PHILADELPHIA – Children who present to the emergency department with mild community-acquired pneumonia probably do not require a routine blood culture, but blood cultures can help in the management of children with moderate to severe pneumonia, based on a review of 291 patients.
"The benefit of blood cultures is likely limited to the patient subgroups who are at increased risk for bacteremia," Maria H. Dugan said at the annual meeting of the Eastern Society for Pediatric Research. In the study population, bacteremia occurred with a significantly higher prevalence in patients with pneumonia complications, especially pulmonary complications, said Ms. Dugan, a researcher at Children’s Hospital of Philadelphia (CHOP).
Maria H. Dugan
The analysis also showed that in five of the six pneumonia patients in the series identified as having bacteremia, the culture results led to a change in management.
"Even though blood cultures were infrequently positive, the positive results often led to meaningful changes in clinical management," said Dr. Samir S. Shah, a pediatric infectious diseases physician at CHOP and the senior investigator for this study. "Equally important, those children with more severe forms of pneumonia, such as empyema, had fairly high rates of bacteremia, about 13%. We think this is sufficiently high to warrant a blood culture," he said in an interview.
Ms. Dugan and her associates performed this analysis because blood cultures are often obtained from children who present to an emergency department with community-acquired pneumonia, even though blood cultures rarely influence the management of adults with pneumonia. The study tried to assess the impact that culture results have on management in children.
"In studies of adults with pneumonia, investigators have found that blood cultures were uncommonly positive, and that even when blood cultures were positive, physicians seldom did anything different as a result. We found a very different story in children," Dr. Shah said.
The investigators’ review included children aged 0-18 from 35 primary care pediatric practices affiliated with CHOP in Pennsylvania, New Jersey, and Delaware who were seen in the emergency department at CHOP during 2006 or 2007 with a discharge diagnosis of pneumonia. The 877 patients evaluated in the emergency department averaged 4 years old, with 78% aged 5 or younger.
The emergency department staff obtained blood cultures on 291 (34%) of the 877 children with pneumonia. The decision of whether to obtain a culture rested solely with the physicians who cared for each child. "There is no protocol [at CHOP] regarding the decision to obtain blood cultures in children with pneumonia," Dr. Shah explained. "We suspect that blood cultures were more commonly obtained in children with a higher degree of illness severity."
Comparison of the children who underwent culturing and those who did not showed that the cultured children were older, with 38% older than 5 years, compared with 13% in this age range among those who were not cultured. Greater disease severity also appeared to distinguish the children who underwent culturing. The cultured children had a higher prevalence of hypoxia, and more often their records said that they appeared ill at presentation, compared with the children who did not undergo culturing, Dr. Shah said.
Six (2%) of the 291 children tested by culturing had a confirmed positive culture. Three additional cultures initially tested positive, but subsequent study showed contaminations that made these cultures false positives. The six true-positive cultures included four with Streptococcus pneumoniae, one with Staphylococcus aureus, and one with Haemophilus influenzae.
Patients with an infiltrate on their chest x-ray, and patients who eventually required hospitalization did not have a significantly higher prevalence of a positive culture compared with the other children. But the analysis showed a statistically significant higher level of positive cultures among the children who presented with any pneumonia complication (8%), and especially in those with pulmonary complications (13%).
For four (1.4%) children, results from the blood culture led the hospital staff to narrow their antibiotic treatment compared with the initial treatment the children received, and in two cases (0.7%) the culture results led to a broadening of the antibiotic coverage. In one of these patients, the culture results led to both broadening and narrowing of the treatment regimen. Dr. Shah explained that in this case when the culture initially showed positive, the medical staff broadened the child’s antibiotic coverage. Soon after, when they had identified the specific pathogen as S. pneumoniae, the staff narrowed the antibiotic treatment. For the sixth patient, the blood culture results led to no change from the initial, empiric regimen. This patient had responded well to the initial regimen of amoxicillin, and was subsequently found infected by an S. pneumoniae strain sensitive to amoxicillin, so no change occurred, Dr. Shah said.