Actinomycetales Microbiology Flashcards

Vocabulary flashcards covering pathogenic bacteria in the order Actinomycetales, including Actinomyces, Nocardia, Dermatophilus, Trueperella, and Actinobaculum species.

Trueperella pyogenes

Formerly named Arcanobacterium pyogenes, a Gram-positive pleomorphic bacterial pathogen causing suppurative infections like mastitis, metritis, pneumonia, and abscesses in livestock.

Actinobaculum suis

Formerly named Actinomyces suis, a Gram-positive anaerobic rod that colonizes the preputial diverticulum of boars and causes cystitis and pyelonephritis in sows.

Pyolysin

A major known exotoxin produced by Trueperella pyogenes belonging to the cholesterol-dependent cytolysin family that lyses red blood cells by forming transmembrane pores.

Actinomyces bovis

An anaerobic, Gram-positive, non-acid-fast branching filamentous bacterium that causes bovine actinomycosis, also known as lumpy jaw.

Lumpy jaw

A chronic osteomyelitis of the mandible or maxilla in cattle caused by Actinomyces bovis invasion following mucosal trauma or tooth eruption, producing painful swellings and sinus tracts discharging pus containing sulfur granules.

Sulfur granules

Yellowish macroscopically visible granules found in purulent exudate from Actinomyces bovis infections, consisting of mineralized calcium phosphate club-like structures surrounding branching bacterial filaments.

Club colony

A microscopic lesion arrangement seen in Actinomyces bovis infections consisting of central filamentous branching bacteria surrounded by radially arranged clubs composed of mineralized calcium phosphate.

Actinomyces viscosus

A catalase-positive, Gram-positive filamentous bacterium with surface fibrils that causes cutaneous pyogranulomas and pyothorax in dogs, cutaneous pustules in horses, and abortion in cattle.

Molar tooth colony

A characteristic colony morphology on solid culture media exhibited by Actinomyces species, resembling the physical shape of a mammalian molar tooth.

Nocardia asteroides

A strict aerobic, soil saprophytic bacterium characterized by Gram-positive, MZN-positive branching filaments that break up into rods or coccobacilli, causing canine nocardiosis and bovine chronic mastitis.

MZN stain

Modified Ziehl-Neelsen stain used to demonstrate partial acid-fastness, where organisms like Nocardia species retain the red stain in branching filaments.

Canine nocardiosis

An opportunistic infection in dogs caused by Nocardia asteroides, characterized by MZN-positive fragmenting filaments, growth on Sabouraud dextrose agar, resistance to penicillin, and infrequent granule formation in exudates.

Nocardia farcinica

A species of Nocardia that serves as the causative agent of bovine farcy in cattle.

Dermatophilus congolensis

An aerobic/capnophilic Gram-positive bacterium with keratinolytic activity that causes exudative epidermitis (streptothricosis) marked by crusty scab lesions that lift off with tufts of hair.

Zoospores

Motile, flagellated coccal reproductive spores produced by Dermatophilus congolensis that are chemotactically attracted to carbon dioxide.

Strawberry footrot

A clinical condition caused by Dermatophilus congolensis infection specifically involving the lower limbs of sheep.

Haalstra's Method

A primary isolation technique for Dermatophilus congolensis from scab material by incubating it in distilled water inside a candle jar, exploiting the chemotactic attraction of motile zoospores to carbon dioxide.

Actinobacillus suis

A Gram-negative rod bacterium causing septicemia and pneumonia in young piglets and adult pigs, distinct from the Gram-positive Actinobaculum suis.

CAMP test (in Trueperella pyogenes)

A diagnostic test where Trueperella pyogenes enhances the beta-hemolytic effect of Staphylococcus aureus on sheep blood agar.

Diaminopimelic acid (meso-DAP)

A distinctive cell wall amino acid constituent present in many Actinomyces species.