Academic Half-Day

BONE/JOIN FECTIONS – CHP 134

SOFT-TISSUE INFECTIONS – CHP 135

BONE/JOIN FECTIONS – CHP 134

Q1. Name RF for OM/jnt infections?

-IVDU

-Post-Operative

-Post-trauma (esp open fractures)

-immunosuppressed

-sickle cell disease

-Pre-existing jnt disease (i.e. RA)

Q2. Duration of acute OM? Chronic OM?

Acute <6 wks, Chronic >6wks

Q3. What is an involucrum? Which patient population does it typically occur in?

  • periosteal formation/reaction in response to bone infection
  • more common in kids

Q4. What is a sequestrum? Complication associate with this?

  • ischemic segments of bone that become separated from surrounding bone;
  • can result in pathologic fractures through sequestrum

Q5. 3 mechanisms of OM and example of who is at risk for this form of OM

A.Hematogenous spread – pediatric patients

B.Contiguous infection – device implantation/prosthesis

C.Direct inoculation – open fracture

Q6.MC organism overall? S. aureus

Most likely organisms based on RF

NeonatesGroup B strep (Staph still MCC), ecoli

ElderlyGram -ves (ecoli etc)

Foot puncturePseudomonas

Human biteOral anaerobes, eikinella, streptococcus

Animal bitePasteurella

Fresh water Aeromonas hydrophila

Chronic osteoPolymicrobial (almost always)

IVDUPseudomonas, staph aures, ecoli

Sickle cellSalmonella

HIVStaph, candida, Bartonella

Q7. Who gets polymicrobial infections?

Diabetics (in particular foot ulcers)

Chronic osteomyelitis

Post-trauma

Q8. Who gets pseudomonas?

Puncture wounds

Implanted devices

IVDU

Q9. Treatment for aeromonas hydrophilia?

Fluoroquinilones or SMP/TMX

Q10. Tx algorithm

Q11. Draw bone and label different sections (epiphysis, metaphysis and diaphysis).

Where do most OM occur?

metaphysis

Any specific population that gets infection in other areas?

Sickle cellers, diaphysis

Q12. X-ray findings in OM

Early

­Soft tissue edema 3-5 days

­Normal Xray in 70% < 10 days

­Lucent areas from cortical bone loss (after 50% bone loss)

­Involucrum: elevation of the periosteum; more common in kids

­Periosteal thickening from inflammation; more common in kids

Late signs (2-3 weeks)

­Lytic bone lesions

­Sclerotic bone formation around the lytic lesion

­Sequestra = hypodense ischemic segments of dead bone that become separated from surrounding bone

­Deep soft tissue swelling

Q13. Discuss phases of bone scan and results

  • 1st phase (done w/I 1min) = assess relative blood flow
  • 2nd phase (5-15 min) = blood pool
  • 3rd phase (2-4H) = bone uptake
  • All three phases + then OM likely
  • All three phases - then OM unlikely
  • First two phases +, 3rd –ve = cellulitis
  • Sensitivity (if patient has underlying normal bone) > 90%
  • Specificity as low as 50%
  • False +ve bone scan: surgery, tumor, soft tissue infection

Q14. Antibiotic regimes and duration (look at bugs and drugs)

  • First line therapy = Cloxacillin if not penicillin allergic
  • Need to consider covering for MRSA now with Vancomycin
  • Penicillin allergy: ancef or clindamycin
  • Foot puncture: prophylaxis with cipro 500 bid X 10 days
  • Other situations (see table 130-2)
  • 0-3 months: Cloxacillin + Cefotaxime
  • 3mo - 14yrs: Cloxaxillin + Ceftriaxone
  • 14yrs - adults: Cloxacillin
  • Sickle cell: Ceftriaxone
  • IVDU: Cloxacillin + Ciprofloxacin
  • Plantar puncture: Ceftazidime or PIP/TAZO
  • HIV: Cloxacillin + Ceftriaxone
  • Animal bites: Penicillin +/- clavulin (or Ceftriaxone + septra)

Q15. Complications of OM

  • Chronic osteomyelitis
  • Septic arthritis
  • Brain abscess
  • Meningitis
  • SC compression
  • Pneumonia
  • Growth problems in kids
  • Sepsis complications
  • Staph toxic shock syndrome

Q16. MC organisms for septic arthritis

-sexually active/at risk of STI’s; gonorrhea

-all others;s. aureus

Q17. Describe the presentation of Disseminated Gonococcal Infection.

Two presentations. Most are Sx with their oral or genital infections

1.triad of tenosynovitis, dermatitis and polyarthralgias w/o purulent arthritis

2. Purulent arthritis without skin manifestations

THESE TWO PROCESSES CAN CO-EXIST

Q18. Does the presence of crystals r/o s.a.?

NO!

Pt with RA presents with acute arthritic jnt – is it a acute of chronic exacerbation or septic jnt

-Need to tap the joint to make the Dx.

Pts with underlying jnt disease and crystal arthopathies are at higher risk of septic arthritis

Q19. You only have enough fluid to send one tube. What are you going to send for?

Joint fluid analysis? Prognosis? Do they typically require operative washout?

