Actinomycetes- Anaerobes

Gram Pos rods and branching filaments, chronic purulent and granulomatous infections; hard to treat with Abx

AKA Actinomyces pyogenes, Corynebacterium pyogenes

mucosal flora of swine, facultative anaerobe; chronic purulent infections- mastitis, endometritis, endocarditis,etc; opporunistic, polymicrobial infections

Drainage, penicillin

Anaerobe, necrotic purulent pyelonephritis & cystitis in swine

oral flora of dogs,humans; factultative anaerobe

Actinomyces viscosus- chronic pyogranulomatous infections under skin or in body cavities (pyothorax); Tx- drainage, pencillin

Oral flora of cattle, strict anaerobe, sulfur granules on microscopy (see club formation of proteins and CaPO4)

Actinomyces bovis; traumatic lesions in the oral cavity leading to chronic granulomas involving bones (NOT actinobacillosis); fistulation through the skin or oral mucosa

Drainage, Iodine solutions, penicillin

Ubiquitous in soil, Strict Aerobe, produces mycolic acid, Facultative intracellular pathogen (cell mediated immunity Imp't)

chronic, granulomatous fistulous infections in the oral cavity, the subcutis and internal organs (lungs - aspiration pneumonia); mastitis (iatrogenic)

bind to and invade endothelial cells (can invade midbrain); mycolic acid- toxic, inhibits killing by macrophages and neutrophils; immunostimulant

long branching filaments, weakly gram +, +/- acid-fast

Drainage, Sulfonamide-trimethoprim (pencillin resistant)

obligate parasite of animals, Strict aerobe, parallel filaments (divides in both directions); release of zoospores; germ tube formation

Streptothricosis (dermatophilosis) in ruminants, horses (dogs, cats, humans) - exudative dermatitis (“ rain rot” or “rain scald” in horses; "lumpy wool", "strawberry foot rot" in sheep)

extracellular proteases (keratinase)

Hygiene, Iodine, Penicillin + Streptomycin

Oral and gut flora and humans; infections require simultaneous trauma of deep tissus, ischemia, decr. O2 tension, and contamination (fecal, bites); Polymicrobial infections with facultative anaerobic bacteria, synergistic process (maintenance of a low redox potential); causes gingivitis, abscesses, perotinitis, tissue necrosis

Sealed Syringe (Bx > Swab); if use swab, used anaerobic transport media

Sx (drainage), Abx (resistant to aminoglycosides, fluoroquinolones)

Gram neg with beaded filaments (gram stain); found with mixed infections (A. pyogenes, bacteroides spp,etc.); found in necrobacillosis, phlegmonous and ulcerative stomatitis in cattle and swine; rumenitis; liver abcess; Pericarditis (foreign body); Footrot in cattle (Interdigital phlegmonous infections); Thrush in horses

Penicillin- susc., no Vx, Good Hygiene (survive for months in humid bedding or soil)

Gram neg anaerobes mixed w/ other anaerobes; cause oral infections, aspiration pneumonia, pyothorax, castration wounds, umbilical infections, sepsis

Obligate of hooves ruminants (short life in soil); causes contagious footrot in sheep

A. pyogenes, F. necrophorum, etc.

have heat-stable protease (keratinase); fimbriae impart antigenic variability

Penicillin- susc.; hygiene- hoof trimming, disinfectant baths

commensal in oral cavity of cats and dogs; complicates bite wounds (sepsis); obligate anaerobe

LPS, sialidase removes acids on host surface; blocks macrophage killing

Gram +, cause abscesses, mastitis in cows; mixed with other infections

Lg, Gram + rods; spores only killed by 121 deg. C for 20 min; widely distributed saprophytes- soil, intestine; some produce serious exotoxins

widespread- intestine of animals and humans, soil

Clostridium tetani in humans and horses (most susceptible; typically occurs after wound infections; environment with anaerobic conditions prompts spore germination and exotoxin production

Neurotoxin (tetanospasmin)- a highly toxic protein that binds to peripheral nerves near wound (irreversible binding to gangliosides of nerve cells),Transmitted to cranial nerve nuclei; has protease activity on specific vesicle-associated membrane proteins; Blocks release of inhibitory transmitters (e.g.GABA); Spastic paralysis (protrusion of the nictitating membrane, sawhorse stance; in humans, "sardonic smile", lockjaw - trismus); death by respiratory failure

Toxoid Vx; sedation; sx debridement, penicillin; antitoxin (frequently too late)

Habitat- soil and marine sediment; food contamination by spores; cattle, horses, and birds are highly susceptible (Not carnivores and swine); suspicious food- 100 deg. C for 10 min inactivates toxin

by C. botulinum; Intoxication by exotoxins previously produced in food, after germination of spores under anaerobic conditions, e.g. spoiled silage, rotting vegetables or carcasses, contaminated cans; wound botulism; infant botulism "shaker foal syndrome"

Neurotoxins (8 serotypes)- Most potent known toxins; Heat-labile proteins, resistant to enteric proteases; Bind to gangliosides at motor-neuromuscular junctions; Protease activity on specific vesicle-associated membrane proteins; Block the release of the neurotransmitter acetyl-choline, inhibition at peripheral cholinergic synapses; Death by resp. failure (flaccid paralysis)

Toxoid Vx for cattle (need specific serotype); ASAP tracheotomy and antitoxin

C. Novyi, haemolyticum, chauvoei, perfringens, septicum

have at least 2 major lethal toxins; produces Gas gangrene (type A); affects ruminants, horses, humans (wartime-civilwar); needs anaerobic conditions; 2 hemolysins responsible for leukostasis, vasc. dysfunction, and capillary leak -> necrosis, and gas formation in muscles (gangrene), and toxemia; often mixed infection with other Clostridia

Sx and Abx, Vx (toxoid specific)

Enterotoxemia by: Type C - b toxin (protease sensitive), necrotizing hemorrhagic enteritis in neonatal farm animalsType D - e toxin (prototoxin, activated by enteric proteases - necrosis, lethal, plasmid-encoded), "Pulpy kidney" disease of sheep and goats (sudden change to a rich diet); brain edema

Blackleg in ruminants; entry through gut or wounds (bacteremia); germination and multiplication in traumatized muscle; typical lesions (bubbles, rancid odor) rarely found; Vx prevents this

Exotoxins

Malignant edema- ruminants, horses, pigs (due to exotoxins similar to C. chauvoei); entry through wounds

various types produce different toxins (and cause different dz); Gas Gangrene (type A)- sheep, cattle, human;

C. Novyi; "Black Dz"- sheep, cattle, horse); Liver fluke infections cause anaerobic conditions for the germination of spores in the liver -Exotoxins (4)

Elimination of the snail (flukes); vaccines

Causes Bacillar hemoglobinuria ("red water")- cattle and sheep; pathogenesis similar to "Black Dz" from flukes; produces exotoxins cause intravascular hemolysis

causes Pseudomembranous colitis- humans, horses, dogs; Assoc. with previous Abx treatment which suppresses normal anaerobic flora; unharmed spores germinate; Toxins A and B