S13C147 - soft tissue infections

Question 1

cellulitis

Answer 1

=infection of deep dermis and sc fat of skin
-80% caused by gm+ bacteria, most common are beta-hemolytic strep and s aureus and gm-aerobic bacilli
-red, tender, warm, NOT sharply demarcated, gradual onset
-tx: keflex 500mg q6h/dicloxacillin 500mg q6h/clinda
or IV: cefazolin

Question 2

erysipelas

Answer 2

=infection of upper dermis with prominent lymphatic involvement

• usually caused by beta-hemolytic strep
• abrupt onset, fever, chills, malaise, nausea, erythema, burning sensation, indurated, raised, sharply demarcated, desquamation on resolution
• milian ear sign - erysipelas will involve ear while cellulitis will not b/c there is no deep dermis

-Tx: give IV dose of cefazolin if mild with PO PCN/amoxicillin
PCN 500mg PO q6h / amox 500mg QID
severe: CTX 1g OD or cefazolin 1-2g IV q8h or cefuroxime
-NB:cefazolin will cover b-h strep and staph a (CTX will only cover b-h strep)

Question 3

MRSA tx

Answer 3

• clinda (check local susceptibility)
• septra
• doxy
• if severe: vanco

Question 4

Necrotizing STI: types of infection

Answer 4

Type 1: polymicrobial, 75% of Nec STI, gm+ coci and gm- rods, anaerobes,
Type 2: GAS +/- s aureus, usually extremity with hx of trauma or procedure (MRSA)
Type 3: vibrio vulnificus, from a scratch in seawater

Question 5

Nec fasc pathopys

Answer 5

• bacteria invade SC tissue and deep fasciarelease exotoxin causing ischemia, liquefaction encrosis and systemic toxicity and gangrene
• vasculitis, thrombosis
• infxn spreads at 1in/h
• tissue ischemia prevents adequate delivery of Abx which is why abx alone are not enough to stop this infxn

Question 6

Nec fasc: dx

Answer 6

• signs: POOP, insensate with progression, usually skin trauma 48h before onset of pain, cellulitis, crepitus, late finding of bronze/brown skin, malodorous d/c, vullae, fever, tachy
• clinical
• xr may show SC gas (but not deep fascia gas)
• CT very sensitive (80%)
• MRI best but delays things too much
• labs: acidosis, leukocytosis, anemia, coagulopathy, hyponatremia

Question 7

Nec Fasc: tx

Answer 7

• aggressive fluid resusc
• tfn of PRBC may be needed
• surgical consult
• Abx: vanco plus meropenem/pip-tazo

Question 8

Folliculitis

Answer 8

-superficial bacterial infeciton of hair follicles with purueltn material in the epidermis, usually apocrine areas,

Question 9

Bartholin gland Abscess

Answer 9

• infection with vaginal flora, anaerobes and sometimes NG/CT
• requires marsupilization, analgesia, if severe give keflex plus flagyl

Question 10

Sporotrichosis

Answer 10

• mycotic infection by fungus sporothrix schenckii
• subtropical zones, found in soil, moss, decaying vegetation, usually from a thorn/splinter
• usually self-limited skin/lymph infxn but can spread to joints directly or hematogenously and may be inhaled causing granulomatous pneumonitis with cavitation
• incubation 3w
• ulcer or verrucous plaque, SC nodule/pustule, erythematous skin with ulceration, chancre, lymphadenitis, can develop chronic lymphocytic meningitis
• dx: tissue bx c+s or pus, sputum, blood
• DD: tularemia, cat-scrath dz, leishmaniasis, staph lymphangitis, blastomycosis, pyoderma, syphilis
• tx: itraconazole