IDSA guidelines call for accurate diagnoses, fewer antibiotics for skin and soft-tissue infections

Skin and soft-tissue infections (SSTIs), even those caused by methicillin-resistant Staphylococcus aureus (MRSA), are often minor and either heal on their own or can be easily treated without antibiotics, according to updated practice guidelines.

The guidelines, issued by the Infectious Diseases Society of America, are meant to help physicians make the correct diagnosis, establish the source and cause of the infection, determine its severity, and help physicians know when antibiotics are and are not necessary.

Emergency department visits due to SSTIs nearly tripled from 1.2 million in 1995 to 3.4 million in 2005, much of the increase driven by MRSA, the guideline noted. SSTIs account for more than 6 million visits to doctors' offices every year.

The guidelines appeared online June 19 in Clinical Infectious Diseases.

About half of SSTIs are caused by staph bacteria and are purulent, typically red, swollen, hot to the touch, and painful. Purulent infections are usually no larger than a few inches, have a focal point of infection, and are filled with pus. Most will clear on their own or should be treated with incision and draining alone, not antibiotics, the guidelines said.

Specifically, the guidelines recommend performing a Gram stain and culture of pus from carbuncles and abscesses, but treatment without these studies is reasonable in typical cases (evidence: strong, moderate). It is not recommended to perform a Gram stain and culture of pus from inflamed epidermoid cysts (evidence: strong, moderate). The guidelines recommend incision and drainage as primary therapy for inflamed epidermoid cysts, carbuncles, abscesses, and large furuncles (evidence: strong, high).

Use of antibiotics for S. aureus as an adjunct to incision and drainage should be based on whether there are symptoms of systemic inflammatory response syndrome, such as temperature higher than 38° C or less than 36° C, tachypnea more than 24 breaths per minute, tachycardia more than 90 beats per minute, or white blood cell count greater than 12,000 or less than 4,000 cells/μL (evidence: moderate).

Other SSTIs are caused by non-staph bacteria such as group A streptococcus, which produce toxins instead of pus and are more likely to be severe and even deadly, causing serious infections such as cellulitis, necrotizing fasciitis, or gangrene, the guideline stated. Non-purulent SSTIs do not have a focal point and continue to spread. Even mild or moderate non-purulent cases typically require antibiotic treatment, sometimes provided intravenously. These infections require speedy diagnosis, surgery to remove the infection, and antibiotic treatment. In the case of severe non-purulent SSTIs such as necrotizing fasciitis or group A streptococcus gangrene, the infected material should be removed surgically.

The guidelines contain a chart to help physicians quickly diagnose and treat the SSTI based on whether or not it is purulent; determine whether the infection is mild, moderate or severe; and recommend appropriate treatment. Again, physicians should be most concerned when a patient with any SSTI, whether purulent or not, has a fever higher than 38° C, a high white blood cell count, or a rapid heart rate; is breathing fast; or is immunocompromised.

The updated IDSA guidelines also provide extensive recommendations for:

• treating SSTIs in immunocompromised patients, including those with HIV/AIDS or those who have had an organ transplant,
• treating recurrent skin abscesses and cellulitis,
• providing preferred management of surgical-site infections, and
• treating animal bite wounds.