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Board Review > Basic Bacteriology > Flashcards

Basic Bacteriology Flashcards

1
Q

peptidoglycan – structure and function

A

Gives rigid support, protects against osmotic
pressure.

Sugar backbone with peptide side chains crosslinked
by transpeptidase.

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2
Q

cell wall – structure, function, inflammatory portion

A

Cell wall Major surface antigen. Peptidoglycan for support. Lipoteichoic acid
induces TNF and IL-1.

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3
Q

outer membrane, types of bacteria that possess, what type of toxin exists here, which port is inflammatory, which part is antigenic

A 
(gram negatives)
Site of endotoxin (lipopolysaccharide [LPS]);
major surface antigen.
Lipid A induces TNF and IL-1;
O polysaccharide is the antigen.
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4
Q

Ribosome - types of ribosomes

A

50S and 30S subunits.

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5
Q

Periplasm - between what two layers,

A

Space between the cytoplasmic membrane and
outer membrane in gram-negative bacteria.

Contains many hydrolytic enzymes, including
β-lactamases.

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6
Q

Spore - composition

A

Keratin-like coat; dipicolinic acid;

peptidoglycan.

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7
Q

function of the bacterial capsule, composition

A 
Glycocalyx Mediates adherence to surfaces, especially
foreign surfaces (e.g., indwelling catheters).
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8
Q

two examples of gram-negative cocci

A

Moraxella catarrhalis

Neisseria

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9
Q

why can’t Legionella, be easily stained ?

A 
Legionella pneumophila (primarily
intracellular).
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10
Q

what staining method would you use for mycobacteria

A

mycolic acids fluorescent antibody staining.
in cell wall detected by carbolfuchsin in acidfast
stain

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11
Q

why is Treponema difficult to visualize a microscope

A

too thin, utilize `dark field microscopy

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12
Q

why is chlamydia unsustainable

A

(intracellular parasite; lacks classic

peptidoglycan because of low muramic acid

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13
Q

indications for the Giesma stain

A

Chlamydia, Borrelia, Rickettsia, Trypanosomes,
Plasmodium.

Certain Bugs Really Try my Patience.

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14
Q

Ziehl-Neelsen (carbol

fuchsin) indications

A

Acid-fast bacteria (Nocardia, Mycobacteria),

protozoa (Cryptosporidium oocysts).

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15
Q

Ziehl-Neelsen alternative, sensitivity and specificity?

A

Alternative is auramine-rhodamine stain for
screening (inexpensive, more sensitive but less
specific.

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16
Q

India ink indications

A 
Cryptococcus neoformans (mucicarmine can
also be used to stain thick polysaccharide
capsule red
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17
Q

silver stain indications

A

Fungi (e.g., Pneumocystis), Legionella,

Helicobacter pylori

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18
Q

special culture for H. influenzae, contents

A

chocolate agar – Factors V (NAD+) and X (hematin

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19
Q

N. gonorrhoeae,

N. meningitidis - culture dish , contents

A

Thayer Martin plate - Vancomycin (inhibits gram-positive organisms),
Trimethoprim, Colistin (inhibits gramnegative
organisms except Neisseria), and
Nystatin (inhibits fungi)

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20
Q

B. pertussis - culture plate x2 - contents

A

Bordet-Gengou agar (Bordet for Bordetella), potato

Regan-Lowe medium contains Charcoal, blood, and antibiotic

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21
Q

C. diphtheriae - culture dishes x2

A

C. diphtheriae Tellurite agar, Löffler medium

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22
Q

mycobacteria tuberculosis - culture dish

A

Löwenstein-Jensen agar

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23
Q

Mycoplasma pneumoniae culture dish, special contents

A

eat-in agar, contains cholesterol

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24
Q

indication for Maconkey plate

A

gram-negative bacteria that ferment lactose, appear pink on culture

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25
Q

special plating for E. coli,, appearance on colonies

A

Eosin–methylene blue (EMB) agar Colonies with green metallic sheen.

26
Q

Fungi - culture dish

A

Sabouraud agar

27
Q

4 important aerobic bacteria

A

Nocardia, Pseudomonas
aeruginosa, and MycoBacterium tuberculosis.

Nagging Pests Must Breathe.

28
Q

Anaerobes - characteristics, enzymes lacking, antibiotic resistance

A

They lack
catalase and/or superoxide dismutase and
are thus susceptible to oxidative damage.
Generally foul smelling (short-chain fatty
acids), are difficult to culture, and produce gas
in tissue

AminO2glycosides are
ineffective against anaerobes because these
antibiotics require O2 to enter into bacterial
cell.

