Micro Quick Facts Flashcards
microbes that do not Gram stain well
Treponema, Leptospira (too thin to be visualized); Mycobacteria (cell wall has high lipid content); Mycoplasma, Ureaplasma (no cell wall); Legionella, Rickettsia, Chlamydia, Bartonella, Anaplasma, Ehrlichia
“These Little Microbes May Unfortunately Lack Real Color But Are Everywhere”
microbes visualized with Giemsa stain
Chlamydia, Rickettsia, Trypanosomes, Borrelia, Helicobacter pylori, Plasmodium
“Clumsy Rick Tripped on a Borrow Helicopter Plastered in Gems”
microbes visualized with periodic acid-Schiff stain
Tropheryma whipplei (used to diagnose Whipple disease - stains glycogen, mucopolysaccharides)
microbes visualized with Ziehl-Neelsen stain (carbol fuchsin)
acid-fast bacteria (Mycobacteria, Nocardia - stains mycolic acid in cell wall), protozoa (Cryptosporidium oocysts)
microbes visualized with India ink stain
Cryptococcus neoformans
mucicarmine can also be used to stain thick polysaccharide capsule red
microbes visualized with silver stain
Helicobacter pylori, Legionella, Bartonella henselae, and fungi (Coccidioides, Pneumocystis jirovecii, Aspergiluus fumigatus)
culture requirements: H. influenzae
chocolate agar
contains factor V (NAD+) and X (hematin)
culture requirements: N. gonorrhoeae, N. miningitidis
Thayer-Martin agar
inhibits growth of gram positive organisms (vancomycin), gram negative organisms except Neisseria (trimethoprim and colistin), and fungi (nystatin)
culture requirements: B. pertussis
Bordet-Gengou agar, Regan-Lowe medium
culture requirements: C. diphtheriae
Tellurite agar, Loffler medium
culture requirements: M. tuberculosis
Lowenstein-Jensen medium, Middlebrook medium, rapid automated broth cultures
culture requirements: M. pneumoniae
Eaton agar
culture requirements: lactose-fermenting enterics
MacConkey agar
culture requirements: E. coli
eosin-methylene blue (EMB) agar
culture requirements: Brucella, Francisella, Legionella, Pasturella
charcoal yeast extract agar buffered with cysteine and iron
“The Ella Siblings, Bruce and Francis, a legionnaire and a pastor, built the Sistine chapel out of charcoal and iron”
culture requirements: fungi
Sabouraud agar
“Sab’s a fun guy!”
encapsulated bacteria
“Please SHINE my SKiS”:
Pseudomonas aeruginosa, Streptococcus pneumoniae, Haemophilus Influenzae type b, Neisseria meningitidis, Escherichia coli, Salmonella, Klebsiella pneumoniae, group B Streptococcus
anaerobic bacteria
Clostridium, Bacteroides, Fusobacterium, Actinomyces israelii
“anaerobes can’t breathe fresh air”
facultative anaerobes
streptococci, staphylococci, enteric gram negative bacteria
obligate intracellular bacteria
Rickettsia, Chlamydia, Coxiella
“stay inside when it’s really chilly and cold”
facultative intracellular bacteria
Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis
“Some Nasty Bugs May Live facultativeLY”
urease-positive organisms
Proteus, Cryptococcus, H. pylori, Ureaplasma, Nocardia, Klebsiella, S. epidermidis, S. saprophyticus
“Pee CHUNKSS”
catalase-positive organsims
Bordetella pertussis, Helicobacter pylori, Burkholderia cepacia, Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, E. coli, Serratia, Staphylococci
Borderline Helpful Buttons, Nokia Phones Listen Astutely. Can Even Sarah Stop?
[?] produce yellow “sulfur” granules, which are composed of filaments of bacteria
Actinomyces israelli
[?] produces a golden yellow pigment
S. aureus
[?] produces a blue-green pigment
P. aeruginosa (pyocyanin and pyoverdin)
[?] produces a red pigment
Serratia marcescens
in vivo biofilm-producing bacteria
S. epidermidis: catheter and prosthetic device infections:
Viridans streptococci (S. mutans, S. sanguinis): dental plaques, infective endocarditis
P. aeruginosa: respiratory tree colonization in CF patients, ventilator-associated pneumonia, contact lens-associated keratitis
non-typeable (unencapsulated) H. influenzae: otitis media
spore-forming bacteria
B. anthracis, B. cereus, C. botulinum, C. difficile, C. perfringes, C. tetani
all spore-forming bacteria are gram positive
protein A is a virulence factor expressed by [?]
