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Blood cultures in the evaluation of children with cellulitis
1Department of Pediatrics, George Washington University School of Medicine and Health Sciences and Children's Hospital, Washington, DC, USA.
Insights
Blood cultures for pediatric cellulitis are rarely positive and often contaminated, making them not cost-effective. A band-to-neutrophil ratio threshold could reduce unnecessary testing and save costs.
Area of Science:
- Pediatric Infectious Diseases
- Clinical Microbiology
- Health Economics
Background:
- Cellulitis is a common pediatric infection.
- The introduction of the Haemophilus influenzae type b (Hib) vaccine has altered the spectrum of causative organisms.
- Evaluating the utility of blood cultures in this context is crucial.
Purpose of the Study:
- To assess the diagnostic yield of blood cultures in immunocompetent children hospitalized with cellulitis.
- To determine the cost-effectiveness of routine blood cultures for pediatric cellulitis.
- To identify potential criteria for selective blood culture utilization.
Main Methods:
- Retrospective case series analysis of pediatric patients admitted with cellulitis.
- Inclusion criteria: patients aged 2 days to 22 years, 1994-1995.
- Data collected: demographics, immunization status, clinical presentation, and blood culture results.
Main Results:
- Of 243 enrolled patients, only 2% had positive blood cultures (Streptococcus, Staphylococcus).
- Contamination rate was 5.4%, exceeding the positive yield.
- No patients were bacteremic with H. influenzae; positive cultures often associated with varicella.
- Patient management was not altered by positive blood culture results in uncomplicated cases.
Conclusions:
- Blood cultures are not cost-effective for evaluating uncomplicated pediatric cellulitis due to low yield and high contamination rates.
- Streptococci are the predominant pathogens post-Hib vaccine.
- Implementing a band-to-neutrophil ratio threshold (e.g., 0.20) could significantly reduce unnecessary blood cultures and associated costs.
Objective:
To evaluate the yield of blood cultures obtained from immunocompetent children admitted for cellulitis in the post-Haemophilus influenzae type b (Hib) vaccine era and to determine whether these cultures are cost-effective.
Design:
Retrospective case series.
Setting:
Urban pediatric emergency department. Study Population. Patients 2 days to 22 years of age admitted with cellulitis from 1994 through 1995.
Measurements And Results:
Of 381 patients identified, 266 (70%) had blood cultures and 243 of these children were enrolled. Data recorded include demographics, immunization status, initial clinical appearance, antibiotic pretreatment, preexisting illness, location and precipitating cause of cellulitis, white blood cell count, and band-to-neutrophil ratio (BNR). Blood cultures were categorized as positive, negative, or contaminant. Five cultures (2%) were positive, and 13 (5.4%) were contaminants. The positive blood cultures grew streptococcus and staphylococcus organisms, and none of the children were bacteremic with H influenzae. All patients with group A beta-hemolytic streptococcus had active varicella. The mean age was lower (26 vs 75 months) in those with a positive blood culture, and mean BNR was higher (0.32 vs 0.07). Patient management did not change for bacteremic patients with uncomplicated cellulitis. All repeat cultures were negative. The cumulative charge for all blood cultures was $50 986.
Conclusions:
Blood cultures are not cost-effective and are more frequently contaminated than positive in the evaluation of a patient with uncomplicated cellulitis. Since introduction of the H influenzae type b vaccine, the most common organisms are streptococci. Using a BNR = 0.20 as a threshold for sending blood cultures, we would have missed one positive culture, but would have avoided blood cultures in 213 patients (88%) with an estimated savings of $42 850.