Skin, Soft Tissue Infection Flashcards

1
Q

What percentage of cat bites become infected compared to dog bites?

A

80% vs 5%

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2
Q

What is empiric treatment for dog or cat bites?

A

Amoxicillin-Clavulanate

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3
Q

What are the most common infectious organisms in a human bite? (7)

A
  • Viridins strep 100%
  • Bacteroides 82%
  • Staph epidermidis 53%
  • Corynebacterium 41%
  • Staph aureus 29%
  • Peptostreptococcus 26%
  • Eikenella 15%
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4
Q

What are two vaccine-able disease that always need to be considered with animal bites?

A
  • Tetanus

- Rabies

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5
Q

What are the conditions when a bite would be treated for tetanus?

A
  • Vaccine: minor wound and no vaccine in last 10 years or major wound and no vaccine in last 5 years
  • Tetanus Ig: major wound and has not had at least 3 vaccine doses
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6
Q

What is the treatment plan if an animal bite might have passed on rabies?

A
  • Rabies Ig around the wound

- Rabies vaccine at day 0, 3, 7 and 14

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7
Q

What organism causes Cat Scratch Disease?

A

Bartonella henselae

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8
Q

What is the typical and atypical presentations of Cat Scratch Disease?

A

Typical: Local lymphadenitis +/- cutaneous lesions several days after exposure that can last 1-3 weeks
Atypical (10%): liver, spleen, ocular, neurological or MSK involvement, fever of unknown origin

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9
Q

What tests are typically used to diagnose Cat Scratch Disease? What would you treat it with?

A
  • Serology (IFA), blood culture, tissue PCR

- Treatment: Azithromycin

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10
Q

What presents as these two classic syndromes:

  • triad of tenosynovitis, polyarthritis, dermatitis
  • purulent arthritis
A

Disseminated Gonococcal Infection

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11
Q

What is not common in Disseminated Gonococcal infection?

A

Urethritis/Cervicitis (but swabs often +ve)

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12
Q

What treatment is used for disseminated gonococcal infection?

A

Ceftriaxone + Doxycycline x 7 days

Don’t forget to Tx partners!

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13
Q

What is the most common cause of septic arthritis?

A

Hematological spread > trauma/bite > post-surgery > direct spread from osteomyelitis

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14
Q

What is the most common organism that causes septic arthritis?

A

Staph aureus

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15
Q

What is the treatment for septic arthritis?

A
  • IV antibiotics based on Gram stain x 4 weeks making sure to cover Staph
  • Joint aspiration in all cases, surgical drainage in hip or prosthetic infection
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16
Q

What is Ludwig’s Angina?

A

Cellulitis of the submandibular/sublingual spaces

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17
Q

What does Ludwig’s Angina almost always result from?

A
  • Oral infection of 2nd or 3rd molars

- 80% of patients report tooth pain or recent dental work

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18
Q

How do you manage Ludwig’s Angina?

A
  • Manage and protect airway (1/3 of cases require intubation)
  • IV antibiotics based on organism
  • Surgical evalualtion
  • CT scan to evaluate abscess and extent of spread
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19
Q

What are the two most common causes of impetigo?

A
  • S. aureus

- Group A strep

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20
Q

What are the two types of impetigo and their most obvious clinical feature?

A

Bullous (vesicles) and non-bullous (golden crust)

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21
Q

What are some risk factors for having a diabetic foot infection? (7)

A
  • Previous amputation
  • Wound extending to bone
  • Peripheral vascular disease
  • Ulcer duration >30days
  • Loss of sensation
  • History of recurrent ulcers
  • Wound caused by trauma
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22
Q

Would you need to culture a minor infection if the patient has not received antibiotics within the last month?

A

No

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23
Q

If you are treating a foot infection in a patient that HAS received antibiotics in the past month, what modifications to antibiotic therapy must you make?

A

Cover gram negative rods

24
Q

What is the presentation of a mild infection?

A

Local infection involving only the skin and subcutaneous tissue. If erythema is present, must be <2 cm around the wound.

25
Q

What is the presentation of a moderate infection?

A

Local infection with erythema >2 cm or involving deeper structures than skin and subcutaneous tissues (eg: acbess, osteomyelitis, septic arthritis, faciitis) AND no systemic inflammatory response.

26
Q

What is the presentation of a severe infection?

A

Local infection with signs of SIRS, as manifested by 2+ of the following:

  • Temperature >38 Celsius or 90 bpm
  • RR >20/min or PaCO2 12,000/mcL or 10% immature forms
27
Q

What is empiric therapy for a severe infection?

A

Vancomycin and Pipercillin-Tazobactam/4th gen cephalosporin/carbapenem

28
Q

Rank the most likely places to get cellulitis?

A

lower extremities > upper extremity > face

29
Q

What organisms almost always cause cellulitis?

A

Staph or Strep

30
Q

What is the presentation of simple cellulitis?

