EXTREMELY LOW BIRTH WEIGHT INFANT INFECTION

Extremely Low Birth Weight Infant Infection
Infection remains a major contributing factor to the morbidity and mortality of ELBW infants (extremely low birth weight) and can present at any point in the clinical course. Early infection that occurs during the first 3-4 days of life is believed to result from maternal factors, particularly if chorioamnionitis was diagnosed prenatally. Late nosocomial infections typically occur after the first week of life and result from endogenous hospital flora. Signs of infection are myriad, may be nonspecific, and include temperature instability (hypothermia or hyperthermia), tachycardia, decreased activity, poor perfusion, apnea, bradycardia, feeding intolerance, increased need for oxygen or higher ventilatory settings, and metabolic acidosis.

Laboratory studies may include complete blood count with differential, blood culture, cerebrospinal fluid culture, urine culture, and cultures from indwelling foreign bodies, such as central lines or endotracheal tubes. The most common causes of early sepsis in the immediate newborn period are group B streptococci (GBS), Escherichia coli, and Listeria monocytogenes.

Nosocomial sources of infection include coagulase-negative staphylococci (CoNS), and Klebsiella and Pseudomonas species, which may necessitate a different antibiotic regimen than antibiotics typically started after birth for suspected sepsis. CoNS and fungi, most commonly Candida albicans, are causes of late-onset sepsis and may manifest with the above-mentioned symptoms and with thrombocytopenia. Importantly, fulminant late-onset clinical sepsis rarely is caused by CoNS and is more commonly secondary to gram-negative organisms.

Late-onset sepsis is especially common in ELBW infants who have indwelling catheters, and it may occur in as many as 40% of these infants. In most institutions, first-line therapy in infants with early sepsis is with ampicillin and gentamicin or a third-generation cephalosporin. Vancomycin should be reserved for proven CoNS infections and organisms resistant to other agents to prevent the emergence of resistant organisms. Vancomycin and a third-generation cephalosporin often are used to treat late-onset sepsis.

Therapy with amphotericin commonly is initiated in infants with fungal infections. Cultures should dictate antibiotic management whenever possible.