Abscess, Skin/Soft Tissue

Abscess, Skin/Soft Tissue

Description

• A localized collection of pus surrounded and walled off by inflamed tissue
• The collection may be classified as bacterial or sterile:
• Bacterial: most abscesses are bacterial with the microbiology reflective of the microflora of the involved body part.
• Sterile: more associated with intravenous drug abuse and injection of chemical irritants

Pathophysiology

Microbiology is related to abscess type:

• Dog/cat bites:
• Pasteurella species/anaerobes
• Usually polymicrobial
• Capnocytophaga canimorsus:
• Gram-negative rod associated with severe sepsis from dog bites
• Immunocompromised patients
• 25% mortality
• Orbital:
• Associated with paranasal sinusitis, hematogenous spread, or local skin trauma
• Organisms include staphylococci, streptococci, Haemophilus influenza, Escherichia coli.
• May be polymicrobial
• Breast: dependent on type of abscess:
• Puerperal:
• Classically occurs during lactation
• Located in peripheral wedge
• Caused by staphylococci
• Duct ectasia:
• Caused by ectatic ducts
• Periareolar location
• Caused by several organisms (polymicrobial), with a mix of staphylococci, anaerobic streptococci, bacteroids, and enterococci
• Hidradenitis suppurativa:
• Chronic abscesses of apocrine sweat glands:
• Groin and axilla
• Staphylococcus aureus and Staphylococcus viridans common pathogens
• E. coli and Proteus species may be present in chronic disease.
• Pilonidal abscess:
• Caused by epithelial disruption of gluteal fold over coccyx
• Staphylococcal species most common
• May be polymicrobial with bacteroides and E. coli
• Bartholin abscess:
• Obstruction of Bartholin duct
• Mixed vaginal flora
• May include Neisseria gonorrhoeae, Chlamydia trachomatis, and E. coli
• Perirectal:
• Originates in anal crypts and extends through ischiorectal space
• Inflammatory bowel disease and diabetes are major predisposing factors.
• Bacteroides fragilis and E. coli most common pathogens
• Requires treatment in operating room
• Muscle (pyomyositis):
• Typically occurs in tropics
• Increasingly common in patients with human immunodeficiency virus or diabetes
• S. aureus most common
• Intravenous drug abuse:
• Most common pathogens staphylococcal species, Streptococcus milleri, and anaerobes
• Methicillin-resistant S. aureus (MRSA) common
• Isolates often oral origin
• May be sterile
• Furuncle:
• Arises from infected hair follicle
• Most common on back, axilla, and lower extremities
• Staphylococcal species most common
• Community-acquired MRSA increasingly common
• Carbuncle:
• Larger and more extensive than furuncle
• Often multiple in honeycomb pattern on back of neck
• More common in diabetics
• Usually caused by staphylococci
• Community-acquired MRSA increasingly common
• Paronychia:
• Infection surrounding the nail fold
• Usually caused by S. aureus
• Felon:
• Closed-space abscess in distal pulp of finger
• Usually caused by S. aureus

Etiology

Conditions associated with soft-tissue abscess formation include the following:

• Soft-tissue trauma
• Mammalian bites
• Bacteremia with hematogenous seeding
• Obstruction of normal drainage (i.e., sweat glands)
• Tissue ischemia
• Intravenous drug use
• Endocarditis
• Lactation disease
• Crohn disease

Diagnosis

Signs and Symptoms

• Local:
• Erythema, tenderness, pain, heat, swelling, fluctuance
• Systemic:
• Ranges from absent to fever, rigors, hypotension, and altered mentation
• Regional lymphadenopathy and lymphangitis may occur.
• May be associated with surrounding cellulitis

Essential Workup

• History and physical examination:
• Identify subcutaneous air and involvement of deeper structures.
• Gram stain unnecessary for simple abscesses in healthy patients
• Wound cultures:
• Not indicated in simple abscesses unless MRSA is a consideration
• May help differentiate aerobic from anaerobic infections
• May be useful in confirming community-acquired MRSA in patients with recurrent abscesses
• May guide specific therapy in a compromised host, abscesses of the central face or hand, and treatment failures

Tests

Lab

• Glucose determination is a useful screening test for diabetics.
• CK if myositis suspected
• Blood cultures indicated if endocarditis is suspected or patient is systemically ill

Imaging

• Plain films may reveal gas in tissue planes.
• Ultrasound, CT, or MRI helpful when diagnosis is in question

Differential Diagnosis

• Cellulitis
• Aneurysm (especially with intravenous drug abusers)
• Cysts
• Hematoma

Treatment

Pre Hospital

Caution: septic patients may require rapid transport with intravenous access and volume resuscitation.

