skin and soft tissue infections Flashcards Preview

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Flashcards in skin and soft tissue infections Deck (59)
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1
Q

how can infections be classified

A
  • by microbe = bacteria, virus or fungi

- by anatomy = superficial, deeper tissues

2
Q

what type of microbe is staphylococcus aureus

A
  • bacteria
  • gram positive cocci
  • can cause a wide range of diseases
3
Q

what is the virulence factor of staphylococcus aureus

A
  • Panton Valentine Leukocidin (PVL) toxin
4
Q

how does PVL work

A
  • toxin that attacks the white blood cells
  • works by punching holes in the outer membrane of the epithelial cells and causes the content of the cell to leak out
  • can also work on polymorphs = cause all enzymes in it to be released and causes tissues atrophy
5
Q

where is staphylococcus aureus most common

A
  • nose throat and groin are most affected = 20-30% of us will carry it in these areas of our body
6
Q

what are pyogenic infections caused by staphylococcus aureus

A
  • boils, carbuncles
  • wound infections
  • abscesses
  • impetigo
  • mastitis
  • pneumonia
  • endocarditis
  • bacteraemia
  • osteomyelitis
7
Q

what are toxin mediated infections caused by staphylococcus aureus

A
  • scalded skin syndrome
  • toxic shock syndrome
  • food poisoning
8
Q

what type of microbe is streptococcus pyogenes

A
  • bacteria
  • pus producing
  • other name is Group A streptococcal infections
  • gram positive
  • chains rather than clump together
9
Q

what is the haemolytic occurring around colonies of streptococcus pyogenes

A
  • beta haemolysis
10
Q

what is the virulence factor of streptococcus pyogenes

A
  • superantigens causing toxic shock syndrome
11
Q

why are they called super antigens

A
  • because it is an effect on our immune system that is disproportionate to the amount of antigen present
  • activates all the pathways and bypasses other control systems
12
Q

what else can streptococcus pyogenes cause

A
  • enzyme release causing skin infection, pharyngitis, otitis media
  • bacteraemia causing meningitis, arthritis and osteomyelitis
  • antigen causing post-streptococcal glomerulonephirits or acute rheumatic fever
13
Q

how does streptococcus pyogenes cause toxic shock syndrome

A
  • releases a super antigen that then causes cytokine release leading to toxic shock syndrome
14
Q

what is a disease caused by streptococcus pyogenes

A
  • cellulitis

- get streptococcus skin and soft tissue infections in neck

15
Q

what type of microbe is streptococcus anginosus group

A
  • bacteria
  • gram positive
  • chains
16
Q

what is the virulence factor for streptococcus anginosus

A
  • intermedilysin
  • it is a cytotoxin
  • it is produced by an anginosus group
17
Q

what disease can be caused by streptococcus anginosus

A
  • dental abscesses
18
Q

what type of microbes are anaerobes

A
  • bacteria
  • gram positive
  • purple rice shaped structures
  • bacilli
  • clostridium species is an example
19
Q

what is the virulence factor of anaerobes

A
  • alpha toxin (lecithinase)

- like an enzyme, it breaks down the outer cell membrane and allows infection to spread

