Moraxella, Alcaligenes, and Neisseria

Question 1

What are the names of the organisms within the genus Moraxella and list the species they are associated with?

Answer 1

Moraxella bovis (cattle)

Moraxella ovis (sheep and cattle)

Moraxella lacunata (humans)

Question 2

Moraxella bovis is resposible for causeing what DZ in cattle

Answer 2

Infectious bovine keratoconjunctivitis (pinkeye or IBK)

Question 3

What are the other two organisms which are have been implicated in some cases of pinkeye in cattle?

Answer 3

Moraxella bovoculi and Moraxella ovis

Question 4

Describe the distinguishing morphology of Moraxella bovis

Answer 4

Short rods or cocci

Found in pairs or short chains often with adjacent sides flattened

Virulent strains have fimbriae which are readily lost on subculture

Question 5

Biochemically describe Moraxella bovis

Answer 5

• Non-fermentative
• Oxidase positive
• Alkalinizes litmus milk in three zones
• Strict aerobe

Question 6

List the toxins of Moraxella bovis

Answer 6

Fimbriae

Cytotoxin

Hemolysin

Enzymes: Hyaluronidase, Fibrinolysin, Aminopeptidase,Phosphoamidase, Phosphatase

Question 7

1. What does the Fimbriae toxin of Moraxella bovis provide for the cell?
2. What about the cyotoxin?

Answer 7

1. Fimbriae: Help attach the organism attach to the corneal epithelium
2. Cytotoxin: is an RTX toxin (pore forming) that lyses corneal epithelial cells and neutrophils. The neutrophils release their degradative enzymes onto the surface of the cornea and can cause extensive damage.

Question 8

What does the hemolysin toxin of Moraxella bovis provide for the cell?

Answer 8

Hemolysin: loss of hemolysin correlates with a loss of virulence. Hemolysin is an RTX toxin (pore forming) that lyses corneal epithelial cells and neutrophils. Similar action as cytotoxin

Question 9

List the enzyme toxins which Moraxella bovis produces

Answer 9

Hyaluronidase

Fibrinolysin

Aminopeptidase

Phosphoamidase

Phosphatase

Question 10

True or False

Collagenase enzyme is produced by the Moraxella bovis organism. and is responsible for assisting in the degradation of the surface of the cornea.

Answer 10

False

No collagenase produced by this organism. However, collagen is broken down when the animal’s PMN’s release degradative hydrolytic enzymes on the surface of the cornea.

Question 11

What is the normal habitat for the Moraxella bovis organism?

Answer 11

Conjunctiva of cattle. Non-invasive under normal conditions.

Question 12

What is the pathogenesis of a Moraxella bovis organism?

Answer 12

Subtle damage to the corneal epithelium that initiates the disease –> generally Mycoplasma bovoculi moves in and creates further damage –> Moraxella bovis then creates a mild to severe inflammatory response –> cornea becomes opaque and may ulcerate –> blindness

Question 13

List some treatment options for a cow infected with Moraxella bovis?

Answer 13

Sulfas with steroids

Tylosin

Long-acting tetracyclines

Subconjunctival injections w/ penicillin and steroids

Eye patches

Powders (furacin) salt (ouch…)

Question 14

Moraxella ovis is associated with what Dz in sheep and cattle?

Answer 14

Pinkeye

Question 15

Moraxella lacunata has been associated with what Dz in what species?

Answer 15

Pinkeye in humans

Question 16

1. Where are Alcaligenes generally found?
2. What are three general characteristics?

Answer 16

1. Occurs in water, soil, intestinal tract of vertebrates as a saprophyte
2. Gram-negative rods, obligate aerobes (some exceptions), motile, urease negative. Oxidase positive.

Question 17

What role do Alcaligenes primarily play?

Answer 17

Generally a role as a contaminant

Question 18

What are the two primary orgainsms of Neisseria which we talked about in class?

