16- Soft tissue infections Flashcards
manifestations of all soft tissue infections
heat, erythema, tenderness, pain
impetigo is found in which age group
children
erysipela is found in which age group
adults
most common etiology for soft tissue infections
S aureaus, S pyogenes
does S aureaus colonizes us
yes
epidermidis: impetigo
superficial dermis: folliculitis
deep derma: furuncles, erysipela
subcutaneous: cellulitis, fascitis, piolyositis
s aureus infection according to zone
staphylococcal scalded skin syndrome is due to what type of toxin
exfoliative exotoxin produced by S aureus
community acquired MRS occurs due to
S aureus strains that are resistant to oxacillin, that produce panton velentine toxin (leucocidine)
tx of S aureus based on location
superficial infection: disinfection, topical tx
invasive/extensive infection: systemic tx
abscesses/necrotic areas: surgical drainage or debridement
PVL producing strains: linezolid, clindamycin
impetigo: def, incidence, cause
- common crusted (NOT SCAR) and superficial infection skin
- 2-5 y/o
- B hemolytic streptococci/ S aureus
tx for impetigo
topical tx with mupirosin
oral antibiotics: amoxicillin/clauvulonate, cephalosporins
if MRSA is suspected: trimethorpim, sulfamethoxazole, clindamycin
erysipelas: def, cause, rf
- 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
erysipelas vs cellulitis
e is more supercifical than c
onset of erysipelas and symptoms
onset is sudden, one day, fever, shivering, vomiting, enlarged lymph nodes
skin is bright red shiny and hot, the lesion has defined borders
tx for erysipelas
B lactams (macrolides, or clindamycin for allergic pts)
cellulitis def, etiology? sharp or not borders?
- bacterial non necrotizing inflammation of the inner layers of the skin and subcutaneous tissues; BORDERS NOT SHARP
- streptococci, and S aureus
tx for cellulitis
B lactams
anaerobic cellulitis etiology? RF? TX?
clostridium perfringens or C septicum (is necrotizing cellulitis that spares muscle fascia)
Often due to dirty wounds, contaminated surgical wounds
Surgical debridment is essential
necrotizing fascitis affects which layer of skin? types?
is bacterial infection of subcutanous tissues producing soft tissue necrosis
- type 1: polymicrobial (anaerobes, facultative anaerobes, enterobacteria)
- type 2: group A strepto
which is more common type of necrotizing fascitis
type 1 (70%) note the disproportion between intense pain and local appearance of the lesion; skin crackes due to air collection
apperance of type 1 necrotizing fasciitis
turns from reddish to gray (necrosis) with bullous formation
type 2 necrotizing fascitis is aka
haemolitis streptococcal gangrene
occurs in young healthy adults with history of injury
lymphatic filariasis is due to
nematodes (roundworms) that inhabit lymphatics and subcutaneous tissues
- wuchereria bancrofti
- brugia malayi
- brugia timori
infection is transmitted by mosquito vectors
dx of filariasis
ID microfilariae in blood smear by microscopic examination
IgG4
tx of filariasis
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
Two most common pathogens that cause soft tissue infection are
S aureus
S pyogenes
Healing pattern of impetigous lesions
they heal slowly and leave depigmentated areas but DO NOT FORM SCARS
Does erysipelas relapse
yes
T/F cellulitis lesions grow in size over days, and do not have defined borders
T
The skin turns white under pressure, is painful
SX, DX, TX for type 1 necrotizing fascitits
high fever
very early surgical intervention is crucial
DX needs imaging
Antibacterial tx targeting a large # of bacteria is used
MX of skin ulcers
- 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)
What 3 things are involved in pathogenesis of diabetic foot
peripheral nerve dysfunction, immunosuppression, peripheral artery dx
Do you need culture to treat diabetic foot? How do you tx it?
yes, and surgical debridement, note that it is often with osteomyelitis
T/F most people infected with filiarsis will never have symptoms
T
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.
T
What do you stain the smear of filiarisis for
giemsa, or hematoxylin and eosin
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.
T
