Soft tissue abscesses associated with parenteral drug abuse: presentation, microbiology, and treatment

Abscess formation at the site of drug injection is the commonest infectious complication in drug addicts. This study characterizes the clinical presentation of the condition, its current microbiology, and treatment outcome. All patients presenting for treatment of soft tissue abscesses associated with parenteral drug abuse over a 21-month period were studied. Sixty-six patients with 70 subcutaneous abscesses after injection of cocaine (85%), heroin (5%), or unreported drugs (10%) were identified. Only 42% were febrile (T > 37.5 degrees C), 54 percent had leukocytosis, and 47 percent had wound fluctuance. Wound cultures (243 isolates in 57 patients) grew predominately anaerobes (143 isolates) and facultative gram-positive cocci (88 isolates). Twenty-six blood cultures were obtained, and five (19%) were positive, two with the same bacteria isolated from the wound. Of the patients tested, 29 percent were positive for hepatitis B surface antigen and 9 percent for HIV. Simple incision and drainage was effective in all cases. Classical signs and symptoms of infection and abscess formation may be absent in this patient population. Many of these patients carry other blood-borne infections which the health professional must guard against. Cocaine injection, and "mixed" aerobic-anaerobic infections predominated, in contrast to earlier reports, when narcotics and aerobes predominated. Simple incision and drainage is adequate treatment; antibiotics, when given, should cover gram-positive and anaerobic bacteria; gram-negative coverage is unnecessary.