Moraxella

To what phylum does the genus Moraxella belong?

Pseudomonadota

To what taxonomic class is the genus Moraxella assigned?

Gammaproteobacteria

What is the taxonomic family for Moraxella?

Moraxellaceae

Which bacterium is the primary causative agent of Infectious Bovine Keratoconjunctivitis (IBK)?

Moraxella bovis

What is the common name for the highly contagious ocular condition known as Infectious Bovine Keratoconjunctivitis (IBK)?

Pinkeye

What is the Gram-stain classification and shape of Moraxella?

Gram-negative coccobacilli

What are the typical dimensions of Moraxella cells?

1.0-1.5 times 1.5-2.5 mu m

How are Moraxella cells typically arranged microscopically?

Pairs (diplobacilli) or short chains

Why is Moraxella technically classified as non-motile despite showing movement?

It lacks flagella.

What specific phenotype allows Moraxella to exhibit jerky movement on surfaces?

Twitching motility

What surface structure is responsible for the twitching motility in Moraxella?

Type IV pili

What is the mechanical process behind Moraxella twitching motility?

Pili extension and retraction

What laboratory observation on agar is often associated with the twitching motility of fresh Moraxella isolates?

Agar corrosion (pitting)

What are the primary key traits of M. bovis in a clinical profile?

Hemolytic and fimbriated

Which species is frequently isolated from IBK cases but has unproven pathogenicity despite possessing RTX toxin genes?

M. bovoculi

Where is M. canis typically found as normal flora?

Oral flora of dogs

What is the clinical significance of M. canis in human medicine?

It can infect dog-bite wounds.

From which host is M. ovis typically isolated?

Healthy sheep (also causes ovine keratoconjunctivitis)

What condition is associated with M. equi?

Conjunctivitis in horses

What is the current classification of the bacterium formerly known as Moraxella anatipestifer?

Riemerella anatipestifer

What pathology is caused by Riemerella anatipestifer in ducks?

Infectious serositis/septicemia

Where is the primary reservoir for Moraxella in asymptomatic carrier cattle?

Mucous membranes of the nasopharynx or vagina

Which insect is the primary vector for Moraxella transmission in cattle?

The Face Fly (Musca autumnalis)

How long can Moraxella survive on the body surface or in the crop of a fly?

Up to 72 hours

What environmental factor makes M. bovis extremely short-lived outside of a host?

Extreme susceptibility to desiccation

Why are strains of Moraxella that lack pili considered avirulent?

Fimbriae (pili) are essential for the adherence required for pathogenesis.

What is the specific function of Type Q pili in Moraxella infection?

Adherence and colonization (resisting the washing action of tears)

What is the primary role of Type I pili in Moraxella infection?

Persistence of infection

What is the name of the calcium-dependent pore-forming cytolysin produced by M. bovis?

MbxA

To which toxin family does MbxA belong?

RTX (Repeats in Toxin)

Which host cells are the primary targets of the MbxA toxin?

Corneal epithelial cells and neutrophils

In the pathogenesis of IBK, how do bacteria initially 'pit' the corneal membrane?

Through the release of hydrolytic enzymes like fibrolysin and phosphatase

How does the lysis of neutrophils by MbxA accelerate the formation of corneal ulcers?

It releases the host's own enzymes, which break down the collagen matrix.

What synonym for IBK is commonly used in certain geographical regions like the UK?

New Forest Disease

What is the typical age range of cattle most susceptible to IBK?

Cattle less than 2 years old

Between Bos taurus and Bos indicus breeds, which is more susceptible to IBK?

Bos taurus

What are the early clinical signs of IBK?

Blepharospasm (squinting), photophobia, and excessive tearing

What characterizes the acute stage of IBK progression?

Central corneal opacity (cloudiness), edema, and vesicle formation

What vascular change occurs during the severe stage of IBK?

Vascularization extending from the limbus toward the ulcer

What does 'coning' of the cornea indicate in chronic IBK?

Severe weakening leading to protrusion or rupture

What is the term for total inflammation of the eyeball, a potential chronic outcome of IBK?

Panophthalmitis

What is the primary direct economic loss caused by IBK in beef cattle?

Decreased weight gain

What is the primary direct economic loss caused by IBK in dairy cattle?

Reduced milk production

List the environmental irritants that act as predisposing factors for an IBK outbreak.

UV light, dust, and tall grass

Which nutritional deficiency is a known predisposing factor for IBK?

Vitamin A deficiency

Which viral co-infection is often linked to the 'Perfect Storm' of an IBK outbreak?

IBR (Infectious Bovine Rhinotracheitis)

What is the preferred clinical sample source for diagnosing M. bovis?

Lacrimal secretion swabs

Why is immediate transport in media or sterile water critical for M. bovis samples?

The bacteria are extremely susceptible to desiccation, which leads to false negatives.

Within what timeframe should M. bovis specimens be cultured after collection?

Within 2 hours

What alternative diagnostic method can be used on direct smears if culture is unavailable?

Fluorescent antibody technique

What is the typical size of M. bovis colonies on blood agar?

1-2 mm (small)

What cultural characteristic on blood agar serves as a marker for virulent M. bovis strains?

Complete (Beta) hemolysis

How does Moraxella growth on MacConkey agar help distinguish it from Enterobacteriaceae?

Moraxella does not grow on MacConkey agar.

What is the oxygen requirement for M. bovis growth?

Strict aerobe

Is Moraxella capable of sugar fermentation?

No, it is asaccharolytic.

How does Moraxella behave in a liquid motility test?

It is non-motile (no swimming motility).

What is the result of the Indole production test for Moraxella?

Negative

What are the results for Catalase and Oxidase tests in the genus Moraxella?

Both are positive (+).

What evidence of proteolytic activity is seen in Moraxella cultures?

Gelatin hydrolysis (+) and serum slope pitting

What diagnostic method is required to distinguish M. bovis from M. bovoculi?

PCR-based methods

What is the purpose of using insecticidal ear tags in IBK management?

To control the Face fly vector (Musca autumnalis)

Why is mowing pastures recommended for IBK prevention?

To reduce mechanical irritation to the eyes from tall grass

Why is providing shade important in reducing the severity of IBK outbreaks?

It minimizes UV exposure, which is a predisposing environmental irritant.

What type of commercial vaccines are available for IBK?

Fimbriae-derived bacterins

Why is the efficacy of commercial Moraxella vaccines considered variable?

Pilar antigens are serotype-specific, and protection against one strain does not guarantee protection against others.