04-08 Skin, Soft Tissue and Bone Infx Flashcards Preview

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Flashcards in 04-08 Skin, Soft Tissue and Bone Infx Deck (27):
1

Spreading infx is usually from _______ which is treated with _______.

  • If 2° to trauma add ____

**distinguish focal vs. spreading**

Spreading infx (e.g. cellulitis) is usually from GROUP A STREP (a.k.a. STREP PYOGENES) which is treated with PENICILLIN to which it's "exquisitely sensitive".

—I.E. you DON'T NEED KEFLEX! (Overkill)

—Usuallly 2° to microtrauma (zipper, toenail infx, surgery)

If 2° to trauma, add Rx for MSSA/MRSA

2

Focal skin/soft tissues infx are usually caused by _________ and treated with ______.

we're talking boils/furuncles/carbuncles

  • usually caused by STAPH AUREUS.
  • Treatment: Apply heat and drain if > 1cm; often sufficient.
  • Add abx if pt is sick or cellulitis is surrounding focus; cover for MRSA "unless you have a culture cooking"
  • best options: TMP/SMX > doxy > clinda
    • vanco if hospitalized

3

What is this?

  • bug?
  • tx?

Q image thumb

impetigo

  • usually strep
  • Treatment
    • mild: topical mupirocin
    • more severe: cephalexin +/- TMP/SMX depending on likelihood of staph

4

What is this?

  • presentation?
  • causal organism?
  • tx?

Q image thumb

Erysipelas

  • Well-demarcated, uniform erythema w/ systemic sx
  • Cause: Group A strep
  • Tx: penicillin

A image thumb
5

Cat bite infections

Pasturella

6

Human bite infxs

Eikenella

7

Fresh water trauma worry about...?

Aeromonas

8

Salt water trauma worry about...

Vibrio vulnificus

9

Rose gardener w/ nodular lesions worry about...

Spoptrichosis (fungal)

10

Fish tank owner w/ skin/soft tissue infx worry about...

Mycobacterium marinum

11

Name the tissue layers and the infections that occur at each level.

See image below

A image thumb
12

Treatment for pts w/ recurrent MRSA?

Nasal mupirocin, bleach baths, chlorhexidine washes

13

Necrotizing Faciitis

  • Presentation
  • Dx
  • Causative Bugs
  • Tx strategy

  • Presentation: rapidly spreading soft tissue infx, can be accompanied w/ systemic shock sx
  • Dx: MRI + culture
  • Bugs: usu Grp A Strep or Staph
    • more rare: Gm negs
  • Tx: often surgical debridement plus
    • broad spectrum abx
    • PLUS clinda (ribosomal inhib) to stop toxin elaboration

14

Paronychia

  • Presentation?
  • Tx?

Inflamm around nail bed

  • usually tx w/ "moist head" is enough
  • rarely drainage +/- abx

15

Folliculitis

  • Causal org?
  • Tx

Usu staph

tx w/ topical abx (e.g. Polymyxin B or mupirocin)

16

Anthrax presentation

  • bug name?

painless eschar in someone w/ exposure to animal hides or terrorists

  • Bacillus anthracis

17

Lyme

  • Derm finding name?
  • non-derm findings?
  • should you check serology?

  • Erythema chronicum migrans
  • Non-Derm Findings
    • septic, monoarticular arthritis
    • facial nerve (CN VII) palsy
    • meningitis
    • complete heart block
  • If pt has ECM, no need for serology
    • also no need if suspected "chronic Lyme"

18

Two ways of osteomyelitis spreading

  1. heamtogenous
  2. contiguous

19

Contiguous Osteomyelitis

  • Pt population?
  • Risk factors?
  • w/o vasc insuff vs. w/ vasc insuff
    • s/sx differences between two
  • Common sites?
  • Pathogens?
  • Dx?

