Skin Flashcards
True or False: Skin is an extensive barrier between the interior of our body and the external environment
True
Skin has a vital role in (5):
- Regulation body temp
- Protection UV (melanine)
- Protection dehydration
- Protection microorganisms
- Immune response
Layers of the skin (3)?
Epidermis (4-5)
Dermis (2)
Hypodermis (AKA SQ)
Specialized skin structures (appendages)?
Hair follicles, horns, nails, antlers, claws, sebaceous and sweat glands
Epidermis protects invasion of pathogens through what?
Anatomy - physical barrier
Innate and acquired immune response
Resident bacteria
4 (+1) layers of epidermis?
Outside to inside:
Stratum corneum - tightly packed keratin rich, dead, layered cells. Also lipid enriched extracellular matrix, and is where commensals are.
Stratum granulosum - secrete antimicrobial peptides
Stratum spinosum - secrete antimicrobial peptides
Stratum basale - secrete antimicrobial peptides
Basement membrane
What risk factors are predisposing to bacterial infections?
Thin stratum corneum
Small amount of intracellular lipids
High skin pH
(Dogs have all of these)
What is Cellulitis?
diffuse, deep, acute inflammation that
involves both dermis and subcutis
What is Folliculitis?
inflammation of hair follicles
What is Furunculosis?
deep infection of the hair follicle
leading to abscess formation with accumulation of pus
What is Urticaria?
raised, itchy rash that appears on the skin
What is Seborrhea?
excess secretion by sebaceous glands
What is Alopecia?
deficiency of hair
What are the most common resident bacteria of the skin?
Staphylococcus spp., Streptococcus spp., Corynebacterium spp.,
Enterococcus spp.
(Staph #1)
What are the most common resident bacteria in the oral cavity?
Pasteurella multocida, Staphylococcus
spp., Streptococcus spp., Neisseria spp. and Corynebacterium spp.
(P. multiocida #1)
When do you use topical vs systemic tx?
Depends on location. Deep (dermis) is systemic tx, and superficial (epidermis) is topically
Why does the choice of antimicrobial matter for prolonged therapies?
- Compliance - needs to be easy for client
- Side effects - long term use increases chance of them
- AMR
What has to be considered in the tx?
Reduce pruritis - sedative, steroids, anesthetic
Loss of fluid and electrolytes - give fluids
Identify underlying factor - allergies, endocrinopaties, fleas, compromised immune system
Adequate diet?
What are the two presentations of pyoderma in companion animals?
Superficial - pustular dermatitis ( no follicular involvement)
Deep - folliculitis, furunculosis, SQ abscess, cellulitis
See difference in images in ppt
How does pyoderma present in kittens and what causes it?
Lesions on dorsum of the neck and shoulders - where mom grabs them with her mouth)
Itchy
Impetigo
Caused by uncontrolled growth of oral bacteria: Pasteurella spp., Streptococcus spp.
How does pyoderma present in dogs and what causes it?
Lesions on areas not covered in hair
Impetigo (puppies)
Itchy
Caused by uncontrolled growth of resident skin bacteria:
Staphylococcus spp., (intermedius/pseudintermedius)
What are predisposing risk factors for pyoderma in companion animals?
- Fleas
- Food allergy
- Insect bite
- Mange
- Urine scalding
- Compromised immune system
- Weakened endocrine system
Give some descriptors for pyoderma causing bacterium (the skin one) and the virulence factors (REMEMBER THESE)
Staphylococcus spp. is pyogenic and causes suppurative lesions.
It is gram-positive coccus and makes grape-like formations.
Virulence factors that protect Staph from the immune system are:
* Capsular polysaccharide, teichoic acids, protein A - Interfere with phagocytosis
* Catalase - Aids in survival within phagocytes
* Coagulase - Shield from phagocytic cells
Staphs four C’s - coccus, capsular polysaccharide, catalase, coagulase (I’m just trying here…)
Give me some tx options for pyoderma
- Resolve on their own - don’t rely on it though
- Topical antiseptic shampoo
- Systemic antimicrobials ( will require 6-8 weeks of tx, even for superficial)
What are first and second choice antimicrobials for pyoderma?
