Lecture 13: Actinomyces, Nocardia, Dermatophilus and Corynebacterium Flashcards
are actinobacteria gram negative or positive
Positive
What are the different lifestyles of actinobacteria
- Free living saprophytes (in soil)
- Mutualists
- Commensals
- Pathogens
What is the cell morphology of actinomyces
Typically rods or filaments, often branching
Actinomyces are ___ or ___ anaerobes
Facultative or obligate
T or F: actinomyces are capnophilic
True
identify species
Actinomyces spp
What is the primary habitat for actinomyces in mammals
Oral mucosa and tooth surfaces, MM of nasopharynx, urogenital tract, and intestinal tract
What is the cause of actinomyces
Traumatic inoculation of resident bacteria into susceptible tissues
Actinomyces is typically a ___infection
Polymicrobial
Pathogenicity of actinomyces ___with mixed infections
Increases
What is the pathogens is of actinomyces
Pyogranulomatous reactions, suppurative inflammation surrounded by granulomatous elements, fistulous tracts secrete purulent exudate- which contains sulfur granules made up of club colonies
Sulfur granules are useful in dx which organism
Actinomyces spp
what are these and what organism spp is likely
Sulfur granules, actinomyces spp
What does Actinomyces Bovis cause in cattle
Lumpy jaw, suppurative lesions of soft tissue and bone, abscesses
Osteomyeltitis—> tooth dislodgment, inability to chew, mandibular fractures
Cow presents with tooth dislodgement, inability to chew, and mandibular fractures, and lumpy jaw. What is likely bacterial cause
Actinomyces Bo is
What does Actinomyces suis cause in swine
Mastitis (lumpy udder) and ventral SQ lesions in sows
What causes A. Suis in sows
Traumatic inoculation during suckling and weaning
what is likely cause
Actinomyces bovis
What is likely cause
A. Suis
What does A. Bovis cause in horses
Mandibular lymphadenopathy (mimics strangles), fistulous withers and poll evil, skin nodules
What actinomyces species typically effects dogs and cats
A. Viscous
What does A. Viscous cause in dogs and cats
SQ abscesses, thoracic infections (pyothorax, pneumonia), abdominal and retroperitoneal infections
what is likely cause
A. Viscous
How do you dx actinomycis
- Clinical presentation
- Lumpy jaw- rads
- Exudates/ aspirates containing sulfur granules, club colonies
- PCR
- MALDI-TOF
What are these and what species does this indicate
sulfur granules, club colonies—> Actinomyces
What is tx for actinomycosis
- Surgery- drainage, excision and debridement of lesions
- Prolonged antibiotics- penicillin
- Bovine lumpy jaw- sodium iodide IV with antibiotics, debridement of bone lesion
What is the appropriate treatment of lumpy jaw from A. Bovis
Sodium iodide IV with antibiotics
Debridement of bone lesion followed by lavage with iodine solution
How can you prevent actinomycosis
- Good oral care
- Limit amount of rough forage fed
- Protect pets from grass awns
Dermatophilus congolensis is a ___anaerobe
Facultative
T of F: dermatophilus congolensis is capnophilic
True
Dermatophilus is a ___ parasite commonly found in cattle, sheep and horses
Obligate
How is dermatophilus congolensis transmitted
Direct contact, fomites, biting arthropods
What is the main reservoir for Dermatophilus congolensis
Asymptomatic chronically infected hosts
What is the pathogens is of D. Congolensis
- Trauma/ persistent wetting facilitates invasion of epidermis and hair follicles
- Virulence factors: enzymes (keratinases) increase epidermal permeability
- Infected epidermis and neutrophil exudate—> scab and crusting skin lesion
What is dermatophilosis
Exudative dermatitis with formation of scabs/crusts
The following was removed from dairy cow and histo performed what is cause
Dermatophilus congolensis
Histo: alternating bands of keratinized epidermal cells and inflammatory cells
What are the predisposing factors for dermatophilosis
- Prolonged wetting from rain—> lesions on dorsum and head
- Trauma from thorny scrub—> lesions on face and legs
- Arthropod bites
What is the lesion progression for dermatophilosis
Papules—> exudate—> paintbrush lesions of matted hair—> lesions form scab
Cow spent long time in rain and developed these lesions, what is likely cause
Dermatophilus congolensis
What bacteria could have caused this scab to form on horse
D. Congolensis
What are the treatment options for mild cases of Dermatophilosis
Grooming and isolation in dry quarters
What are the treatment options for severe causes of dermatophilosis
Antibiotics- penicillin-streptomycin
What is a treatment option for horses following dermatophilosis
Topical treatment with povidone iodine following grooming
What hemolysis is seen with dermatophilus congolensis
