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Patient Story

A 7-day-old infant is seen in the emergency department because of a rash that was noted on the infant’s trunk and back. The rash consisted of crops of vesicular lesions on an erythematous base (Figure 187-1). The infant was born at term gestation to an 18-year-old mother who had poor prenatal care. The mother denied a history of herpes simplex infection or other sexually transmitted infections. A direct fluorescent antibody test for herpes simplex virus (HSV) was positive and an HSV culture from the lesion was positive. A lumbar puncture was normal, and blood and CSF tests for HSV DNA were negative. The infant was admitted and treated with intravenous acyclovir for 14 days and recovered without sequelae.

FIGURE 187-1

Vesicular lesions of HSV in an infant. (Used with permission from Johanna Goldfarb, MD.)


Many microbiological agents can cause infection in the newborn infant. These infections may be acquired in utero, at the time of delivery, or in the immediate newborn period. Although the majority of congenital infections result in inapparent infection, it is imperative to recognize infections that manifest symptomatically. Although the clinical manifestations of these infections may be similar regardless of the pathogen, specific clinical findings and patterns may serve as important clues for specific microorganisms.


  • The epidemiology varies depending on the organism responsible for the infection:

Streptococcus agalactiae (Group B Streptococci)

  • Incidence of early onset disease (presentation in the first week of life) is 0.3/1000 live births.1,2

  • Early-onset disease is related to perinatal transmission of the organism.

  • Fifteen to forty percent of pregnant women are colonized with the organism in the genital and/or gastrointestinal tract.

  • Fifty to seventy percent of colonized mothers transmit the organism to their infants; 1 to 2 percent of colonized infants develop early-onset sepsis (if intrapartum antimicrobial prophylaxis is not provided); risk higher if risk factors are present (see the following section “Risk Factors”).

  • Incidence of early-onset GBS infection has decreased significantly since the implementation of maternal intrapartum antibiotic prophylaxis.3

Herpes Simplex Virus (HSV)

  • Incidence is estimated to be 1 per 3200 deliveries.4

  • Most neonates acquire the virus from an infected maternal genital tract at the time of delivery.5

  • HSV-2 accounts for 70 percent of neonatal cases while HSV-1 accounts from 30 percent of cases.

  • Because most maternal genital infections are asymptomatic, 60 to 80 percent of neonates who have HSV infection are born to mothers who have no history of current or past genital HSV infection.5

  • The transmission rate from mother to infant during maternal primary infection is 35 to 50 percent, while the transmission rate during a recurrence of HSV is 2 to 5 percent.


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