Exam 2 Flashcards
(96 cards)
1
Q
- Entry through break in skin
- Mucous membrane contact
- Ingestion of fecal matter
A
Direct, horizontal transmission
2
Q
- Congenital transfer
- From mother to fetus/newborn
A
Direct, vertical transmission
3
Q
- Inhalation of respiratory droplets from an infected person
- Large, travel less than 1 meter before dropping out of the air
A
Direct, droplet transmission
4
Q
- Inhalation of small droplets
- travel more than 1 meter, hang in the hair for long periods of time
A
Indirect, airborne/aerosol transmission
5
Q
- Inanimate surface/reservoir contaminated
- Pathogen enters through break in skin, mucosal membranes, or ingestion
A
Indirect, contaminates fomite transmission
6
Q
- vertebrate animal
- indirect or direct
- vector-borne
- vehicle transmission from contaminated food/water to humans
A
zoonoses
7
Q
- ingestion of contaminated food or water
A
Vehicle transmission
8
Q
- arthropod carries pathogen, but pathogen does not replicate in vector
A
vector-borne, mechanical transmission
9
Q
- arthropod is essential for the pathogen to complete their life cycle
A
vector-borne, biological transmission
10
Q
- proteins or carbohydrates on bacterial surfaces that help with adherence
- Ag43/AIDA
- LPS
A
Afimbrial adhesins
11
Q
- P fimbriae
- Curli
- Type I pili
- Type 4 pili
A
Fimbrial adhesins
12
Q
- Flagella
- Capsule
A
Atypical adhesins
13
Q
- common in Gram-negative bacteria
- form bundles at bacterial poles
- adhere tp sugar residues on host cells
- responsible for twitching motility/can “walk” across moist surfaces without flagella
A
Type IV Pili
14
Q
- produces shield to inhibit opsonization and phagocytosis
- usually polysaccharide/sometimes protein
A
capsule
15
Q
- more sugar residues
- produces shield to inhibit MAC formation
- Long O-antigen
A
Long LPS
16
Q
- shield that inhibits opsonization and phagocytosis
- related to binding antibodies
- Protein G
A
Surface protein with affinity for Fc of antibodies
17
Q
- possessing hyaluronic acid or sialic acid (common host molecule)
- not immunogenic
A
how capsule or LPS prevents opsonization
18
Q
- when original antibody mediated response is no longer effective because they cannot find their target
- variation when some proteins are changes
- switch when completely changes
- on/off when no longer produces
A
Antigenic switching
19
Q
- cirvumvention of natural barriers
- Avoids agglutination by antibodies
- e.g., enters through M cells, allowing breach of mucosal barrier without prior injury
A
disarming the enemy
20
Q
- production of IgA protease
A
Avoids agglutination by antibody
21
Q
- Receptor binding
- Invasin proteins
- effector proteins
A
mechanisms of intracellular pathogens to induce endocytosis/phagocytosis “hide”
22
Q
- replicate in phagosome, need to prevent phagosome/lysosome fusion
- replicate in cytoplasm, must escape from the phagosome
A
how intracellular pathogens enter host cells
23
Q
- siderophores that compete for iron
- removal or iron from hemoglobin, transferrin, or lactoferrin
- production of proteases
- production of hemolysins
A
how iron/nutrients are acquired from the host
24
Q
- actin from host aids in motility to infect neighboring cells
- cell-wide membrane damage results in necrotic cytolysis
A
dissemination
25
- break down DNA in pus (dead neutrophils)
DNases, dissemination
26
- degrade proteins in connective tissue
Collagenases, elastases, and proteases, dissemination
27
- degrade hyaluronic acid in host connective tissue
Hyaluronidases
28
- LPS (Endotoxin-Lipid A)
- LTA
Non-protein toxins
29
- binds TLRs on phagocytes
- strong cytokine response, stimulates vasodilation and capillary leakage
- active coagulation cascade (disseminated intravascular coagulation/hemorrhage)
- can cause septic shock and heath
LPS and LTA/ effect of non-protein toxins
30
- an inflammatory response triggered throughout the body
- due to bacteria or bacterial products in blood
- hypoglycemia and hypotension observed along with DIC thrombosis
septic shock
31
- bind to target cell surface and exert effect extracellularly
- do not enter host cell
- cause indirect damage due to overstimulation of immune system
- crosslink MHC on T cells
T-cell superantigens, actively released, protein exotoxin, indirect damage
32
- act on eukakaryotic cell membranes
membrane disrupting toxins, direct damage
33
- active only after entry into host cell
A-B dimeric/bicomponent toxins, direct damage
34
- bacteria usually not in blood
- cytokines produced by T cells
vs.