20
Q

what type of reaction is used to identify clostridium

A
  • Nagler reaction

- zone of inhibition around the white streaks show that it is clostridium

21
Q

what type of microbe is herpes simplex virus

A
  • virus
  • DNA virus with envelope around it
  • “fried egg virus”
22
Q

what is the virulence factor of herpes simplex virus

A
  • causes lysis of other cells
23
Q

what disease can be caused by herpes simplex virus

A
  • herpes labialis
24
Q

what type of microbe is Candida albicans

A
  • fungi
  • yeast cells
  • they are 10 times bigger then bacteria
25
Q

what is the virulence factor of Candida albicans

A
  • phospholipase

- breaks down phospholipids in cell membrane

26
Q

what disease can be caused by Candida albicans

A
  • candidiasis
27
Q

where is impetigo and angular cheilitis found

A
  • epidermis
28
Q

what is angular cheilitis and impetigo

A
  • golden honey coloured crusted lesion
29
Q

what is the common cause of impetigo and angular cheilitis

A
  • group A streptococci and maybe sometimes staph aureus
30
Q

where is the herpes simplex virus found

A
  • epidermis
31
Q

what can the herpes simplex virus cause

A
  • chicken pox = can sometimes get secondary infection by staphylococcus due to itching of lesion
  • shingles = reactivation of varicella’s (chicken pox)
  • herpetic whitlow = a lesion that occurs on the tip of the finger
32
Q

Where does erysipelas occur

A
  • in the dermis
33
Q

what does erysipelas show as

A
  • a butterfly rash on the face
34
Q

what is the common cause of erysipelas

A
  • group A streptococcus is the most common

- can sometimes swab and not find any pathogen however

35
Q

where are hair follicle infections

A
  • in the dermis
36
Q

what is folliculitis

A
  • hair follicle infection

- red spots on the skin that are raised and inflamed

37
Q

what is the common cause of folliculitis

A
  • staphylococcus is important here
38
Q

what are boils

A
  • hair follicle infection
  • furuncle
  • red boils on the skin
  • boils = furuncle deep seated infection
39
Q

what is the common cause of boils

A
  • staph aureus
40
Q

what are carbuncles

A
  • hair follicle infection
  • multiple heads
  • number of boils in one area
  • deep hearted infection with multiple heads
  • multiple deep infections of hair follicles
41
Q

what is the common cause of carbuncles

A
  • staph aureus
42
Q

where does cellulitis occur

A
  • subcutaneous fat
43
Q

what does cellulitis show as

A
  • swollen red inflamed area
44
Q

why is a blue line often drawn around cellulitis

A
  • marking for surgical and medical monitoring

- know if it is spreading or receding

45
Q

what is the common cause of cellulitis

A
  • group A streptococcus or staph aureus too
46
Q

what can cellulitis cause

A
  • the introduction of anaerobes to that area

- depends on the area and extent

47
Q

what causes odontogenic infections

A
  • streptococcus anginosus and a mixture of anaerobes cause these
48
Q

where does necrotising fascitis occur

A
  • in the fascia = in the subcutaneous fat and tissue over the muscles
49
Q

what is the common cause of necrotising fascitis

A
  • staph aureus and streptococcus pyogenes
50
Q

what is the treatment of necrotising fascitis

A
  • need to debride the area
  • and need antibiotics
  • need both of these for ti cure
51
Q

what are a common diagnostic symptoms of necrotising fascitis

A
  • also known as flesh eating disease
  • large, dark, boil-like blisters
  • pockets of gas
52
Q

where does myonecrosis, gangrene occur

A
  • muscle necrosis
  • muscle
  • can get abdominal wall myonecrosis from burst appendix or trauma = clostridium perfringens is the cause
53
Q

what is the common cause of surgical wound infections

A
  • healthcare associated infections

- staph aureus

54
Q

what is the common cause of bite wound infections

A
  • depends on what bites you
  • human = missed anaerobes, prevotella intermedia
  • animals = pasteurella multicoda
55
Q

what is prevotella intermedia

A
  • gram negative, obligate anaerobic pathogenic bacterium involved in periodontal infections and often found in acute necrotising ulcerative gingivitis
56
Q

what is pasteurella multicoda

A
  • gram negative microbe in the oral cavity of cats and dogs

- depends on the animal that bites you what you will find

57
Q

what are the treatment principles

A
  • diagnosis
  • surgical debridement
  • antibiotics
  • review
  • needs to be a combo of both debridement and antibiotics
58
Q

what are the most common microbes outside of the head and neck

A
  • staph aureus and strep pyogenes
59
Q

what do you give for streptococcus anginosus and anaerobes

A
  • give intravenous penicillin for streptococcus anginosus

- give metronidazole for anaerobes