Common Bacterial Skin Infections

Common Bacterial Skin Infections

DANIEL L. STULBERG, M.D., MARC A. PENROD, M.D., and RICHARD A. BLATNY, M.D., Utah Valley Family Practice Residency, Provo, Utah

Am Fam Physician. 2002 Jul 1;66(1):119-125.

Family physicians frequently treat bacterial skin infections in the office and in the hospital. Common skin infections include cellulitis, erysipelas, impetigo, folliculitis, and furuncles and carbuncles. Cellulitis is an infection of the dermis and subcutaneous tissue that has poorly demarcated borders and is usually caused by Streptococcus or Staphylococcus species. Erysipelas is a superficial form of cellulitis with sharply demarcated borders and is caused almost exclusively by Streptococcus. Impetigo is also caused by Streptococcus or Staphylococcus and can lead to lifting of the stratum corneum resulting in the commonly seen bullous effect. Folliculitis is an inflammation of the hair follicles. When the infection is bacterial rather than mechanical in nature, it is most commonly caused by Staphylococcus. If the infection of the follicle is deeper and involves more follicles, it moves into the furuncle and carbuncle stages and usually requires incision and drainage. All of these infections are typically diagnosed by clinical presentation and treated empirically. If antibiotics are required, one that is active against gram-positive organisms such as penicillinase-resistant penicillins, cephalosporins, macrolides, or fluoroquinolones should be chosen. Children, patients who have diabetes, or patients who have immunodeficiencies are more susceptible to gram-negative infections and may require treatment with a second- or third-generation cephalosporin.

Bacterial skin infections are the 28th most common diagnosis in hospitalized patients.1 Cellulitis, impetigo, and folliculitis are the most common bacterial skin infections seen by the family physician. The percentage of office visits for cellulitis was 2.2 percent, and for impetigo, it was 0.3 percent, in a cohort of almost 320,000 health plan members (data taken from primary physician diagnosis codes from January 1, 1999 to December 1, 1999 for Intermountain Health Care, Salt Lake City). Knowledge of the presentation, histopathology, and microbiology for each type of infection is important for proper care of the patient. The presentation, etiology, and current management of these diseases are presented.

Cellulitis

Cellulitis is a painful, erythematous infection of the dermis and subcutaneous tissues that is characterized by warmth, edema, and advancing borders (Table 1). Cellulitis commonly occurs near breaks in the skin, such as surgical wounds, trauma, tinea infections (Figure 1), or ulcerations, but occasionally presents in skin that appears normal. Patients may have a fever and an elevated white blood cell count. Cellulitis can occur on any part of the body. Among the patients in the cohort above, the most common sites of cellulitis were the legs and digits, followed by the face, feet, hands, torso, neck, and buttocks (data taken from primary physician diagnosis codes from January 1, 1999 to December 1, 1999 for health plan members of Intermountain Health Care, Salt Lake City).

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