Role of Blood Cultures in Pediatric Cellulitis

ABSTRACT & COMMENTARY

Synopsis: In the absence of existing Varicella or an additional site of infection, the yield from blood cultures obtained in children with cellulitis may be too low to warrant their performace.

Source:Sadow KB, Chamberlain JM. Pediatrics 1998;101: URL:http:/www.pediatrics.org/cgi/content/full/101/3/e4.

Investigators from the children's hospital in Washington, DC, studied the yield of blood cultures in the evaluation of children admitted with cellulitis. Data were collected retrospectively on all children hospitalized in 1994 and 1995 with a discharge diagnosis of cellulitis.

Three hundred eighty-one patients were identified. Blood cultures were obtained in 266 (70%), and 23 patients were excluded because of missing charts or the development of cellulitis after hospitalization. Data collected on the remaining 243 children included demographics, immunization status, clinical appearance, antibiotic pretreatment, pre-existing illness, location and cause of the cellulitis, blood culture result, leukocyte count, and band-to-neutrophil ratio. Immunizations were current in 94% of patients, and 22% of the children were pretreated with antibiotics. Three-fourths of the cases occurred on the extremities, hands, or feet; the cause of the cellulitis was most often skin trauma or unknown.

Five cultures (2%) were positive, and 13 (5%) had contaminants. None of the bacteremic children were pretreated with antibiotics, had pre-existing illness, or were described as toxic-appearing. The positive blood cultures grew group A streptococci (3), Streptococcus pneumoniae (1), and Staphylococcus aureus (1). All three children with group A strep had active varicella infection. The child with S. aureus had a septic elbow and osteomyelitis, and the child with S. pneumoniae had a septic hip and psoas abscess.

COMMENT BY LEONARD FRIEDLAND, MD

These data are from the post-Haemophilus influenzae type b vaccine era, and none of the children were bacteremic with H. influenzae. Only 2% of cultures were positive, and three of the five positive cultures were from children with varicella associated with prolonged fever. The other two positive cultures were from children with other foci of infection. In the current era of H. influenzae vaccination and attention to resource use, routinely obtaining blood cultures on all admitted children with cellulitis is not indicated. The small number of bacteremic patients prevents commenting on toxic appearance and immunocompromise as risk factors for bacteremia. These data suggest limiting blood cultures to patients with cellulitis who also have varicella or other foci of infection. (Dr. Friedland is Assistant Professor of Pediatrics and Medicine, Temple University School of Medicine, Temple University Hospital, Philadelphia, PA.)