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micro quiz 2 > MICR_041813 haemo_bordetella > Flashcards

MICR_041813 haemo_bordetella Flashcards

1
Q

What are some characteristics of haemophilus influenza (Hi)?

A

gram (-) bacillus or coccobacillus, non-motile, non-spore forming, can be either encapsulated (typeable) or unencapsulated (non-typeable)

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2
Q

What does encapsulated (typeable) haemophilus influenza cause?

A

acute meningitis in young children

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3
Q

What does UNencapsulated (non-typeable) haemophilus influenza cause?

A

ear aches + respiratory disease; predominant form in population

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4
Q

What is the critical virulent component of encapsulated (typeable) haemophilus influenza?

A

capsule - required for virulence because it confers anti-phagocytic properties

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5
Q

There are 6 serotypes of encapsulated (typeable) haemophilus influenza. What’s the difference between them? Which one is the most virulent?

A

Types a-f. Type B has a ribose, while the rest has hexose. Type B is the most virulent one.

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6
Q

What is the most common cause of meningitis in children under 4 y.o. up until the 90s?

A

type B encapsulated haemophilus influenza; reduction due to antibiotics and vaccines

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7
Q

What kinds of symptoms can encapsulated haemophilus influenza cause? (5)

A

1) nasopharyngitis w. otitis media or sinusitis, 2) epiglottis + obstructive laryngitis, 3) cellulitis (rash), 4) pyarthrosis (pus in joint), 5) pneumonia

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8
Q

What is the mechanism of pathogenesis of encapsulated haemophilus influenza?

A

aerosol droplets are inhaled, leading to respiratory tract colonization

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9
Q

What are 3 virulence factors that encapsulated haemophilus influenza produce?

A

1) IgA protease - aids in immune evasion. 2) LPS - induces ciliary stasis. 3) capsule - antiphagocytic properties

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10
Q

What are the 3 types of immunity can be developed against encapsulated haemophilus influenza?

A

1) passive immunity (0-4mo.), 2) acquired immunity (3-4yo), 3) vaccine

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11
Q

When is the most susceptible age to encapsulated haemophilus influenza?

A

6-12mo

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12
Q

What is the vaccine against encapsulated haemophilus influenza?

A

conjugated capsular vaccine: capsule protein (PRP) linked to diphtheria toxoid to increase dependence of T cells/memory and to increase immunogenicity

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13
Q

How would you treat encapsulated haemophilus influenza?

A

Ampicillin, 3rd generation cephalosporin (cefotaxime, ceftrixone), Augmentin (ampicillin + clavulanate)

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14
Q

What are some complications of encapsulated haemophilus influenza?

A

residual neurological damage, which can be reduced by incorporating corticosteroid into the treatment regime to reduce inflammation

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15
Q

Where does UNencapsulated (non-typeable) haemophilus influenza usually infect?

A

generally respiratory tract and ear, but can also cause conjunctivitis or meningitis (usually in patients with predisposing factors, such as trauma, sinusitis, CSF leak)

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16
Q

What are the virulence factors that UNencapsulated haemophilus influenza produce? (2)

A

1) adhesion molecules (Hap, HMW1/2, Hia, Hsf), 2) biofilm, which confers antibiotic resistance

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17
Q

T/F UNencapsulated haemophilus influenza is an intracellular pathogen.

A

False. It is an intracellular AND extracellular pathogen

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18
Q

What are the 3 routes that UNencapsulated haemophilus influenza use to invade cells?

A

1) macropinocytosis, 2) paracytosis (between tight junctions), 3) LPS-platelet activating factor

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19
Q

What are the 3 types of immunity can be developed against UNencapsulated haemophilus influenza?

A

1) passive immunity (0-4mo.), 2) adults are susceptible to infection; not sure if long-term immunity develops b.c. of strain variation, 3) NO vaccine

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20
Q

How would you treat UNencapsulated haemophilus influenza? (3)

A

1) amoxicillin, 2) amoxicillin w. b-lactamase inhibitor (clavulanate), 3) ceftriaxone

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21
Q

T/F UNencapsulated haemophilus influenza is an obligate anaerobe.

A

False. It’s a facultative anaerobe

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22
Q

Why are UNencapsulated haemophilus influenza considered “fragile”?

A

it is susceptible to disinfectants and drying

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23
Q

T/F encapsulated haemophilus influenza can spontaneously convert to UNencapsulated haemophilus influenza.

A

True.

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24
Q

Why is UNencapsulated haemophilus influenza considered a fastidious pathogen?

A

it requires growth factors X (hemin) and V (NAD or NADP) to grow.

25
Q

What type of medium would be appropriate for UNencapsulated haemophilus influenza? Inappropriate?

A

appropriate: CHOCOLATE AGAR, because the heating causes RBCs to release X, V via actions of staphylococci and streptococci. Inappropriate: BLOOD AGAR because it lacks factors X, and V

26
Q

How would you diagnose UNencapsulated haemophilus influenza?

A

1) blood + CSF culture - gram stain followed by growth on chocolate agar. 2) immunofluorescence - detect type B capsular antigen in spinal fluid. 3) biochemical tests

27
Q

What vaccine is available for UNencapsulated haemophilus influenza?

