Bacterial Meningitis in Young Infants

Clinical Presentation and Evaluation

The American College of Emergency Physicians guidelines describe a classic presentation of serious bacterial infection in young infants, including fever, listlessness, and bulging fontanelle, which requires immediate evaluation for bacterial meningitis 1, 2
The combination of lethargy and bulging fontanelle in a 2-month-old infant is concerning for bacterial meningitis, with a 0.35% incidence in febrile infants aged 90 days or younger 1, 2
The American Academy of Pediatrics recommends that febrile infants aged 29-90 days undergo lumbar puncture, as there are no adequate predictors to identify which infants require cerebrospinal fluid evaluation 1, 2, 4, 6

The most common pathogens in bacterial meningitis in young infants are Escherichia coli (43.7% of cases) and Group B Streptococcus [5, @9@, 4]
Listeria monocytogenes is also a potential pathogen in neonates [@9@, 4]
Empiric antibiotics should be initiated immediately after cultures if bacterial meningitis is suspected, as 71% of bacterial meningitis cases have positive blood cultures 1, 2

The risk of cerebrospinal fluid pleocytosis increases to 17.4% during summer months (June-September) compared to 5.0% in non-summer months (October-May) 1, 2, 5
The presence of high-risk features, such as temperature >38.4°C (101.1°F) with WBC >6,100/mL, increases the risk of cerebrospinal fluid pleocytosis to 7.3% 1, 2, 5