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Flashcards in #2 microbiology Deck (67):

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

1. foodborne - eating foods w/ botulism toxin (i.e. canned)
2. wound botulism - toxin production in a wound infected w/ c. botulinum
3. 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

1. strep pnemoniae
2. nontypable haemophilus influenza
3. 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?

1. APSGN: either strep skin infxn (impetigo) or strep pharyngeal infxn
2. 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?

1. alcohols (isopropanol, ethanol) - disrupt membrane, denature proteins. NOT sporicidal
2. chlorhexidine - disrupt membrane, coagulate cytoplasm. NOT sporicidal
3. hydrogen peroxide - produces free radicals. SPORICIDAL
4. 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


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

1. staph aureus
2. strep pyogenes


organs affected by cryptococcus neoformas. where is it found?

1. first pulmonary, but often asymptomatic
2. 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 +
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?

1. 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

1. high risk for chronic infxn
2. high replicative rate
3. 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

1. edema factor: increase cAMP, edema
2. lethal factor: zinc-dependent protease, inhibits MAPK signaling, causes apoptosis, multisystemic physiologic disruption
3. 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

1. diptheria antitoxin
2. penicillin / erythromycin
3. 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



complications of herpes zoster

1. 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]
1. gag - antigens in virion core, like nucleocapsid proteins p24 and p7
2. pol - reverse transcriptase, integrase, protease
3. env - envelope proteins gp160

regulatory genes:
1. tat - needed for repl; transcriptionally activates other viral genes. contributes to virulence
2. rev - needed for repl; facilitates transport of unspliced viral transcripts out of nucleus
3. vif
4. vpr
5. nef - enhance viral repl, downreg cd4 & mhcI expression
6. vpu


common organisms for..
- urethritis
- cystitis
- pyelonephritis

- n. gonorrhoeae, c. trachomatis

- e.coli, s. saphrophyticus, p. mirabilis, klebsiella, enterococci

-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)