Microbial skin disease

Question 1

List 3 microbial infections causing pruritus

Answer 1

bacterial pyoderma (surface/superficial)
Malassezia dermatitis
Dermatophytosis- variably pruritic - but mostly alopecia

Question 2

microbial skin infections are very rarely …….

Answer 2

a primary problem

Question 3

List 4 situations when normal skin commensals can cause microbial skin infections

Answer 3

Compromise of cutaneous defences
Increased microbial adherence
Changes to skin microclimate
Changes to skin microbiome

Question 4

what is dysbiosis

Answer 4

involves imbalance between types of organism in the microbiome
occurs with surface microbial overgrowths

Question 5

describe the dysbiosis that occurs in canine atopic dermatitis

Answer 5

decrease in bacterial/ fungal diversity
increase in proportion of Staph/ Malassezia

Question 6

what is the most common organism involved in bacterial pyoderma in dogs

Answer 6

staphyylococci pseudintermedius

Question 7

Describe surface pyoderma

Answer 7

Bacteria proliferate on epidermal surface

Question 8

Describe superficial pyoderma

Answer 8

bacteria invade epidermis

Question 9

List the 4 most common examples of surface pyoderma

Answer 9

canine intertrigo (skin fold infection)
acute moist dermatitis (hotspots)
Bacterial overgrowth syndrome
Mucocutaneous pyoderma

Question 10

Decsribe acute moist dermatitis (hotspos)

Answer 10

very acute lesions caused by skin self trauma
triggered by an irritant
very rapid development of bacterial overgrowth

Question 11

Describe Bacterial overgrowth syndrome

Answer 11

Bacterial multiplication with no/minimal inflammation on cytology
highly pruritic - usually involves staphylococci
greasy, malodorous, erythematous, alopecia –> leads to hyperpigmentation and lichenification

Question 12

Describe Mucocutaneous pyoderma

Answer 12

pyoderma on the mucocutaneous junctions

Question 13

Describe Exfoliative superficial pyoderma (ESP)

Answer 13

rapidly expanding erythematous rings with peripheral peeling (epidermal collarettes)
often highly pruritic

Question 14

Describe impetigo

Answer 14

large flaccid pustules up to 15mm diameter, often with erythematous rims

Usually associated with immature immune system/ immunosuppression
occur between hair follicles

Question 15

what is the most common presentations of pyoderma in cats

Answer 15

uncommon in cats
feline achne
surface pyoderma
folliculitis

any of the 4 cutaneous reaction patterns

Question 16

when is pyoderma a differential in cats

Answer 16

any of the 4 feline cutaneous reaction patterns
focal/multifocal alopecia

Question 17

if pyoderma is on our d/d list what do we do

Answer 17

cytology- impression smear or stained acetate tape strip depending on lesion
C and S testing occasionally

Question 18

what do we see on cytology with surface pyoderma

Answer 18

bacterial overgrowth- Increased numbers of bacteria but no inflammatory cell response

Question 19

what do we see on cytology with superficial pyoderma

Answer 19

Degenerate neutrophils, high numbers of cocci

Question 20

List 4 indications for C and S testing when treating pyodermas

Answer 20

1. Superficial pyoderma unresponsive to initial empirical therapy
2. History of repeated antibiotic use
3. Previous isolation of a meticillin resistant Staphylococcus (MRS)
4. Rods seen on cytology

Question 21

How to perform C&S in pyoderma cases

Answer 21

sample primary lesions- papules/pustules - direct swab of exudate
secondary lesions- under the crusts or under rim of collarettes
if no primary or secondary lesions- small punch tissue biopsy

Question 22

Describe the general principles of treating pyoderma

Answer 22

address infection
use of antipruritic agents? (e.g. corticosteroids)- surface and superficial pyoderma - DON’T USE in dee pyodermas
address underlying disease

Question 23

Describe how to treat acute moist dermatitis

Answer 23

Clip lesions (under sedation/GA if painful)
Treat with topical antimicrobial – e.g. chlorhexidine, fusidic acid*
Control pruritus – corticosteroids* usually

Question 24

when do you not use corticosteroids to treat acute moist dermatitis

Answer 24

when there are satellite lesions - papules extending out into the hair- suggests deeper infection

Question 25

Describe how to treat surface pyodermas

Answer 25

topical treatment only Chlorhexidine If not responsive= fusidic acid+/- glucocorticoid

Question 26

Describe how to treat superficial pyoderma

Answer 26

topical treatment ONLY is appropriate chlorohexidine if not responsive to topical antibiotic therapy- clindamycin

Question 27

what is the most proven antiseptic for dermatological use

Answer 27

2-4% chlorhexidine shampoo

Question 28

In cats what is the order for use of Abs for derm use

Answer 28

amoxyclav > clindamycin > cephalexin

Question 29

List the 3 main risk factors for development of clinical MRS infections

Answer 29

Previous antimicrobial therapy Repeated visits to vet surgery Invasive procedures

Question 30

Decsrieb treatment of MRS surface/ superficial infections

Answer 30

topical therapy alone Avoid systemic antibiotics if at all possible (selects for more resistance!)

Question 31

Describe how to treat MRS deep infections

Answer 31

Systemic antibiotics, using lowest EMA Category drug shown to be effective (NB never amoxyclav, even if test indicates susceptibility) Plus topical therapies

Question 32

List the clinical signs seen with Malessezia dermatitis

Answer 32

pruritus varies- mild to severe Initially erythema with greasy exudate, scale, crust --> lichenification, alopecia, hyperpigmentation +/- rancid malodour

Question 33

Describe how to diagnose malassezia dermatitis

Answer 33

cytology- stained acetate tape or direct/indirect impression smear (if moist/waxy) look like peanut no fixed number for significance- interpret in light of clinical signs - basically response to treatmet

Question 34

Describe management of malassezia dermatitis

Answer 34

topical treatment very effective often need regular treatment if primary cause can't be fully controlled as generally a secondary problem

Question 35

List 3 types of superficial pyoderma

Answer 35

folliculitis impetigo exfoliative superficial pyoderma

Question 36

what is the most common form of pyoderma in dogs

Answer 36

folliculitis

Question 37

why are crusts and epidermal collarettes seen more than papules/pustules in superficial pyoderma

Answer 37

because the papules/pustules are short-lived primary lesions that turn into crusts/epidermal collarettes

Question 38

you have diagnosed surface pyoderma on the ventrum of a dog, what is the treatment of choice

Answer 38

topical 2-4% chlorhexidine shampoo