Cellulitis in Patients With Diabetes: Strep or Staph?
In patients with diabetes who do not have foot ulcers, cellulitis is most often caused by Streptococcus and only occasionally by Staphylococcus species.
Advances in environmental sanitation, immunizations, antimicrobial therapy, and medical research have greatly reduced the impact of infectious diseases (IDs) on our communities. Nonetheless, infections and the cost of treating them remain a burden to the health care system.
In primary care practice, we may spend more time making referrals for suspected ID than actually treating infected patients. Here, as a brush up, is the fourth in our series of 10 practical ID pearls.
4. Is cellulitis in patients who have diabetes but do not have diabetic foot ulcers more likely to be caused by Streptococcus or Staphylococcus species?
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In patients with diabetes who do not have diabetic foot ulcers, cellulitis is most often caused by Streptococcus and only occasionally by Staphylococcus species.
Streptococcus is usually the culprit in when cellulitis develops in this setting. Group A Streptococcus is very aggressive because of toxin production that precipitates tissue damage. Cellulitis may worsen before it gets better, even with proper IV antibiotic coverage. Cellulitis sometimes presents with an elevated white blood cell count. The blood culture may or may not be positive. Cellulitis accounts for up to 3% of all hospital admissions.1
If the patient does have a diabetic foot ulcer, empiric antibiotic therapy should be widened to cover gram-negative, gram-positive, and anaerobic organisms. Obtain surgical consultation early on to evaluate the need for incision and drainage. One study reported that at least 25% of infected diabetic ulcers spread deeper; among those, up to 30% progressed to amputation.2 An infected foot ulcer precedes the majority of amputations. As such, infection is perhaps the most important cause of this tragic outcome.
1. Wingfield C. Lower limb cellulitis: a dermatological perspective. Wounds. 2009;5:26-36. (Full text)
2. Lipsky B. Medical treatment of diabetic foot infections. Clin Infect Dis. 2004;19:104-114. (Full text)
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