M.05 Moraxella

Gram-negative facultative or obligate anaerobic infections in animals

Very rare; Gram-negative cocci in animals are usually strict aerobes

Examples of Gram-negative aerobic cocci in animals

Moraxella (slightly coccobacillary), Neisseria (diplococci arrangement, normal flora, rarely a primary pathogen), Acinetobacter (slightly coccobacillary, often opportunistic)

Clinically significant Moraxella species

Moraxella bovis, Moraxella anatipestifer (now Riemerella anatipestifer)

Morphology of Moraxella

Gram-negative, aerobic, cocci to coccobacillary, non-spore forming, rough forms are fimbriated and hydrophobic, pili and capsules present in fresh isolates

Enzymes produced by Moraxella

Active on lipids, peptides, and carbohydrates

Growth characteristics of Moraxella

Colonies grow in presence of serum or blood agar, best at 35°C, corrode agar and digest protein

Reservoir of Moraxella

Bovine conjunctiva and upper respiratory mucosa

Transmission of Moraxella

Direct and indirect contact, flying insects, airborne

Disease caused by Moraxella bovis

Infectious Bovine Keratoconjunctivitis (IBK) in cattle, marked by epiphora, corneal clouding, ocular edema, vascularization, pan-ophthalmitis

Disease caused by Moraxella anatipestifer

New Duck Disease (Duck septicemia/Infectious serositis), marked by sneezing, coughing, nasal/ocular discharges, CNS involvement

Virulence factors of Moraxella

Leukotoxin, lipopolysaccharide, collagenase, hyaluronidase, pili/fimbriae (for adherence to corneal epithelial cells), capsule, RTX-like pore-forming toxin, hemolysin

Samples for laboratory diagnosis of Moraxella

Infected corneal epithelium, conjunctival swabs, lacrimal secretions

Preferred culture media for Moraxella

Blood agar

Identification of Moraxella

Bacterial culture and isolation, Gram staining of smears, PCR using specific primers

Treatment for Moraxella infections

Tetracycline, Neomycin, Erythromycin, Topical corticosteroids (Betamethasone to relieve inflammation)

Control and prevention of Moraxella infections

Vaccinate with fimbrial vaccine, confine animals in dark, dust-free stall