Answer 18

• Neisseria meningitidis*
• Neisseria gonorrhoeae*

Question 19

List the common morphological features of Neisseria sp.

Answer 19

Gram-negative cocci

Tend to appear in pairs with adjacent sides flattened

Question 20

Why are species belonging with to the genus Neisseria difficult to culture?

Answer 20

They have complex nutritional requirements:

• Require iron-containing media for growth
• Starch, cholesterol or albumin need to be added to the media to neutralize the effects of fatty acids that inhibit the growth of the organisms

Question 21

True or False

Species from the genus Neisseria have a strong oxidase positive test result

Answer 21

TRUE

These organisms are strongly oxidase positive!

Question 22

What Dz does Neisseria meningitidis cause?

Answer 22

Meningococcal meningitis

Disease can vary from a mild febrile episode with pharyngitis to fulminant septicemia. The majority of overt disease presents as septic shock and/or meningitis. Severe disease is marked by fever, prostration, DIC, Gram-negative shock, and a characteristic petechial eruption on the skin due to vascular thrombosis.

Question 23

What is the natural habitat for Neisseria meningitidis?

Answer 23

The nasopharynx of humans

Question 24

What two specific groups are expected to have the highest carrier rates of Neisseria meningitidis?

Answer 24

Military recruits (as high as 90%)

Teenagers (30%)

Question 25

1. What is the serogroup of Neisseri meningitidis responsible for majority of the cases which are reported in the U.S?
2. What are the other serogroups?

Answer 25

1. Serogroup B organisms (50-55%)
2. Serogroups C, W135, Y, and A (20, 15, 10, and 1% respectively)

Question 26

The meningococcal meningitis Dz from Niesseria meningitidis tends to occur most frequently to what two groups of people?

Answer 26

Those in day care (children 6 to 24 mths) and military recruits

Question 27

Name the two important factors of Neisseria meningitidis’s pathogenesis

Answer 27

IgA

Shared antigens

Question 28

What is the significance in the pathogenesis of Neisseria meningitidis’s correlation to IgA?

Answer 28

Disseminated disease has been linked to the presence of blocking IgA in the serum of affected patients.

IgA class antibodies 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. Disabling killing of these organims by phagocytic cells.

Question 29

What is the significance in the pathogenesis of Neisseria meningitidis’s correlation to Shared antigens?

Answer 29

Shared antigens between N. meningitidis and certain enteric flora such as E. coli and Enterococcus faecalis may lead to the production of IgA specific for certain serogroups.

These organisms infect the intestinal mucosa and by doing so tend to stimulate the production of a systemic immune response that is primarily IgA in character. This IgA could then function as a blocking antibody and be responsible for the dissemination of the bacterium into the bloodstream.

Question 30

True or false

Neisseria gonorrhoeae in the U.S. alone has 400,000 cases reported per year and is considered one of the most common venereally transmitted disease.

Answer 30

True…

Question 31

List three virulenc factors of Neisseria gonorrhoeae and their function if known

Answer 31

Lipooligosaccharide: Damages host cells. It causes a loss of ciliary activity and sloughing of ciliated epithelium. Antibody against the LOS is bactericidal.

Peptidoglycan monomers: These damage ciliated epithelial cells, activate complement and modulate mononuclear cell proliferation.

IgA protease: Cleaves IgA preventing binding

Question 32

What does Neisseria gonorrhea used for initial attachment to the mucosal surface?

Answer 32

Initial attachment via pili and attachment solidified by outer membrane proteins

Question 33

Where does invasion of Neisseria gonorrhoeae occur at?

Answer 33

Invasion and intracellular residence occurs in the mucosae of the cervix or urethra and the organism is transcytosed to basal surface of these cells.

Question 34

Some individuals have substantial protection to N. gonorrhea. How is this?

Answer 34

Through the presence of “natural antibodies” that are generated in response to cross-reactive antigens on other Gram-negative bacteria.