Management of Abscesses and Cysts

Definition and Characteristics

• Abscesses are collections of pus within the dermis and deeper skin tissues, usually painful, tender, and fluctuant red nodules often surrounded by erythematous swelling, and are typically polymicrobial, containing bacteria that constitute normal regional skin flora, often combined with organisms from adjacent mucous membranes 1
• Epidermoid cysts contain skin flora in cheesy keratinous material, and inflammation and purulence in cysts typically occur as a reaction to rupture of the cyst wall and extrusion of contents into the dermis, rather than as a primary infectious complication 1

Treatment Approach

• The primary treatment for abscesses is incision and drainage, and antibiotics are generally not needed for simple superficial abscesses or boils, according to the World Journal of Emergency Surgery 2, 3
• Complex abscesses, such as those located in perianal, perirectal, or IV drug injection sites, require incision and drainage, and antibiotic therapy is recommended if systemic signs of infection are present, the patient is immunocompromised, source control is incomplete, or significant cellulitis surrounds the abscess 2, 3, 4, 5
• Empiric broad-spectrum antibiotics covering Gram-positive, Gram-negative, and anaerobic bacteria are recommended for complex abscesses 5
• Infected cysts, which have essentially become abscesses, require incision and drainage 1

Drainage Technique

• Thorough evacuation of pus and probing the cavity to break up loculations is essential for abscesses 1
• Large abscesses should be drained with multiple counter incisions rather than a long incision to prevent step-off deformity and delay in wound healing 5
• Simply covering the surgical site with a dry dressing is usually effective, though some clinicians pack it with gauze 1

Size Considerations

• Larger abscesses (>5 cm) may require more aggressive management, including surgical intervention in some cases, as suggested by the Journal of the American College of Radiology 6

Special Considerations

• For echinococcal cysts, special precautions must be taken as cyst rupture or spillage of contents can result in anaphylaxis, and for complex cysts that communicate with other structures, surgical cystectomy may be required, according to the Journal of the American College of Radiology 6

Key Differences in Management

• Abscesses almost always require drainage, while cysts can often be observed unless infected or symptomatic 2, 1, 5
• Simple abscesses typically don't require antibiotics after drainage, while complex abscesses often need broad-spectrum coverage, and antibiotics are not indicated for uninfected cysts 2, 1, 5

Treatment of Giant Axillary Abscess

Indications for Antibiotic Therapy

• For axillary location specifically, cefoxitin or ampicillin-sulbactam are the agents of choice due to the mixed flora from skin and adjacent areas, as recommended by the Infectious Diseases Society of America 7

Duration of Antibiotic Therapy

• When antibiotics are indicated, treat for 4-7 days based on clinical response and resolution of inflammation, as suggested by the World Journal of Emergency Surgery 8
• Immunocompromised or critically ill patients may require up to 7 days of therapy, according to the World Journal of Emergency Surgery 8
• Patients with ongoing signs of infection beyond 7 days warrant diagnostic re-evaluation, as recommended by the World Journal of Emergency Surgery 8

Treatment of Multiloculated Abscess with Intraosseous Extension

Classification and Treatment Rationale

• Multiloculated abscesses with intraosseous extension require aggressive surgical drainage combined with broad-spectrum intravenous antibiotics, as these complex abscesses cannot be adequately managed with antibiotics alone or simple drainage procedures, according to the World Journal of Emergency Surgery guidelines 9

Primary Treatment Approach

Surgical Management (First Priority)

• Immediate surgical drainage is mandatory for multiloculated abscesses with intraosseous extension, with technical considerations including multiple counter-incisions, thorough evacuation of pus, and bone debridement if necessary, as recommended by the World Journal of Emergency Surgery 9

Antibiotic Therapy (Concurrent with Surgery)

• Empiric broad-spectrum intravenous antibiotics must be initiated immediately, covering Gram-positive organisms, Gram-negative bacteria, and anaerobic organisms, according to the World Journal of Emergency Surgery guidelines 9