- live bacteria may be in blood
- cytokines produced mainly by phagocytes
superantigen/toxic shock vs. endotoxin/septic shock
35
- digestion of phospholipids
- formation of pores in membranes
two mechanisms of membrane-disrupting toxins
36
- binds host receptor
- allows for endocytosis into endosome
vs.
- enzymatically active inside the cell
- alters protein production
subunit B vs. subunit A in A-B toxins
37
How is the A subunit of the A-B toxin activated
Host cell cleaves sulfide bond, active when released
38
which secretion systems have an injectosomes that can deliver effector proteins into the cytosol of host cells
type III and IV
39
- structure similar to flagella
- promotes mainly G- survival
Type III secretion system
40
- effector proteins secretion along with DNA protein complexes
- G+ and G-
Type IV secretion system
41
which secretion system acts like a plunger, releasing effector proteins that kill, intoxicate, or hijack the target cell
Type VI
42
what in a lab
- increases safety
- streamlines routine procedures
- may be faster
- may be less prone to human error
total lab automation
43
what is usually used for the detection of mycobacteria?
acid-fast stain
44
what requires
- dyes that bind microorganisms
- rapid screening
- needs special dyes and microscopes
fluorescent microscopy
45
- can be modified to support growth of specific organisms
vs.
-supports growth of most bacteria
- haemophilus and neisseria will grow
blood agar vs. chocolate agar
46
used for antibiotic susceptibility testing
Mueller-hinton agar
47
helps recover low numbers of aerobic and anaerobic bacteria
thioglycolate broth
48
chocolate agar, blood agar, mueller-hinton agar, thioglycolate broth
non-selective enriched media
49
G- selective, lactose v non-lactose
MacConkey agar
50
staphylococcus, differentiates epidermis and aureus
Mannitol Salt Agar
51
salmonella, shigella and e coli
XLD agar
52
mycobacteria
LJ and Middlebrook agar
53
what are phenotypic and biochemical characteristics used for
e.g., api strip
species identification based on ability to ferment different nutrients
54
Immunofluorescence assay (IFA)
Enzyme-linked immunosorbent assay (ELISA)
Latex agglutination
Serological methods
55
direct evidence of bacterial cells or bacterial products present in sample (evidence of infection)
Detection of antigen
56
evidence of infection at some point in the past
Detection of antibody
57
- fluorescence
- colorimetric
- chemiluminescent
signals for immunoassays (ELISA all three, IFA first)
58
detects antigen
vs.
detects antibody or antigen
direct vs. indirect
59
- detects antigen directly
- useful for intracellular pathogens that cannot be cultured
- microscope slide with tissue cells
direct IFA
60
what type of assay results in an enhanced signal
Indirect IFA for detection of antigen
61
- operates like IFA
- uses a plate reader rather than a microscope
- can be biofluids or tissue
- assay can be quantitative
ELISA
62
what type of ELISA results in a higher specificity and sensitivity than regular ELISA
- can be direct or indirect
- capture antibody base
63
latex agglutination
- latex beads coated with antigen to detect antibody
vs.
- antibody coated to detect antigen
not quantitative, cheap easy and quick, lower sensitivity than IFA and ELISA
can test against several pathogens at once
indirect vs. direct
64
What is MALDI-ToF MS used for and what does it initially require that PCR does not
used for species identification, requires sample culture
65
- the epidermis, papillary dermis, and reticular dermis
- epidermis most protective
layers of the skin
66
- sample environmental antigens
- control commensal-specific T cells in the skin
- produce pro-inflammatory cytokines and chemokines to recruit immune cells
Langerhans cells and dermis DCs
67
- produce inflammatory cytokines and secrete histamine for recruiting T cells
mast cells
68
what doe neutrophils release in skin to immobilize pathogens along with secreting laminin to induce keratinocyte adhesion (which closes wounds)
neutrophil extracellular traps (NET)s
69
which cells induce antiviral state in the skin through IFNgamma and recruit other lymphocytes to the skin
CD8+ lymphocytes
70
which cells can localize around hair follicles, controlling commensal populations in proximity and releasing cytokines to modulate other cells
CD4+ lymphocytes
71
-cellulitis
-erysipelas
-impetigo
Inflammation of hair follicles:
-folliculitis
-furuncles
-carbuncles
superficial skin infections
72
What bacteria are superficial skin infections usually caused by
staphylococcus -- or streptococcus in cases of cellulitis erysipelas or impetigo
73
Group A strep
vs.