S. aureus
binds Fc region of IgG; prevents opsonization and phagocytosis
IgA protease is a virulence factor expressed by [?]
S. pneumoniae, H. influenzae type b, Neisseria
enzyme that cleaves IgA, allowing bacteria to adhere to and colonize mucous membranes
M protein is a virulence factor expressed by [?]
group a streptococci
helps prevent phagocytosis; sequence homology with human cardiac myosin (molecular mimicry) - may underlie autoimmune response seen in acute rheumatic fever
diphtheria toxin
Corynebacterium diphtheriae
inactivates elongation factor (EF-2)
pharyngitis with pseudomembranes in throat and severe lymphadenopathy (bull neck), myocarditis
exotoxin A
Pseudomonas aeruginosa
inactivates elongation factor (EF-2)
host cell death
Shiga toxin
Shigella species, Enterohemorrhagic E. coli (EHEC)
inactivates 60S ribosome by removing adenine from rRNA
dysentery, hemolytic-uremic syndrome (EHEC)
heat-labile toxin (LT)
enterotoxigenic E. coli (ETEC)
over-activates adenylate cyclase (increases cAMP) => increase Cl- secretion in gut and H2O efflux
watery diarrhea
heat-stable toxin (ST)
enterotoxigenic E. coli (ETEC)
over-activates guanylate cyclase (increases cGMP) => decrease resorption of NaCl and H2O in gut
watery diarrhea
anthrax toxin
Bacillus anthracis
mimics adenylate cyclase (increases cAMP)
edematous borders of black eschar in cutaneous anthrax
cholera toxin
Vibrio cholerae
over-activates adenylate cyclase (increase cAMP) by permanently activating Gs
voluminous “rice-water” diarrhea
bacteria that increase cAMP = [?]
Cholera, Anthracis, Pertussis, E. Coli
“increase cAMP with CAPE”
pertussis toxin
Bordetella pertussis
activates adenylate cyclase (increase cAMP) by inactivating Gi inhibitory subunit
whooping cough (child coughs on expiration and “whoops” on inspiration), “100-day cough” in adults, posttussive emesis
tetanospasmin
Clostridium tetani
protease that cleaves SNARE (a set of proteins required for neurotransmitter release via vesicular fusion) => prevents release of inhibitor neurotransmitters (GABA, glycine)
spastic paralysis, risus sardonicus, trismus (lockjaw), opisthotonos
botulism toxin
Clostridium botulinum
protease that cleaves SNARE (a set of proteins required for neurotransmitter release via vesicular fusion) => prevents release of excitatory neurotransmitter (acetylcholine)
infant botulism, foodborne botulism
alpha toxin
Clostridium perfringens
phospholipase (lecithinase) that degrades tissue and cell membranes
myonecrosis (“gas gangrene”) and hemolysis (“double zone” of hemolysis on blood agar)
streptolysin O
Streptococcus pyogenes
protein that degrades cell membrane; lyses RBCs
contributes to B hemolysis; host antibodies against toxin (ASO) used to diagnose rheumatic fever
toxic shock syndrome toxin (TSST-1)
Staphylococcus aureus
cross-links B region of TCR to MHC class II on APCs outside of antigen binding site => overwhelming release of IL-1, IL-2, IFN-gamma, and TNF-alpha
toxic shock-like syndrome: fever, rash, shock, scarlet fever
novobiocin sensitivity test: [?] is resistant; [?] is sensitive
saprophyticus is resistant, epidermidis is sensitive
optochin sensitivity test: [?] is resistant; [?] is sensitive
Viridans is resistant, Pneumoniae is sensitive
bacitracin sensitivity test: [?] is resistant; [?] is sensitive
group B strep are resistant; group A strep are sensitive
alpha-hemolytic bacteria
partial oxidation of hemoglobin => greenish or brownish color without clearing around growth on blood agar
Streptococcus pneumonia, viridans streptococci
beta-hemolytic bacteria
complete lysis of RBCs => pale/clear area surroudnign colony on blood agar
Staphylococcus aureus, Streptococcus pyogenes (group A strep), Streptococcus agalactiae (group B strep), Listeria monocytogenes
