Skin and Soft Tissue Infections

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Chapter 38 Skin and Soft Tissue Infections

Erica S. Shenoy, MD, PhD , David C. Hooper, MD

General Principles

1 If patients with skin or soft tissue infection are seen with signs of systemic toxicity, what laboratory studies should be undertaken?

Blood cultures, cultures of drainage from skin infection site, complete blood cell count with differential, and serum creatinine, bicarbonate, creatine phosphokinase, glucose, albumin, and calcium levels should be obtained. (See Table 38-1.)

Table 38-1 Evaluation of Cellulitis and Soft Tissue Infections

image

2 What are clinical signs of potential severe deep tissue infection?

image Pain disproportionate to physical findings

image Skin findings: violaceous bullae, ecchymoses, cutaneous hemorrhage, sloughing, anesthesia

image Rapid progression

image Gas in tissue

image Edema beyond the margin of erythema

image Signs and symptoms of systemic involvement

3 Which common causative organisms have shown emerging antibiotic resistance?

image Staphylococcus aureus (methicillin resistance with resistance to all β-lactams except ceftaroline): Assume resistance because of high prevalence of methicillin-resistant S. aureus (MRSA), both community and hospital acquired.

image Streptococcus pyogenes (erythromycin resistance): Resistance is increasing to macrolides (approximately 7% in the United States, 2% to 32% reported in Europe), although the majority remain susceptible to clindamycin, and all are susceptible to penicillin.

Cellulitis

4 What are the common presentation patterns of cellulitis caused by S. aureus or S. pyogenes?

image S. aureus: cellulitis with associated furuncles, carbuncles, or subcutaneous abscesses

image S. pyogenes: cellulitis that is more diffuse and can spread rapidly

5 What distinguishes impetigo from cellulitis?

Impetigo is characterized by discrete purulent lesions, usually on the face, arms, and legs. Bullous and nonbullous forms exist. Whereas impetigo is superficial, cellulitis involves the deep dermis and subcutaneous fat.

6 Lack of response to initial therapy could signify what?

image If a patient does not respond to initial therapy, consider the possibility of resistant strains, atypical organisms, deeper processes such as necrotizing fasciitis or abscess (which may require surgical intervention), as well as underlying conditions such as diabetes, chronic venous insufficiency, or lymphedema (which may slow the clinical response to antimicrobial therapy).

image Timely administration of appropriate antibiotic therapy is essential. One study found that each hour of delay between documented hypotension and administration of antibiotics was associated with an average decrease in survival of 7.6% across all sources of infection; subgroup analysis for patients with skin and soft tissue infections demonstrated a significant increase in the adjusted odds ratio of death. This same study found that time to initiation of effective antimicrobial therapy was the strongest predictor of hospital survival. Despite the impact of delayed therapy, the study found that the median time to effective therapy was 6 hours.

7 What risk factors predispose individuals to development of cellulitis?

image Obesity

image Previous episodes of cellulitis in the same location (may result in damage to lymphatics)

image Toe-web abnormalities (i.e., maceration, tinea pedis)

image Breach in skin barrier, such as ulcers, trauma, fungal infection, eczema

image Surgical procedures that affect lymphatic drainage such as radical mastectomy with lymph node dissection or coronary artery bypass graft for which the saphenous vein has been harvested

image Chronic medical conditions such as diabetes, arterial insufficiency, chronic venous insufficiency, chronic renal disease, neutropenia, cirrhosis, hypogammaglobulinemia

8 What organisms are associated with cellulitis in:

image Cat or dog bites? Pasteurella multocida, Capnocytophaga canimorsus

image Fresh water exposure? Aeromonas hydrophila

image Saltwater exposure? Vibrio vulnificus and other vibrios

image Exposure to fish farming and aquaculture? Streptococcus iniae

image Exposure to meatpacking or shellfish? Erysipelothrix rhusiopathiae

image Preorbital cellulitis in children? Haemophilus influenzae

image Hosts with deficiencies in cell-mediated immunity? Cryptococcus neoformans

image Combat trauma patient? Acinetobacter baumannii

See Table 38-2.

