Skin Pathogens Flashcards
(75 cards)
1
Q
What is the function of skin
A
Skin: barrier between the interior of our body and external environment
* Regulate body temperature
* Protection from UV light
* Protect from dehydration
* Protect from microorganisms
* Immune response
2
Q
What are the main structures and layers of the skin
A
- Epidermis: 4-5 layers
- Dermis: 2 layers
- Hypodermis/SC
- Adnexa: follicles/nail/antler/claw/feather/sebaceous gland/sweat glands
3
Q
What is the main function of the epidermis
A
- Epidermis: 4-5 layers = physical barrier (innate and acquired immune/microbiome)
4
Q
List the 4 layers of the epidermis
A
o Stratum corneum: lipid enriched ECM
o Stratum granulosum
o Stratum spinosum
o Stratum basale (attached to basement membrane)
5
Q
What 3 risk factors predispose to skin infection
A
- Predisposed by a thin stratum corneum, small amount of lipid, high skin pH
6
Q
What is the primary way bacteria enter the skin
A
- Direct entry: epidermal damage
- wound
- chemical irritant
- burns
- moist/diry
- allergy
7
Q
Define Blister
A
- Blister: serum or lymph filled lesion
8
Q
Define Pustule
A
- Pustule: pus filled lesion
9
Q
Define Furunculosis
A
- Furunculosis: deep infection of the hair follicle
10
Q
Define Scab/crust
A
- Scab/crust: crust of coagulated blood/pus/skin debris
11
Q
Define Scale
A
- Scale: dry/flaky exfoliation
12
Q
Define Excoriation
A
- Excoriation: traumatic abrasion and scratches
13
Q
Define Eczema
A
- Eczema: erythematous/itchy skin inflammation
14
Q
Define Fissure
A
- Fissure: deep cracks
15
Q
Define Hyperpigmentation
A
- Hyperpigmentation: increased deposits of melanin
16
Q
Define Hyperkeratosis
A
- Hyperkeratosis: excessive overgrowth of kertatinized, epithelium like skin
17
Q
Define Hypopigmentation
A
- Hypopigmentation: decreased deposits of melanin
18
Q
Define Cellulitis
A
- Cellulitis: diffuse, deep and acute inflammation of the dermis and SC
19
Q
Define Folliculitis
A
- Folliculitis: inflammation of hair follicles
20
Q
Define urticaria
A
- Urticaria: raised, itchy rash on skin
21
Q
Define seborrhea
A
- Seborrhea: excess secretion by sebaceous glands
22
Q
Define Alopecia
A
- Alopecia: hair loss
23
Q
List the 4 main commensals/opportunistic bacteria of the skin
A
o Staph/Strep/Cornybacterium/Entereococcus
24
Q
List the 5 main commensals/opportunistic bacteria of the oral cavity
A
o Pasturella multocida (main)
o Staph/Strep/Neisseria/Cornybacterium
25
What are other considerations to have when administering antibiotics to treat skin infection
* Antibiotics will not remove the underlying cause of bacterial skin infection
o Treat pruritis: sedative/anesthetics/corticosteroids
o Treat fluid/electrolyte losses
o Address underlying factors
26
What are the things to consider when choosing an antibiotic to treat skin infections
* Topical vs systemic: superficial vs deep infection
* Antimicrobial choice: route of administration/duration/adverse effects
27
What are the main lesions of pyoderma? What are the lesions associated with the 2 forms?