Group B strep
vs.
pneumoniae
beta hemolysis (complete destruction_, pyrogenes
vs.
beta hemolysis, agalactiae
vs.
alpha hemolysis
74
- is gram positive, arranged in chains
- can be part of normal flora
- person-to-person via droplets
- contact with break in skin
- transient infection of upper respiratory track and skin
- prone to different host cells
- only reservoir is humans
streptococcus pyrogenes
75
what causes
- impetigo (most common)
- erysipelas and cellulitis
- necrotizing fasciitis
- streptococcal toxic shock syndrome
streptococcus pyrogenes
76
- pus inducing
- most often caused by s. pyrogenes, clinically indistinguishable from s. aureus
- 10 day incubation
- 2-5 yr olds more likely to develop infection
- requires abrasion/cutaneous cuts
impetigo
77
pharyngitis (strep throat) -- common 5-15 yrs old
rheumatic fever, kidney infection (glomerulonephritis) -- risk in patients with prior pharyngitis
non skin infections caused by s. pyrogenes
suppurative (pus-inducing)
vs.
non-suppurative
78
is invasive GAS infection common, mortality rate?
- uncommon
- high mortality rate
79
- hyaluronic acid capsule
- fimbriae with M protein that binds Fc region and blocks binding of C3b
- fibronectin-binding adhesin
- pili
virulence factors of s. pyrogenes
80
has pore-forming toxins that can lyse red blood cells and directly damage MO and Neutrophils
SLS,SLO, and SPE (____ pyrogenic exotoxins) -- latter are superantigens
extracellular toxins secreted by s. pyrogenes
81
- mildly erythematous lesion
- extensive inflammation 24-72 hrs (dusty then purplish/bullae appear, bacteremia, metastatic)
- skin becomes gangrenous and undergoes extensive sloughing
- ill with high fever (high likelihood of mortality)
necrotizing fasciitis
82
- G+
- Beta hemolysis
- catalase negative
- PYR positive
- susceptible to bacitracin
- Group A antigen/antibodies
- M & F fimbriae protein + PCR
- coagulase negative
S. pyrogenes
83
what is main treatment for s. pyrogenes, use combination with what for systemic infections
-- resistance to tetracycline and sulfonamides is common
- increasing resistance to erythromycin and newer macrolides is increasingly common
beta lactams, clindamycin (protein synthesis inhibitor)
84
- G+ cocci
- arranged in clusters
- non-motile
- non-spore forming
- facultative anaerobes
- toxigenic
staphylococcus aureus
85
more common infections:
- impetigo
- folliculitis
- furuncles
- carbuncles
- cellulitis
- wound infections
less common infections:
- bacteremia
- toxin mediated diseases
s. aureus
86
- beta hemolysis
- coagulase positive
vs.
- gamma hemolysis
- coagulase negative
s. aureus vs. s. epidermidis
87
- skin that looks like boiled water was poured over it
- caused by exfoliative toxins (ETA-heat stable, ETB-heat liable, plasma mediated)
- proteases split bridges in skin cells, which leads to desquamation
- only affects top dermis layer, does not cause scarring
staphylococcal scalded skin syndrome
88
- usually seen in neonates and young children
- neutralizing antibodies against toxin develop and resolves in 7-10 days
- cultures can show s. aureus
staphylococcal scalded skin syndrome
89
- common in high absorbance tampons, trauma, wound infections
- toxin production requires oxygen and neutral pH (uncommon conditions in wound/abscesses)
- release of TSST-1 and entry of toxin into bloodstream
staphylococcal toxic shock syndrome (TSS)
90
- what leads to apoptosis in low concentrations by damaging mitochondrial membrane
- cell lysis at high concentrations
forms heptamer
Panton-Valentine leucocidin (PVL)
91
- small Gram-negative rod
- motile
- obligate aerobe
- opportunistic pathogen
- associated with nosocomial infections
Pseudomonas aeruginosa
92
- important nosocomial pathogen
- causes ~29% pulmonary infections in intensive care unit
- most common pathogen involved in sepsis
- can contaminate hospital-based water reservoir systems
- most common G-in burn wound infections
- primary (skin) secondary (associated with bacteremia)
p. aeruginosa
93
- hot tub folliculitis
- interdigital infections
- green nail syndrome
- burn wound infections
- ecthyma gangrenosum
primary skin infections caused by p. aeruginosa
94
- pili (adhesion)
- flagellum (motility)
- alginate polysaccharide capsule (immune evasion, biofilm, adhesion)
virulence factors of p. aeruginosa
95
- exotoxin A (disrupts protein synthesis in host cells)
- secreted enzymes (elastase, proteases, phospholipases -- dissemination)
- type III ss (injects toxins into cell)
secreted virulence factors of p. aeruginosa
96
- oxidase positive
- cannot ferment carbohydrates
- can grow on cetrimide agar
- growth at 42C
pseudomonas
