Short-term pasteurization of breast milk may reduce the incidence of postnatally acquired cytomegalovirus (CMV) infection through breast milk, according to a recently published study in Clinical Infectious Diseases.

Breast milk is advantageous for preterm infants. However, postnatally acquired CMV infection can be transmitted through the breast milk of mothers who are seropositive for CMV, resulting in severe illness, including sepsis-like symptoms and sometimes death. Further, recent studies have suggested that postnatally acquired CMV can result in a reduced long-term neurocognitive outcome in affected infants. Conventional CMV-inactivation methods either do not prevent transmission efficiently or impair milk quality. Therefore, effective methods to prevent this transmission are needed. A new method of short-term pasteurization through the generation of a milk-film may eliminate CMV while preserving key enzymes; however, whether this method can be applied consistently to reduce the risk for CMV transmission in a busy neonatal intensive care unit (NICU) is unknown. This interventional trial assessed the effectiveness of short-term pasteurization in preventing CMV transmission through breast milk in preterm infants. 

In 2 German level-3 NICUs, 87 preterm infants with a birth weight of <1500 g or a gestational age of <32 weeks born to 69 mothers who were seropositive for CMV IgG were included, along with 83 historic controls. The participants selected as controls were mothers and infants from a cohort from the Tübingen NICU from 1995 to 1998. Breast milk samples were pasteurized (62°C for 5 seconds) from postnatal day 4 to discharge. The primary end point was CMV status at discharge evaluated by polymerase chain reaction and short-term microculture from urine. Differences in CMV transmission were compared with reference to the cumulative time at risk for CMV transmission. There were no significant differences in relevant infant characteristics.

Overall, short-term pasteurization of breast milk significantly reduced the incidence of postnatally acquired CMV in the NICU. Only 2 of 87 (2.3%) infants had postnatal CMV transmission in the pasteurized breast milk group compared with 17 of 83 (20.5%) infants in the control group. Further, the total time for risk for infection was 9.6 years in the pasteurized breast milk group and 10.0 years in the control group, which yielded an incidence of 0.21/year in the pasteurized breast milk group compared with 1.70/year in the control group. The risk ratio of control infants vs study infants according to Cox proportional hazard model was 8.3 (P =.0003).

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Overall, the study authors concluded that although short-term pasteurization of breast milk may be an effective method for reducing postnatal CMV infection rates significantly, “the method is time consuming, needs a precise pre-processing and requires constant training of the nursing staff involved. These efforts have to be balanced against the well-known short- and long-term adverse sequelae of postnatal CMV infection in very preterm infants.”

Reference

Bapistella S, Hamprecht K, Thomas W, et al. Short-term pasteurization of breast milk to prevent postnatal cytomegalovirus transmission in very preterm infants [published online November 8, 2018]. Clin Infect Dis. doi: 10.1093/cid/ciy945