Skin and soft-tissue infections: Classifying and treating a spectrum
ABSTRACTSkin and soft-tissue infections (SSTIs) are a common presenting problem in both inpatients and outpatients. SSTIs have been broadly classified as complicated or uncomplicated, but specific disease processes and patient characteristics are important in guiding clinical management. Early recognition of the extent of infection, close follow-up, and familiarity with local antibiotic susceptibility data are critical to successful treatment.
KEY POINTS
- Categories and definitions of specific subtypes of infections are evolving and have implications for treatment.
- Methicillin-resistant Staphylococcus aureus (MRSA) and streptococci continue to be the predominant organisms in SSTIs.
- A careful history and examination along with clinical attention are needed to elucidate atypical and severe infections.
- Laboratory data can help characterize the severity of disease and determine the probability of necrotizing fasciitis.
- Although cultures are unfortunately not reliably positive, their yield is higher in severe disease and they should be obtained, given the importance of antimicrobial susceptibility.
- The Infectious Diseases Society of America has recently released guidelines on MRSA, and additional guidelines addressing the spectrum of SSTIs are expected within a year.
INDICATIONS FOR HOSPITALIZATION
Patients who have evidence of tissue necrosis, fever, hypotension, severe pain, altered mental status, an immunocompromised state, or organ failure (respiratory, renal, or hepatic) must be hospitalized.
Although therapy for MRSA is the mainstay of empiric therapy, polymicrobial infections are not uncommon, and gram-negative and anaerobic coverage should be added as appropriate. One study revealed a longer length of stay for hospitalized patients who had inadequate initial empiric coverage.33
Vigilance should be maintained for overlying cellulitis which can mask necrotizing fasciitis, septic joints, or osteomyelitis.
Perianal abscesses and infections, infected decubitus ulcers, and moderate to severe diabetic foot infections are often polymicrobial and warrant coverage for streptococci, MRSA, aerobic gram-negative bacilli, and anaerobes until culture results can guide therapy.
INDICATIONS FOR SURGICAL REFERRAL
Extensive perianal or multiple abscesses may require surgical drainage and debridement.
Surgical site infections should be referred for consideration of opening the incision for drainage.
Necrotizing infections warrant prompt aggressive surgical debridement. Strongly suggestive clinical signs include bullae, crepitus, gas on radiography, hypotension with systolic blood pressure less than 90 mm Hg, or skin necrosis. However, these are late findings, and fewer than 50% of these patients have one of these. Most cases of necrotizing fasciitis originally have an admitting diagnosis of cellulitis and cases of fasciitis are relatively rare, so the diagnosis is easy to miss.15,16 Patients with an LRINEC score of six or more should have prompt surgical evaluation.20,24,34,35
