Moraxella, Alcaligenes, and Neisseria Flashcards
What are the names of the organisms within the genus Moraxella and list the species they are associated with?
Moraxella bovis (cattle)
Moraxella ovis (sheep and cattle)
Moraxella lacunata (humans)
Moraxella bovis is resposible for causeing what DZ in cattle
Infectious bovine keratoconjunctivitis (pinkeye or IBK)
What are the other two organisms which are have been implicated in some cases of pinkeye in cattle?
Moraxella bovoculi and Moraxella ovis
Describe the distinguishing morphology of Moraxella bovis
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
Biochemically describe Moraxella bovis
- Non-fermentative
- Oxidase positive
- Alkalinizes litmus milk in three zones
- Strict aerobe
List the toxins of Moraxella bovis
Fimbriae
Cytotoxin
Hemolysin
Enzymes: Hyaluronidase, Fibrinolysin, Aminopeptidase,Phosphoamidase, Phosphatase
- What does the Fimbriae toxin of Moraxella bovis provide for the cell?
- What about the cyotoxin?
- Fimbriae: Help attach the organism attach to the corneal epithelium
- 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.
What does the hemolysin toxin of Moraxella bovis provide for the cell?
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
List the enzyme toxins which Moraxella bovis produces
Hyaluronidase
Fibrinolysin
Aminopeptidase
Phosphoamidase
Phosphatase
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.
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.
What is the normal habitat for the Moraxella bovis organism?
Conjunctiva of cattle. Non-invasive under normal conditions.
What is the pathogenesis of a Moraxella bovis organism?
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
List some treatment options for a cow infected with Moraxella bovis?
Sulfas with steroids
Tylosin
Long-acting tetracyclines
Subconjunctival injections w/ penicillin and steroids
Eye patches
Powders (furacin) salt (ouch…)
Moraxella ovis is associated with what Dz in sheep and cattle?
Pinkeye
Moraxella lacunata has been associated with what Dz in what species?
Pinkeye in humans
- Where are Alcaligenes generally found?
- What are three general characteristics?
- Occurs in water, soil, intestinal tract of vertebrates as a saprophyte
- Gram-negative rods, obligate aerobes (some exceptions), motile, urease negative. Oxidase positive.
What role do Alcaligenes primarily play?
Generally a role as a contaminant
What are the two primary orgainsms of Neisseria which we talked about in class?
- Neisseria meningitidis*
- Neisseria gonorrhoeae*
List the common morphological features of Neisseria sp.
Gram-negative cocci
Tend to appear in pairs with adjacent sides flattened
Why are species belonging with to the genus Neisseria difficult to culture?
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
True or False
Species from the genus Neisseria have a strong oxidase positive test result
TRUE
These organisms are strongly oxidase positive!
What Dz does Neisseria meningitidis cause?
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.
What is the natural habitat for Neisseria meningitidis?
The nasopharynx of humans
What two specific groups are expected to have the highest carrier rates of Neisseria meningitidis?
Military recruits (as high as 90%)
Teenagers (30%)
- What is the serogroup of Neisseri meningitidis responsible for majority of the cases which are reported in the U.S?
- What are the other serogroups?
- Serogroup B organisms (50-55%)
- Serogroups C, W135, Y, and A (20, 15, 10, and 1% respectively)
The meningococcal meningitis Dz from Niesseria meningitidis tends to occur most frequently to what two groups of people?
Those in day care (children 6 to 24 mths) and military recruits
Name the two important factors of Neisseria meningitidis’s pathogenesis
IgA
Shared antigens
What is the significance in the pathogenesis of Neisseria meningitidis’s correlation to IgA?
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.
What is the significance in the pathogenesis of Neisseria meningitidis’s correlation to Shared antigens?
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.
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.
True…
List three virulenc factors of Neisseria gonorrhoeae and their function if known
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
What does Neisseria gonorrhea used for initial attachment to the mucosal surface?
Initial attachment via pili and attachment solidified by outer membrane proteins
Where does invasion of Neisseria gonorrhoeae occur at?
Invasion and intracellular residence occurs in the mucosae of the cervix or urethra and the organism is transcytosed to basal surface of these cells.
Some individuals have substantial protection to N. gonorrhea. How is this?
Through the presence of “natural antibodies” that are generated in response to cross-reactive antigens on other Gram-negative bacteria.
