Microbio Basic Bacteriology2 Flashcards
Ziehl-Neelsen stain
Acid fast bacteria (nocardia, mycobacteria), protozoa (cypto oocytes)
India ink stains what?
crypto neoformans (mucicarmine can also be used)
Silver stain is good for what?
fungi (pneumocystis), legionella, and h. pylori
Best media for H. influenza culture
chocolate agar
best media for Neisseria (gonorrhea and meningitidis) cx
thayer-martin agar (vanc, trimethoprim, colisin, and nystatin)
best cx for bordatella pertussis cx
Bordet-gengou agar (made of potato)
best cx medium for c. diptheriae
tellurite agar, loffler medium
best cx for m. tuberculosis
Lowenstein-jensen agar
best cx medium for mycloplasma pneumoniae
eaton agar (requires cholesterol)
best cx for e coli
EMB agar
best cx medium for lactose-fermenting enterics
macconkey agar (ferentaton produces acid, causing colonies to turn pink)
best cx for legionella
charcoal yest extract agar buffered with cysteine and iron
best cx medium for fungi
sabouraud agar (“Sab’s a fun guy!”)
pseudomonas, nocardia, and mycobacterium are all?
aerobes
fusobacterium, clostridium, bacteroides, and actinomyces are all what?
anaerobes (generally foul smelling, difficult to cx, and produce gas in tissue)
obligate intracellular bugs
rickettsia, chlamydia, coxiella
facultative intracellular bugs
salmonella, neisseria, brucella, mycobacterium, listeria, francisella, legionell, yersinia pestis
encapsulated bacteria
strep pneumo, HIB, neisseria meningitidis, e. coli, salmonella, klebsiella pneumoniae, and group b strep
urease positive organisms
cryptococcus, h. pylori, proteus, ureaplasma, nocardia, klebsiella, s. epidermis, staph saprophyticus; “CHuck norris hates PUNKSS”
catalase pos organisms
people with chronic granulomatous disease (NADPH oxidase def) hav recurrent infections w certain catalase pos organisms; nocardia, pseudomonas, listeria, aspergillus, candida, e. coli, staphylococci, seratia; “Cats need PLACESS to hide”
pigment producing bacteria
actinomyces israelii is yellow’ staph aureus is yellow; pseudomonas is blue/green; serratia marcescens is red
protein A
expressed by staph aureus; bind sthe Fc region of IgG; prevents opsonization an dphagocytosis
IgA protease
enzyme that cleaves IgA; secreted by strep pneumo, Hib and Neisseria in order to colonize the respiratory mucosa
M protein
helps prevent phagocytosis; expressed by group a strep; possibly underlies the autoimmune response seen in acute rheumatic fever
Type III secretion system
aka “injectisome”; needle-like protein appendage facilitating direct delivery of toxins from certain GN bacteria to eukaryotic host cell
exo versus endotoxin
endotoxins are expresed on the outer cell membrane of most gram neg bacteria as lipopolysaccharides; exotoxins are secreted by certain gram pos and gram negs;
bacteria with exotoxins
corynebacterium diptheriae, pseudomonas, shigella, EHEC, ETEC,, bacillus anthracis, vibrio cholerae, bordatella pertussis, c. tetani,c. botulinum, c. perfringens, strep pyogenes, staph aureus
corynebacterium diptheriae exotoxin characteristics
called the “diptheria toxin”; inactivates elongation factor EF-2; causes pharyngitis with pseudomembranes in the throat ad severe lymphadenopathy (bull’s neck)
pseudomonas exotoxin
called “Exotoxin A”; it inactivates EF-2; causes host cell death
shigella exotoxin
“shiga toxin”; inactivates 60S ribosome; causes GI mucosal damage leading to dysentery; the shiga toxin also enhances cytokine release causing HUS
EHEC exotoxin
shiga-like toxin; inactivates the 60S ribosome; enhances cytoine release causing HUS, esp serotype EHEC 0157:H7; unlike shigella, EHEC does not invade host cells
ETEC exotoxin
there is the heat labile toxin (increaes chloride secretion in gut and water efflux) and heat stable toxin (decreases resorption of NaCl and water in the gut); both toxins cause watery diarrhea
b. anthracis toxin
“edema toxin”; likely responsible for characteristic edematous borders of black eschar in cutaneous anthrax
vibrio cholera exotoxin
“cholera toxin”; increases secretion in gut and water efflux; causes voluminous rice water diarrhea
bordatella pertussis toxin
“pertussis toxin”; impairs phagocytosis to permit survival of the microbe; cause of whooping cough
clostridium tetani toxin
tetanospasmin; it is a protease that cleaves SNARE, which is required for neurotransmitter release; causes spasticity, risus sadonicus and lockjaw; toxin prevents release of inhibitory nts from Renshaw cells in spinal cord
clostridium botulinum
botulinum toxin; protease that cleaves SNARE; causes flaccid paralysis, floppy baby; toxin prevents release of stimulatory (Ach) signals at NMJs
clostridium perfringens exotoxin
“alpha toxin”; phospholipase that degrades tissue and cell membrane; you get gas gangrene and hemolysis (“double zone “ of hemolysis on blood agar)
strep pyogenes exotoxin
Streptolysin O; protein that degrades the cell membrane; lyses RBCs; contributes to beta hemolysis; host antbodies against toxin (ASO) used to dx rheumatic fever
what organisms can produce superantigens causing toxic shock syndrome?
staph aureus (fever, rash, shock, scaeded skin syndrome and food poisoning); strep pyogenes (fever, rash, shock)
endotoxin
LPS found on the outer membrane of gram neg bacteria (both cocci and rods)
how does the endotoxin work?
activates macrophages (which produce IL-1, TNF-a, nitric oxide); activates complement (C3a, C5a) and activates tissue facto (coag cascade to DIC)
transformation
a bacteria’s ability to take up naked DNA from the environment (aka “competence”). A feature of many bacteria, esp strep pneumo, HIB and Neisseria
Conjugation F+xF-
F+ plasmid contains the genes reqd for sex pilus and conjugation. Bacteria without this plasmid are F-. Sex pilus on F+ contacts the F- and a single strand of plasmid DNA is transferred across theconjugal bridge. No transfer of chromosomal DNA
Conjugation Hfr x F-
F+ plasmid can become incorporated into bacterial chromosomal DNA, termed high-freq recombination (Hfr) cell. Transfer of plasmid and chromosomal genes
Transposition
segment of DNA (transposon) that can jump from one location to another. Can transfer genes from plasmid to chromosome and vice versa; can include flanking chromosomal DNA that is transferred to another bacterium
generalized transduction
lytic phage infects the bacterium and parts of bacteral chromosomal DNA may become packaged in viral capsid. Page infects another bacterium, transferring these genes
specialized transduction
an excision event in which phage infect bacterium and viral DNA incorportates into bacterial chrom. When phage DNA is excised, flanking bacterial genes may be excised with it. DNA s packaged into pahage viral capsid and can infect other bacterium
Genes for which 5 bacterial toxins are encoded in a lysogenic phage?
ABCDE; ShigA like toxin, botulinum toxins, cholera, diptheria, erythrogenic toxin of strep pyogenes
