16- Soft tissue infections

Question 1

manifestations of all soft tissue infections

Answer 1

heat, erythema, tenderness, pain

Question 2

impetigo is found in which age group

Answer 2

children

Question 3

erysipela is found in which age group

Answer 3

adults

Question 4

most common etiology for soft tissue infections

Answer 4

S aureaus, S pyogenes

Question 5

does S aureaus colonizes us

Answer 5

yes

Question 6

epidermidis: impetigo
superficial dermis: folliculitis
deep derma: furuncles, erysipela
subcutaneous: cellulitis, fascitis, piolyositis

Answer 6

s aureus infection according to zone

Question 7

staphylococcal scalded skin syndrome is due to what type of toxin

Answer 7

exfoliative exotoxin produced by S aureus

Question 8

community acquired MRS occurs due to

Answer 8

S aureus strains that are resistant to oxacillin, that produce panton velentine toxin (leucocidine)

Question 9

tx of S aureus based on location

Answer 9

superficial infection: disinfection, topical tx
invasive/extensive infection: systemic tx
abscesses/necrotic areas: surgical drainage or debridement
PVL producing strains: linezolid, clindamycin

Question 10

impetigo: def, incidence, cause

Answer 10

• common crusted (NOT SCAR) and superficial infection skin
• 2-5 y/o
• B hemolytic streptococci/ S aureus

Question 11

tx for impetigo

Answer 11

topical tx with mupirosin
oral antibiotics: amoxicillin/clauvulonate, cephalosporins
if MRSA is suspected: trimethorpim, sulfamethoxazole, clindamycin

Question 12

erysipelas: def, cause, rf

Answer 12

• acute infection with rash of the upper dermis and superficial lymphatics
• B hemolytic group A streptococcus
• impaired lymphatic drainage, immune deficiency, diabetes, alcoholism, skin ulceration

Question 13

erysipelas vs cellulitis

Answer 13

e is more supercifical than c

Question 14

onset of erysipelas and symptoms

Answer 14

onset is sudden, one day, fever, shivering, vomiting, enlarged lymph nodes
skin is bright red shiny and hot, the lesion has defined borders

Question 15

tx for erysipelas

Answer 15

B lactams (macrolides, or clindamycin for allergic pts)

Question 16

cellulitis def, etiology? sharp or not borders?

Answer 16

• bacterial non necrotizing inflammation of the inner layers of the skin and subcutaneous tissues; BORDERS NOT SHARP
• streptococci, and S aureus

Question 17

tx for cellulitis

Answer 17

B lactams

Question 18

anaerobic cellulitis etiology? RF? TX?

Answer 18

clostridium perfringens or C septicum (is necrotizing cellulitis that spares muscle fascia)
Often due to dirty wounds, contaminated surgical wounds
Surgical debridment is essential

Question 19

necrotizing fascitis affects which layer of skin? types?

Answer 19

is bacterial infection of subcutanous tissues producing soft tissue necrosis

• type 1: polymicrobial (anaerobes, facultative anaerobes, enterobacteria)
• type 2: group A strepto

Question 20

which is more common type of necrotizing fascitis

Answer 20

type 1 (70%)
note the disproportion between intense pain and local appearance of the lesion; skin crackes due to air collection

Question 21

apperance of type 1 necrotizing fasciitis

Answer 21

turns from reddish to gray (necrosis) with bullous formation

Question 22

type 2 necrotizing fascitis is aka

Answer 22

haemolitis streptococcal gangrene

occurs in young healthy adults with history of injury

Question 23

lymphatic filariasis is due to

Answer 23

nematodes (roundworms) that inhabit lymphatics and subcutaneous tissues
- wuchereria bancrofti
- brugia malayi
- brugia timori
infection is transmitted by mosquito vectors

Question 24

dx of filariasis

Answer 24

ID microfilariae in blood smear by microscopic examination

IgG4

Question 25

tx of filariasis

Answer 25

diethylcarbamazine (kills microfilariae and some adult worms)
NOTE that ppl with lymphedema and elephantiasis are unlikely to benefit form this, bc most people with lymphedema are not actively infected

Question 26

Two most common pathogens that cause soft tissue infection are

Answer 26

S aureus

S pyogenes

Question 27

Healing pattern of impetigous lesions

Answer 27

they heal slowly and leave depigmentated areas but DO NOT FORM SCARS

Question 28

Does erysipelas relapse

Answer 28

yes

Question 29

T/F cellulitis lesions grow in size over days, and do not have defined borders

Answer 29

T

The skin turns white under pressure, is painful

Question 30

SX, DX, TX for type 1 necrotizing fascitits

Answer 30

high fever
very early surgical intervention is crucial
DX needs imaging
Antibacterial tx targeting a large # of bacteria is used

Question 31

MX of skin ulcers

Answer 31

• evaluate extension of the lesion (exclude osteomyelitis)
• plan for wound dressing
• empiric antibiotic therapy
• Microbiological exams should be done on biopsy of deep vital tissue (superficial swabs are useless)

Question 32

What 3 things are involved in pathogenesis of diabetic foot

Answer 32

peripheral nerve dysfunction, immunosuppression, peripheral artery dx

Question 33

Do you need culture to treat diabetic foot? How do you tx it?

Answer 33

yes, and surgical debridement, note that it is often with osteomyelitis

Question 34

T/F most people infected with filiarsis will never have symptoms

Answer 34

T

Question 35

Filarial infection can also cause tropical pulmonary eosinophilia syndrome, typically in Asia. Symptoms include cough, shortness of breath, and
wheezing. The eosinophilia is often accompanied by high levels of Immunoglobulin E ( IgE)
and antifilarial antibodies.

Answer 35

T

Question 36

What do you stain the smear of filiarisis for

Answer 36

giemsa, or hematoxylin and eosin

Question 37

W. bancrofti, B. malayi, and B. timori can be differentiated from each other on blood smear by their morphologic
characteristics. W. bancrofti and both Brugia species have acellular sheath stains
and are visible on light microscopy. B. malayi has terminal and subterminal nuclei
in its tail; W. bancrofti has no nuclei in its tail.

Answer 37

T