Monitoring and Follow-up

• Patients with ongoing signs of infection beyond 7 days warrant diagnostic re-evaluation, and persistent fever, bacteremia, or failure to improve indicates inadequate source control requiring repeat imaging and potential reoperation, as suggested by the Journal of Crohn's and Colitis and Circulation 10, 11

Critical Pitfalls to Avoid

• Delayed surgical intervention worsens outcomes, and control of sepsis prior to definitive surgery improves postoperative outcomes, but prolonged delay increases risk of complications, according to the Journal of Crohn's and Colitis 10

Management of Cutaneous Abscesses

Indications for Drainage

• The American College of Physicians recommends that all cutaneous abscesses, large furuncles, and carbuncles should be drained, regardless of size, as it is the most important therapy for these infections 12, 13
• Any fluctuant abscess confirmed clinically or by ultrasound requires drainage, regardless of size 12
• Large furuncles should be drained 13
• All carbuncles require incision and drainage 13

Criteria for Antibiotic Use

• The Infectious Diseases Society of America recommends that antibiotics are unnecessary after drainage if the patient has minimal systemic signs of infection, including temperature <38.5°C, leukocytes <12,000 cells/µL, and pulse <100 beats/minute 12, 14, 15
• Antibiotics should be administered when there are signs of systemic inflammatory response syndrome (SIRS), including temperature >38°C or <36°C, tachypnea >24 breaths/minute, tachycardia >90 beats/minute, or leukocytes >12,000 or <400 cells/µL 12, 13
• Antibiotics should be used in patients with significantly compromised host defense 15

Techniques to Avoid

• Aspiration with a needle should not be attempted, as it has a low success rate of 25% and <10% with MRSA infections 12

Management of Abscesses: Laboratory Tests

Indications for Laboratory Tests

• For abscesses requiring percutaneous or surgical drainage, culture of the drained fluid should be performed to adapt antibiotic therapy according to microbiological results, as recommended by the World Journal of Emergency Surgery 16
• In cases of suspected bacteremia or sepsis, blood cultures should be ordered, as suggested by the World Journal of Emergency Surgery 16
• A complete blood count (CBC) and C-reactive protein (CRP) should be evaluated to assess leukocytosis and infection severity, with a CRP >100 mg/L indicating a more severe infection requiring increased surveillance 16

Diagnostic Evaluation

• For abscesses necessitating drainage, a biochemical workup including liver and kidney function should be considered if prolonged antibiotic therapy is planned, as recommended by the World Journal of Emergency Surgery 16
• In cases of persistent infection signs beyond 7 days, a complete diagnostic re-evaluation is necessary, including repeating CBC and CRP to assess treatment response, as suggested by the World Journal of Emergency Surgery 16

Treatment Principles

• The American College of Surgeons recommends that drainage should not be delayed while waiting for laboratory results, as drainage is the priority therapeutic intervention 16
• The World Journal of Emergency Surgery suggests that abscesses should not be treated solely with antibiotics without drainage, even if inflammatory markers are elevated, as control of the infectious source is essential 16

Antibiotic Use in Infected Sebaceous Cysts

Indications for Antibiotics

• The Infectious Diseases Society of America recommends avoiding antibiotics after drainage if the patient has a temperature <38.5°C, white blood cell count <12,000 cells/µL, pulse <100 beats/minute, and erythema and induration extending <5 cm from the cyst 17, 18
• Antibiotics are indicated in patients with systemic signs of infection, such as temperature >38.5°C, heart rate >110 beats/minute, or signs of SIRS, as recommended by the Infectious Diseases Society of America 17, 18, 19
• The World Journal of Emergency Surgery suggests that antibiotics should be prescribed for immunocompromised patients 20

Antibiotic Selection

• For trunk or extremity cysts, the Infectious Diseases Society of America recommends first-line oral options, including cephalexin 500 mg every 6 hours or dicloxacillin 500 mg every 6 hours 17
• For axillary or perineal cysts, the Infectious Diseases Society of America recommends broader coverage, including cephalexin 500 mg every 6 hours plus metronidazole 500 mg every 8 hours 17
• The American Academy of Pediatrics suggests that clindamycin 300-450 mg every 6-8 hours can be used as an alternative if MRSA is suspected or there is a penicillin allergy 21

