VLBW infants require lumbar punctures if sepsis is suspected

July 2004

Researchers have found that a lumbar puncture (LP) is necessary in very low birth weight (VLBW) infants with suspected sepsis because meningitis can occur even without a positive blood culture. The data suggest that the LP should be part of the diagnostic evaluation of VLBW infants with suspected late-onset infection.

Neonatal meningitis is uncommon but remains a serious complication among VLBW infants and is often associated with increased severity of illness and risk of death as well as late neurodevelopmental sequelae, according to the recent study.

“Perhaps the most important finding of this study is that one-third of the patients with meningitis had negative blood cultures within a week of the CSF [cerebrospinal fluid] culture,” researchers stated in their study. “We speculate that the failure to perform an LP routinely in infants with suspected late-onset sepsis might result in an underdiagnosis of meningitis.” The identification of fungal agents or gram-negative organisms in the CSF may affect the drug choice and length of therapy.

Methods and findings

The study reviewed the epidemiology of late-onset meningitis in VLBW infants ranging from 401 g to 1,500 g and evaluated the concordance of blood cultures and CSF results, rates of infection, infecting pathogens, risk factors for disease, in-hospital morbidity and mortality. VLBW infants, excluding those with intraventricular shunts, born at centers of the National Institute of Child Health and Human Development Neonatal Research Network between Sept. 1, 1998, through Dec. 31, 2001, were involved in the study.

Of the 9,641 VLBW infants involved in the research, 2,877 (30%) had one or more LP performed after the third day, and 6,056 (63%) had one or more blood culture. Late-onset meningitis occurred in 134 infants, equating to 1.4% of all patients or 5% of those who had an LP. Of the infants with meningitis, one-third (45 of 134) had negative blood cultures, and it was found that lower gestational age and prior sepsis increased the child’s risk for meningitis. One in four suffered from seizures, a clinical sign that could lead to earlier LP and diagnosis.

In this study, only one-half of all infants who had a blood culture performed also had an LP. Moreover, there were major practice differences: the percentage of infants who had a blood culture and an LP performed ranged from 22% to 85% across centers. Although LPs were performed more frequently in infants with positive blood cultures, only 66% of the infants with culture-confirmed sepsis had an LP performed.

VLBW infants with meningitis were significantly more likely to die (23%), compared with infants with sepsis alone (9%) or those who were uninfected (2%). Infants with gram-negative or fungal meningitis were at particularly high risk for death (41% and 32%, respectively). Infants with meningitis were significantly more likely to have seizures, to stay on mechanical ventilation longer, to take longer to reach full feeds and to have extended hospital stays than uninfected infants.

“Although too sick to tap and risk of complications are cited often as reasons to defer the LP, we found no difference in the risk of death between infants who did and did not have an LP,” researchers wrote in the study. “However, meningitis increased the risk of death substantially.”

Clinical expertise not a factor

Researchers speculated that a possible limitation of their analysis is physician disparity in the decision to perform an LP on the VLBW infant. They found that infants with a positive blood culture were more likely to have an LP performed, but there was no information on why an LP was not performed if a sepsis evaluation was conducted. Among those who had an LP performed, there was no significant difference across centers in the rate of positive CSF cultures, suggesting that although there are LP practice differences, they probably are not explained by better clinical expertise.

The researchers suggested that developing strategies to decrease the risk of meningitis would reduce neonatal morbidity and improve
survival.

The study was funded by the National Institute of Child Health and Human Development and was published in Pediatrics.

For more information:

• Stoll BJ, Fanaroff AA, Carlo WA, et al. To tap or not to tap: High likelihood of meningitis without sepsis among very low birth weight infants. Pediatrics. 2004;113(5):1181-1186.