A

conjugate vaccine of H1b polysaccharide and carrier protein

28
Q

What does bordetella pertussis cause?

A

whooping cough

29
Q

What are some characteristics of bordetella pertussis?

A

gram (-) coccobacillus, obligate aerobe

30
Q

What are the hosts of bordetella pertussis?

A

humans only

31
Q

What is the epidemiology of bordetella pertussis?

A

highest fatality in children; immunization caused a dramatic decline

32
Q

What are the clinical features of bordetella pertussis?

A

upper respiratory symptoms characterized by two stages: 1) catarrhal stage, 2) paroxysmal stage

33
Q

What is the catarrhal stage of a bordetella pertussis infection?

A

runny nose, sneezing, low grade fever w. a mild occasional cough

34
Q

What is the paroxysmal stage of a bordetella pertussis infection?

A

burst of coughing (to dislodge mucus) followed by a high pitch “whoop” and occasional vomiting. Pts can turn blue/cyanotic.

35
Q

What is the pathogenesis of bordetella pertussis?

A

1) inhaled respiratory droplets 2) adherence to ciliated epithelial cells 3) multiplication and production of toxins, 4) local inflammation + mucous production, 5) patchy ulceration of respiratory epithelium, 6) diminished O2 supply and pneumonia

36
Q

T/F bordetella pertussis has the potential to cause bacteremia

A

No. it does not invade the bloodstream, it remains in the respiratory tract.

37
Q

What are the virulence factors (toxins) that bordetella pertussis produce? (4)

A

1) Dermonecrotic Toxin, 2) Tracheal cytotoxin, 3) Adenylate cyclase toxin, 4) Pertussis toxin (THINK: DTaP - same as the vaccine that is available!!)

38
Q

How does the pertussis toxin aid in bordetella pertussis’s virulence?

A

inhibits adenylate cyclase, leading to cAMP ACCUMULATION. Leads to lymphocytosis, histamine sensitization, and insulin production

39
Q

How does the adenylate cyclase toxin aid in bordetella pertussis’s virulence?

A

it catalyzes cAMP PRODUCTIONdirectly from ATP; IMPAIRED MACROPHAGE FXN and can cause CELL LYSIS

40
Q

How does the demonecrotic toxin aid in bordetella pertussis’s virulence?

A

aka “Heat-Labile Toxin”, which causes smooth muscle contraction that result in ischemic NECROSIS and INFLAMMATION of lung tissue

41
Q

How does the trachael cytotoxin aid in bordetella pertussis’s virulence?

A

causes CILIOSTASIS, KILLS trachael epithelial cells, promotes CYTOKINE RELEASE

42
Q

What does the bordetella pertussis use to attach to lung epithelium? (4)

A

1) pili, 2) filamentous hemagglutinin (FHa), 3) pertactin, 4) trachael colonization factor

43
Q

T/F immunization with DTaP provides lifelong immunity.

A

False. It does not confer life-long immunity

44
Q

What is the difference between DTP and DTaP?

A

both are trivalent vaccines, but DTP can cause encephalopathy and permanent neurological sequelae. DTaP contains acellular pertussis and avoids problems observed with DTP

45
Q

How would you diagnose bordetella pertussis?

A

Using nasopharyngeal swabs, use 1) PCR, 2) culture test, 3) antibody test

46
Q

How would you treat bordetella pertussis?

A

Erythromycin, Tetracycline, Chloramphenicol

47
Q

What are the virulence determinants of proteus vulgaris/proteus mirabilis? (2)

A

flagella (“swarming” motility) and urease

48
Q

Why is urease production importance in the pathogenicity of proteus vulgaris/proteus mirabilis?

A

it converts urea into ammonia, which increases the pH/alkalinity of the urine, leading to an increase in chronic UTI

49
Q

Where is acinetobacteria normally found?

A

opportunistic infection in hospitalized patients, often associated with use of indwelling medical devices (IVs, grafts)

50
Q

What are the virulence factors of acinetobacteria?

A

capsule, adhesins, proteolytic and lipolytic enzymes

51
Q

What is characteristic of acinetobacteria that cause opportunistic infections?

A

multi-drug resistant strains are increasing

52
Q

How can you diagnose gram (-) pathogens? (3)

A

colony morphology, selective medium, and biochemical tests.

53
Q

Which gram (-) pathogens are facultative anaerobes?

A

1) proteus mirabilis, 2) e. coli, 3) enterobacter cloacae, 4) klebsiella pneumonia, 3) serratia marcesens (THINK: facultative anaerobe PEEKS out every once in a while for air)

54
Q

Which two gram (-) pathogens are aerobes?

A

1) acinetobacteria, 2) pseudomonas aeruginosa (THINK: aerobes Prefer Air)

55
Q

Which 3 gram (-) pathogens are lactose fermenters?

A

1) e. coli, 2) klebsiella pneumonia, 3) enterobacter cloacae

56
Q

How can Shigella be prevented?

A

better sanitation

57
Q

What is the Kigler Iron Agar test?

A

biochemical test that detects sugar (glucose, lactose) fermentation and gas (H2S) production

58
Q

How do you intepret a Kigler Iron Agar test?

A

Yellow Slant = fermented lactose. Yellow BUTT = fermented glucose. BLACK PPT = H2S production.

micro quiz 2 (8 decks)

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