IDSA: Skin and Soft Tissue Infections Guidelines Updated

Laurie Barclay, MD

June 26, 2014

The Infectious Diseases Society of America (IDSA) has updated its 2005 guidelines for the diagnosis and treatment of skin and soft tissue infections (SSTIs), which have increased because of the spread of methicillin-resistant Staphylococcus aureus (MRSA). The new recommendations were published online June 18 in Clinical Infectious Diseases.

"These comprehensive, evidence-based guidelines will greatly assist clinical decision-making in SSTI management," R. Andrew Seaton, MBChB, MD, DTM&H, FRCP, told Medscape Medical News. Dr. Seaton is consultant in infectious diseases and general medicine and lead doctor, National Health Service Greater Glasgow and Clyde Antimicrobial Management Team, Brownlee Centre, Gartnavel General Hospital in Glasgow, Scotland. "A 'one treatment fits all' approach is not appropriate for this potentially complex group of infections, and these guidelines carefully address this by stratifying therapy for bacterial SSTI depending on the clinical presentation and risk of MRSA."

A10-member US panel of SSTI experts developed these guidelines, which should support individualized management, rather than replace clinical judgment.

"The emergence of community-acquired MRSA as a common etiology of SSTI has changed the clinical approach to these infections for over a decade, especially in the outpatient and emergency department setting," Rakesh D. Mistry, MD, associate professor of pediatrics at the University of Colorado School of Medicine, Aurora, and associate director of research, Section of Emergency Medicine, Children's Hospital Colorado, told Medscape Medical News when asked for independent comment. The recommendation against adjuvant antibiotic therapy in uncomplicated skin abscess after incision and drainage and [the] recommendation to ensure group A streptococcal (GAS) coverage for cellulitis have the greatest impact for [clinicians]."

Guidelines Changes

When asked about changes in the updated guidelines, lead author Dennis L. Stevens, MD, PhD, chief of the Infectious Diseases Section of the Veterans Affairs Medical Center in Boise, Idaho, told Medscape Medical News that "increased resistance of microbes that cause a wide variety of SSTIs is of concern, and these guidelines address these issues."

A new algorithm addresses purulent vs nonpurulent staphylococcal infections (abscesses, furuncles, and carbuncles), helping the clinician to classify the infection as mild, moderate, or severe and to treat appropriately.

"[C]linicians [need] sufficient information to know what kinds of microbes [cause] mild, moderate and severe infections," Dr. Stevens said. "The clinician must gauge [infection severity] to determine the best [surgical and antimicrobial treatment approaches, with collaboration] of surgeons and infectious disease experts."

Fever greater than 100.4°F, leukocytosis, tachycardia, tachypnea, and immunocompromise may signal severe SSTIs.

SSTIs are generally red, swollen, hot to the touch, and painful. Purulent SSTIs usually do not exceed a few inches in diameter, have a focal point of infection, and are filled with pus, whereas nonpurulent SSTIs have no focal point and continue to spread.

Even mild or moderate nonpurulent cases typically require antibiotics, sometimes given intravenously. Severe nonpurulent SSTIs such as necrotizing fasciitis or GAS gangrene should be surgically debrided.

"In the age of antibiotic stewardship, the clinical skills of the practitioner are paramount," Dr. Stevens said. "Best-guess treatment must be based upon appropriate diagnostic tests and clinical acumen. Patients die of severe SSTI frequently because the causative agent is not recognized."

The updated guidelines offer extensive teaching parameters to better educate clinicians regarding varied SSTI presentations, ranging from simple infections resolving without antibiotics to potentially fatal conditions mandating prompt, correct diagnosis and treatment. Patient history should include geographic and host factors, as well as animal exposure.

Causes of SSTIs

Bacteria causing SSTIs include skin flora or fresh- or saltwater pathogens, entering through open wounds, surgical incisions, animal bites, human bites, or penetrating skin injuries. Interpersonal contact, particularly among sports teams or in gyms, schools, and prisons, may transmit MRSA and other SSTI pathogens. MRSA or other staphylococci cause approximately half of SSTIs.

