COMMENTARY

Blood Cultures in Children Hospitalized With CAP? Don't Bother, in Most Cases

William T. Basco, Jr., MD

Disclosures

January 03, 2018

Blood Cultures in Children With Pneumonia

Current guidelines suggest obtaining a blood culture in any hospitalized child whose community-acquired pneumonia (CAP) is "moderate or severe," including those with complicated pneumonia.[1] This recommendation exists even though previous data suggest that <10% of children with CAP may be bacteremic, limiting the potential utility of blood culture. If a blood culture is positive, however, the information may substantially improve antibiotic selection for the patient.

Neuman and colleagues[2] sought to add to what is known about the potential utility of blood culture testing in hospitalized children with CAP. They used the Pediatric Health Information System-Plus, a database with both administrative and clinical data from six children's hospitals. The study children were aged 3 months to 18 years, and were hospitalized between 2007 and 2011. Using results from blood cultures obtained only on the first or second hospital day, the investigators calculated the prevalence of bacteremia, then evaluated the distribution of pathogens as well as the proportion that were susceptible to penicillin.

The study evaluated more than 7500 hospitalized children with CAP, 34.2% of whom had undergone blood culture testing. This was a young cohort; almost 73% were aged 1-5 years, and 21% were aged 6-12 years. There was a good racial and ethnic distribution.

Bacteremia was diagnosed in 0.9% of all children, and in 2.5% of the children from whom blood cultures were taken. Streptococcus pneumoniae comprised 78.5% of all pathogens, followed by Staphylococcus aureus (7.7%), Haemophilus influenzae (4.6%), and other bacteria (3%). Available susceptibility data showed that 82% of the pathogens were susceptible to penicillin, including 92% of the Streptococcus pneumoniae isolates.

Among the subset of patients who were either admitted to the intensive care unit (ICU) or had complicated pneumonia, the prevalence of bacteremia was 4.2%. The investigators conclude that among hospitalized children with CAP without medical comorbidities, the rate of bacteremia in non-ICU patients was very low, with most pathogens being susceptible to penicillin. They argue against routine blood culture in hospitalized children with CAP.

Viewpoint

One additional variable of interest that the study authors could not include in these analyses was the vaccination status of the patients. Certainly, one might be more inclined to obtain cultures in a very young infant with pneumonia who is unvaccinated. Nevertheless, I think these are very valuable data.

First, it's important to remember that these patients were generally healthy but hospitalized—they weren't children who had been frequently exposed to antibiotics or with chronic medical conditions or immunosuppression. Blood culture may still be warranted in children with CAP who have chronic medical conditions or recent antibiotic exposure.

Second, the investigators are correct that these findings argue against routine blood culture in all children with CAP. These data do not suggest that clinicians should avoid obtaining cultures in patients who are ill-appearing or otherwise concerning; they are saying only that not every patient needs a blood culture.

Finally, this was not a universal survey of hospitalized children, in that blood culture was not obtained in every child with CAP. In fact, among the six institutions, the highest frequency of blood culture testing was < 50%, so this is just an estimate of what the positive culture frequency might be in the whole population.

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