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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 may not be clear whether the source is maternal or the hospital environment.
Hospital-acquired infection is primarily a problem for premature infants and for term infants with medical disorders requiring prolonged hospitalization. Healthy, term neonates have infection rates < 1%. For those in special care nurseries, the incidence increases as birth weight decreases. The most common infections, sepsis and pneumonia, have a combined rate of 6.2 cases per 1000 catheter or ventilator days for infants weighing 1501 to 2500 g, 8.9 cases for those weighing 1001 to 1500 g, and 13.9 cases for those weighing ≤ 1000 g.
Overall mortality rates are about 33%; for neonates whose birth weight is < 1000 g, the mortality rate is 16 to 45%, and for those whose birth weight is > 2000 g, the mortality rate is 2 to 12%.
Etiology
In term neonates, skin infection due to Staphylococcus aureus (both methicillin sensitive and methicillin resistant) is the most frequent hospital-acquired infection. Although nursery personnel who are S. aureus nasal carriers are potential sources of infection, colonized neonates are usually the reservoir. The umbilical stump and groin are most frequently colonized during the first few days of life, whereas the nares are more frequently colonized later. Often, infections do not manifest until the neonate is at home.
In very-low-birth-weight (VLBW; < 1500 g) infants, gram-positive organisms cause about 70% of infections, the majority being with coagulase-negative staphylococci. Gram-negative organisms, including Escherichia coli, Klebsiella, Pseudomonas, Enterobacter, and Serratia, cause about 18%. Fungi (Candida albicans and C. parapsilosis) cause about 12%. Patterns of infection (and antibiotic resistance) vary among institutions and units and change with time. Intermittent “epidemics” sometimes occur as a particularly virulent organism colonizes a unit.
Infection is facilitated by the multiple invasive procedures VLBW infants undergo (eg, long-term arterial and venous catheterization, endotracheal intubation, continuous positive airway pressure, NGTs or nasojejunal feeding tubes). The longer the stay in special care nurseries and the more procedures done, the higher is the likelihood of infection.
Prevention
Bathing neonates with 3% hexachlorophene decreases frequency of S. aureus colonization, but this product can cause neurotoxicity, particularly in low-birth-weight infants, and is no longer used. The American Academy of Pediatrics recommends dry umbilical cord care, but this care may result in high rates of colonization with S. aureus, and epidemics have occurred in some hospitals. During disease outbreaks, application of triple dye to the cord area or bacitracin or mupirocin ointment to the cord, nares, and circumcision site reduces colonization. Routine cultures of personnel or of the environment are not recommended.
Prevention of colonization and infection in special care nurseries requires provision of sufficient space and personnel. In intensive care, 150 sq ft (about 14 sq m)/infant and 8 ft (about 2.4 m) between incubators or warmers, edge-to-edge in each direction, and a nurse:patient ratio of 1:1 to 1:2 are required. In intermediate care, 120 sq ft (about 11.2 sq m)/infant and 4 ft (about 1.2 m) between incubators or warmers, edge-to-edge in each direction, and a nurse:patient ratio of 1:3 to 1:4 are required. Proper techniques are required, including placement and care of invasive devices and meticulous cleaning and disinfection or sterilization of equipment. Active surveillance for infection (not colonization) and monitoring of techniques are essential.
Other preventive measures include frequent hand washing and wearing gowns and gloves. Washing with alcohol preparations is more effective than soap and water in decreasing bacterial colony counts on hands but does not eliminate Clostridium difficile spores. Incubators provide limited protective isolation; the exteriors and interiors of the units rapidly become heavily contaminated, and personnel are likely to contaminate their hands and forearms. Universal blood and body fluid precautions add further protection.
In an epidemic, establishing a cohort of diseased or colonized infants and assigning them a separate nursing staff are useful. Continuing surveillance for 1 mo after discharge is necessary to assess the adequacy of controls instituted to end an epidemic.
Prophylactic antimicrobial therapy is generally not effective, hastens development of resistant bacteria, and alters the balance of normal flora in the neonate. However, during a confirmed nursery epidemic, antibiotics against specific pathogens may be considered—eg, penicillin G for prophylaxis against group A streptococcal infection or oral colistin or neomycin for prophylaxis against enterotoxigenic or enteropathogenic E. coli.
Vaccination according to the routine schedule (see Table 12: Approach to the Care of Normal Infants and Children: Recommended Immunization Schedule for Ages 0–6 yr ) should be given to any infant who is in the hospital at that time.
Last full review/revision October 2009 by Mary T. Caserta, MD
Content last modified February 2012
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