29
Q

obligate intracellular bacteria x 3

A

Rickettsia, CHlamydia, COxiella. Rely on host
ATP.
Stay inside (cells) when it is Really CHilly and
COld

30
Q

facultative intracellular bacteria

A

Salmonella, Neisseria, Brucella, Mycobacterium,
Listeria, Francisella, Legionella, Yersinia pestis.

Some Nasty Bugs May Live FacultativeLY.

31
Q

encapsulated bacteria, people at risk of infection by these bacteria

A

Streptococcus pneumoniae,
Haemophilus influenzae type B, Neisseria
meningitidis, Escherichia coli, Salmonella,
Klebsiella pneumoniae, and group B Strep.

SHiNE SKiS.
Are opsonized, and then cleared by spleen.
Asplenics have decreased opsonizing ability and
thus increased risk for severe infections.

32
Q

Encapsulated bacteria

vaccines - nature of antigen, type of immune response promoted, mild limitation

A

Some vaccines containing polysaccharide
capsule antigens are conjugated to a carrier
protein

enhancing immunogenicity by
promoting T-cell activation and subsequent
class switching.

A polysaccharide antigen
alone cannot be presented to T cells.

33
Q

Urease-positive organisms

A

Cryptococcus, H. pylori, Proteus, Ureaplasma,
Nocardia, Klebsiella, S. epidermidis,
S. saprophyticus.

CHuck Norris hates PUNKSS.

34
Q

the function of catalase, people susceptible to infection by catalase positive organisms?

A

Catalase degrades H2O2 into H2O and
bubbles of O2 A before it can be converted to microbicidal products by the enzyme myeloperoxidase.

People with chronic
granulomatous disease (NADPH oxidase
deficiency) have recurrent infections with
certain catalase ⊕ organisms.

35
Q

catalase positive organisms -

A

Catalase - Nocardia, Pseudomonas, Listeria,
Aspergillus, Candida, E. coli, Staphylococci,
Serratia.

Cats Need PLACESS to hide.

36
Q

bacteria that produce pigment: yellow? Green? Red?

A

Actinomyces israelii—yellow “sulfur” granules
S. aureus—yellow pigment.
Pseudomonas aeruginosa—blue-green pigment
Serratia marcescens—red pigment.

37
Q

function of the type III secretion system, bacteria that possess it.

A

Needle-like protein appendage facilitating direct delivery of
toxins from certain gram-negative bacteria (e.g., Pseudomonas, Salmonella, Shigella, E. coli) to
eukaryotic host cell

38
Q

locations for genes for exotoxins, relative toxicity compared to endotoxins, Heat stability?

A

Plasmid or bacteriophage, toxicity is quite high, denature at 60°C, as opposed to endotoxins that can be stable at 100°C for one hour

39
Q

locations of endotoxins, nature of structure, genes are located where, clinical effects?

A

located in the outer membrane of most gram-negative bacteria, are lipopolysaccharides, as opposed to polypeptides, the genes are located within the bacterial chromosome, and can lead to TNF alpha release, IL-1 release, thus leading to hypotension shock, and febrile illness.

40
Q

target of diphtheria toxin and exotoxin a (Pseudomonas)

A

inactivation of the EF2, DT lead to pseudo-membranes and severe lymphadenopathy

exotoxin a leads to cell death

both are ADP ribosylating

41
Q

function of Shiga and Shiga like toxin. ADP ribosylating?

A

inactivation of 60 S ribosome, removal of adenine from the tRNA
SLT - enhances cytokine release leading to HUS

ST- leads to cell damage and eventually dysentery

both are ADP ribosylating

42
Q

Target of heat stable toxin and effect. ADP ribosylating?

A

Overactivates guanylate
cyclase ( increased cGMP)
decreased resorption of NaCl
and H2O in gut)

ETEC -causes watery diarrhea

heat-stable toxin is ADP ribosylating

43
Q

target of heat labile toxin and affect. ADP ribosylating?

A

Overactivates adenylate
cyclase (increased cAMP) increased Cl−
secretion in gut and H2O
efflux

ETEC - watery diarrhea

heat labile toxin is not ADP ribosylating

44
Q

Edema toxin in anthrax - function

A

mimics adenylate cyclase leading to increasing camp

causes of edematous borders in the black eschar

45
Q

function of cholera toxin

A

Overactivates adenylate cyclase ( cAMP) by permanently activating Gs (increased Cl− secretion in gut
and H2O efflux) ADP ribosylating

46
Q

Pertussis toxin

A

inhibits Gi G protein indirectly leading to an increase in Gs and Camp. ADP ribosylating

47
Q

tetanus toxin and Botulin toxin which is ADP ribosylating?