Table 38-2 Antimicrobial Therapy for MSSA and MRSA Skin and Soft Tissue Infections

image

Cutaneous abscesses

9 How are abscesses managed?

image Large abscesses should be incised and drained, with careful attention to the potential for loculated cavities (and the disruption of these cavities through probing of the pus pocket).

image Once drained, the lesion can be left packed or unpacked depending on its extent.

image In the absence of multiple lesions, gangrene, impaired host defenses, fever, or systemic signs and symptoms of infection, once a cutaneous abscess is drained, systemic antimicrobial therapy may not be needed.

10 What are the common organisms implicated in cutaneous abscesses?

image Monomicrobial infection with S. aureus occurs in approximately 25% of cases.

image Consider polymicrobial infection given predisposing conditions (i.e., diabetes mellitus, trauma resulting in a dirty wound) or the location of the abscess (i.e., perianal).

Necrotizing skin and soft tissue infections

11 Is necrotizing fasciitis usually monomicrobial or polymicrobial?

image Both. Organisms seen in monomicrobial infection include S. pyogenes, V. vulnificus, A. hydrophila, S. aureus, and anaerobic streptococci. An average of five different organisms is cultured in the case of polymicrobial infections. Surgical procedures involving the bowels, penetrating abdominal trauma, decubitus ulcer, perianal abscesses, infection at the site of injection drug use, and spread for a Bartholin abscess are associated with polymicrobial necrotizing fasciitis.

image Necrotizing fasciitis is categorized as type I (usually mixed aerobic and anaerobic) and type II (caused usually by group A Streptococcus but also S. aureus).

image Vibrio infections have been associated with saltwater exposures. Individuals with hepatic dysfunction are at greater risk for Vibrio infection.

12 Which organisms cause gas gangrene?

image Clostridial gas gangrene, or myonecrosis, is caused by Clostridium perfringens, Clostridium septicum, Clostridium histolyticum, and Clostridium novyi.

image Predisposing factors include penetrating trauma, crush injuries, and intravenous (IV) drug abuse.

image C. perfringens is the most common cause of trauma-related gas gangrene—symptoms develop within 24 hours of infection. C. septicum is the most common cause of spontaneous gangrene and is associated with neutropenia and gastrointestinal malignancies.

image Antimicrobial therapy includes clindamycin and penicillin because 5% of strains of C. perfringens are clindamycin-resistant.

image Rapid surgical debridement is the most important determinant of outcome.

13 What is appropriate antimicrobial therapy for necrotizing skin and soft tissue infections?

image For mixed infection, ampicillin-sulbactam plus clindamycin plus ciprofloxacin or a third-generation cephalosporin. For patients with severe allergies to penicillin, clindamycin or metronidazole plus an aminoglycoside or fluoroquinolone can be substituted.

image For streptococcal infections, including streptococcal toxic shock syndrome (TSS), treat with penicillin plus clindamycin. In patients with severe allergies to penicillin, vancomycin, linezolid, quinupristin-dalfopristin, or daptomycin can be substituted for penicillin.

image The value of IV immunoglobulin (IVIG) in these circumstances has yet to be fully defined. One study showed no improved survival in patients with TSS randomly assigned to receive IVIG, whereas a retrospective cohort analysis did demonstrate improved outcomes. A more recent study in the pediatric population found no difference in outcomes for patients treated for TSS with and without IVIG.

image For S. aureus infections, nafcillin, oxacillin, or cefazolin are drugs of choice for susceptible strains. If concern exists for methicillin resistance, vancomycin or clindamycin are options.

Infections after animal bites

14 Which organisms are commonly isolated after cat bites?

Pasteurella spp., most commonly, but these infections are usually polymicrobial. Common organisms found in the oral cavity of cats include Bartonella henselae, Moraxella spp., staphylococci, streptococci, and anaerobes. Cats with outdoor exposure can additionally carry Leptospira, Listeria, and Nocardia spp. as well as Francisella tularensis, Streptobacillus moniliformis, Erysipelothrix rhusiopathiae, and Coxiella burnetii, but these organisms are uncommon causes of cat-bite infections. (See Table 38-3.)