Pediatric Considerations

Incision and drainage are painful procedures that often require procedural sedation and analgesia.

Initial Stabilization

Septic patient:

• Immediate intravenous access
• Oxygen
• Crystalloid volume resuscitation
• Central venous pressure monitoring
• Mixed venous sampling
• Blood cultures
• Early antibiotic therapy

ED Treatment

• Incision and drainage are the mainstays of treatment.
• Antibiotics are indicated for the following conditions:
• Sepsis
• Systemic illness
• Endocarditis
• Facial abscesses drained into the cavernous sinus
• Concurrent cellulitis (see Medication)
• Mammalian bites
• Immunocompromised hosts

Medication (Drugs)

• Augmentin (particularly mammalian bites): 250-500 mg PO q8h (pediatric dose: 40-80 mg/kg per day divided into three doses)
• Cephalexin: 250-500 mg PO q8h or 500 mg PO q12h (pediatric dose: 25-50 mg/kg per day PO in four doses)
• Clindamycin (MRSA): 150-450 mg PO q6h (pediatric dose: 10-20 mg/kg per day PO or IV in three-four divided doses)
• Dicloxacillin: 250-500 mg PO q6h (pediatric dose: 50-100 mg/kg per day in four divided doses)
• Erythromycin: 500 mg-1 g PO or IV q6h (pediatric dose: 40 mg/kg per day PO divided q6h)
• Gentamicin: 5 mg/kg per day IV q24h (pediatric dose: 7.5 mg/kg per day IV divided q8h)
• Levaquin: 500 mg IV q24h (contraindicated in children)
• Rifampin (MRSA): 300 mg PO q.i.d. (pediatric dose 10 mg/kg up to 300 mg)
• Septra DS (MRSA): one tab PO b.i.d. (pediatric 5 mL susp/10 kg up to 20 mL per dose)
• Unasyn: 1.5-3.0 g IV q6h (pediatric dose: <40>40 kg, adult dose)
• Vancomycin: 1 g IV q12h (pediatric dose: 40 mg/kg per day IV divided q6h)

Surgery

Perirectal abscess requires treatment in the operating room.

Follow-Up

Disposition

In accordance with abscess type and severity of infection

Admission Criteria

• Sepsis
• Endocarditis
• Systemic illness
• Perirectal involvement
• Any abscess requiring incision and debridement in the operating room

Discharge Criteria

Most patients with uncomplicated abscesses can be treated with incision and drainage and close follow-up.

References

1. Benson EA. Management of breast abscesses. World J Surg. 1989;13:753-756.
2. Buescher ES. Community-acquired methicillin-resistant Staphylococcus aureus in pediatrics. Curr Opin Pediatr. 2005;17(1):67-70.
3. Canales FL, Newmeyer WL, Kilgore ES. The treatment of felons and paronychias. Hand Clin. 1989;5:515-522.
4. Chiedozi LC. Pyomyositis: review of 205 cases in 112 patients. Am J Surg. 1979;137:255-259.
5. Loyer EM, DuBrow RA, David CL, et al. Imaging of superficial soft-tissue infections: sonographic findings in cases of cellulitis and abscess. AJR. 1995;166:149-152.
6. Summanen PH, Talan DA, Strong C, et al. Bacteriology of skin and soft-tissue infections in intravenous drug users and individuals with no history of intravenous drug use. Clin Infect Dis. 1995;20(Suppl 2):S279-282.
7. Talan DA, Citron DM, Abrahamian FM, et al. Bacteriologic analysis of infected dog and cat bites. N Engl J Med. 1999;340:85-92.

Codes
ICD9-CM
682.9
ICD10
L02.9