Skin Infections 2 Flashcards
Pyogenic bacteria
Staph, strep, Trueperella, corynebacterium
Classical granulomatous inflammation
Central necrosis surrounded by giant epithelioid cells, macrophages, lymphocytes, granulocytes surrounded by thick fibrous capsule
Difficulty w granulomatous inflammation
Classic lesions are caused by mycobacteria
Difficult to get rid of
Associated w chronic pyo to Gran inflammation
Diseases caused by mycobacterium
Tuberculosis
Johne’s
Feline leprosy
Canine leproid granuloma
Panniculitis syndrome
What type of bacteria is mycobacteria
Gram positive rods
Stict aerobes
Lipid rich cell wall -
Acid facts - Ziehl Nielsen stain
Resistant!! To disinfectants, antibodies, acid and desiccation
Survive intracellularly in mononuclear phagocytes
Classification of mycobacteria
Obligate parasites - do not multiple outside host
Saprophytic mycobacteria - live in environment
How do mycobacteria cause disease
Cord factor - inhibits chemotaxis and are leukotoxic
Can survive intracellularly and replicate in macrophages
- glycolipids
- sulfatides
- sulfolipids
Superoxide dismutase - higher amt in virulent strains
Mycobactins & exochalins - iron acquisition
Glycolipids prevent
Macrophage activation by INFgamma
Sulfatides (glycolipids) prevent
Phagolysozome formation by macrophages
Sulfolipids prevent
Phagosomal lysosomal fusion
Canine leproid granuloma syndrome
Spread by biting insects - short coats (boxer) predisposed
Lesions can be single /multiple nodules
lesions of CLGS
Predominantly on head and ears - bite zone
Painless, sometime pruritic - doesn’t spread internally
DX of CLGS
On cytology, histology or PCR
Cant culture organism in VITRO
TX of CLGS
Lesions typically self resolve
Respond to rifampicin & clarithromycin - enter and treat intracellular organisms
Feline leprosy syndrome
Group of diseases that present similarly
- non culturally mycobacteria
- tuberculosis bacteria (m bovis)
- m. Avium complex (MAC)
Transmission and lesions of FLS
Transmitted through active wounds
Can be cutaneous, subcutaneous granulomas
- focal - head, face, limb, trunk
- peripheral lymphadenopathy
- can be widespread and ulcerated
DX and TX for FLS
DX
- FNA & cytology
- biopsy & Histopathology
- PCR
TX
- difficult
- surgery on lesions
- appropriate drugs
Panniculitis syndrome in cats (& dogs)
Due to rapidly growing mycobacteria
More common in cats than dogs
Common in geographical areas - Australia, UK or US
Follows trauma that penetrates fatty tissues where dirty contaminates wounds
Commonly seen in inguial fat pad in cats
Infection of PSC
Mycobacteria is introduced to fat by trauma
Survive in macrophages in fat - down regulate MHC expression
Fat provides triglycerides for growth & promotes them from host immune response
Tx for superficial pyoderma
creams, gels, ointments, shampoos) should be
used as sole on-animal antibacterial treatment for surface and superficial infections whenever a pet and owner can be expected to be compliant!
Systemic treatment for systemic superficial pyoderma
cephalosporins, pot ampicillin, lincosamides, macrolides
Empirical therapy usually effective
Treating surface pyoderma
Topical - shampoo is common
Treating deep pyoderma
Systemic antibiotics is often needed
Susceptibility testing ** if suspect mixed infection
Problems w treating staph
Facultative intracellular parasites
Antimicrobials resistance
Biofilm production
Non responsive therapy - perform susceptibility test
Which lesions almost NEVER self cure?
Panniculitis syndrome in cats
