From the Journals

Study findings cast doubt on community-acquired pneumonia diagnostic practices

Dr. Susan Millard

Dr. Susan Millard

Susan Millard, MD, FCCP, comments: This study is important, because it included a large number of children. We have known for a long time that blood cultures are typically not helpful in older infants and children with CAP. The study also reminds me when educating residents and medical students that physical exam won't necessarily distinguish between bacterial vs viral pneumonias.


 

FROM PEDIATRICS

New studies raise doubts on the reliability of physical exam findings in suspected pediatric community-acquired pneumonia cases and on the value of blood cultures in hospitalized pediatric CAP cases.

In one study, 128 cases of suspected CAP in children aged 3 months to 18 years presenting to an ED from July 2013 to May 2016 underwent paired assessments within 20 minutes of each other. Only 3 of 19 exam findings used to diagnose CAP – wheezing, retractions, and respiratory rate – had acceptable levels of inter-rater reliability, with the lower end of the 95% confidential interval at a Fleiss’ kappa value of 0.4 or higher.

blood vials CDC/Amanda Mills
Eight exam findings – capillary refill time, cough, rhonchi, head bobbing, behavior, grunting, general appearance, and decreased breath sounds – had poor to fair reliability, with a kappa of 0-0.4, the investigators found. These results came from an ongoing prospective cohort study of children with suspected CAP called Catalyzing Ambulatory Research in Pneumonia Etiology and Diagnostic Innovations in Emergency Medicine, or CARPE DIEM.

“The reliability of these findings must be considered in the clinical management and research of children with CAP,” said lead author Todd Florin, MD, associate research director in emergency medicine at Cincinnati Children’s Hospital Medical Center and his associates. (Pediatrics. 2017;140[3]:e20170310)

In a retrospective cohort analysis, researchers found that just 2.5% of 2,568 hospitalized children with CAP who had a blood culture performed actually grew a pathogen. And of the detected pathogens, 82% were susceptible to penicillin. Streptococcus pneumoniae accounted for 78% of all the pathogens that were found; it was detected in only 2% of all children who had blood cultures taken.

Just 11 children – or 0.43% of the children with a blood culture performed – had growth of a pathogen that was not treatable with penicillin, said lead author Mark Neuman, MD, director of research at Boston Children’s Hospital and his associates (Pediatrics. 2017;140[3]:e20171013).

The analysis was drawn from a cohort of 7,509 children hospitalized from 2007 to 2011, with children with complex chronic conditions excluded. Data for the analysis came from the Pediatric Health Information System Plus database, in which administrative, billing, laboratory, and radiographic information is stored from six tertiary children’s hospitals.

The investigators said that one challenge is that when blood cultures are drawn early in the course of evaluation and treatment, the severity of the child’s CAP might not be apparent, which makes it difficult to know which children would benefit from a blood culture.

“The routine performance of blood cultures in these children may not be indicated,” Dr. Neuman and his associates said. “Researchers in future studies should seek to identify the clinical characteristics of children in whom obtaining blood cultures would lead to changes in clinical management, especially when identifying those patients at risk for CAP caused by organisms not susceptible to guideline-recommended, narrow-spectrum antibiotics.”

Next Article: