#2 microbiology Flashcards
Haemophilus will not grow on sheep agar unless Staph aureus is plated, why?
S. aureus, beta-hemolytic, will lyse RBCs and free hematin (X) and secrete NAD+ (V), which is necessary for H. flu growth
3 types of botulinism
- foodborne - eating foods w/ botulism toxin (i.e. canned)
- wound botulism - toxin production in a wound infected w/ c. botulinum
- infant botulism - consumes c. botulinum spores, mature into vegetative toxin producing cells in intestine (i.e. contaminated honey)
all three forms can be fatal – medical emergency
3 most common clinical manfifestation of botulinism, and Rx?
3 D’s – dipolpia, dysphagia, dysphonia. 12-46 hrs later. antitoxin to sequester circulating toxin, but can’t stop toxin already in cells. supportive.
most common bacterial causes of acute otitis media, sinusitis, AND bacteria conjunctivitis are… name 3
- strep pnemoniae
- nontypable haemophilus influenza
- moraxella cattarrhalis
what fraction of the body’s total immunoglobulis are produced by splenic B cells
nearly 50%
acute rheumatic fever and acute post streptococcal glomerulonephritis are both post-strep infections, following what TYPE of infxn?
- APSGN: either strep skin infxn (impetigo) or strep pharyngeal infxn
- rheumatic fever: only with GAS throat infxn
classic triad of arthritis, uveitis/conjunctivitis, urethritis
reactive arthritis (HLA-B27 related)
strep pnemoniae cannot grow in the presence of…
bile or optochin
commonly used clinical disinfectants [4]? which are sporicidal?
what is formaldehyde/glutaraldehyde used for?
- alcohols (isopropanol, ethanol) - disrupt membrane, denature proteins. NOT sporicidal
- chlorhexidine - disrupt membrane, coagulate cytoplasm. NOT sporicidal
- hydrogen peroxide - produces free radicals. SPORICIDAL
- Iodine - halogenation of proteins & nucleic acids. SPORICIDAL
formaldehyde/glutaraldehyde – alkylating and cross-linking DNA, sterilize hospital equipment that can’t stand autoclave (high pressure steam
which anti-malarial drug treats hypnozites?
primaquine (p=prevent relapse). no effect on merozites!
most serious long-term adverse effect of chloroquine
retinopathy!! (primaquine doesn’t have this)
chloroquine resistant malaria rx: [2]
mefloquine or quinine/doxycycline
48hour cycle malaria
p. vivax or ovale (which have hepatic latent stages)
lechithinase (or phospholipase C) toxin released by?
Clostridium perfringens - degrades phospholipids. gas gangrene
pertussis toxin
exotoxin by bordetella pertussis – stimulates G-proteins to increase cAMP production. increased insulin (hypoglycemia), lymphocyte & neutrophil dysfunction, and increased histamine sensitivity
shiga toxin (shigella) and shiga-like toxin (e. coli)
inactivate 60s ribosomal subunit
microbes that can cause necrotizing fasciitis [5]
- step pyogenes
- staph aureus
- clostridium perfinges
- strep agalactiae
- aeromonas hydrophila (gram neg rod, non-lactose, oxidase +)
coag -, cat-, PYR+, hyaluronidase, m-protein (prevents complement fixation)
strep pyogenes
(s aureus is PYR -)posi
positive cAMP test
enhancement of s. agalactiae beta-hemolysis when plated perpendicular to s. aureus
medium for isolation of N. gonorrhoeae
thayer-martin;
chocolate agar +
- vancomycin (inhibit gram +,
- colistin (polymixin) to inhibit gram negative (inclu other neisserias),
- nystatin to inhibit yeast, and trimethoprim to inhibit proteus
what do nonspecific treponemal test look for (VDRL, RPR)
cardiolipin, by product of treponemal infxn
though it is too thin to see on gram stain, treponema is..
gram negative
haemophilus ducreyi
forms “chancroid”. similar primary lesion to chancre in syphilis, but painful and swollen regional lymph nodes
histoplasma capsulatum
mississippi and ohio river valley. bird and bat droppings. chicken coops and caves.
