Neonatal infection can be acquired
In utero transplacentally or through ruptured membranes
In the birth canal during delivery (intrapartum)
From external sources after birth (postpartum)
Common viral agents include herpes simplex viruses Neonatal Herpes Simplex Virus (HSV) Infection Neonatal herpes simplex virus infection is usually transmitted during delivery. A typical sign is vesicular eruption, which may be accompanied by or progress to disseminated disease. Diagnosis... read more , HIV Human Immunodeficiency Virus (HIV) Infection in Infants and Children Human immunodeficiency virus (HIV) infection is caused by the retrovirus HIV-1 (and less commonly by the related retrovirus HIV-2). Infection leads to progressive immunologic deterioration and... read more , cytomegalovirus 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 (CMV), and hepatitis B Hepatitis B, Acute Hepatitis B is caused by a DNA virus that is often parenterally transmitted. It causes typical symptoms of viral hepatitis, including anorexia, malaise, and jaundice. Fulminant hepatitis and... read more . Intrapartum infection with HIV or hepatitis B occurs from passage through an infected birth canal or by ascending infection if delivery is delayed after rupture of membranes; these viruses can less commonly be transmitted transplacentally. CMV is commonly transmitted transplacentally.
Bacterial agents include group B streptococci Neonatal Listeriosis Neonatal listeriosis is acquired transplacentally or during or after delivery. Symptoms are those of sepsis. Diagnosis is by culture or polymerase chain reaction testing of mother and infant... read more , enteric gram-negative organisms (primarily Escherichia coli Escherichia coli Infections The gram-negative bacterium Escherichia coli is the most numerous aerobic commensal inhabitant of the large intestine. Certain strains cause diarrhea, and all can cause infection when... read more ), Listeria monocytogenes Listeriosis Listeriosis is bacteremia, meningitis, cerebritis, dermatitis, an oculoglandular syndrome, intrauterine and neonatal infections, or rarely endocarditis caused by Listeria species. Symptoms... read more , gonococci Gonorrhea Gonorrhea is caused by the bacteria Neisseria gonorrhoeae. It typically infects epithelia of the urethra, cervix, rectum, pharynx, or conjunctivae, causing irritation or pain and purulent... read more , and chlamydiae Chlamydial, Mycoplasmal, and Ureaplasmal Mucosal Infections Sexually transmitted urethritis, cervicitis, proctitis, and pharyngitis not due to gonorrhea are caused predominantly by chlamydiae and infrequently by mycoplasmas or Ureaplasma sp. Chlamydiae... read more .
In utero infection
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 delivery of a dead fetus at > 20 weeks gestation. Maternal and fetal testing is done to determine the cause. Management is as for routine care after live delivery. Stillbirth,... 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 clinical, symptomatic stages separated by periods of asymptomatic latent infection. Common... 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 factors for neonatal infection
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 loosely defined as the number... read more . Neonates are immunologically immature, with decreased polymorphonuclear leukocyte, monocyte, and cell-mediated immune function; premature infants Premature Infants An infant born before 37 weeks gestation is considered premature. Prematurity is defined by the gestational age at which infants are born. Previously, any infant weighing 2.5 kg was termed premature... 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. Also see 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.
Symptoms and Signs of Neonatal Infections
Symptoms and signs of infection in neonates tend to be nonspecific (eg, vomiting or poor feeding, increased sleepiness or lethargy, fever or hypothermia, tachypnea, rashes, diarrhea, abdominal distention). Many congenital infections acquired before birth can cause or be accompanied by various symptoms or abnormalities (eg, growth restriction, deafness, microcephaly, anomalies, failure to thrive, hepatosplenomegaly, neurologic abnormalities).
Diagnosis of Neonatal Infections
A wide variety of infections, including sepsis Diagnosis Neonatal sepsis is invasive infection, usually bacterial, occurring during the neonatal period. Signs are multiple, nonspecific, and include diminished spontaneous activity, less vigorous sucking... read more , should be considered in neonates who are ill at or shortly after birth, particularly those with risk factors. Infections such as congenital rubella Diagnosis 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 , syphilis Diagnosis 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 , toxoplasmosis Diagnosis Congenital toxoplasmosis is caused by transplacental acquisition of Toxoplasma gondii. Manifestations, if present, are prematurity, intrauterine growth restriction, jaundice, hepatosplenomegaly... read more , and CMV Diagnosis 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 should be pursued in neonates with abnormalities such as growth restriction, deafness, microcephaly or other physical anomalies, hepatosplenomegaly, or neurologic abnormalities.
Treatment of Neonatal Infections
The primary treatment for presumed bacterial infection in the neonate is prompt empiric antimicrobial therapy with drugs such as ampicillin and gentamicin or ampicillin and cefotaxime. Final drug selection is based on culture results similar to the practice in adults, because infecting organisms and their sensitivities are not specific to neonates. However, drug dose and frequency are affected by numerous factors, including age and weight (see tables in Antibiotics in Neonates Antibiotics in Neonates In neonates, the extracellular fluid (ECF) constitutes up to 45% of total body weight, requiring relatively larger doses of certain antibiotics (eg, aminoglycosides) compared with adults. Lower... read more ).