Background: The clinical evaluation of febrile neonates ≤ 60 days has been extensively debated in the age of doing less invasive testing to yield the same clinical outcomes with fewer complications. Rates of serious bacterial infections (SBI) in this population have been reported to be between 8.5% and 12%, and up to 20% in neonates ≤ 28 days old. Rates of bacteremia or sepsis are reported as 2.4-3%; rates of bacterial meningitis are 0.3-0.6%. Due to low rates of bacterial meningitis, it has been speculated that fewer lumbar punctures need to be performed. This retrospective review of febrile infants provides local institutional rates of bacterial and viral infections to help guide appropriate evaluation of febrile neonates.

Methods: We used chart review to identify infants age ≤ 60 days with diagnostic codes of fever hospitalized from 1/1/13-1/13/16. Inclusion criteria were documented or reported fever of ≥38 degrees Celsius and a lumbar puncture completed at our institution with at least a cell count and culture. Variables were abstracted by reviewing clinical records. Primary outcomes were a proven viral or bacterial infection or documented focal source of infection on exam. Data are reported as proportions.

Results: Overall 536 infants met inclusion criteria. A source of infection was found in 223 (41.6%) as shown in Image 1; 64 (11.9%) with urinary tract infection, 63 (11.8%) with positive viral swabs (either mucosal or rectal) or blood PCR, 53 (9.8%) with either enterovirus or parechovirus meningitis, 29 (5.4%) with bacteremia, 9 (1.7%) with another focal source of infection (otitis media, skin/soft tissue infection, or joint/bone infection), 4 (0.7%) with bacterial meningitis, and 1 (0.2%) with HSV meningitis. Of the infants with positive viral studies, 2 (1.7%) had both RSV and a concurrent UTI, and none had concurrent bacteremia or bacterial meningitis.

Conclusions: In our cohort of febrile infants who received lumbar punctures, rates of confirmed viral infection far exceeded rates of SBI, as expected. Our study results are consistent with national data with the risk of bacterial and HSV meningitis being <1%. No infant with an identified viral infection had bacteremia or bacterial meningitis, suggesting that infants with positive viral studies may not require more invasive testing. With low rates of bacterial and HSV meningitis, providers can be reassured that cerebrospinal fluid evaluation is not needed for all febrile neonates; however, it is encouraged that providers thoughtfully perform this evaluation in non-low risk infants due to the high morbidity and mortality associated with these infections. Larger studies should be done evaluating the necessity of invasive testing in well-appearing infants with an identified viral infection.

IMAGE 1: Image 1:Source of infection in a cohort of febrile neonates <60 days old (N=536)