Acyclovir Use in Sick Infants

Background: Infantile herpes simplex virus encephalitis (HSVE) infection remains a significant cause of morbidity and mortality. Diagnosis is often difficult in this population, where a specific pattern of clinical and laboratory signs are lacking. This often results in unnecessary treatment of infants with empiric acyclovir. This study evaluates the use of empiric acyclovir at the Kentucky Children's Hospital and attempts to correlate any laboratory or clinical findings that may be highly suggestive of HSVE. Methods: Medical records of infants younger than 1 year admitted and treated with acyclovir were evaluated for any consistent pattern of clinical findings suggestive of HSVE. Specifically, serum and cerebrospinal fluid (CSF) white blood cell counts, red blood cell counts, cerebrospinal glucose and protein, and clinical neurological findings upon admission were evaluated. Results: Two hundred eighteen infants were identified and included in the study. Three infants were identified with polymerase chain reaction-positive HSVE. Only CSF leukocytosis was consistent among HSVE-positive infants. All infants with HSVE exhibited generalized neurological findings. Neither hemorrhagic CSF nor focal neurological findings were indicative of HSVE infection. Discussion: Herpes simplex virus encephalitis has a very low prevalence within this population. Clinically significant neurological findings as well as specific risk factors must be present to consider treatment with empiric acyclovir. Apnea and focal seizures are not specific risk factors for herpetic meningitis in infants. Lack of a CSF leukocytosis is a strong negative predictor for HSVE, and hemorrhagic fluid is not specific for HSVE.