Antibiotic Treatment for Skin Abscesses

Introduction to Antibiotic Selection

• The American College of Physicians recommends clindamycin as the superior choice for uncomplicated skin abscesses when antibiotics are indicated, due to its coverage of both S. aureus and streptococci, with a cure rate of 83.1% in high-quality trials 22, 23
• The Infectious Diseases Society of America suggests that metronidazole has no role as monotherapy for skin abscesses, as it lacks activity against S. aureus and streptococci, and should only be used in combination regimens for complex polymicrobial infections 22, 24, 25

Antibiotic Regimens for Specific Clinical Scenarios

• For simple abscesses, the American College of Physicians recommends clindamycin 300-450 mg PO every 6-8 hours for 7-10 days, with an alternative being TMP-SMX, although clindamycin has a higher cure rate and lower recurrence rate 23
• For complex abscesses in the axilla or perineum, the Infectious Diseases Society of America recommends clindamycin 600-900 mg IV every 8 hours plus ciprofloxacin 400 mg IV every 12 hours, or metronidazole 500 mg IV every 8 hours plus ciprofloxacin or ceftriaxone, with metronidazole only being appropriate as part of combination therapy for mixed aerobic-anaerobic flora 23, 26
• For necrotizing fasciitis, the Infectious Diseases Society of America suggests ampicillin-sulbactam plus clindamycin plus ciprofloxacin, or ceftriaxone plus metronidazole, with metronidazole providing anaerobic coverage 24, 25, 22, 26

Critical Considerations for Antibiotic Use

• The American College of Physicians advises against using metronidazole alone for skin abscesses, as it lacks activity against the primary pathogens, with a recommendation to always use combination therapy for complex infections 24, 25
• The Infectious Diseases Society of America recommends considering decolonization with intranasal mupirocin and chlorhexidine washes for recurrent infections, to reduce the risk of future abscesses 23

Urgent Surgical Drainage and Empirical Antibiotic Therapy for Subscapularis Muscle Abscess

Diagnostic Indicators

• Fever > 38.5 °C and tachycardia > 100 bpm are common systemic signs accompanying subscapularis muscle abscesses, aiding early recognition of infection. 27

Primary Surgical Management

• Immediate open surgical drainage is mandatory for all patients and must not be postponed while awaiting culture results or trialing antibiotics alone; delayed drainage leads to rapid clinical deterioration and joint destruction. 28
• Complete evacuation of pus, infected granulation tissue, and any loculations is required during debridement to achieve adequate source control. 27

Empirical Antibiotic Therapy

• Empiric intravenous antibiotics covering Staphylococcus aureus (including MRSA) should be started without delay, as this organism is the predominant pathogen in subscapularis abscesses. 28
• First‑line regimen: Vancomycin 30 mg/kg/day administered intravenously in two divided doses. This dosing strategy is recommended for initial empiric coverage. [28][27]
• Alternative regimen (when MRSA susceptibility is confirmed): Clindamycin 600–900 mg IV every 8 hours. 28
• Antibiotics alone are insufficient; successful treatment requires surgical source control in addition to antimicrobial therapy. 27

Management of Large Buttock Abscesses

Primary Surgical Management

• Incision and drainage is the mandatory first‑line treatment for a large buttock abscess, and it must be performed promptly before any antimicrobial therapy is considered. 29

Indications for Adding Adjunctive Antibiotics after Drainage

• Antibiotics should be prescribed after drainage when any of the following are present: systemic signs of infection, extensive surrounding cellulitis, multiple infection sites or rapid progression, immunocompromised status or major comorbidities (e.g., diabetes, HIV), or when the abscess is located in an area that is difficult to drain completely (such as the face, hand, genitalia, or perirectal region). [29][30]