Q20. Fill out the following chart:

Q21. Top three joints affected (three biggest joints)

Knee>hip>shoulder

Q22. Convert cell counts

Tap a knee; WBC is 3.2 10^9/L

cells/mm3 = 10^6/L

cells/mm3 is the way numbers are represented in the american texts

10^6/L is the way numbers are represented in canadian texts

OFTEN TESTS HERE ARE PRESENTED IN CELLS/10^9/L (i.e have to move the decimal place over to the L three places)

SOFT-TISSUE INFECTIONS – CHP 135

Q23.Fill out this chart:

CELLULITIS / NEC FASC / MYONECROSIS
DEPTH / Skin and subQ tisse / Skin, subQ tissue, fascia / Fascia, muscle
PREDISPOSING
FACTORS / Trauma
Superficial infection / Trauma, surgery, DM, deep soft tissue infection / Trauma, surgery, contaminated wounds
SKIN / Red, streaking, mild swelling / Red
May have blebs, bullae or patches of gangrene
Severe swelling / Blancehd with massive swelling
Hemorraghic bullae to frank necrosis or gangrene
GAS / NO / Variable / Often
PAIN / Mild / Moderate / Severe
TOXICITY / NO / Moderate / Severe
BUGS / Staph, strep / Miexed Anaerobea and aerobes / Clostridia, anaerobes, aerobes
THERAPY / Ancef / Wide debridement
Clindamycin (1st) + Penicillin G (or ceftriaxone) / Radical excision
Clinda + Pen G
MORTALITY / < 0.1% / 20% / 30%

Q24.

MC organisms (3)ABX

Staph aureusPRP (ex)

GASPCN

MRSASMP/TMX, Clinda

Q25.

Periorbital Cellulitis / Orbital Cellulitis
Anatomic location / Preseptal / Pass the orbital septum
Dec VA / No / +/-
Pain w/EOM, decresed EOM / No / Yes
Proptosis / No / +/-
Systemic unwell / May have fever, not toxic / Can be toxic
Bugs / s. aureus, GAS / s. aureus, GAS, pneumococcus
Tx / IV ABx – cefotaxime
-usu outpt management / -IV ABx; cefotaxime + clox +/- flagyl (?vanco)
-ENT/ophtho consult
-admission to hospital

Q26. Complications of orbital cellulitis

-subperiosteal abscess

-CNS infection (meningitis, abscess)

-orbital compartment syndrome

-cavernous sinus thrombosis

Q27. Compare Erysipelas and Cellulitis

Cellulitis / Erysipelas
Tissue Layers involved / Extends into subQ tissue / Superficial, cutaneous
Physical exam features / Erythema, blanching, flat, poorly demarcated / Indurated, clearly demarcated, raised
Most likely organism / Staph aureus / GAS
Specific Tx / PRP (i.e. ancef/keflex) / PCN G

Q28. Compare TEN vs staph scalded skin

SSS / TEN
Depth / superficial / Full thickness
Nickolsky’s sign / + everywhere / Only +ve at lesions
Precipitant / Staph infection / Usually Rx induced
Tx / ABX + supportive care / Supportive care

Q29. Dx criteria for Staph Toxic Shock and Tx

-Fever >38.9

-Rash (diffuse macular erythema): sunburn or sandpaper looking –> resembles scarlet fever

-(desquamation of skin)–happens at 1-2 wks :.Not helpful in ED

-hypotension (BP<90, orthostatic drop >15 or orthostatic Sx)

-evidence of 3 organs systems affected

  • GI: N/V/D
  • MSK: myalgias, CK doubled
  • Mucous membranes: vaginal, oral, conjunctival
  • Renal: BUN or Scr doubled or pyuria > 5 cells/hpf
  • Hepatic: bili , AST/ALT doubled
  • Hem: platelets < 100
  • Neuro: altered LOC with no focality

TX:

Fluids, +/- vasopressors

ABx – Clinda + Vanco

?IVIG (more likely to be helpful in staph and strep TS)

May need surgical debridbment for abscess (or vaginal if tampon was source)

Q30. Dx criteria for Strep Toxic Shock and Tx

DIAGNOSTIC CRITERIA (must meet both)

Isolation of Group A strep

­From a normally sterile site (blood, CSF) is a definitive case

­From a normally non-sterile (sputum, skin) is a probable case

Hypotension + at least two of....

­Renal failure

­Coagulopathy

­Liver involvement

­ARDS

­Generalized macular rash (may desquamate)

­Soft tissue necrosis

Tx

IVF, +/- vasopressors

ABXPenicillin + clindamycin

Ceftriaxone + clindamycin

Surgical Consult for debribdment

Q31 Draw rectum on board and have abscesses drawn (see pg 2206)

Perirectal / Ischiorectal / Intersphincteric / Supralevator
Location / Next to anus / variable / Bulge in rectal mucosa (lower) / Bulge in rectal mucosa (higher)
Systemic Sx / No / Usually no (unless comes to a point on skin) / +/- / +/-
Drain in ED / Yes / Usually No / No / No

Q32. Nec fasc

Types

Which drug do you give? Which one first

Clindamycin (bacteriostatic) – Pen/vanco(bactericidal) –

Eagle effect – give bacteriostatic agent first then bactericidal agent to minimize endotoxin/inflammatory effect