Module 5.2 Gram Positive Aerobic Rods (Part 1) Flashcards
What are the four major genera of the gram positive aerobic rods?
Bacillus, Listeria, Tryprella, Actinomyces
Case Report:
- beef cow died suddenly
- blood seeping out of orifices
- 3 other cows severely ill
- high fever and respiratory distress
- blood smear, gram and giemsa stain
- encapsulated gram-positive bacilli which showed the pink capsule under giemsa stain
What disease should we immediately think of?
Anthrax!
- immediately call CFIA
Key characteristics of Bacillus species
- large rods
- spore-forming
- fast growing, aerobic
- mostly saprophytes
- often skin contaminants
Bacillus anthacis 2-OBL-Z-R
- Reportable disease!!!!
- sporulation occurs in air
- do not open carcass
- spores can persist in the ground for decades
- endemic in Wood Buffalo National Park
- sporadic along rivers in Alberta and Saskatchewan
- sudden death, no blood clotting, generalized hemorrhage
Virulence factors of Bacillus
- highly resistant endospore form = antiphagocytic
- toxins that are phagocytic to phagocytes: PA = protective antigen which creates a spore transportation of LF and EF, EF = edema factor which is associated with perinuclear endosomal membrane, LF = lethal factor which affects cellular activities and apoptosis
- release of pro-inflammatory cytokines
- septicemia (overwhelming proliferation of bacteria in body)
Prevention and treatment of Bacillus species
- safe disposal of carcass and contaminated material
- sensitive to Penicillin G, aminopenicillins, macrolides
- vaccination in endemic regions (designed against toxins)
Case Report:
- 7 mos. steer acting stupid, drops food from mouth, tongue out, ear drooped, head tilt
- no improvement with Penicillin
- brain sent to AHL for pathology and microbiology
- bacteria was gram positive
What is a likely cause?
Listeria monocytogenes
Listeria monocytogenes 2-OPP-Z
- gram positive coccobacillus (cocci/rod)
- hemolysis causing
- widespread, saprophytic
- tolerates low pH (bad silage)
- grow slowly
usually a food borne infection
What is the pathogenesis of Listeria monocytogenes?
- Adherence
- Phagocytosis
- Lysis of phagolysosome
- Multiplication in cytoplasma
- Movement and transfer to neighboring cell
- it has the ability to penetrate epithelial cells
- causes generalized septicemia, local necrosis and micro-abscesses
What is listeriosis and what does it cause?
- silage disease
- circling disease
- encephalitis in ruminants
- abortion
- septicemia
- mastitis
- can only treat in early stages with Penicillin, ampicillin, tetracyclines
- there is a live attenuated vaccine
Case Report:
- dairy calf in a group that got bacterial pneumonia at 6 weeks
- treatment resolved the pneumonia but this calf relapsed
- continued cough, severe emaciation
- AHL did a necropsy and microbiology and the lab reported multiple lung abscesses
What is a likely cause?
Trueperella pyogenes!
Trueperella pyogenes 1-OPP
- pleomorphic
- facultative anaerobic
- slow growing
- skin and exposed mucosal surfaces in ruminants and pigs
- hemolytic
- survives in the environment and multiplies in the host
- purulent infections
- bacteremia typically
- often mixed infection with anaerobic organisms
- metritis, endocarditis, abscesses, abortion, foot rot, chronic pneumonia
- virulence is poorly understood
Diagnosis of Trueperella pyogenes
- smear of purulent material
- culture
Prevention of Trueperella pyogenes
- avoid primary cause/lesion
- no efficient vaccine because it is an opportunist
Actinomyces species
- branchin filaments
mouth flora in animals
chronic infections associated with the mouth (bites) - characteristic micro-colonies surrounded by sulphur granule