     

Contiguous focus infections and those due to vascular insufficiency are most common in those over 50 years old, reflecting increased likelihood of precipitating factors:

  • Surg, ortho surg (e.g., knee, hip replace)
  • History of DM and/or PVD
  • Trauma, incl open fxs

20

Hematogenous Osteomyelitis

  • Presentation
  • Pt population?
  • Risk factors?
  • Which bone(s)?

Hematogenous Osteomyelitis

  • Presentation: local sx + systemic sx
  • Pt population: children
  • Risk factors?
  • Which bone(s): usually single, long bone

21

Vertebral Osteomyelitis:

  • Pathophysiology
  • Most common bug?
    • Others in adults?
    • Old men?
    • IVDUs?
    • Sickle Cell pts?
  • Risk Factors?
  • S/Sx
  • Dx

Pathophys

  • Organisms reach the well-perfused vertebral body via spinal arteries.
  • Most often involves the lumbar or thoracic spine.
  • Infection spreads from end plate into disk space.

Most common bugs (95%  single org)

  • Most common: 50% S. aureus
    • other adult paths: Viridans streptococci, including S. milleri
  • E.coli and other enterics in~25%
  • Old men: Enterococci
  • IVDUs: S. aureus, P. aeruginosa, Serratia
  • Sickle: Salmonella spp., S. aureus

Risk Factors

  • Age > 50
  • Sickle cell
  • DM
  • Hemodialysis
  • Endocarditis
  • IVDU
  • Nosocomial bacteremia
  • Long-term vascular access
  • UTI, esp. elderly men
  • Preceding minor trauma or fall

S/Sx

  • Often starts insidious -> subacute or chronic
  • May have hx of fever +/- rigors weeks b4 presentation w/ back pain
  • Presents as back or neck pain (>90%)
  • Fever often low-grade or absent (50%)
  • Constitutional symptoms: anorexia, malaise
  • Percussion tenderness of spine and paraspinal muscles, with spasm (85%)

Dx

  • Cultures
  • Plain films: irregular erosions in end plates of adjacent vertebral bodies and narrowing of intervening disk space – virtually diagnostic
  • CT/MRI: may show epidural, paraspinal, retropharyngeal, mediastinal, retroperitoneal, or psoas abscess originating in the spine

22

Treatment for General Osteomyelitis

See Slides 32 and 33

23

Most sensitive and specific test of osteomylelitis?

MRI

24

Tx for acute hematogenous osteo

  • Duration of therapy typically 4 to 6 weeks
  • Home therapy (OPAT) is appropriate for motivated and stable patients
  • Drugs with a long half-life, such as ceftriaxone vancomycin, and ertapenem, facilitate OPAT.
  • Children can be switched from parenteral to oral therapy after 5 to 10 days if signs of infection have resolved.
  • Few data support the use of oral therapy in adults except with quinolones (for GNRs) and possibly linezolid.

25

Tx for vertebral osteomyelitis

  • Key: evaluate carefully for epidural abscess.
  • Usual duration for 6 weeks, but longer course if ESR and/or CRP do not normalize by end of planned course.
  • Surgery necessary only for:
    • Spinal instability
    • New or progressive neurologic deficits
    • Large soft tissue abscesses
    • Failure of medical therapy
  • Bed rest only until back pain improved.

26

Tx of Chronic Osteo

  • Combined surgical and medical approach.
  • Thorough debridement of necrotic bone and abnormal soft tissues is essential.
  • Use of CT or MRI to delineate extent of infection before surgery.
  • After surgery, 4 to 6 weeks of parenteral therapy (or oral equivalent), based on culture data.
  • The benefit of prolonged oral therapy after 4 to 6 weeks i.v. is unproven, but often done.

27

skeletal TB

  • Most commonly involves thoracic spine
  • Usually accompanied by abnormal chest x-ray, e.g., chronic fibrotic changes or nodules
  • Suspect TB on the basis of epidemiology (where a patient is from, likelihood of TB exposure), chest x-ray findings, and PPD or interferon- release assay.
  • Histopathology shows necrotizing granulomas, but the infection is “paucibacillary,” so stains may be negative (with culture taking 6 weeks)