May11 M1-Soft Tissue Infections

Question 1

layers of the skin and subcutaneous tissue

Answer 1

1. epidermis (melanocytes and Langerhans immune cells)
2. dermis (upper lower and hypo. follicles, glands, nerves, corpuscules Meissner’s and Pacini)
3. subcutaneous tissue (FASCIA, blood vessels, nerves)
4. muscle

Question 2

uncomplicated vs complicated soft tissue infections

Answer 2

• uncomplicated = cellulitis, erysipelas, abscess, folliculitis, furunculosis, impetigo, ecthyma
• complicated = bigger wounds, inflected by humans or animals or surgical problem + affected by underlying state of pt (immunosuppressed, diabetic, etc.): includes necrotizing infections (NI), myonecrosis
• the more there is soft tissue (buttocks and perianal area), the easier it gets infected*

Question 3

(exam) skin layers affected by cellulitis

Answer 3

epidermis and dermis

Question 4

(exam) skin layers affected by erysipelas

Answer 4

dermis (lymphatics of the dermis)

Question 5

(exam) skin layers affected by a skin abscess

Answer 5

• more often: epidermis and dermis

- sometimes: subcutaneous tissues and muscle

Question 6

most common bug seen in the community (#1 cause of infections)

Answer 6

MRSA (staph aureus)

Question 7

how do you treat an MRSA infection, or infection that you suspect to be ‘‘MRSA type’’

Answer 7

Septra

Question 8

(exam) felon (hand infection of inoculation of compartmentalized fibrous septae of the hand): layers of skin affected

Answer 8

possibly all layers (including ligaments, tendon sheaths, bones)

Question 9

(exam) paronychia (skin infection) affects what skin

Answer 9

skin over the mantle of the nail or of the lateral nail fold. can progress to felon (so all layers possibly)

Question 10

(exam) tenosynovitis (hand infection, penetrating injury, painful extension of finger)

Answer 10

• volar surface and tendon sheath (is a penetrating infection)
• tendon (so deep)

Question 11

most common organism causing tenosynovitis

Answer 11

staph aureus

Question 12

(exam) human bites: skin layers affected

Answer 12

possibly all layers + joint space, muscle, etc.

Question 13

(exam) #1 and #2 most common species in cat bite infections

Answer 13

1. pasteurella spp

2. staph spp

Question 14

(exam) #1 and #2 most common species in dog bite infections

Answer 14

1. pasteurella spp

2. staph spp

Question 15

(exam) #1 and #2 most common species in human bite infections

Answer 15

1. strep viridans (alpha hemolytic)

2. strep pyogenes (GAS) and staph aureus

Question 16

(exam) diabetic foot (ulcer) skin layers affected

Answer 16

can go from cellulitis (epidermis and dermis) to chronic osteomyelitis very hard to tx (all layers, bone)

Question 17

necrotizing infections include what infections

Answer 17

• clostridial infections
• necrotizing fasciitis
• bacterial synergistic gangrene
• streptococcal gangrene

Question 18

most common bacteria of NIs

Answer 18

skin bacteria

1. staph aureus
2. pseudomonas aeruginosa
   * BUT ASSUME POLYMICROBIAL*

Question 19

(EXAM) most frequent site of spontaneous NI

Answer 19

perineum (space between the anus and scrotum in the male and between the anus and the vulva in the female)

Question 20

(EXAM) most frequent site of NI overall (includes everything, not just spontaneous. so wound, puncture, injury, etc.)

Answer 20

limbs

Question 21

(imp?) gold standard for NI diagnosis

Answer 21

• tissue bx or some sort of culture

- high suspicion

Question 22

(exam) skin layers affected by bacterial synergistic gangrene

Answer 22

epidermis and dermis

FASCIA IS OK. ONLY ABOVE FASCIA

Question 23

(exam) necrotizing fasciitis (flesh eating disease): skin layers affected

Answer 23

-epidermis
-dermis
-fascia
(NOT MUSCLE)

Question 24

(imp?) management of necrotizing fasciitis

Answer 24

radical debridement on surgery + broad spectrum Abx

Question 25

(imp?) key thing GAS produces that makes it bad and key concept related to that

Answer 25

- produces exotoxin A, makes you septic. is a superantigen | - everyone responds differently (sick to a diff level) to a superantigen bc of genetics*

Question 26

(imp?) what is the key thing that makes GAS dangerous

Answer 26

having an unbalanced immune response (too many pro-inflam signals, because of exotoxin A for example), and some people, bc of genetics, are more likely to have more pro-inflam signals

Question 27

(imp?) key tx to a GAS infection

Answer 27

surgical debridement

Question 28

(exam) skin layers affected by a clostridial cellulitis

Answer 28

-dermis -fascia -muscle (NOT EPIDERMIS)