nontuberculous mycobacterium lung disease
MAC
- upper lung cavitary disease - male smokers
- lower and middle lung with bronchiectasis and nodular infiltrates in middle-aged non-smoking women
smallest free-living organisms capable of self-replication
mycoplasma
- no peptidoglycan wall
- cell membrane with sterol
- can contort shape
walking pneumoniae
mycoplasm pneumoniae
-gradual onset of fever, sore throat, malaise, persistent dry hacking cough
patients don’t feel very sick
number one cause of bacterial bronchitis and pneumonia in teenagers and young adults
mycoplasma pneumoniae
stevens-johnson syndrome
severe skin reaction with erythematous vesicles in mucocutaneous junctions of mouth, eyes, skin
mycoplasm pneumoniae
cold agglutinins
monoclonal IgM Abs against RBC antigens
-cause them to aggllutinate
in patients infected with mycoplasm pneumoniae
test for cold agglutinins
patient blood in tube
- put in ice - blood will clump
- when warmed up - will unclump
T-strain mycoplasm
ureaplasma urealtyticum
breaks down urea
normal flora in sexually active women
-causes lower urinary tract infection - urethritis
can metabolize urea into ammonia and CO2
no cell wall
mycoplasm pneumoniae
ureaplasma urealyticum
