Skin and Soft Tissue Infections Flashcards
1
Q
What is the epidermis ?
A
Hard, Horny layer of dead cells
- constantly being replenished
2
Q
First Impressions of SSTIs
A
What do I need to be worried about ?
- type of infection
Is this going to kill my patient ?
3
Q
SSTI
A
Skin and Soft Tissue Infections
4
Q
Features of the epidermis - defensive barrier
A
Surface is dry
Acidic pH
Sweat secretion (salty)
Rich blood and lymphatic supply
5
Q
What does the epidermis produce ?
A
Antimicrobial substances
- fatty acids
- sebum
- defensins
6
Q
IS the skin a sterile environment ?
A
NO
Normal skin microbiota is present
- many different bacteria colonising you
7
Q
State some normal skin microbiota
A
Staphylococci
Streptococcus pyogenes
Propionibacterium acnes
Corynebacterium sp.
Candidia sp.
8
Q
Staphylococcus epidermidis
A
Coagulase negative
9
Q
Staphylococcus aureus
A
Coagulase positive
10
Q
Function of normal microbiota
A
Important roles for educating the innate and adaptive arms of the cutaneous immune system.
11
Q
What is associated with skin diseases ?
A
Dysbiosis is associated with some skin diseases.
12
Q
Abscess
A
Collection of pus; pustule
13
Q
Cutaneous vesicle
A
Blister; bullae; fluid filled sac
14
Q
Pyoderma
A
Pus forming skin infection
(pus in the skin)
15
Q
Impetigo
A
Vesicles developing into rupturing pustules, then forming dried crusts
16
Q
Ecthyma
A
Rupturing vesicles leading to erythematous lesions and dried crusts
17
Q
Folliculitis
A
Inflammation at hair follicle
18
Q
Furuncle
A
Boil, deep folliculitis
19
Q
Carbuncle
A
Collection of boils
20
Q
What is Erysipelas ?
A
Erythema and Inflammation affecting deeper dermis and subcutaneous fat
21
Q
Cellulitis
A
Erythematous inflammation affecting deeper dermis and subcutaneous fat
22
Q
Acne
A
Infection of sebaceous follicles
23
Q
What is Necrotising Fascitis ?
A
Cellulitis with necrosis affecting skin, deeper fascia and sometimes muscle
24
Q
Dehiscence
A
Wound rupture along surgical suture
25
State some routes of infections
Skin
Wounds
Bites
26
What do the skin, wounds and bites - routes of infection have in common ?
Breach in the defensive barrier
27
Skin - routes of infection
Pores
Hair follicles
28
Wounds - routes of infection
Scratches
Cuts
Burns
29
Bites - routes of infection
Insects
Animals
30
Things to consider when taking a patient history
Onset, Evolution, Duration and Location of lesions
Contacts with a similar rash
Past medical history - noting skin conditions
Previous treatments including antimicrobial therapy
Skin trauma or insect bites
Systemic features - fever
Co-morbidities present
Pre-dispositions
31
Pre-dispositions
Foreign travel
Saltwater exposure
32
Why is it important to understand if a patient has previously been prescribed antibiotics ?
ABx can cause the pathogen to become more virulent
ABx will affect their normal flora
Failure of an ABx to treat symptoms can provide information for future treatment.
33
What organisms cause skin infections ?
Viral pathogens
Fungal pathogens
Toxin mediated
BACTERIA
34
State some bacterial infections
Staph aureus
- coagulase positive
Streptococci (e.g. S. pyogenes)
E coli / Pseudomonas spp. / Salmonella
35
What type of bacteria is more prevalent in skin infections ?
Gram + bacteria
36
Superficial skin infections
Impetigo
Erysipelas
37
Deep skin infections
Cellulitis
Necrotising Fasciitis
38
Co-morbidities and other interventions
S. aureus infection in a patient with diabetes mellitus
- uses increased blood sugar for proliferation
Catheter Related infection
39
Clinical management of bacterial skin infections
Draw a line around the infected area, to identify whether it is spreading or reducing.
This gives an indication if the treatment is working or not.
40
Blood/ wound cultures
Not always necessary, but will take 24-48 hrs to return, so empiric therapy is usually required before.
41
What causes impetigo ?
Staph aureus
Strep pyogenes
Common bacterial infection in children
42
Feature of impetigo
Highly contagious
- normally superficial (epidermis)
43
State the 2 main types of impetigo
Non-bullous
Bullous (blisters)
44
Feature of non-bulbous impetigo
Characteristic golden/brown crust
Thin walled vesicles/pustules
Satellite lesions may develop
45
Feature of bullous impetigo
Flaccid, fluid filled vesicles and blisters
Thin flat yellow/ brown crust
46
Management of impetigo
Advise hygiene measures
- wash affected areas with soap+water
- avoid scratching affected areas
Treatment
47
Treatment of impetigo
Hydrogen peroxide cream if it's in one area.
Antibiotic cream or tablets if it is more widespread
Antibiotic tablets if bullous impetigo or very unwell.
48
When is referral of impetigo required ?
If part of an outbreak
If diagnostic uncertainty
Resistant to maximal treatment
Complications
49
SSSS
Staphylococcal Scalded Skin Syndrome
50
What is SSSS ?