* Presentations: pruritis (lead to excoriation)
o Superficial: pustular dermatitis
o Deep: furunculosis and cellulitis
o Puppy and kitten: impetigo
28
Where do the lesions of pyoderma occur? How does this vary between cats and dogs?
o Location
Kitten: on neck/shoulders (where mom grasps)
Dog: anywhere not covered by hair
29
What are the primary causative agents of pyoderma in dogs and also cats
o Dog: Staph pseudointermedius/intermedius
o Cat: Pasurella/Strep (oral)
o Staphylococcus (gram +)
30
What are the main features of Staph? What are the 3 primary virulence factors?
o Staphylococcus (gram +)
Pyogenic = suppurative lesions
Virulence factors:
* Capsular polysaccharides/teichoic acids/protein A (prevent phagocytosis)
Catalase (allow survival in phagocytes)
Coagulase (shield from phagocyte)
31
What are the 6 main risk factors of pyoderma infection
* Risk factors: skin damage or immune system failure
o Fleas/insect bites
o Food allergy
o Mange
o urine scald
o compromised immune system
o Weakened endocrine system
32
How is pyoderma treated? What antimicrobials are used?
* Tx: some can resolve
o Topical antiseptic shampoo
o Systemic antimicrobials: clindamycin/1st generation cephalosporins
o Long duration of treatment = use antimicrobials with minimal side effects
o MRSA more prevalent
33
What is another name for greasy pig disease
Exudative epidermitis (greasy pig disease)
34
Whaat is the causative agent of exudative epidermitis? Where does it come from?
* Agent: Staph hyicus
o Commensal in healthy sow vagina
35
What is the primary virulence factor of staph hyicus
o Virulence factors: exfoliative toxins (disrupt cell attachment causing clinical signs)
36
What animals are targeted by exudative epidermitis? What is the prognosis
* Target: up to 3 month old sucklers and piglets
o High mortality if untreated
o Extremely contagious
37
What are the main lesions of exudative epidermitis?
* Lesions: extensive, non-pruritis dermatitis
o Greasy exudate (excess sebaceous secretion, exfoliation, cellulitis, scab, blister, pustule)
38
What is the main risk factor of exudative epidermitis?
* Risk factors
o Stress (low immunity/bites)
39
How is exudative epidermitis treated? What antimicrobials are used?
* Tx: 5d of antimicrobials
o Systemic; amoxycillin/ceftiofur/cephalexin/gentimycin
o Topical: mix antimicrobial with mineral oil
o Maintain hydration
40
What is another name for diamond skin disease?
Swine Erysipelas (diamond skin disease)
41
What is the causative agent of Swine Erysipelas? What are the main features?
* Agent: Erysipelothric rhusiopathiae (gram + rod, catalase -)
o Zoonotic
42
What are the virulence factors of Swine Erysipelas?
o Virulence factors
Capsule (protect from phagocytosis)
Neuraminidase (adhere to endothelial cells)
43
Where is Erysipelothric rhusiopathiae found?
o Commensal in tonsils (in 50% pigs) – excrete in feces/urine/saliva/nasal discharge
44
What are the 4 main presentations of Swine Erysipelas? What is a pathognumonic sign?
* Lesions
o Cutaneous (diamond shaped erythema = pathognomonic)
o Septicemia
o Arthritis
o Endocarditis
45
How is Swine Erysipelas treated and prevented?
* Tx; 3-6d antimicrobials
o Penicillin (main)/tetracycline)
* Prevent with vaccine
46
What is the features of Dermatophilus congolensis?
* Agent: Dermatophilus congolensis (gram +, filamentous branching cocci)
o Class: actinobacteria
o Has coccal zoospores that germinate into hyphae
Form tram track/rail road on cytology
47
Where is Dermatophilus congolensis found
o Commensal on skin (trauma or persistant wetting allows entry = acute inflame)
Transmitted by direct contact with infective animals or blood sucking insects
48
What are the 2 main virulence factors of Dermatophilus congolensis
o Virulence:
phospholipase
proteolytic enzymes
49
What animals does Dermatophilus congolensis target? What are the clinical presentations in the main animal species?
