Which infants with invasive bacterial infections are at risk for adverse outcomes?
TORONTO – Among infants up to 60 days old with an invasive bacterial infection, adverse outcomes are associated with prematurity, ill appearance, and bacterial meningitis, a multicenter retrospective analysis found.
“Young infants are susceptible to serious bacterial infections, particularly when they’re less than 60 days of age,” Christopher Pruitt, MD, said at the annual Pediatric Academic Societies meeting. “Among these infants, bacteremia and bacterial meningitis, also referred to as invasive bacterial infections, are associated with higher rates of morbidity and mortality.”
Doug Brunk/MDedge News
Dr. Christopher Pruitt
While many studies have reported the rates of serious bacterial infections in infants, few have examined clinical outcomes for infants with invasive bacterial infections who are initially evaluated in the ED, said Dr. Pruitt, who directs research for the division of pediatric emergency medicine at the University of Alabama at Birmingham. To this end, he and his associates at 11 children’s hospital emergency departments in the United States set out to describe the outcomes of infants up to 60 days old with invasive bacterial infections and to identify factors associated with adverse outcomes. In this 5-year study, they included infants aged 60 days and younger who presented to the ED with pathogen growth in the blood and/or cerebrospinal fluid (CSF). Subjects were excluded from analysis if their cultures were treated clinically as contaminants. “If there was bacterial growth only from CSF broth cultures, we excluded these infants if there was no associated CSF pleocytosis and if there was an associated negative blood culture,” Dr. Pruitt explained. “If one of these criteria was absent, the infant was considered to have bacterial meningitis.”
The primary outcome measure was occurrence of an adverse clinical outcome within 30 days following the index ED visit. Adverse outcomes were defined as use of mechanical ventilation, vasoactive medications, any neurologic sequelae, and death. The researchers used a mixed-effects logistic regression model and retained covariates with a P value of less than .10. Covariates analyzed included age less than 28 days, prematurity, presence or absence of a complex chronic condition, presence of fever, ill appearance, bacterial meningitis, and concordant empiric antimicrobial therapy.
Of the 442 infants included in the final analysis, the majority (80%) had bacteremia, 14% had bacterial meningitis plus bacteremia, and 6% had bacterial meningitis only. “For purposes of this study, patients with bacterial meningitis with or without bacteremia were categorized as having bacterial meningitis,” Dr. Pruitt said. He and his associates found that 14.5% of infants had one or more adverse outcomes. Adverse outcomes occurred in 39% of infants with bacterial meningitis, compared with 8.2% of infants with isolated bacteremia. Need for mechanical ventilation, vasoactive medications, and neurologic disability also was more common among infants with bacterial meningitis than it was among children with isolated bacteremia. There were 10 deaths overall, which amounted to about 2% in both groups.
On multivariate analysis, the rate of adverse outcomes was significantly higher for patients with bacterial meningitis than it was for those with isolated bacteremia (adjusted odds ratio, 8.8), for premature versus term infants (AOR, 5.9), for infants who were ill appearing versus non-ill appearing (AOR, 3.9), and for infants with no fever versus those with fever (AOR, 2.4). No significant associations with 30-day adverse outcomes were seen in patients with a complex chronic condition, compared with those without a complex chronic condition (AOR, 2.0), nor in the those aged 29-60 days versus those younger than 29 days (15% vs. 14%, respectively; AOR 0.7).
“When looking at the most common scenario – a full-term infant without an ill appearance, and bacteremia as opposed to bacterial meningitis – 3 of these 219 infants, or 1.4%, had an adverse outcome,” said Dr. Pruitt, who cares for patients in the ED at Children’s of Alabama in Birmingham. “And there were no deaths.” He also reported that 12 infants with invasive bacterial infections were discharged from the index ED visit without antimicrobial treatment. All had bacteremia and none had an adverse outcome.