1st: Clindamycin or first-generation cephalosporins (e.g.,
cephalexin, cefadroxil)
2nd: Amoxicillin-clavulanate, sulphonamides and trimethoprim,
lincomycin, or erythromycin
Why do we culture pustules if they have pyoderma?
Because of methicillin resistant Staph aureus (MRSA) are problematic in vet med, and might need different antibiotics if they’re resistant.
7 % prevalence in dogs in NA
Describe the lesion of exudative epidermis and what is the causing organism?
Lesion: Extensive, non-pruritic dermatitis with greasy exudate. (Excess sebacious secretion, exfoliation, cellulitis, scabs, blisters and
pustules)
Cause: Staphylococcus hyicus - gram positive coccus
What is another name for exudative epidermitis?
Greasy-pig disease
Who are affected by exudative epidermitis and what is the mortality and morbidity?
Sucklers and piglets ( up to 3 mo)
20-100% morbidity (extremely contagious) and high mortality
Where can S. hyicus be found in healthy sows?
Vaginal mucosa ( it colonizes piglet during birth)
What is the pathogenesis of exudative epidermitis, virulence factor, and what are stress factors?
Present on skin from birth > minor lesions on piglets skin > organism enters skin > exfoliative toxins > disrupts cell attachment > CS
Exfoliative toxin is the virulence factor
Stress factors:
Decreased immunity and bites > piglets will likely also show lethargy, depression, and anorexia because of this.
What are tx options for exudative epidermitis?
Antimicrobials for 5 days
Systemic > amoxycillin, ceftiofur, cephalexin, gentamycin,
lincomycin or penicillin.
Topic > antimicrobials mixed with mineral oil
Keep them hydrated > prevents shock and reduces mortality
What is another name for swine erysipelas?
diamond-skin disease
Describe the causative organism of Swine erysipelas, and what are the virulence factors and what
Cause: Erysipelothrix rhusiopathiae - gram positive, catalase-negative, rod
Virulence factors:
Capsule - protects against phagocytosis
Neuraminidase - adherence to endothelial cells
What is pathognomonic for swine erysipelas?
Diamond shaped erythema
Where is Erysipelothrix rhusiopathiae carried on a pig?
- Tonsillar tissue
- Exerted on feces, urine, saliva, and nasal discharge
Carried by up to 50% of piggies
What are the 4 forms of Swine erysipelas?
- Cutaneous - septicaemic, arthritis, endocarditis
- Diamond skin - diamond shaped erythema (pathognomonic)
- Mixture of presentations
- ??? Lemme know what the 4th type is if you know
Is Erysipelothrix rhusiopathiae zoonotic?
YES - self limiting and mild
Tx and prevention for diamond skin disease?
Tx:
Antimicrobials
-Penicillin (choice)
- Tetracycline in water/feed > easy to treat whole herd.
Tx of chronic infection is costly and ineffective
Vaccines are preventative.
Give me some characteristics of Dermatophilus congolensis
Class: Actinobacteria
Gram positive, filamentous > long branches of cocci.
Cocci zoospores germinate into hyphae that look like train tracks.
Superficial infections
What is a different name of Dermatophilus congolensis? (think of path)
Rain scald
Where can we find Dermatophilus congolensis
On skin of healthy animals.
What is the pathogenesis of Dermatophilus congolensis, and what are the virulence factors?
Trauma, or PERSISTENT WETTING (rain scald) > skin invasion (does not invade healthy skin) > acute inflammation
Virulence factors:
Phosphilipases and proteolytic enzymes - both to gain invade the skin
What are the diseases caused by Dermatophilus congolensis called in different animals?
Cutaneous Streptotrichosis - cattle, goats, horses
Lumpy wool - sheep
Strawberry foot rot - sheep
Rain rot - horses, cattle
Can also infect pets, reptiles, and humans
What is the different cause between dermatophytosis and dermatophilosis?