pulmonary – similar to tuberculosis (lung granulomas w/ calcifications). disseminate to lung, spleen, liver.
hides in macrophages
blastomycoses dermatitidis
great lakes. mississippi and ohio river valley.
doubly refractive wall, single broad-based bud
coccidioides immitis
southwestern states (desert areas). thick-walled spherules w/ endospores. pulmonary flu-like. disseminated skin, bones, meninges
paracoccidiodes basiliensis
also dimorphic. mucocutaneous or cutaneous ulcers. progress to lymph nodes and lung. central and south america.
two most common causes of hematogenous osteomyelitis
- staph aureus
2. strep pyogenes
organs affected by cryptococcus neoformas. where is it found?
- first pulmonary, but often asymptomatic
- meningitis
pigeon droppings!
test: red on mucicarmine stain, india ink, serologic testing (latex agglutination) capsular antigen. thick polysacc capsule
can form pulmonary nodules.
hot tub folliculitis
superficial pseudomonas infection of hair follicle
common source of pseudomonas infection
water! hot tub folliculitis, swimmer’s ear
psuedomonas characterestics
gram neg non lactose fermenting oxidase + motile produce pigment (pyocyanin, pyoverdin)
which viruses acquire membrane from host nucleus
CMV and EBV (herepesviridae family)
describe where gp160 is from?
encoded from env gene, glycosylated. proteolytically cleaved in ER and golgi to make gp120 and gp41. both needed to bind to CD4 receptor
s. epidermidis causing opportunistic infections in which two scenarios?
- endocarditis in pts w/ prosthetic valves
2. septic arthritis in pts w/ prosthetic joints
which staff can ferment mannitol?
s. aureus
neonates born to HBsAg and HBeAg moms have 1. what risk of chronic infxn 2. replicative rate 3. severity of hepatic injury
- high risk for chronic infxn
- high replicative rate
- MILD hepatic injury (not inherently cytopathic)
Guillan-Barre key finding and associated pathogen
loss of deep tendon reflexes, ascending paralysis
associated w/ history of camplyobacter jejuni infxn (diarrhea)
demyelinating syndrome of peripheral nerves. ascending muscle weakness and paralysis.
b. anthracis virulence factors: anthrax exotoxin (edema, lethal, protective) & capsule
- edema factor: increase cAMP, edema
- lethal factor: zinc-dependent protease, inhibits MAPK signaling, causes apoptosis, multisystemic physiologic disruption
- protective antigen – translocates edema and lethal factor into cytosol
antiphagocytic poly-y-D-glutamic acid capsule
b. pertussis: (1) pertussis toxin and (2) adenylate cyclase toxin
- pertussis toxin: disinhibits adenylate cyclase through Gi ADP ribosylation, increasing cAMP, edema & phagocyte dysfxn
- adenylate cyclase: increased cAMP, edema & phagocytosis
two toxins, same end effect
c. difficile (toxin A and toxin B)
toxin A: recruits & activates neutrophils, cytokine release –> mucosal inflammation, fluid loss & diarrhea
toxin B: induces actin depolymerization; mucosal cell death, bowel wall necrosis, pseudomembrane formation
s. pyogenes (pyrogenic exotoxin and streptolysis O&S)
pyrogenic exotoxin: superantigen, induces fever & shock –> scarlet fever and toxic shock
streptolysin O & S: damages erythrocytes, beta-hemolysis
treatment of acute C. diptheriae infection
- diptheria antitoxin
- penicillin / erythromycin
- DPT vaccine
toxin infects neural and cardiac tissue. acute infxn affects naso and oropharynx
most common cause of death post-C. diptheriae infxn
cardiomyopathy. (late neuro effects as well)
schistosomiasis [3 types]
s. haematobium, urinary
s. mansoni, intestinal
s. japonicum, hepatic
contact w/ freshwater snails, penetrate skin, enter vascular / lymphatics
