This document discusses infections in neonatal infants, including the pathogenesis, epidemiology, clinical presentations, and common infections. It notes that as many as 2% of fetuses are infected in utero and up to 10% of infants have infections in their first month of life. Infections can be transmitted from mother to fetus or newborn in various ways. Clinical manifestations vary from subclinical to severe systemic infection and depend on factors like timing of exposure and immune status. Common infections discussed include chorioamnionitis, late-onset infections acquired after birth like Group B Strep, and other agents that can infect newborns in utero, during delivery, or postpartum.

1. Infections of neonatal infant
By Rayan Hejazi

2. Outline
 Pathogenesis and epidemiology
 Clinical Presentations
 Examples of common infections

3. Pathogenesis and epidemiology
Infections are a frequent and important cause of
neonatal and infant morbidity and mortality. As
many as 2% of fetuses are infected in utero, and
up to 10% of infants have infections in the 1st mo
of life. Neonatal infections are unique in several
ways:
1. Infectious agents can be transmitted from the
mother to the fetus or newborn infant by diverse
modes.

4. Pathogenesis and epidemiology
4. The clinical manifestations of newborn
infections vary and include subclinical infection,
mild to severe manifestations of focal or systemic
infection, and, rarely, congenital syndromes
resulting from in utero infection. The timing of
exposure, inoculum size, immune status, and
virulence of the etiologic agent in? uence the
expression of disease.
5. Maternal infection that is the source of

5. Clinical presentation
 First-trimester infection may alter
embryogenesis, with resulting congenital
malformations .
 Third-trimester infection often results in active
infection at the time of delivery (toxoplasmosis,
syphilis) .
 Infections that occur late in gestation may lead
to a delay in clinical manifestations until some

6. Systemic inflammatory response
syndrome
 The clinical manifestations of infection depend
on the virulence of the infecting organism and
the body í s in? ammatory response. The term
systemic in? ammatory response syndrome
(SIRS) is most frequently used to describe this
unique process of infection and the subsequent
systemic response ( Chapter 64 ). In addition
to infection, SIRS may result from trauma,
hemorrhagic shock, other causes of ischemia,

7. Systemic inflammatory response
syndrome
 In neonates and pediatric patients, SIRS
manifests as temperature instability, respiratory
dysfunction (altered gas exchange, hypoxemia,
acute respiratory distress syndrome [ARDS]),
cardiac dysfunction (tachycardia, delayed
capillary refill, hypotension), and perfusion
abnormalities (oliguria, meta- bolic acidosis) (
Table 103-13 ). Increased vascular
permeability results in capillary leak into

8. Systemic inflammatory response
syndrome

10. Examples of common diseases

11. Chorioamnionitis
 Chorioamnionitis refers to the clinical syndrome
of intrauterine infection, which includes
maternal fever, with or without local or
systemic signs of chorioamnionitis (uterine
tenderness, foul-smelling vaginal
discharge/amniotic ? uid, maternal leuko-
cytosis, maternal and/or fetal tachycardia).
Chorioamnionitis

12. Chorioamnionitis
 The rate of histologic chorioamnionitis is
inversely related to gestational age at birth and
directly related to duration of membrane
rupture.
 Rupture of membranes for longer than 24 hr
was once considered prolonged because
microscopic evidence of inflammation of the
membranes is uniformly present when the

13. Late-onset infections
 After birth, neonates are exposed to infectious
agents in the nursery or in the community.
Postnatal infections may be trans- mitted by
direct contact with hospital personnel, the
mother, or other family members; from breast
milk (HIV, CMV); or from inanimate sources
such as contaminated equipment.
 The most common source of postnatal

14. A number of agents may infect newborns in utero, intrapartum,
or postpartum ( Tables 103-1 and 103-2 ). Intrauterine transpla-

15. Read more
 Nelson textbook pediatrics, 19th edition