Sepsis, a serious infection, remains a major threat to 'late preterm' infants

Sepsis is a serious infection that is a major cause of death in very premature infants. But sepsis is also a threat in "late preterm" infants born just a few weeks prematurely, according to a study in the December issue of The Pediatric Infectious Disease Journal. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals, and institutions in medicine, nursing, allied health, and pharmacy.

Late preterm infants show a distinct pattern of risk for sepsis in the initial days and weeks of life, with one type of bacterial sepsis causing a sharp increase in mortality, reports the new research, led by Dr. Michael Cohen-Wolkowiez of Duke University, Durham, N.C.

Nationwide Data on Rates and Risk Factors for Sepsis in Late Preterm Infants
The researchers analyzed data on more than 225,000 late-preterm infants—born between 34 and 36 weeks' gestation—treated at newborn intensive care units (NICUs) across the United States. Sometimes called bloodstream infection or "blood poisoning," sepsis is a serious complication in which the body is invaded by infectious bacteria or other organisms. The infection and resulting immune system response can lead to organ damage and death.

The study included 119,000 infants admitted to the NICU within the first three days after birth. In this group, sepsis occurred at rate of 4.5 per 1,000 infants, based on positive culture tests for bloodstream infection. Hispanic infants, those with lower birth weights, and those delivered by cesarean section were at higher risk of early-onset sepsis; infants whose mothers were treated with antibiotics before delivery were at lower risk.

Another 106,000 infants were seen in the NICU between 4 days and 4 months after birth. In this group, sepsis occurred at a rate of about 6 per 1,000. Late-onset sepsis was more likely in infants with teenaged mothers and those who were in poorer condition a few minutes after birth (based on 5-minute Apgar score).

Type of Bacteria Affects Mortality Risk
In both groups, roughly 30 percent of patients with sepsis had infection with a group of bacteria called gram-negative, which tend to be more resistant to antibiotics. These gram-negative infections were more likely to be fatal than other causes of sepsis. Among infants with early-onset sepsis, risk of death increased from about one percent overall to 19 percent for infants with gram-negative infections. Compared to all infants admitted to the NICU, the risk of death was three to four times higher for those with gram-negative sepsis.

Intensive care doctors and nurses are well aware of the dangers of sepsis in very premature infants: babies born before 33 weeks' gestation or with birth weights of less than 1,500 grams (about three pounds). However, more than 70 percent of preterm infants are born 34 to 36 weeks. These late preterm infants are often viewed as similar to full-term infants (born at 37 weeks or later) and treated similarly.

The new results add to recent evidence showing that late-preterm infants are at increased risk of sepsis, including fatal sepsis. The study was part of an effort by the U.S. National Institute of Child Health and Human Development to increase knowledge and understanding of complications of preterm birth.

The study lends new insights into the rates, risk factors, infection patterns, and mortality rates for sepsis among late preterm infants. Dr. Cohen-Wolkowiez and colleagues hope their findings will be of value to hospitals treating late preterm infants in the NICU or special care nursery. However, they emphasize that some key questions still need to be addressed—including the impact of recent guidelines to give antibiotics to prevent one type of infection (with group B strep bacteria) at delivery.