Skin and Soft Tissue Infections (Case 20)

Chapter 51 Skin and Soft Tissue Infections (Case 20)



Lindsay Chase, MD , Gary Frank, MD, MS




Case


A 5-year-old boy has a “rash” on his right thigh. A bug bite from several days earlier has enlarged and become painful. On examination there is a 5- × 7-cm tender, swollen, erythematous lesion.




Differential Diagnosis













Cellulitis Abscess Necrotizing fasciitis
Pyomyositis Erysipelas Superficial thrombophlebitis


Speaking Intelligently


Most skin and soft tissue infections can be treated with oral antibiotics in the outpatient setting. However, you need to always carefully check for evidence of systemic infection. Vital signs are “vital”—check for fever, tachycardia, and blood pressure abnormalities (elevations with pain or hypotension with sepsis and shock). I assess perfusion by checking quality of pulses and capillary refill along with mental status. Think about underlying structures, because the infection can descend from the skin or could have started deeper and spread to the skin. An important consideration is methicillin-resistant Staphylococcus aureus (MRSA). Given the high prevalence of community-acquired MRSA, it is prudent to act as if all skin infections are caused by MRSA until proved otherwise by culture.



Patient Care



Clinical Thinking



• Measure and mark the area of erythema to monitor progression.

• Check for pus (fluctuance), because cellulitis may be accompanied by abscess. Pus often requires drainage.

• Culture, culture, culture. If possible, obtain Gram stain and culture of pus before starting antibiotics.

• Know local bacterial susceptibility patterns and the patient’s risk factors.

• Are there underlying structures to worry about such as in osteomyelitis?

• Consult specialists if needed.

• Are there any special circumstances to suggest unusual organisms (nail through tennis shoe, diabetes)?

• Imaging studies are not usually needed, but may be helpful for infections overlying a joint or near the eyes, to evaluate for penetration into deeper structures, and to evaluate for drainable abscesses.


History



• Are there any special circumstances to suggest unusual organisms (nail through tennis shoe, diabetes)?

• Any family history of recent abscess or skin infection?


Physical Examination



• With isolated cellulitis with or without abscess, vital signs are usually normal. Signs of systemic infection include fever, tachycardia, hypotension, brisk capillary refill with bounding pulses (warm shock), prolonged capillary refill (cool shock), or altered mental status.

• First assess airway, breathing, and circulation. Evaluate heart, lungs, abdomen, and mental status.

• If the patient is stable, evaluate the skin—all of it! Look for erythema, warmth, edema, tenderness, drainage, abrasions, lacerations, and ulcers.

• Mark the area of erythema to monitor progression and resolution.

• Palpate for fluctuance.

• If there is extreme sensitivity to light touch, consider compartment syndrome or necrotizing fasciitis.

• Palpate for lymph node enlargement.

• Examine underlying structures such as mouth (gums and teeth), sinuses, muscles, and joints.

• When the affected skin overlies a joint, evaluate that joint for fluid and for range of motion to rule out septic arthritis (a surgical emergency).

• With facial involvement, evaluate (and document) extraocular movements to rule out orbital cellulitis.

• Remove the diaper to check for rashes, gluteal and perirectal abscesses, and inguinal adenopathy.


Tests for Consideration



• Complete blood count (CBC) with differential $116

• To follow response to therapy:
• C-reactive protein $69

• Erythrocyte sedimentation rate $85

• Blood culture: In ill-appearing patients $152

• Wound Gram stain and culture: To identify an organism and sensitivities $180

• Electrolytes, blood urea nitrogen (BUN), and creatinine: In sicker patients or if contrast will be administered $174

• Purified protein derivative (PPD): If concern for atypical mycobacterium $174


Imaging Considerations


→ Computed tomography (CT) of affected area with contrast: To evaluate for abscess or deeper involvement


• CT neck $150

• CT abdomen/pelvis $1691

→ CT of face and orbits with contrast: If concern for orbital cellulitis $1875


→ Ultrasound or magnetic resonance imaging (MRI) of affected joint: To evaluate for septic arthritis


• Ultrasound hip $675

• MRI hip $1700

→ MRI or bone scan: If there is concern for osteomyelitis


• MRI leg $1100

• Bone scan $1512
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Jul 18, 2016 | Posted by in PEDIATRICS | Comments Off on Skin and Soft Tissue Infections (Case 20)

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