gram positive rods: species- bacillus and Nocardia

genus overview for bacillus:

• large, gram positive rods

• spore-forming (wide spread on agar)

• catalase positive

• aerobic or facultatively anaerobic

• motile (except B. anthracis)

• natural habitat: soil, air, water

• spores that are highly resistant and live for a long time

bacillus anthracis:

• zoonotic, reportable disease!

• characteristics: 3-5mm, flat, dry, whiteish-grey, ground-glass appearance, “medusa head” under low magnification, Gamma hemolysis

• lab results: catalase +, VP +, TSI alkaline slant/ acid butt (glucose fermentation only), urease -, maltose +, mannitol -, non-motile

• diseases associated with it: ANTHRAX (although carnivores and pigs are somewhat resistant- unknown reason why)

• organs: systemic (blood), gastrointestinal, respiratory, skin

• treatment: penicillin, oxytetracycline

• clinical signs: incomplete rigor mortis (only some part of body is loose while other is floppy)

bacillus cereus:

• characteristics: 2-7mm, irregular edge, slightly greenish hue, beta/double zone hemolysis

• lab results: catalase +, VP +, TSI alkaline slant/ acid butt, urease -, glucose +, lactose -, maltose +

• diseases associated with it: rare mastitis (cattle), food poisoning (rare in dogs and cats)

• organs: gastrointestinal, mammary

• treatment: supportive care, antibiotics, culture and sensitivity

• NOTE** more of an issue in humans than animals

bacillus subtilis:

• characteristics: colonies are round to irregular, large, dull, granular, cream to brownish surface, variable hemolysis

• lab results: catalase +, VP +, TSI alkaline slant/ acid butt, urease -, glucose +, lactose variable, maltose +, mannitol +, esculinase +

• diseases associated with it: abortion (sheep), mastitis (cattle)

• organs: reproductive and mammary

• treatment: yes, antibiotics, culture and sensitivity

bacillus licheniformis:

• characteristics: opaque, dull, rough, wrinkled, strongly adherent (hard to get off the agar), gamma hemolysis

• lab results: catalase +, VP +, TSI alkaline slant/ acid butt, urease variable, glucose +, lactose +, maltose +, mannitol +, esculinase +

• diseases associated with it: abortion (cattle, sheep/goat), mastitis (cattle and goats/sheep)

• organs: reproductive and mammary

• treatment: yes, antibiotics, culture and sensitivity

nocardia asteroides:

• characteristics: gram-positive rods, sometimes branched filaments, small irregular colonies (0.3-3mm), yellowish

• lab results: esculinase -, catalase +, does not ferment carbohydrates (dextrose, maltose, mannitol, etc)

• diseases associated with it: pyogranulomatous infections, pneumonia, systemic abscesses (dog), mastitis (cattle)

• organs: respiratory, skin, mammary, systemic (NOTE** all the wounds need oxygen to grow, so no oxygen= dead bacteria)

• treatment: prolonged use of antibiotics required, sulfonamides are often first choice

nocardia brasiliensis:

• characteristics: colonies chalky, mat-like or velvety, colors range from brown, tan, pink, orange, red, purple, gray or white, texture smooth or granular, irregular, wrinkled, or heaped

• lab results: catalase +, oxidase +, urease +, bile esculin +

• diseases associated with it: primarily causes cutaneous infections (in dogs and occasionally other species)

• organs: skin

• treatment: prolonged use of antibiotics required, sulfonamides are often first choice, surgical intervention may be required for abscesses or severe cutaneous lesions (lavaging it and taking away oxygen)