Page 964 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 74: Soft Tissue Infections 695

may be present. Gas bubbles may be present in the discharge. Crepitus because some clostridia are resistant to clindamycin. In patients whose
is usually present but is not a prominent feature. Tense blebs containing renal function is impaired or rapidly changing owing to underlying
a thin serosanguineous fluid develop in the overlying skin, and areas of disease or acute tubular necrosis, a third-generation cephalosporin,
cutaneous necrosis appear in later stages. If an open wound is present, such as cefotaxime, ceftriaxone, or ceftazidime, or a fluoroquinolone
edematous muscle may herniate through the wound to the skin surface. can be used in place of the aminoglycoside for gram-negative coverage.
In nonclostridial myonecrosis, the process has its onset over several Alternatively, a carbapenem such as imipenem, meropenem, or doripe-
days. The port of entry is usually evident in the vicinity of the area of nem may be used as a single agent. 1,7,18,37 If streptococcal myonecrosis
involvement. Moderate to severe pain and erythema, rather than edema, or myofasciitis is suspected, the use of clindamycin plus penicillin in
are more prominent. Progression is rapid, and systemic toxicity is severe; combination is recommended. In settings where community associ-
it may progress to shock and multisystem organ failure. Local crepitus ated MRSA is suspected, vancomycin (2 g/day in two divided doses) or
may be present, as may a “dirty dishwater” discharge. Progression of the another agent with reliable activity against MRSA in skin and soft tissue
infection is rapid and may involve fascia and subcutaneous tissues. With infections, including linezolid, daptomycin, or ceftaroline is indicated.
7,18
infection due to group A streptococci and CA-MRSA, it is not uncommon In addition, the use of intravenous immunoglobulin, as discussed in the
to find myofasciitis and a toxic shock syndrome. previous section, may be a useful adjunct.
Management: Early diagnosis is critical; its importance cannot be Hyperbaric oxygen has been advocated as an adjunctive measure in
overemphasized. Confusion about the types of gas gangrene, failure to patients with clostridial myonecrosis, but its role is controversial. 30,37,45
recognize that the infection does not have the usual signs of pyogenic Randomized controlled trials have not been completed to date and are
inflammation, and failure to recognize that clostridial infections can unlikely to be done because of the limited number of cases that might
develop without a history of recent trauma can create diagnostic dif- be seen at a given institution and ethical considerations. Evidence sup-
ficulties. The major considerations are other gas-forming necrotizing porting the use of hyperbaric oxygen comes from animal experiments,
infections of the soft tissues, including anaerobic cellulitis and necrotiz- case reports, and uncontrolled small series. Its role at present appears to
ing fasciitis. However as mentioned previously, it is most important to be in the management of selected patients with extensive involvement
simply differentiate a necrotizing soft tissue infection, given the common in whom extensive surgical debridement would be so mutilating as to
pathophysiology, diagnostic schemes, and management strategies. threaten life or limb.
1,7
Severe toxemia, limited crepitus, tense edema, and characteristic bronz-
ing of the skin are suggestive, but not definitive, evidence of clostridial
myonecrosis. Similarly, areas of cutaneous necrosis in a severely toxic KEY REFERENCES
patient with a “dirty dishwater” discharge suggest a nonclostridial myo-
necrosis. Adjunctive diagnostic tools include Gram stain and imaging • Anya DA, Dellinger P. Necrotizing soft tissue infection: diagnosis
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destroyed by the clostridial lecithinase). A mixed flora or gram-positive • Chen SC, Chan KS, Chao WN, et al. Clinical outcomes and
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mandatory for the mere suspicion of clostridial or nonclostridial myo- • Goh T, Goh LG, Ang CH, Wong CH. Early diagnosis of necrotiz-
necrosis. Urgent surgical intervention is the ultimate diagnostic and ing fasciitis. Br J Surg. 2014;101:e119-e125.
therapeutic maneuver, and its importance cannot be overemphasized. • Grice EA, Kong HH, Renaud G, et al. A diversity profile of the
Bacterial myonecrosis is characterized by a darkened, “cooked” appear- human skin microbiota. Genome Res. 2008;18:1043-1050.
ance of the muscle, which does not contract on stimulation and bleeds
very little on incision. Excision of involved muscles or amputation, if • Ki V, Rotstein C. Bacterial skin and soft tissue infections in adults:
necessary, and decompressive fasciotomies are the mainstays of surgi- a review of their epidemiology, pathogenesis, diagnosis, treatment
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debrided. General supportive therapy includes insertion of appropriate • Kuncir EJ, Tillou A, St Hill CR, et al. Necrotizing soft-tissue
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blood pressure, maintenance of adequate oxygenation, correction of • May AK, Stafford RE, Bulger EM, et al. Treatment of complicated
severe acidosis, and maintenance of electrolyte balance. Blood should be skin and soft tissue infections. Surg Infect. 2009;10:467-499.
given sparingly during the acute stages if evidence of extensive hemo-
lysis is present. Nutritional support is necessary in these critically ill • Phan HH, Cocanour CS. Necrotizing soft tissue infections in the
patients, especially in the postoperative period. intensive care unit. Crit Care Med. 2010;38(suppl):S460-S468.
For clostridial myonecrosis, the antimicrobial treatment of choice is • Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for
large-dose penicillin G, 20 to 24 million U/day in six to eight divided the diagnosis and management of skin and soft-tissue infections.
doses. The dose must be reduced appropriately if a significant degree Clin Infect Dis. 2005;41:1373-1406.
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of renal failure is present. Metronidazole, 1 to 2 g/day in two to four • Turecki MB, Taljanovic MS, Stubbs AY, et al. Imaging of muscu-
divided doses, and chloramphenicol, 1 to 2 g/day in four divided doses, loskeletal soft tissue infections. Skeletal Radiol. 2010;39:957-971.
are alternatives in the penicillin-allergic patient. If a mixed flora is found
on Gram stain, the antimicrobial regimen should include an aminogly-
coside (gentamicin or tobramycin), 3 to 5 mg/kg per day in three divided
doses, or 5 to 7 mg/kg per day as a single daily dose, plus clindamycin, REFERENCES
1200 to 2400 mg/day in three to four divided doses. If clostridia are pres-
ent on Gram stain, then penicillin should also be added to the regimen Complete references available online at www.mhprofessional.com/hall

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