SSTI guidelines stress diagnostic skill, careful treatment

Skin and soft tissue infections are one of the most common causes for patient evaluation in emergency departments and are common reasons for consultations by surgeons. SSTIs occur across a broad continuum of severity and often require only antimicrobial therapy (such as cellulitis), but they may be fulminate and life-threatening necrotizing infections that require aggressive surgical intervention. The guidelines provided by a distinguished group of clinicians from the Infectious Diseases Society of America provide an excellent organizational framework to understand this heterogenous collection of infections and provide a meaningful structure to direct management.

Several points in these guidelines deserve emphasis. First, considerable discussion in the guidelines has focused on the immunocompromised patient with SSTIs, and appropriately so. A broader consideration might have been to also include those patients with health care-associated exposure in addition to clinical immunosuppression. About 40 million hospitalizations occur annually in the United State, which makes over 3 million patients within 30 days of discharge. A larger number of patients have had recent antibiotic exposure. About 1.5 million patients are in chronic care facilities and nearly 500,000 are receiving chronic hemodialysis. Accordingly, immunocompromised and health care-associated patient exposures require that assumptions about the microbiology of SSTIs have "sensitivity" to the resistant pathogens (such as MRSA) not traditionally typical of community-acquired infections.

Second, the guidelines refer to the use of Gram stains for directing antimicrobial therapy. Although the Gram stain does not have the high-technology flare of contemporary health care, it remains a useful tool in differentiating pathogens, especially in necrotizing SSTIs.

Of the major microbiological presentations of necrotizing SSTIs, Streptococcus pyogenes is a gram-positive cocci in chains, Staphylococcus aureus is a gram-positive cocci in clusters, Clostridium perfringens is a gram-positive rod, and polymicrobial infections will have an assortment of different morphologic and gram-staining characteristics in identified bacteria. Aeromonas hydrophilia and Vibrio vulnificus will appear as gram-negative rods in those necrotizing SSTIs associated with fresh or salt-water recreational exposure. The Gram stain provides immediate direction for therapy when culture results will often be too late for a meaningful impact on patient care. Unfortunately, many hospitals have abandoned the use of Gram stains for clinical specimens.

Finally, prompt diagnosis of necrotizing SSTIs is essential. A cause of potentially preventable morbidity and deaths is a delay in the recognition of necrotizing SSTIs and the need for urgent surgical debridement. Necrotizing SSTIs are common issues in medicolegal actions because of the issue of failure to make the timely diagnosis. The hallmark of necrotizing SSTIs is pain out of proportion to the inciting injury. Trivial cutaneous injuries that are associated with an advancing perimeter of palpable tenderness and induration are necrotizing SSTIs until proven otherwise. Importantly, S. pyogenes in particular is associated with "metastatic" infection. Patients with soft-tissue contusions, joint effusions, and even fractures may have blood-borne streptococcal contamination of the injury site and yield a necrotizing infection without any cutaneous source of microbial contamination.

Because monitoring the progression of SSTIs is so important in differentiating necrotizing infections, I would only take to task the recommendation for the use of corticosteroids in treatment of cellulitic infections. Pharmacologic immunosuppression of the patient with an active SSTI in the interest of providing symptomatic relief compromises the clinical evaluation of disease progression.

In summary, the guidelines and the two algorithms for managing community-acquired and surgical incision infections are very useful for providing surgical clinicians direction in patient management. The increased incidence of S. aureus-associated necrotizing SSTIs and the emergence of community-associated MRSA over the last 20 years indicate that this is a dynamic area with changing characteristics. The changing pattern of pathogens and antimicrobial choices require a more frequent updating of these important guidelines for patient management.

Dr. Donald E. Fry is an ACS Fellow, executive vice-president for clinical outcomes management of MPA Inc. of Chicago, adjunct professor of surgery at the Northwestern University in Chicago, and professor emeritus of surgery at the University of New Mexico. He is a fellow of the Infectious Diseases Society of America, a past president of the Surgical Infection Society, and associate editor of the journal Surgical Infections.