RARE bacterial infection
Staph aureus
- exotoxin release
51
Diagnosis of SSSS
SSSS requires prompt recognition and treatment
52
Treatment of SSSS
Parenteral antibiotics to cover staph aureus
53
Outcomes of SSSS
Children generally recover well
SSSS is an infection control issue, may be a carrier in care home / nursery
54
Erysipelas
Bacterial skin infection (upper dermis)
Caused by:
- strep pyogenes
- other bacteria can cause it too
55
Characteristics of erysipelas
Clear boundary with normal skin
Fever, rise in WBC count
Treatment is as for cellulitis
56
Cellulitis
Common bacterial skin infection of lower dermis and subcutaneous tissue
Typically caused by s. pyogenes (2/3) and s. aureus (1/3)
57
Characteristics of cellulitis
Diffuse inflammation
Starts in a small area of redness, tenderness/ swelling.
Progresses to fever or chills
May lead to life threatening conditions (e.g. sepsis)
58
Classes of cellulitis
Class 1-4
59
Class 1 cellulitis
NO signs of systemic toxicity
Person has no uncontrolled comorbidities
60
Class 2 cellulitis
Person is either systemically unwell / well but with a co-morbidity
61
Class 3 cellulitis
Person has significant systemic upset or unstable co-morbidities that may interfere with a response to treatment.
62
Class 4 cellulitis
Person has sepsis or severe life-threatening infection, such as necrotising fasciitis.
63
Management of Class 1 cellulitis
Draw a line around lesion
Prescribe high dose oral antibiotics
Pain relief and elevation
Review in 48 hours
64
Necrotising fasciitis
Very serious bacterial infection of the soft tissue and fascia
65
Causes of necrotising fasciitis
Polymicrobial
S. pyogenes / S. aureus
Gas gangrene
Marine organisms / fungal infections
66
Gas gangrene
Clostridium spp.
67
How does necrotising fasciitis develop ?
Infection starts in the superficial fascia and spreads vertically up into the skin and down into deeper structures.
68
Fungal infections of the skin
Ringworm - aka Tinea
Yeasts
69
What causes ringworm ?
Trichophyton
Microsporum
Edpidermopythyton
70
Yeasts
Candida albicans
Malassezia furfur
71
Ringworm of the body
Tinea corporis
72
Ringworm of the foot - athletes foot
Tinea pedis
73
Ringworm of the groin
Tinea cruris
74
Viral infections of the skin
Herpes simplex virus
Human papilloma virus
Chickenpox - Varicella-Zoster virus
75
Warts / Gential warts
HPV
76
Cold Sores
Herpes simplex virus 1
77
Genital Herpes
Herpes Simplex virus 2
78
Chicken pox, Shingles
Varicella Zoster Virus (VZV)
79
Hand, Foot and Mouth Disease
Coxsackie A virus
80
HPV
Affects the skin and moist membranes lining the body - cervix, anus, mouth and throat
Changes to cells within the cervix can lead to cervical cancer
81
Parasites of the skin
Sarcoptes scabei (mites)
82
Sarcoptes scabei (mites)
Causes scabies
Mite buries into the skin
Female lays eggs
Infection is asymptomatic
Hypersensitivity may occur
May lead to superinfection
83
Most common types of bites
Dogs (80-90%)
Cats
Human children
Adults
84
How common are bites ?
250,000 cases in A&E UK/ year
3% of visits
85
Cat bite : features
Small deep wound (2-5 cm)
Usually periphery - hand/foot
Pasteurella spp.
Cellulitis
86
Sites of animal bites
Children - facial / cervical (neck)
Adults - extremities
87
Host factors
Immune status
Site of injury
Wound management
88
Infection risks
Species
Host factors
89
Dog bites : features
Large wound; tearing, crushing
Usually periphery but can occur anywhere
Secondary infections: large area damaged, higher chance of contamination
Crush damage comes with its own complications
Management: surgery - extensive superficial damage
90
Species - bite causing
Cat (80%)
Dog (36%)
Humans (18%)
91
Pasteurella multocida
Bacterial organism that causes infection - from cat bites
Gram negative coccus
Penicillin sensitive
92
Human bite : features
Wide shallow wound
Anywhere...
Highly polymicrobial
Deep infection is common, viral infection
Drastically different - Assess
93
Animal Bite 'Mantra'
The Solution to Pollution is Dilution
- get rid of the infecting material
- clean the wound
94
Microbiology of bites
Polymicrobial
95
Human - microbiology of bites
Average 5 microorganisms will infect
60% anaerobes
Eikenella corrodes 1/4 hand bites
Group A strep
96
Viral aetiology of human bites
Rabies
Simian herpes virus
Hep B, HIV, Hep C
97
Management of bites
Full History
Radiology
Wound Exploration
Antibiotic therapy
98
Full history - bites
Immunodeficiency
Country of exposure
99
Radiology - bites
Clenched fist
Scalp bites children
100
Wound exploration
Irrigate / Debride = Source of control
Delayed closure
101
Antibiotic therapy - bites
Prophylaxis
Treatment
102
Duration of antibiotics for Tenosynovitis
| Inflammation and swelling of a tendon
21 days
103
State some common antibiotics used mild-moderate bites
Co-amoxyclav
Doxycycline + Metronidazole
104
Duration of antibiotics for Cellulitis
7-10 days
105
Duration of antibiotics for Septic Arthritis
28 days
106
Duration of antibiotics for Osteomyelitis
42 days
107
Why do you need to adapt the duration of antibiotics ?
So that the agent can reach the bacterium and actually kill it.
As depending on where the infection lies, the bacteria can metabolise and will have access to antimicrobials differently, so won't reach it as effectively.
Different metabolic states
