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MBIO 360 > Module 2 > Flashcards

Module 2 Flashcards

1
Q

What is the most common human pathogen?

A

H. influenzae

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2
Q

What is the cellular morphology of Haemophilus?

A

Pleomorphic

Gram negative

Coccobacilli

Pale staining

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3
Q

What due gives a darker stain with Haemophilus?

A

Carbon fuchsin

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4
Q

What are the growth requirements for Haemophilus?

A

Facultative (better growth with oxygen)

Increased CO2 enhances growth

35°C

Moist environment required

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5
Q

What growth factors does Haemophilus require?

A

X factor- synthesis of iron containing respiratory enzymes, hemin or protoporphyrin, heat stable

V factor- NAD, heat labile

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6
Q

What supplies factors X and V?

A

X- Hb, whole or lysed blood cells

V- lysed RBCs, other bacteria

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7
Q

What media can be used to grow Haemophilus?

A

Blood agar with Staph streak- clear, wet, glistening, nonhemolytic colonies

Chocolate agar- small, raised, grey, translucent colonies

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8
Q

Why can’t blood agar alone be used for Haemophilus growth?

A

NADase in RBCs inactivates NAD

Factor V may also be trapped in the cells

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9
Q

Why may you see Haemophilus growth in anaerobic blood cultures first?

A

Can grow anaerobically without V factor

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10
Q

What is required for Haemophilus genus ID?

A

Gram stain

BAP with Staph streak

BAP

Chocolate agar

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11
Q

What tests are used for Haemophilus genus ID?

A

Oxidase- negative with dimethyl reagent

Catalase- positive

No hemolysis (couple exceptions)

Commercial strips with growth factors- growth around required factors

Porphyrin (ALA)- determines whether an organism can synthesize X factor from ALA

Commercial ID kits- biochem and enzymatic test

Serological ID- slide agglutination for different capsular antigens

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12
Q

What is the reagent for the porphryin (ALA)?

A

Buffered delta-aminolevulenic acid

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13
Q

How is porphryin detected?

A

UV light- observation under Wood’s UV lamp shows red-pink fluorescence

Kovac’s reagent- added, colour change to red

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14
Q

What is the QC for the porphryin test?

A

Positive- H. parainfluenzae

Negative- H. influenzae and most other bacteria

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15
Q

What is the most virulent strain of capsulated Haemophilus?

A

B

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16
Q

What is the antimicrobial susceptibility of H. influenzae?

A

Ampicillin resistance has increased- due to B-lactamase (plasmid) and PCP alteration

Testing- nitrocefin, acidimetric and iodometric methods for B-lactamase testing (need disc diffusion for PCPs)

Chloramphenicol- rare resistance due to acetyl transferase

B-lactamase resistant penicillins, trimethoprim sulfa (SXT), amoxicillin-clavulanic acid

17
Q

What growth factors do each Haemophilus species need?

A

H. influenzae- X and V

H. parainfluenzae- V

H. haemolyticus- X and V

H. parahaemolyticus- V

18
Q

What species show hemolysis?

A

H. haemolyticus

H. parahaemolyticus

19
Q

What is the pathogenicity of H. influenzae?

A

Major cause of infections in children

Noncapsulated strains- NF in nasopharynx

Meningitis- increased WBC count

Acute epiglottitis

Pneumonia, sinusitis, conjunctivitis, osteomyelitis

20
Q

What is the pathogenicity of H. aegyptius?

A

Conjunctivitis

Brazilian purpuric fever

21
Q

What are the characteristics of H. haemolyticus?

A

Beta hemolysis

X and V factors

Porphryin test- negative

NF of nasopharynx

Endocarditis and abscesses of internal organs

22
Q

What are the characteristics of H. parahaemolyticus?

A

Filamentous

Beta hemolytic

Requires V factor

Porphryin test- positive

NF of respiratory tract

Rarely causes infections

23
Q

What are the characteristics of H. ducreyi?

A

STI

Clusters/schools of fish

Within or outside PMNs

Catalase- negative

Oxidase- negative

ALA- negative

Can’t use X, V or X/V discs

Plasmid mediated resistance to most antimicrobials except third gen cephalosporins, fluoroquinolones and macrolides

24
Q

What genera belong to the family Pasteurellaceae?

A

Haemophilus

Actinobacillus

Pasteurella

MBIO 360 (14 decks)

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