clinical manifestations –> Th2 mediated immune response against eggs: granulomatous inflammation w/ fibrosis
s. haematobium [location and symptoms]
north africa, sub-saharan africa, middle east
urinary schistosomiasis: terminal hematuria, dysuria, freq urination, hydronephrosis, pyleonephritis, squamous cell carcinoma of bladder
s. mansoni [location and symptoms]
sub-saharan africa, middle east, south america, caribbean
intestinal schistosomiasis: diarrhea, abdominal pain, ulceration -> iron deficiency anemia
s. japonicum
asia [china, philippines, japan]
hepatic schistosomiasis: hepatosplenomegaly, periportal fibrosis, portal hypertension
PIPSTEM FIBROSIS: pathognomonic for hepatic schistosomiasis, caused by eggs settled into presinuosoidal radicals of the portal vein & fibrosis –> portal hypertension
diphtheria toxin (exotoxin w/ AB subunits)
B – binds growth factor receptor on cardiac and neural cells, induces endocytosis
A – ADP-ribosylation of EF-2
nonpulmonary sequelae of mycoplasma pneumonia infection
hemolysis, due to antigenic similarity between cell membranes. COLD AGGLUTINATION! stimulates cross-reactive antibodies.
how does Diphtheria acquire virulence?
bacteriopage-mediated infection w/ tox gene
how does strep pneumonia acquire virulence?
transformation, ability to produce capsules
which bacteria can undergo transformation, take up naked DNA from environment
s. pneumoniae, h. flu, neisseria
SHiN
complications of herpes zoster
- post-herpetic neuralgia (rx: topiramate)
2. herpes zoster ophthalmicus, when VZV is in trigeminal n. v1
polyprotein viral product that must be cleaved, often made by which family?
picornaviridae, i.e. echovirus. typically, single stranded, positive sense, linear, nonsegmented RNA
gram-positive cocci able to synthesize dextrans from glucose?
strep viridans (s. mutans and sanguis). able to produce insoluble extracellular polysaccharides (dextrans) using sucrose as a substrate). help adhere to surfaces
what causes anterior uveitis (inflammation of the iris) [4]
- herpes virus
- syphilis
- lyme disease
- inflammatory conditions like GLA-B27 related diseases and sarcoid
K. pneumoniae is a leading cause of what things
- UTI (e. coli is most common
- spontaneous bacterial peritonitis
- nosocomial pneumonia
HIV-1 provirus. describe 3 structural genes and 6 regulatory genes
structural genes: [needed for virion assembly]
- gag - antigens in virion core, like nucleocapsid proteins p24 and p7
- pol - reverse transcriptase, integrase, protease
- env - envelope proteins gp160
regulatory genes:
- tat - needed for repl; transcriptionally activates other viral genes. contributes to virulence
- rev - needed for repl; facilitates transport of unspliced viral transcripts out of nucleus
- vif
- vpr
- nef - enhance viral repl, downreg cd4 & mhcI expression
- vpu
common organisms for..
- urethritis
- cystitis
- pyelonephritis
urethritis:
- n. gonorrhoeae, c. trachomatis
cystitis:
- e.coli, s. saphrophyticus, p. mirabilis, klebsiella, enterococci
pyelonephritis:
-same as cystitis
common demographic for enterococcal endocarditis in men? women? (i.e. post what procedure)
elderly men who have recently undergone manipulation of areas colonized by this organism, such as GI or GU tract. in women, post-obstetrical procedure
GU is usu sterile, but can be contaminated w/ colonic flora in perineum
cold agglutination associated w/ which 2 infxn?
- mycoplasma pneumonia
- EBV infection
and hematologic malignancy
name cellular receptor: CMV
cellular integrins
name cellular receptor: EBV
CR2 (CD21)
name cellular receptor: HIV
CD4 and CXCR4/CCR5
name cellular receptor: rabies
nAcR (nicotinic acetylcholine receptor) on peripheral nerve
name cellular receptor: rhinovirus
ICAM1 (CD54)