Table 38-3 Major Pathogens Isolated from Cat and Dog Bites

  Aerobes Anaerobes
Cat bites Pasteurella spp., Streptococcus spp., Staphylococcus spp., Moraxella spp. Fusobacterium spp., Bacteroides spp., Porphyromonas spp.
Dog bites Pasteurella spp., Streptococcus spp., Staphylococcus spp., Neisseria spp. Fusobacterium spp., Bacteroides spp., Porphyromonas spp., Prevotella spp., Capnocytophaga spp.

Note: Most infections include a mix of aerobes and anaerobes.

Data from Oehler RL, Velez AP, Mizrachi M, et al: Bite-related and septic syndromes caused by cats and dogs. Lancet Infect Dis 9:439-447, 2009.

15 Which organisms are commonly isolated after dog bites?

As in cat bites, Pasteurella spp. are most common, followed by staphylococci, streptococci, Moraxella, corynebacteria, Neisseria, and Capnocytophaga canimorsus.

16 Which antibiotics should be administered after a cat or dog bite?

Oral amoxicillin-clavulanate, with activity against both Pasturella and anaerobes, is a first choice; IV ampicillin-sulbactam or ertapenem can be chosen if IV therapy is required. In cases of invasive disease in patients with severe penicillin allergies, aztreonam has been reported to be successful.

17 What are the infectious complications of animal bite wounds?

image Septic arthritis

image Osteomyelitis

image Abscess

image Tendinitis

image Bacteremia

18 What are other considerations after animal bite wounds?

image Rabies prophylaxis—in the case of unvaccinated domestic, feral, or wild animal bites

image Tetanus prophylaxis—in cases in which the last tetanus booster was > 5 years previously or unknown

Infections after human bites

19 What are the common bacteria responsible for infections after human bites?

Streptococci are found in 80% of human bite wounds. Other common organisms include staphylococci, Haemophilus spp., Eikenella corrodens, Fusobacterium spp., peptostreptococci, Prevotella spp., and Porphyromonas spp.

20 What viruses can be transmitted by human bites?

Herpesviruses, hepatitis B and C viruses, and HIV.

21 Should antibiotics be administered after a human bite?

Yes. Prophylactic antibiotics should be given to all patients as early as possible after a human bite. Attention should be paid to wound cleaning and the need for debridement as well.

22 What are the potential complications of human bite infections?

image Deep infection of the synovium, joint capsule, and bone in the case of closed-fist injuries—early evaluation by a hand surgeon is recommended. Hospitalization for empiric IV antibiotics may be needed and should be directed at S. aureus, Haemophilus spp., E. corrodens, and β-lactamase–producing anaerobes.

image Radiographs can be useful in identifying foreign bodies (i.e., retained teeth).

Surgical site infections

23 How common are surgical site infections (SSIs), and what factors are related to their incidence?

image The development of a SSI depends on a variety of factors, including location and type of surgery; duration of the surgery; whether or not the wound was classified as “clean,” “clean-contaminated,” “contaminated,” or “dirty,” and a series of patient-related risk factors, including diabetes, obesity, smoking, colonization or nasal carriage with S. aureus, and systemic steroids, among other factors.

image The most commonly isolated organism is S. aureus.

24 What techniques have been shown to reduce the risk of SSI?

image Proper skin preparation: avoidance of preoperative use of a razor for removing hair at the incision site (clippers should be used if hair removal is needed), use of chlorhexidine-alcohol or iodophor-alcohol skin antiseptics

image Surgical techniques: gentle traction during surgery, effective hemostasis, removal of devitalized tissues, obliteration of dead space, irrigation of tissues, use of nonabsorbable monofilament suture material, closed-suction drains, and wound closure without tension

image Antimicrobial prophylaxis: preoperative administration of antibiotics within 1 hour before the incision is recommended. Cefazolin is a common choice, with clindamycin or vancomycin in patients allergic to penicillin. Vancomycin should also be considered in the case of institutions where the rate of MRSA is high and in patients with known history of or current infection with MRSA (See Table 38-4).

