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Microbiology > Unit 3: Moraxella, Alcaligenes, Neisseria > Flashcards

Unit 3: Moraxella, Alcaligenes, Neisseria Flashcards

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Biology 101 flashcards
1
Q

What does Moraxella bovis cause and in what species?

A

infectious bovine keratoconjunctivitis in cattle

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2
Q

What other bacteria is commonly associated with infectious bovine keratoconjunctivitis?

A

M. bovoculi

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3
Q

What does Moraxella bovis look like on gram stain?

A

gram negative short rods or cocci - found in pairs or short chains

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4
Q

What do colonies of Moraxella bovis look like?

A

1 mm colonies on BAP at 48 hours - they are hemolytic, flat, small, and tend to corrode the agar

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5
Q

In regards to oxygen, what type of organism is Moraxella bovis?

A

it is a strict aerobe

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6
Q

Is Moraxella bovis oxidase positive or negative?

A

positive

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7
Q

What does Moraxella bovis due to litmus milk?

A

it alkalinizes it

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8
Q

What is the function of fimbriae in Moraxella bovis infection?

A

to attach to the corneal epithelium

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9
Q

What toxins does Moraxella bovis release?

A

RTX toxin

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10
Q

What is the function of the RTX toxin of Moraxella bovis?

A

it lyses corneal epithelial cells, neutrophils, and RBCs

The neutrophils release their degradative enzymes onto the surface of the cornea and can cause extensive damage

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11
Q

What enzymes does Moraxella bovis release?

A

hyaluronidase, fibrinolysin, aminopeptidase, phosphoamidase, phosphatase

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12
Q

What is the functions of the enzymes that Moraxella bovis releases?

A

to break down the junctions between corneal epithelial cells and initiate an inflammatory response

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13
Q

What is the natural habitat of Moraxella bovis?

A

conjunctiva of cattle

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14
Q

When is infectious bovine keratoconjunctivitis common?

A

in summer and fall

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15
Q

What is infectious bovine keratoconjunctivitis associated with (environment)?

A

dust, UV light, face flies, and long, stemmy pastures

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16
Q

What is thought to initiate infectious bovine keratoconjunctivitis?

A

dubtle damage to the corneal epithelium that initiates the disease

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17
Q

What is the pathogenesis of infectious bovine keratoconjunctivitis?

A

Mycoplasma bovoculi infects the areas of subtle damage to create additional damage. Moraxella bovis takes over and creates a mild to severe inflammatory response. The cornea becomes opaque and may ulcerate, leading to blindness

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18
Q

During acute disease of infectious bovine keratoconjunctivitis what clinical signs are seen?

A

inappetence and poor weight gain

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19
Q

Do cattle get better immunity against Moraxella bovis when they recover from it?

A

no - they can just get reinfected with another fimbrial type

20
Q

What is used to reduce the severity of a Moraxella bovis infection?

A

fimbrial bacterins

21
Q

What treatments are useful for Moraxella bovis infection?

A

steroids, tylosin, long-acting tetracyclines, subconjunctival injections of penicillin and steroids, florfenicol, eye patches, various eye ointments, dyes, powders, and salt
NONE OF THESE ARE TECHNICALLY ALLOWED

22
Q

What is Moraxella ovis typically isolated from?

A

pinkeye infections in sheep and cattle

23
Q

What used to be the cause of pinkeye in humans but is isolated only rarely now?

A

Moraxella lacunata

24
Q

What are some other species of Moraxella been recognized as the cause of?

A

oititis media in children and respiratory infections in adults

25
Q

What does Alcaligenes look on gram stain?

A

they are gram negative rods

26
Q

In regards oxygen, what type of organisms are Alcaligenes?

A

obligate aerobes

27
Q

Is the genus Alcaligenes urease positive or negative?

A

negative

28
Q

Is the genus Alcaligenes oxidase positive or negative?

A

positive

29
Q

What is the natural habitat of the genus Alcaligenes?

A

water, soil, intestinal tract of vertebrates as a saprophyte

30
Q

What clinical materials is the genus Alcaligenes typically isolated from?

A

blood, sputum, urine, ears, spinal fluid, wounds, IV solutions, and catheters

31
Q

What are the two important species of the genus Neisseria?

A

Neisseria meningitidis and Neisseria gonorrhoeae

32
Q

What is Neisseria meningitidis and Neisseria gonorrhoeae the cause of?

A

meningococcal meningitis (N. meningitidis) and gonorrhea in humans (N. gonorrhoeae)

33
Q

What do Neisseria meningitidis and Neisseria gonorrhoeae look like on gram stain?

A

gram-negative cocci

34
Q

What other Neisseria species is associated from bite wounds?

A

Neisseria canis

35
Q

What do the major Neisseria species require for growth?

A

iron-containing media as well as starch, cholesterol, or albumin (to neutralize the effect fatty acids that inhibit growth of the organisms)

36
Q

Are the major Neisseria species oxidase positive or negative?

A

positive

37
Q

What is Neisseria meningitidis the cause of?

A

20% of the meningitis seen in humans

38
Q

What is the natural habitat of Neisseria meningitidis?

A

the nasopharynx of a large percentage of humans

39
Q

What serogroup of Neisseria meningitidis causes the majority of meningitis cases in the United States?

A

serogroup B

40
Q

What is the role of IgA in the pathogenesis of Neisseria meningitidis?

A

IgAs that bind to N. meningitidis are very poor at opsonizing and fixing complement. IgA binding to these organisms blocks the adherence of specific opsonizing IgM and IgG. In the abscence of opsonization by IgM or IgG, these organisms are not readily killed by phagocytic cells. Disseminated disease has been linked to the presence of blocking IgA in the serum of affected patients

41
Q

What does severe disease caused by Neisseria meningitidis look like?

A

fever, prostration, DIC, gram-negative shock, and a characteristic petechial eruption on the skin due to vascular thrombosis

42
Q

What organism is responsible for the most common venereal disease in humans?

A

Neisseria gonorrhoeae

43
Q

What are the three important virulence factors released by Neisseria gonorrhoeae?

A

lipooligosaccharide, peptidoglycan monomers, and IgA protease

44
Q

What is the role of lipooligosaccharide that is released by Neisseria gonorrhoeae?

A

It damages host cells. It causes a loss of ciliary activity and sloughing of ciliated epithelium

45
Q

What is the role of peptidoglycan monomers released by Neisseria gonorrhoeae?

A

these damage ciliated epithelial cells, activate complement, and modulate mononuclear cell proliferation

46
Q

What is the pathogenesis of Neisseria gonorrhoeae?

A

Colonization occurs on the mucosal surfaces line with columnar epithelial cells. Initial attachment is via fimbriae and subsequently solidified by outer membrane proteins. Invasion and intracellular residence occurs in the mucosae of the cervix or urethra and the organism is transcytosed to the basal surface of these cells

Microbiology (50 decks)

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