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• Infections in Neonates
4

Neonatal infection can be acquired in utero transplacentally, through the birth canal during delivery (intrapartum), and from external sources after birth (postpartum).

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, intrauterine growth restriction, premature birth, stillbirth, congenital malformation (eg, rubella), and symptomatic neonatal infection (eg, cytomegalovirus [CMV], toxoplasmosis, syphilis).

Common viral agents include herpes simplex, HIV, CMV, and hepatitis B. 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, enteric gram-negative organisms (primarily Escherichia coli), gonococci, and chlamydiae.

Postpartum infections are acquired from contact with an infected mother either directly (eg, TB, which also is sometimes transmitted in utero) or through breastfeeding (eg, HIV, CMV) or from contact with health care practitioners and the hospital environment (numerous organisms—see Infections in Neonates: Neonatal Hospital-Acquired Infection).

Risk factors: Risk of contracting intrapartum and postpartum infection is inversely proportional to gestational age. Neonates are immunologically immature, with decreased polymorphonuclear leukocyte and monocyte function; premature infants are particularly so (see also Perinatal Physiology: Immunologic function). 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

Symptoms and signs in neonates tend to be nonspecific (eg, vomiting, fever, petechiae, rashes, diarrhea, fever, hypothermia). 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

A wide variety of infections should be considered in neonates who are ill, febrile, or hypothermic. Infections such as congenital rubella, syphilis, toxoplasmosis, and CMV should be considered, particularly in neonates with abnormalities such as growth restriction, deafness, microcephaly, anomalies, failure to thrive, hepatosplenomegaly, or neurologic abnormalities.

Treatment

• Antimicrobial therapy

The primary treatment is usually antimicrobial therapy. Drug selection is similar to that in adults, because infecting organisms and their sensitivities are not specific to neonates. However, numerous factors, including age and weight, affect dose and frequency (see Table 1: Infections in Neonates: Recommended Dosages of Selected Parenteral Antibiotics for Neonates and Table 2: Infections in Neonates: Recommended Dosages of Selected Oral Antibiotics for Neonates*).

Table 1
Recommended Dosages of Selected Parenteral Antibiotics for Neonates This table is presented as a PDF and requires the free Adobe PDF reader. Get Adobe Reader

Table 2
Recommended Dosages of Selected Oral Antibiotics for Neonates* Antibiotic Dosage Interval Comments AmoxicillinSome Trade Names AMOXIL TRIMOX Click for Drug Monograph 15 mg/kg q 8 h Limited data AzithromycinSome Trade Names ZITHROMAX Click for Drug Monograph 5–10 mg/kg q 24 h Preferred drug for treatment or prevention of pertussis in neonates < 1 mo For treatment or prevention of pertussis, 10 mg/kg given once/day for 5 days For most other infections, 10 mg/kg given on day 1 and then 5 mg/kg given on days 2–5 ClindamycinSome Trade Names CLEOCIN Click for Drug Monograph † 5 mg/kg q 6–8 h Limited data ErythromycinSome Trade Names ERY-TAB ERYTHROCIN Click for Drug Monograph ethylsuccinate 10 mg/kg q 6–12 h For chlamydial infections or pertussis in neonates > 1 mo Associated with idiopathic hypertrophic pyloric stenosis FluconazoleSome Trade Names DIFLUCAN Click for Drug Monograph 3–6 mg/kg q 24–72 h For minor candidal infections, 6 mg/kg on day 1, then 3 mg/kg/dose q 24–72 h For serious infections, 12 mg/kg once/day recommend for all gestational and postnatal ages A first (loading) dose of 25 mg/kg also possibly considered During the 1st 2 wk of life, adjustment of dosing interval possibly necessary if renal function is abnormal FlucytosineSome Trade Names ANCOBON Click for Drug Monograph 12.5–37.5 mg/kg q 6 h Limited data Used only with amphotericin BSome Trade Names ABELCET AMBISOME AMPHOCIN AMPHOTEC Click for Drug Monograph to slow emergence of resistance Monitoring of levels recommended NeomycinSome Trade Names NEO-FRADIN NEO-RX Click for Drug Monograph sulfate 33 mg/kg q 8 h For gastroenteritis caused by enteropathogenic strains of Escherichia coli May be systemically absorbed in neonates with severe diarrhea RifampinSome Trade Names RIFADIN RIMACTANE Click for Drug Monograph 10 mg/kg q 24 h For TB 5 mg/kg q 12 h For meningococcus prophylaxis, given for 2 days 10 mg/kg q 24 h For Haemophilus influenzae prophylaxis, given for 4 days *Unless otherwise stated, doses are for neonates who are > 7 days and > 2000 g. †The dose for neonates who are < 7 days old < 2000 g is 5 mg/kg q 12 h.

In neonates, the ECF constitutes up to 45% of total body weight, requiring relatively larger doses of certain antibiotics (eg, aminoglycosides) compared with adults. Lower serum albumin concentrations in premature infants may reduce antibiotic protein binding. Drugs that displace bilirubin from albumin (eg, sulfonamides, ceftriaxoneSome Trade Names
ROCEPHIN
Click for Drug Monograph
) increase the risk of kernicterus.

Absence or deficiency of certain enzymes in neonates may prolong the half-life of certain antibiotics (eg, chloramphenicolSome Trade Names
CHLOROMYCETIN
Click for Drug Monograph
) and increase the risk of toxicity. Changes in GFR and renal tubular secretion during the first month of life necessitate dosing changes for other drugs (eg, penicillins, aminoglycosides, vancomycinSome Trade Names
VANCOCIN
Click for Drug Monograph
).

Last full review/revision October 2009 by Mary T. Caserta, MD

Content last modified October 2009