Trimethoprim‑Sulfamethoxazole (TMP‑SMX) Regimen

• The standard oral regimen of TMP‑SMX 160 mg/800 mg (one double‑strength tablet) twice daily for 7 days provides effective adjunctive therapy after drainage. 29
• A higher dose of TMP‑SMX 320 mg/1600 mg (two double‑strength tablets) twice daily for 7 days is an alternative, but clinical resolution rates are comparable to the standard dose. 29
• A total treatment duration of 7–10 days is appropriate, guided by the patient’s clinical response. 29

Alternative Oral Antibiotic Options (when TMP‑SMX is contraindicated)

These alternatives are supported by the same clinical evidence base as TMP‑SMX. [29][30]

Anaerobic Coverage Considerations for Buttock/Perirectal Abscesses

• TMP‑SMX alone does not reliably cover anaerobic organisms that may be present in polymicrobial buttock or perirectal abscesses; therefore, combination therapy (e.g., adding metronidazole) or broader‑spectrum regimens (e.g., clindamycin plus ciprofloxacin) should be used for complex cases. 29

Situations Requiring Surgical Drainage When Antibiotics Alone Are Insufficient

• For abscesses larger than approximately 5–6 cm where percutaneous drainage is not feasible, definitive surgical drainage with careful clinical monitoring is required. [31][32]

Safety and Contraindications

• TMP‑SMX should not be used during the third trimester of pregnancy or in infants younger than two months because of teratogenic and neonatal safety concerns. 29
• Clindamycin is associated with a higher risk of Clostridioides difficile infection compared with other oral agents and should be used judiciously. 29

Evidence‑Based Management of Injection‑Site Abscesses

Surgical Technique

• Performing multiple counter‑incisions rather than a single long incision for large injection‑site abscesses reduces the risk of step‑off deformity and promotes more effective drainage. 33

Antibiotic Decision Criteria

• Heart rate < 100 beats/min is one of the clinical thresholds used to decide against empiric antibiotic therapy after incision and drainage of an injection‑site abscess. 33

Indications for Empiric Antibiotics

• A history of injection drug use is considered an indication for initiating broader empiric antimicrobial coverage in patients with injection‑site abscesses. 33

Antibiotic Use After Incision and Drainage of Small, Uncomplicated Subcutaneous Abscesses

1. Primary Treatment Recommendation

• In otherwise healthy adults with a small, uncomplicated subcutaneous abscess that has been adequately incised and drained, routine systemic antibiotics are not required. 34, 35

2. Criteria Defining an Uncomplicated Abscess (No Antibiotics Needed)

• Body temperature < 38.5 °C after drainage indicates low systemic inflammation and supports withholding antibiotics. 34, 35
• Heart rate < 100 beats/min after drainage is another marker of limited systemic response, allowing omission of antibiotics. 34, 35
• White‑blood‑cell count < 12,000 cells/µL demonstrates absence of marked leukocytosis, reinforcing a non‑antibiotic approach. 34
• Erythema and induration extending < 5 cm from the wound margin signifies limited local spread and makes antibiotics unnecessary. 34, 35

3. Situations When Systemic Antibiotics Are Indicated

3.1 Systemic Signs of Infection

• Fever > 38.5 °C after drainage signals systemic infection and warrants antibiotic therapy. 34, 35
• Heart rate > 110 beats/min indicates a heightened systemic response, justifying antibiotic use. 34, 35

3.2 Local Extension

• Erythema extending > 5 cm beyond wound margins reflects more extensive tissue involvement and requires antibiotics. 34, 35
• Abscesses located in the perianal or perirectal region are considered complex and need antimicrobial coverage. 34
• Axillary abscesses often involve mixed aerobic‑anaerobic flora; antibiotics are recommended. 35

4. Culture Recommendations

• Routine microbiologic culture is not necessary for typical simple abscesses that have been adequately drained.
• Cultures should be obtained when any of the following apply:
  
  • Abscesses requiring percutaneous or surgical drainage,
  • Cases with suspected bacteremia or sepsis,
  • Treatment failures that may need antibiotic adjustment.