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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, toxoplasmosis, syphilis).

Intrapartum infection occurs from passage through an infected birth canal or by ascending infection if delivery is delayed after rupture of membranes. Common viral agents include herpes simplex, HIV, cytomegalovirus (CMV), and hepatitis B; these can less commonly be 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 intra- and postpartum infection is inversely proportional to gestational age. Neonates are immunologically immature, with decreased PMN and monocyte function; premature infants are particularly so (see also Perinatal Physiology: Immunologic). Maternal IgG antibodies are actively transported across the placenta, but effective levels 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.

Antibacterial therapy: Drug selection is similar to that in adults (see Bacteria and Antibacterial Drugs: Selection and Use of Antibiotics), 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 Amoxicillin Some Trade Names AMOXIL TRIMOX Click for Drug Monograph 15 mg/kg q 8 h Limited data Cefaclor Some Trade Names CECLOR Click for Drug Monograph 15 mg/kg q 8 h Limited data Clindamycin Some Trade Names CLEOCIN Click for Drug Monograph * 5 mg/kg q 6–8 h Limited data Colistin 3–5 mg/kg q 8 h For gastroenteritis caused by enteropathogenic strains of Escherichia coli, and for prophylaxis of neonates at high risk for necrotizing enterocolitis, for 5 days. May be systemically absorbed in the presence of significant diarrhea. Unproven efficacy and safety Erythromycin Some Trade Names ERY-TAB ERYTHROCIN Click for Drug Monograph estolate Erythromycin Some Trade Names ERY-TAB ERYTHROCIN Click for Drug Monograph ethylsuccinate 10 mg/kg 12.5 mg/kg q 8 h q 6 h For chlamydial infections or pertussis For chlamydial infections or pertussis Fluconazole Some Trade Names DIFLUCAN Click for Drug Monograph 3–6 mg/kg q 24 h For candidal infections Flucytosine Some Trade Names ANCOBON Click for Drug Monograph 12.5–37.5 mg/kg q 6 h Limited data. Use only in combination with amphotericin B Some Trade Names ABELCET AMBISOME AMPHOCIN AMPHOTEC Click for Drug Monograph , to retard emergence of resistance Neomycin Some Trade Names NEO-FRADIN NEO-RX Click for Drug Monograph 30–35 mg/kg q 8 h See Colistin Rifampin Some 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 for 2 days   10 mg/kg q 24 h For Haemophilus influenzae prophylaxis for 4 days *The dose for neonates < 7 days who are < 2000 g is 5 mg/kg q 12 h. †Serum levels in preterm infants should be monitored.

In neonates, the ECF constitutes up to 45% of total body weight, requiring relatively larger doses of certain antibiotics (eg, aminoglycosides) compared to adults. Lower serum albumin concentrations in premature infants may reduce antibiotic protein binding. Drugs that displace bilirubin from albumin (eg, sulfonamides, ceftriaxone Some 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 ( chloramphenicol Some Trade Names
CHLOROMYCETIN
Click for Drug Monograph
) and increase the risk of toxicity. Changes in GFR and renal tubular secretion during the 1st month of life necessitate dosing changes for other drugs (eg, penicillins, aminoglycosides, vancomycin Some Trade Names
VANCOCIN
Click for Drug Monograph
).

Last full review/revision November 2005

Content last modified November 2005