"Treatments must be evaluated according to the microorganisms' resistance, which vary widely from country to country, from one community to another, and between hospitals within the same community," Ferran Llopis, MD, internal medicine specialist, Emergency Department, University Hospital of Bellvitge in Barcelona, Catalonia, Spain, told Medscape Medical News when asked for independent comment.

These updated guidelines are the first to offer extensive recommendations for treating SSTIs in immunocompromised patients, including those with organ transplant.

Health Burden of SSTIs

"Guidelines often require greater than 5 to 10 years for complete, large-scale implementation," Dr. Mistry said. "Now it is up to academic clinicians to disseminate these guidelines and individual providers to incorporate them."

Every year, SSTIs result in more than 6 million physicians' office visits, with prevalence dramatically increasing because of MRSA. Emergency department visits for SSTIs nearly tripled from 1995 (1.2 million) to 2005 (3.4 million).

"Institutions will need to adapt [this] guidance to suit local patient populations and antimicrobial stewardship programmes, considering risk of Clostridium difficile, empirical use of cephalosporins, MRSA prevalence, availability of [outpatient parenteral antibiotic therapy], formulary restrictions, and drug acquisition costs," Dr. Seaton noted.

If the new guidelines are widely accepted and implemented, Dr. Stevens and Dr. Llopis anticipate improved diagnosis, treatment, antibiotic stewardship, and outcomes.

Dr. Mistry said that studies through 2009 showed that more than 90% of emergency clinicians still prescribed antibiotics after skin abscess drainage, and 1 in 3 providers failed to provide GAS coverage for simple cellulitis, perhaps driven by unsupported fear of community-acquired MRSA.

With appropriate incision and drainage, skin abscesses often heal, so recommendations to withhold antibiotics are unlikely to directly affect patient outcomes.

"From a public health standpoint, these guidelines are extremely important in directing antibiotic prescribing," Dr. Mistry explained. "Optimization of antibiotic use for SSTI is essential for reduction of selective pressure and development of antimicrobial resistance."

Dr. Seaton agreed that "the clear advice to avoid antibiotic use in mild purulent SSTI is very welcome."

According to Dr. Llopis, increasingly shorter treatments facilitate adherence to therapy and affect antibiotic resistance.

Research Priorities

Dr. Stevens recommends studying point-of-care diagnosis to determine specific pathogens. Dr. Mistry recommends defining which children with skin abscesses benefit from adjuvant antibiotic therapy. Dr. Seaton calls for real-world data comparing clinical outcomes with different empirical regimes and strategies, such as intravenous vs oral administration, for cellulitis and erysipelas.

"Current 'double-coverage' for cellulitis, with both anti-MRSA and anti-GAS antibiotics, is [common but may not be] necessary or appropriate," Dr. Mistry said. "Incorporating these guidelines on a large scale, through implantation science and knowledge translation, will help determine their effect on care of SSTI."

"Resistance of microorganisms to antibiotics is increasingly important, particularly in patients with previous antibiotic treatment and added comorbidity," Dr. Llopis concluded. "We should allocate resources and efforts in developing new antibiotics because it is a very laborious and costly process, which from the early stages of research to commercialization can exceed 10 years."

The IDSA supported the development of this guideline. Dr. Stevens currently receives research support from the Department of Veterans Affairs and the National Institutes of Health. Dr. Mistry and Dr. Llopis have disclosed no relevant financial relationships. Dr. Seaton has reported advisory work and being a speaker for Novartis and Pfizer. Study authors have reported various financial disclosures involving UpToDate, Pfizer, AstraZeneca, Theravance, Trius, Merck, Bayer, Wyeth-Ayerst, Ortho-McNeil, Cubist, Vicuron, InterMune, Peninsula, Johnson & Johnson, Cepheid, Replidyne, Kimberley-Clark, Targanta, Schering-Plough, Enturia, Optimer Pharmaceuticals, Cadence, Implicit, Cardinal, Durata, 3M, Applied Medical, BD-GeneOhm, Tetraphase, ViraPharm, Occulus Innovative Sciences, Cerexa, Cempra Pharmaceuticals, IDSA, the National Institutes of Health, and/or Novartis.

Clin Infect Dis. Published online June 18, 2014. Full text

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