Beta-hemolysis
What spp have branching filaments that fragment into rods and cocci and are partially acid fast
Nocardia spp
Nocardia spp are ___aerobes
Obligate
Nocardia spp are ___ so widespread in soil and water
Saprophytes
What are the routes of infection for Nocardia spp
Trauma to skin, inoculation of teat canal, inhalation, ingestion
What is Nocardiosis characterized by
Suppurating lesions with various granulomatous features, sanguinopurulent exudates
What is the pathogens is of Nocardia
Suppurating lesions with sanguinopurulent exudates, lymph nodes may be involved, hematogenous spread
what spp is this
Nocardia spp
Pathogenic Nocardia are facultative ___organisms so they grow and survive inside ___
Intracellular, phagocytes
What virulence factors protect Nocardia against being killed by phagocytes
Superoxide dismutase and catalase
What species is this
Nocardia (growing inside macrophage)
What does nocardiosis cause in dairy cattle
Mastitis
Can cause pneumonia, abortion (rare)
What does nocardiosis cause in swine
Pneumonia, abortion, lymphadentitis (rare)
What does nocardiosis cause in horses
Pneumonia, pleuritis, systemic abscesses, cutaneous-subcutaneous lesions, abortion (rare)
What does nocardiosis cause in cats and dogs
Utaenous and SQ lesions (often with abscesses), regional lymphadentitis, pulmonary nocardiosis with cough, hemoptysis, respiratory distress, mucopurulent oculonasal discharge
What is likely cause
Nocardiosis
How can you dx nocardiosis
- Gram positive, partially acid fast bacilli
- Culture and ID
Why do you do both a gram stain and acid fast when identifying nocardiosis
Differentiate between actinomyces
what species is this
Nocardia
What is tx for nocardiosis
- Debridement and drainage of lesions
- Prolonged trimethoprim-sulfonamides
What shape are corynebacterium
Pleomorphic
Corynebacterium are ___anaerobes and aerobes
Facultative
Where are corynebacteria found
Skin and mucous membranes (commensals)
How does corynebacterium pseudotuberculosis colonize
Via skin trauma
What is pathogens is of C. Pseudotuberculosis
- Facultative intracellular pathogen (survives in phagocytes)
- Spreads to draining LN
- Virulence factors phospholipase D, cell wall lipids enhance invasion
- Abscess form in LN
T or F: corynebacterium pseudotuberculosis can be a chronic infection that can persist for hosts life
True
What does C. Pseudotuberculosis cause in sheep and goats
Caseous lymphadentitis
What is the external form of C. Pseudotuberculosis
Abscess form in superficial LN, skin, subcutis
What is the internal form of C. Pseudotuberculosis
Abscess form in internal organs and LN
The external form of C. Pseudotuberculosis is more common in goats or sheep? And where are abscess
Goats- abscesses in head/neck regions
The internal form of C. Pseudotuberculosis is more common in goats or sheep? And what is it associated with
Sheep, associated with weight loss, and ill thrift (thin ewe syndrome)
What does the external form of C. Pseudotuberculosis cause in horses
Abscesses in pectoral region or along ventral midline of abdomen
goat presents with these abscesses. What is likely cause
C. Pseudotuberculosis external form
Sheep has these abscesses in liver, what is likely cause
C. Pseudotuberculosis, internal form
What are the vectors for external form of C. Pseudotuberculosis in horses
Horn fly, stable fly
What does the internal form of C. Pseudotuberculosis cause in horses
Abscess in liver, kidney, spleen and lungs, weight loss, fever, depression colic
Which form of C. Pseudotuberculosis in horses has a high case fatality rate (30-40%)
Internal form
Horse presents with severe limb swelling and cellulitis with multiple draining ulcerative lesions along lymphatics, in both hind limbs. What is this and what is cause
C. Pseudotuberculosis causing ulcerative lymphangitis
Horse presents with pectoral abscess with exudates, what is likely cause
C. Pseudotuberculosis, external form
How can you diagnose C. Pseudotuberculosis
- Abscess contents
- culture and ID
- Internal form: rads and ultrasound, serological tests to detect antibodies against PLD and cell wall antigens
How can you diagnose internal C. Pseudotuberculosis
Radiographs, ultrasounds, serological tests to detect antibodies against PLD and cell wall antigens
What is tx for Caseous lymphadentitis caused by C. Pseudotuberculosis in sheep and goats
Abscess is thick walled so refractory antimicrobial therapy:
1. Long term (4-6wks) systemic antibiotics (penicillin G + rifampin)
2. Intralesional tulathromycin
What is the treatment for horses with lymphangitis and internal abscesses due to C. Pseudotuberculosis
Long-term IV antibiotics—> penicillin G and cephalosporins