Table 38-4 Empiric antibiotic therapy for intestinal/Genital Tract and Nonintestinal SSIS

image

Key Points Skin and Soft Tissue Infectionsimage

1. Selection of empiric antimicrobial therapy. In a patient with skin and soft tissue infection, consider host factors including comorbidities, prior microbiologic history, and epidemiologic background.

2. Risk factors that predispose to cellulitis. Obesity, prior cellulitis in the same location, toe-web abnormalities, breach in skin barrier, surgical procedures that affect lymphatic drainage, diabetes, arterial insufficiency, chronic venous insufficiency, chronic renal disease, neutropenia, cirrhosis, and hypogammaglobulinemia are predisposing factors.

3. Appropriate antimicrobial therapy for streptococcal TSS. Penicillin and clindamycin are first-line therapy for patients with severe allergies to penicillin, vancomycin, linezolid, quinupristin-dalfopristin, or daptomycin can be substituted. For S. aureus TSS, use vancomycin if concern exists for MRSA.

4. Human bites. Always treat with prophylactic antibiotics; involve surgical service early if complications including deep infection are suspected.

5. SSI rates. SSI rates depend on many factors, including location and type of surgery; duration of the surgery; surgical classification of the wound, and a series of patient-related risk factors.

Bibliography

1 Anaya D.A., Dellinger E.P. Necrotizing soft-tissue infection: diagnosis and management. Clin Infect Dis. 2007;44:705–710.

2 Chen I., Kaufisi P., Erdem G. Emergence of erythromycin- and clindamycin-resistant Streptococcus pyogenes emm 90 strains in Hawaii. J Clin Microbiol. 2011;49:439–441.

3 Henry F.P., Purcell E.M., Eadie P.A. The human bite injury: a clinical audit and discussion regarding management of this alcohol-fueled phenomenon. Emerg Med J. 2007;24:455–458.

4 Kumar A., Roberts D., Wood K.E., et al. Duration of hypotension before initiation of effective antimicrobial therapy is the critical determinant of survival in human septic shock. Crit Care Med. 2006;34:1589–1596.

5 Liu C., Bayer A., Cosgrove S.E., et al. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children. Clin Infect Dis. 2011;52:1–38.

6 Mangram A.J., Horan T.C., Pearson M.L., et al. Guideline for prevention of surgical site infection, 1999. Infect Control Hosp Epidemiol. 1999;20:247–278.

7 Oehler R.L., Velez A.P., Mizrachi M., et al. Bite-related and septic syndromes caused by cats and dogs. Lancet Infect Dis. 2009;9:439–447.

8 Seaton R.A. Daptomycin: rationale and role in the management of skin and soft tissue infections. J Antimicrob Chemother. 2008;62(suppl 3):iii15–iii23.

9 Sebeny P.J., Riddle M.S., Peterson K. Acinetobacter baumannii skin and soft-tissue infection associated with war trauma. Clin Infect Dis. 2008;47:444–449.

10 Shah S.S., Hall M., Srivastava R., et al. Intravenous immunoglobulin in children with streptococcal toxic shock syndrome. Clin Infect Dis. 2009;49:1369–1376.

11 Stevens D.L., Bisno A.L., Chambers H.F., et al. Practice guidelines for the diagnosis and management of skin and soft-tissue infections. Clin Infect Dis. 2005;41:1373–1406.

12 Stevens D.L., Eron L.L. In the clinic: cellulitis and soft-tissue infections. Ann Intern Med. 2009;150:ITC1–16.

13 Talan D.A., Citron D.M., Abrahamian F.M., et al. Bacteriologic analysis of infected dog and cat bites. N Engl J Med. 1999;340:85–92.

14 Tsai Y.H., Wen-Wei Hsu R., Huang K.C., et al. Comparison of necrotizing fasciitis and sepsis caused by Vibrio vulnificus and Staphylococcus aureus. J Bone Joint Surg Am. 2011;93:274–284.

15 Winner J.S., Gentry C.A., Machado L.J., et al. Aztreonam treatment of Pasteurella multocida cellulitis and bacteremia. Ann Pharmacother. 2003;37:392–394.

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