Dermatophytosis caused by fungi
Dermatophilosis caused by bacteria
What do paintbrush lesions refer to in regards to horses?
Dermatophilus congolensis that causes sticky matted hair with multiple crusts and containing purulent exudate
How is Dermatophilus congolensis transmitted?
Zoospores (in crust) by direct contact with infected animals
Bloodsucking insects can transmit it in the tropics
Tx for dermatophilus congolensis?
Spontaneous in few weeks (esp if dry conditions)
Antimicrobials
Systemic - oxytetracycline
Penicillin - streptomycin for 3-5 days
Topical ANTIMICROBIAL tx generally ineffective
But can use providone-iodine shampoo or chlorhex solution
What does Corynebacterium pseudotuberculosis cause in different species?
- Caseous lymphadenitis > small ruminants
- Ulcerative lymphangitis > Horses (pigeon fever or false strangles)
- Cutaneous granulomas > cattle (often associated with skin trauma)
Characteristics of Corynebacterium pseudotuberculosis subtypes, and virulence factors
Gram positive coccus and rods
Subtypes:
equi biovar for horses and cattle
ovis biovar for small ruminants
Virulence factors: REMEMBER THESE
Phospholipase D > invade skin
Mycolic acid > protects from immune system
Lesions for Corynebacterium pseudotuberculosis ?
Chain of abscesses on limbs - cattle and horse
Abscesses on pectoral or ventral abdomen - horse
In what animal causes Corynebacterium pseudotuberculosis systemic issues, what does that look like, and when in the year?
Horses
Fever, depression, weight loss, diffuse swelling
Summer and fall
How to diagnose and tx Corynebacterium pseudotuberculosis
Dx - culture of pus from abscess
Tx
Horse:
* Lance and drain abscess
* Antimicrobials
- Penicillin G - 1 month or longer (half of the horses with internal abscesses will die)
* Fly control
Cattle:
* No tx or shampoo
Canine nocardiosis characteristics and virulent factors?
Caused by Nocardia spp. Gram positive, rod, and can form filaments, esp in dogs.
Virulence:
Superoxide dismutase
Catalase
Both help survive intracellularly (away from immune system)
Where can you normally find Nocardia spp., and how does it infect animals?
Saprophytes in soil and decaying vegetation.
Enters skin through injury and is opportunistic
(IDK if it causes immunosuppression or if it can infect when immune system is suppressed)
What are three clinical manifestations of Canine nocardiosis?
- thoracic
- cutaneous
- disseminated
What does the cutaneous form of canine nocardiosis looks like?
Indolent ulcers or pyogranulomatous lesions with draining tracts.
firm nodules, abscesses, fistulous tracts, and extensive fibrosis
Tx canine nocardiosis?
- Surgical removal
- Antimicrobials - success depends on susceptibility
- Amikacin, trimethoprim and sulamethoxazole (6 weeks min)
What is a common cause of infection following dog or cat scratches?
Pasteurella multocida
Characterize P. multocida and virulence?
Gram negative (all the others are gram positive) coccobacillus.
Virulence: adhesins
What are causative agents of cellulitis in cats after getting a deep bite wound?
staphylococci, Pasteurella multocida,
Corynebacterium pseudotuberculosis and Clostridium
spp.
How do you treat infected deep bite wounds?
- Drain purulent fluid
- Antimicrobials -> Ampicillin, cefazolin, amoxicillinclavulanate,
cefovecin
All surgical wounds are exposed to bacteria, true or false?
True
Most common causes sx infection dogs?
Staph pseudintermedius, Staph aureus, Streptococcus spp.,
coliforms
Most common causes sx infection cats?
Staph spp., Strep spp., coliforms, Pasteurella multocida
Tx sx infection
PREVENTION
but it failed….
so
Antimicrobials
Ideally broad-spectrum ones - cause often infection by multiple species.
* Clavulanic acid-amoxicillin or ampicillin-sulbactam.
* For serious infections that may involve resistant Grampositive and Gram-negative bacteria, consider a
combination of an aminoglycoside and ampicillinsulbactam
