Micro442 Exam 2

Front 1

Mechanism of Staphylococcal Toxic Shock Syndrome Toxin 1 (TSST-1)?

Back 1

Binds beta chain of TCR nonspecifically --> 20% of all T cells activated --> cytokine storm, systemic inflammation, shock

Front 2

What percentage of staph aureus strains produce TSST-1?

Back 2

<10%

Front 3

Function of Staphylococcal coagulase?

Back 3

forms complex w/prothrombin: STAPHYLOTHROMBIN that converts/polymerizes fibrinogen into fibrin clots.

Front 4

Which Staphylococcal enzymes function in the degradation of skin?

Back 4

lipases
glycerol ester hydrolases

Front 5

Function of Staphylococcal alpha-toxin?

Back 5

forms trans-membrane pores that allow egress of vital molecules

Front 6

Function of Staphylococcal Panton-Valentine Leukocidin (PVL)?

Back 6

effective at lysing PMNs in vitro.
may indicate especially invasive S. aureus strain.

Front 7

Function of Staphylococcal gamma-toxin?

Back 7

lyses PMNs in vitro

Front 8

What is a furuncle and where does it develop?

Back 8

-well defined abscess containing pus enclosed by a fibrin capsule
-forms in the skin, often in a hair follicle or sebaceous/sweat gland
-result of tissue destruction by alpha toxin

Front 9

What disease results from spread of furuncles?

Back 9

multiple furuncles may coalesce into a carbuncle

disseminated deep tissue infections result in cellulitis

Front 10

Which abx are used for tx of Staph saprophyticus UTI's?

Back 10

fluoroquinolones

Front 11

What % of UTI's are caused by Staph Saprophyticus?

Back 11

10-20%
2nd most common cause of UTI's in young women

Front 12

Dx methods for S. aureus infections?

Back 12

Cx overnight growth of catalase positive, coagulase positive GPC in clusters on BA

Blood cultures usually negative for deep abscesses other than endocarditis, osteomyelitis, and arthritis (muscle/bone stuff).

Front 13

Pathogenesis of Staphylococcal food poisoning?

Back 13

only toxins (not cells) necessary for sickness.

enterotoxins A through E
heat-stable (not necessarily destroyed by cooking!)

+ serotonin release in GI tract --> vomiting

Front 14

Pathogenesis of STSS?

Back 14

caused by TSST-1 or enterotoxins B or C, superantigens

High fever, vomiting, diarrhea, sore throat, muscle pain -> in 48 hrs can progress to shock due to massive T cell activation, cytokine storm

Front 15

Pathogenesis of bullous impetigo?

Back 15

superifcial skin infection by S. aureus, usually young children

production of exfoliatin results in fluid-filled, red, itchy blisters filled w/bacteria.

blisters break and scab over w/yellow crust.

Front 16

pathogenesis of scalded skin syndrome?

Back 16

redness, skin peeling off in sheets due to production of exfoliatin at site of infection (may not be clinically apparent) and beyond

most common in <5 y/o

face, armpit, groin affected first; may spread over entire body

Front 17

Which adhesion factors does Staph aureus employ?

Back 17

Fibronectin Binding Proteins: FnbpA, FnbpB

Collagen Binding Proteins

Front 18

What is the functions of Staph aureus Protein A?

Back 18

Binds Fc portion of antibodies to inhibit their ability to trigger phagocytosis.

Front 19

How does Staph aureus evade the immune system?

Back 19

-capsule (inhibit phagocytosis)
-exopolysaccharide --> biofilm formation, resists phagocytosis
-protein A production

Front 20

What abx are Staphylococci resistant to, and why are they resistant?

Back 20

resistant to classical PENICILLINS

PENICILLINASE or BETA-LACTAMASE enzyme allows degradation of beta-lactam abx.

Front 21

What is the mechanism of Staphylococcus' methicillin resistance?

Back 21

Pbp2a (Penicillin Binding Protein 2a) has low beta-lactam affinity --> retains transpeptidase activity and can still make cell wall in presence of methicillin

beta-lactams normally bind PBP and block its transpeptidase activity. PBP2a is mutant.

Front 22

Function of Staphylococcal exfoliatin?

Back 22

ser protease
disrupts desmosomes (cell junctions)

Front 23

Function of Staphylococcal hyaluronidase?

Back 23

hydrolyzes connective tissue
(hyaluronic acid is a component of connective tissue.)

Front 24

Function of Staphylococcal enterotoxin?

Back 24

+ serotonin release in GI tract --> vomiting

Front 25

Toxins produced by Bordetella pertussis?

Back 25

TCT (tracheal cytotoxin)
PT (pertussis toxin)
ACT (adenylate cyclase toxin)

Front 26

List all the AB subunit toxins we've discussed.

Back 26

Pertussis Toxin
Diphtheria Toxin
Botulinum Toxin
Cholera Toxin
Anthrax Toxin
Tetanus Toxin

Front 27

Which of the Rickettsiae and Chalmydiaciae can be cultured on a plate in lab?

Back 27

Bartonella spp.

Front 28

Which two bacteria cause meningitis following hematogenous spread after a respiratory infection?

Back 28

N. meningitidis
H. influenzae

Front 29

What mutations cause Pseudomonas aeruginosa to exhibit increased biofilm formation?

Back 29

MUCOID: mucA mutation --> increased Alginate production

WRINKLY: WspF mutation --> increased cdGMP production --> increased pel, psl gene expression

Front 30

What is unique about the structure of Mycoplasma pneumoniae?