A

both are.

48
Q

function of alpha toxin ( Clostridium perfringens), does what tissues, RBCs?

A

Phospholipase (lecithinase)
that degrades tissue and
cell membranes

Degradation of phospholipids Ž myonecrosis
(“gas gangrene”) and hemolysis (“double zone”
of hemolysis on blood agar)

49
Q

Streptolysin O - function, affects on RBCs,, affects on rheumatic fever, affects on posttstreptococcal glomerulonephritis

A

Protein that degrades cell
membrane

Lyses RBCs; contributes to β-hemolysis;
host antibodies against toxin (ASO) used to
diagnose rheumatic fever (do not confuse
with immune complexes of poststreptococcal
glomerulonephritis)

50
Q

effects of toxic shock Syndrome toxin - 1, and exotoxin a (strep)

A

Binds to MHC II and TCR outside of antigen binding site to cause overwhelming release of IL-1, IL-2, IFN-γ, and TNF-α
shock.

51
Q

characteristics of endotoxins

A 
ENDOTOXIN:
Edema
Nitric oxide
DIC/Death
Outer membrane
TNF-α
O-antigen
eXtremely heat stable
IL-1
Neutrophil chemotaxis

complement activation(C5a), tissue factors come from macrophages

52
Q

definition of bacterial transformation. 3 important culprits

A

Ability to take up naked DNA (i.e., from cell lysis) from environment (also known as
“competence”). A feature of many bacteria, especially S. pneumoniae, H. influenzae type B, and
Neisseria (SHiN)

53
Q

definition of bacterial conjugation (F+ × F–), what type of DNA is transferred

A

F+ plasmid contains genes required for sex pilus and conjugation. Bacteria without this plasmid
are termed F–. Sex pilus on F+ bacterium contacts F− bacterium. A single strand of plasmid DNA
is transferred across the conjugal bridge (also known as the “mating bridge”). No transfer of
chromosomal DNA.

54
Q

)definition of bacterial conjugation (Hfr × F–), what type of DNA is transferred

A

F+ plasmid can become incorporated into bacterial chromosomal DNA, termed high-frequency
recombination (Hfr) cell. Replication of incorporated plasmid DNA may include some flanking
chromosomal DNA. Transfer of plasmid and chromosomal genes.

55
Q

definition of transposition, what type of DNAs included in the transposon.

A

Segment of DNA (e.g., transposon) that can “jump” (excision and reintegration) from one location
to another, can transfer genes from plasmid to chromosome and vice versa. When excision occurs,
may include some flanking chromosomal DNA, which can be incorporated into a plasmid and
transferred to another bacterium

56
Q

bacterial transduction (generalized) – definition, type of bacteriophage involved, mode of transfer.

A

A “packaging” event. Lytic phage infects bacterium, leading to cleavage of bacterial DNA. Parts
of bacterial chromosomal DNA may become packaged in viral capsid. Phage infects another
bacterium, transferring these genes

57
Q

sspecialized transduction - definition, mode of transfer, type of bacteriophage involved.

A

An “excision” event. Lysogenic phage infects bacterium; viral DNA incorporates into bacterial
chromosome. When phage DNA is excised, flanking bacterial genes may be excised with it. DNA
is packaged into phage viral capsid and can infect another bacterium.

58
Q

Five exotoxins coded to bacteriophage transduction.

A 
ƒ ShigA-like toxin
ƒƒ Botulinum toxin (certain strains)
ƒƒCholera toxin
ƒƒDiphtheria toxin
ƒƒ Erythrogenic toxin of Streptococcus pyogenes
59
Q

function of protein a, in staff aureus

A

Binds Fc region of IgG. Prevents opsonization and phagocytosis. Expressed by S. aureus.

60
Q

function of IGA protease, and bacteria with it

A

Enzyme that cleaves IgA. Secreted by S. pneumoniae, H. influenzae type B, and Neisseria (SHiN)
in order to colonize respiratory mucosa

61
Q

M protein - function, relationship to human cellular proteins, role in autoimmune disease.

A

Helps prevent phagocytosis. Expressed by group A streptococci. Shares similar epitopes to human
cellular proteins (molecular mimicry); possibly underlies the autoimmune response seen in acute
rheumatic fever.

Board Review (7 decks)

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