A
  • no fever or systemic symptoms
  • Normal WBC count
  • Lymphadenopathy or lymphangitis common
31
Q

What is the presentation of severe cellulitis?

A
  • systemic symptoms

- bullae, hemorrhage, severe swelling

32
Q

Is needle aspiration or blood cultures useful in mild or localized infections?

A

No

33
Q

When is imaging used in cellulitis management?

A
  • Xray if trauma or foreign body is suspected

- Ultrasound to see if abcess or DVT is suspected

34
Q

What is a very easy technique for tracking the progress of infections?

A

Draw a line around it with a pen.

35
Q

What are the general differences between managing mild vs severe cellulitis?

A
  • Mild: Outpatient, oral antibiotics

- Severe: Admit, IV antibiotics

36
Q

Pt’s presenting with a clenched fist injury are at risk of what?

A
  1. Septic joint
  2. Osteomyelitis
  3. Give IV antibiotics and get imaging done
37
Q

What is the DDx for infectious lymphadenopathy?

A
  1. S. aureus
  2. GAS
  3. Toxoplasmosis
  4. Viral (HIV, CMV, EBV)
  5. Bartonella henselae = Cat scratch disease
  6. Mycobacterium (TB etc.)
38
Q

Risk factors for septic arthritis

A
  1. Old age
  2. DM
  3. Joint disease
  4. Recent joint surgery
  5. Prosthetic joint
  6. IVDU
39
Q

What is the clinical triad for septic arthritis?

A
  1. Fever
  2. Pain
  3. Decreased ROM in joint
40
Q

Approach to Dx of septic arthritis

A
  1. Aspirate synovial fluid (look for WBCs, Gram stain, culture)
  2. Blood cultures
  3. X-ray to rule out osteomyelitis
41
Q

What organism is the most likely cause of non-bullous and bullous impetigo, as well as scalded skin syndrome?

A

S. aureus

42
Q

What is Nikolsky’s Sign?

A

Skin reddens, fluid collects underneath, and skin rubs off, leaving raw red base (S. aureus toxin mediated skin damage)

43
Q

Tx for non-bullous impetigo

A
  1. Topical antibiotic if localized (mupirocin)

2. Cloxacillin or 1st gen Cephalosporin PO

44
Q

Tx for bullous impetigo

A
  1. PO or IV Cloxacillin, 1st gen Cephalosporin, or Vancomycin (MRSA)
45
Q

How should the assessment of a diabetic foot ulcer be structured?

A
  1. Look at whole pt for signs of systemic illness
  2. Affected limb/foot (things that may impair healing, PVD)
  3. The infection itself
46
Q

Questions to ask about diabetic foot ulcer

A
  1. Is there an infection?
  2. What risk factors are present?
  3. How severe is the infection?
  4. How should I manage the infection? What drugs?
47
Q

How do you rank the severity of a diabetic foot infection?

A
  1. No Sx of infection = uninfected
  2. Infection present (2 of: swelling, erythema, pain, warmth, pus)
  3. Mild = local infection (skin/SQ, not deeper), erythema < 2 cm
  4. Moderate = Erythema > 2 cm, or is deeper than SQ, no SIRS
  5. Severe = local infection with > 2 SIRS criteria
48
Q

When should a pt be hospitalized with a diabetic foot infection?

A
  1. Severe infection
  2. Moderate infection with poor social support
  3. Pt’s failing outpatient Tx
49
Q

Most mild-moderate diabetic foot infections can be Tx with what?

A
  1. Agents that cover Strep and Staph
50
Q

What is Erisypelas?

A
  1. Infection limited to upper dermis and superficial lymphatics
  2. Sharp, raised, and well marked erythema
  3. Rapid onset, fever, and signs of systemic toxicity
51
Q

What causes Erisypelas?

A
  1. Almost always beta hemolytic strep
  2. Tx with penicillin V or amoxicillin for outpatient
  3. Severe or facial involvement = IV benzathine penicillin G in hospital
52
Q

What is necrotizing fasciitis?

A

Deep infection of SQ tissue leading to severe destruction of fat and fascia

53
Q

Causes of necrotizing fasciitis

A
  1. Immunocompromised/post-op pt’s = polymicrobial

2. Healthy pt’s = GAS

54
Q

S/S’s of necrotizing fasciitis

A
  1. Systemic signs: fever, tachycardia, hypotension

2. Skin: bullae, disproportionate pain, swelling, erythema, crepitus

55
Q

Management of necrotizing fasciitis

A
  1. Immediate surgical consult
  2. Cultures (best from surgery)
  3. IV antibiotics: polymicrobial (Pip-taz and metronidazole or clinda) and for GAS type = Clindamycin + penicillin G
56
Q

What is the most common infectious agent in cat bites? Dog bites?

A

Cat: Pastuerella multicoda
Dog: Pasteurella canis