Back 30

no peptidoglycan cell wall!

cell wall is sterols stolen from host.

Front 31

Function of Mycoplasma pneumoniae's terminal organelle?

Back 31

Adhesion to host cell (ciliated resp. epithelium)

P1 protein = adhesin, trafficks to terminal organelle and binds host glycopeptides

Also contains actin for coordinating cytoskeletal activities.

Front 32

What causes Q fever?

Back 32

Coxiella burnetii

Front 33

What causes Rocky Mountain Spotted Fever?

Back 33

Rickettsia rickettsii

transmitted by ixodes ticks

Front 34

How do GC and MC evade host immunity?

Back 34

-IgA protease
-pili phase variation
-vary Opa, Por types
-Sialic acid attachment to LOS may block AB binding

Front 35

How does Treponema pallidum evade host immunity?

Back 35

Vary surface Ag with TprK gene

Front 36

How do Borrelia recurrentis and hermesii evade host immunity?

Back 36

~30 vlp/vsp alleles moved from linear plasmid to another plasmid for expression.

serovar switching in population concurrent with fever spikes.

Front 37

What are the two vectors and species that cause relapsing fever?

Back 37

TICK (saliva/feces) Borrelia hermesii.

LOUSE (hemolymph--only if crushed!): B. recurrentis

Front 38

How does Corynebacterium diphtheriae regulate diphtheria toxin production?

Back 38

DtxR gene: repressor turned OFF in low Fe2+ environments (ex. human) --> Dtx expressed.

Front 39

Which toxins are phage-encoded?

Back 39

Diphtheria toxin
Botulinum toxin
Pseudomonas cytotoxins
S. aureus: enterotoxin, exfoliatin

Front 40

Which diseases are transmitted by ticks?

Back 40

Lyme Disease (B. burgdorferi)
Rocky Mountain Spotted Fever (R. rickettsii)
Relapsing Fever (B. hermesii)
Human Monocytic Ehrlichiosis (E. chaffeensis)
Human Granulocytic Ehrlichiosis (Anaplasma phagocytophilum)

Front 41

Which diseases are transmitted by lice?

Back 41

Relapsing Fever (Borrelia recurrentis)
Trench Fever (Bartonella quintana)
Typhus group fevers (Rickettsiae)

Front 42

What is the main killer of whooping cough pts?

Back 42

dehydration, malnutrition, anoxic brain damage

Front 43

How does Bordetella pertussis regulate TCT, ACT, PT production?

Back 43

2-component regulatory system: Bvg genes

Front 44

Attack rate of Bordetella pertussis/whooping cough in unimmunized population?

Back 44

>95%

Front 45

How does Pertussis Toxin work?

Back 45

ADP-ribosylates a Gprotein --> ++host cAMP --> alter lymphocyte homing and function.

Front 46

Which bug has Elementary Bodies and Reticulate Bodies?

Back 46

Chlamydia trachomatis

Front 47

What serovars of C. trachomatis cause Trachoma?

Back 47

A B Ba C

Front 48

What serovars of C. trachomatis cause STD?

Back 48

D-K, L1, L2, L3

Front 49

What serovars of C. trachomatis cause LGV?

Back 49

L1, L2, L3

Front 50

Describe stages of LGV.

Back 50

Genital lesion

Suppurative inguinal lymphadenopathy, fever, headache, chills

Fibrotic changes (formation of xs connective tissue), multiple draining fistulas

Front 51

Describe stages of Lyme Disease.

Back 51

ECM-target lesion at tick bite. (must be attached for >24hr)

Neurologic/cardiac abnormalities, headache, neck and muscle pain, conjunctivitis (weeks after ECM)

Arthritis (months-years after ECM)

Front 52

Describe stages of Syphilis.

Back 52

genital chancre, painless indurated lesion; localized lymphadenopathy

1-3mos later: general lymphadenopathy, rash (foci are where treponemes are proliferating)

2-50yr later: latency OR benign gummatous lesions OR cardiovascular/neurological complications

Front 53

Which diseases are zoonoses?

Back 53

Leptospirosis
Psittacine Fever/Parrot Fever
Rickettsiae and Chlamydiaciae diseases (Rocky Mtn, Cat scratch, Trench, Q Fevers; HGE, HME)

Front 54

What determines whether C. trachomatis causes Trachoma vs. STD/LGV?

Back 54

-serotype
-route of infection: eyes/fomites (trachoma) vs. sexual contact (LGV/STD)

Front 55

Function of metronidazole?

Back 55

disrupt DNA helix --> no replication

Front 56

Function of linezolid?

Back 56

bind 50S ribosomal subunit --> no translation initiation

Front 57

Function of tetracyclines?

Back 57

bind 30S ribosomal subunit --> charged tRNA cannot enter

Front 58

Function of quinolones, fluoroquinolones?

Back 58

attacks gm- DNA gyrase, gm+ topoisomerase IV --> no DNA replication/repair

Front 59

Function of vancomycin?

Back 59

binds NAG/NAM peptide tails --> PBP cannot form crossbridges.

Front 60

Function of Macrolides?

Back 60

binds 50S ribosomal subunit --> no protein synthesis

Front 61

Function of aminoglycoside abx?

Back 61

binds 30S ribosomal subunit --> misread or truncate proteins

Front 62

Which abx disrupt cell wall synthesis?

Back 62

penicillins
cephalosporins
imipinem
vancomycin (glycopeptides)

Front 63

Function of rifampin?

Back 63

binds beta subunit of RNA pol --> no transcription.