Overview of Neonatal Infections

In utero infection, which can occur any time before birth, results from overt or subclinical maternal infection. Consequences depend on the agent and timing of infection in gestation and include spontaneous abortion Congenital Syphilis Congenital syphilis is a multisystem infection caused by Treponema pallidum and transmitted to the fetus via the placenta. Early signs are characteristic skin lesions, lymphadenopathy... read more , intrauterine growth restriction, premature birth Preterm Labor Labor (contractions resulting in cervical change) that begins before 37 weeks gestation is considered preterm. Risk factors include prelabor rupture of membranes, uterine abnormalities, infection... read more , stillbirth Stillbirth Stillbirth is fetal death (fetal demise) at ≥ 20 weeks gestation (> 28 weeks in some definitions). Management is delivery and postpartum care. Maternal and fetal testing is done to determine... read more , congenital malformation (eg, rubella Congenital Rubella Congenital rubella is a viral infection acquired from the mother during pregnancy. Signs are multiple congenital anomalies that can result in fetal death. Diagnosis is by serology and viral... read more ), and symptomatic (eg, CMV Congenital and Perinatal Cytomegalovirus Infection (CMV) Cytomegalovirus infection may be acquired prenatally or perinatally and is the most common congenital viral infection. Signs at birth, if present, are intrauterine growth restriction, prematurity... read more , toxoplasmosis Congenital Toxoplasmosis Congenital toxoplasmosis is caused by transplacental acquisition of Toxoplasma gondii. Manifestations, if present, are prematurity, intrauterine growth restriction, jaundice, hepatosplenomegaly... read more , syphilis Congenital Syphilis Congenital syphilis is a multisystem infection caused by Treponema pallidum and transmitted to the fetus via the placenta. Early signs are characteristic skin lesions, lymphadenopathy... read more ) or asymptomatic (eg, CMV) neonatal infection.

Common infectious agents transmitted transplacentally include rubella, toxoplasma Toxoplasmosis Toxoplasmosis is infection with Toxoplasma gondii. Symptoms range from none to benign lymphadenopathy, a mononucleosis-like illness, to life-threatening central nervous system (CNS) disease... read more , CMV Cytomegalovirus (CMV) Infection Cytomegalovirus (CMV, human herpesvirus type 5) can cause infections that have a wide range of severity. A syndrome of infectious mononucleosis that lacks severe pharyngitis is common. Severe... read more , syphilis Syphilis Syphilis is caused by the spirochete Treponema pallidum and is characterized by 3 sequential symptomatic stages separated by periods of asymptomatic latent infection. Common manifestations... read more , and Zika virus Zika Virus (ZV) Infections The Zika virus is a mosquito-borne flavivirus that is antigenically and structurally similar to the viruses that cause dengue, yellow fever, and West Nile virus. Zika virus infection is typically... read more . HIV and hepatitis B Neonatal Hepatitis B Virus (HBV) Infection Neonatal hepatitis B virus infection is usually acquired during delivery. It is usually asymptomatic but can cause chronic subclinical disease in later childhood or adulthood. Symptomatic infection... read more are less commonly transmitted transplacentally.

Neonatal infections with herpes simplex viruses, HIV, hepatitis B, group B streptococci, enteric gram-negative organisms (primarily Escherichia coli), Listeria monocytogenes, gonococci, and chlamydiae usually occur from passage through an infected birth canal. Sometimes ascending infection can occur if delivery is delayed after rupture of membranes.

Postpartum infections are acquired from contact with an infected mother directly (eg, tuberculosis Perinatal Tuberculosis (TB) Tuberculosis can be acquired during the perinatal period. Symptoms and signs are nonspecific. Diagnosis is by culture and sometimes x-ray and biopsy. Treatment is with isoniazid and other antituberculous... read more , which also is sometimes transmitted in utero) or through breastfeeding (eg, HIV, CMV) or from contact with family or visitors, health care practitioners, or the hospital environment (numerous organisms— see Neonatal Hospital-Acquired Infection Neonatal Hospital-Acquired Infection Some infections are acquired after admission to the nursery rather than from the mother in utero or intrapartum. For some infections (eg, group B streptococci, herpes simplex virus [HSV]) it... read more ).

Risk of contracting intrapartum and postpartum infection is inversely proportional to gestational age Gestational Age Gestational age and growth parameters help identify the risk of neonatal pathology. Gestational age is the primary determinant of organ maturity. Gestational age is usually defined as the number... read more . Neonates are immunologically immature, with decreased polymorphonuclear leukocyte, monocyte, and cell-mediated immune function; premature infants Preterm Infants An infant born before 37 weeks gestation is considered preterm. Prematurity is defined by the gestational age at which infants are born. Previously, any infant weighing < 2.5 kg was termed... read more are particularly so ( see also Neonatal Immunologic Function Neonatal Immunologic Function The transition from life in utero to life outside the womb involves multiple changes in physiology and function. See also Perinatal Problems. (See also Liver Structure and Function and Neonatal... read more ).

Maternal IgG antibodies are actively transported across the placenta, but effective levels for all organisms are not achieved until near term. IgM antibodies do not cross the placenta. Premature infants have decreased intrinsic antibody production and reduced complement activity. Premature infants are also more likely to require invasive procedures (eg, endotracheal intubation, prolonged IV access) that predispose to infection.