* Target: wide host range
o Cattle/goat/horse: cutaneous streptothrichosis
o Sheep: lumpy wool/strawberry foot rot
o Horse/cow: rain rot
o Rare in companion animals
50
What are the main lesions of Dermatophilus congolensis
* Lesion: raised scab-like lesions (full of branching filament containing zoospores)
o Sticky matted hair with multiple crusts containing purulent exudate (paintbrush lesions)
51
How to treat Dermatophilus congolensis
* Tx: spontaneously resolve
o Systemic oxytetracycline: long lasting
o Penicillin (streptomycin) for 3-5d
o Topical antimicrobials = not effective
52
What is the main species targeted by cornybacterium pseudootuberculosis and what are the disease manifestations in each?
* Target: horse/cow
* Lesions
o Small ruminants: caseous lymphadenitis
o Horse: ulcerative lymphangitis (pigeon fever/false strangles)
o Cattle: cutaneous granuloma (skin trauma associated
53
What are the specific Cornybacterium tuberculosis supsp that cause disease? What species do they cause disease in?
* Agent: Cornybacterium pseudotuberculosis (gram =, rod)
o C. pseudotuberculosis equi = horse and cow
o C. pseudotuberculosis ovis = small urminants
54
What are the 2 virulence factors of Cornybacterium tuberculosis
o Virulence factors
Phospholipase D (ability to invade)
Mycolic acid (protect from immune system)
55
How to diagnose Cornybacterium tuberculosis
* Diagnosis: culture abscess pus
56
How to treat Cornybacterium tuberculosis in cow and horses
o Cattle: don’t need +/- topical shampoo
o Horse: lance and drain abscess
Penicillin G (for 1mo)
If internal abscess = 50% die
Fly control
57
What are the features of nocardia bacteria and where is it located
* Agent: nocardia (gram +, rod, filamentous)
o Found in the soil and decaying vegetation
o Opportunistic (require immunosuppression)
58
What are the 2 virulence factors of nocardia
o Virulence factors: allow intracellular survival
Superoxide dismutase
Catalase
59
What are the disease presentations and related lesions of nocardia
* Lesions: thoracic, cutaneous, disseminated forms
o Indolent ulcers or pyogranulomatous lesions with draining tracts
o Firm nodules
o Abscess
o Fistulous tracts and extensive fibrosis
60
How is nocardia infection treated
* Tx: surgical removal
o Antimicrobial use depends on bacterial susceptibility
Amikacin/TMS/sulfamethoxazole (min for 6 weeks)
61
What are the main features of P. multocida bacteria
* Agent: Pasturella multocida (gram =, coccobacilli)
62
What is the main virulence factor of P. multocida
adhesins
63
What type of injury is p. multocida associated with
* Target: cat (cat bite- especially intact males)
64
What lesion is common in P. multocida related cat bites
* Lesion: cellulitis
65
How to treat P. multocida related cat bites
* Tx: drain purulent fluid
o Ampicillin/cefazolin/amoxicillin/clavulanate/cefvecin
66
What are 4 common agents found in cat bite infections
o Cat bite: stapy/P. multocida/C. pseudotuberculosis/Clostridium) = cellulitis
67
What are the 4 common agents causing post surgical wound infections in dogs
o Staph pseudointermedius
o Staph aureus
o Step
o Coliforms
68
What are the 3 common agents causing post surgical wound infections in cats
o Staph and Strep
o Coliforms
o P. multocida
69
How are post surgical wound infections treated
* Tx: broad spectrum abx (clavamox/ampicillin sulbactam)
70
What is the most likely causative agent of deep cellulitis
* Agent: staph
71
What animals ar commonly affected by deep cellulitis
* Target; horse and companion animals
72
How to treat deep cellulitis
* Tx; aggressive systemic abx (cephalosporins)
73
What animal does mycobacterial dermatitis affect
* Target: cat
74
What are the common lesions associated with mycobacterial dermatitis
* Lesion: nodular dermatitis with draining tracts and panniculitis (not systemic)
75
How to treat mycobacterial dermatitis
* Tx: based on abx susceptibility
