Probiotic Lactococcus lactis decreases incidence and severity of necrotizing enterocolitis in a preterm animal model

Necrotizing enterocolitis (NEC) persists as the most common and serious gastrointestinal disorder among premature infants. Lactococcus lactis (LL), a lactic acid producing bacteria commonly found in buttermilk and cheese products, has several unique properties making it an ideal probiotic for neonates. We evaluated if the probiotic LL prevents development of NEC in a preterm rabbit model with Cronobacter sakazakii (CS).

Two-day preterm New Zealand white rabbit pups were randomly assigned to three diets: control (no additives), CS, and CS+LL. Pups were gavage fed and given daily oral ranitidine and indomethacin. Anal blockage was performed using tissue adhesive. Subjects were sacrificed on day four, with tissue from distal ileum and proximal colon graded for NEC by a pediatric pathologist blinded to group assignments. Outcomes were compared using Fisher's exact test.

All pups in the control group survived to sacrifice and none developed NEC. Survival was 26% higher (p = 0.03) and incidence of NEC 51% less (P < 0.001) in CS+LL group compared to CS group. Of the pups that developed NEC, all pups in the CS+LL group had Grade 1 NEC, while one-third of pups in the CS group developed Grades 2-4 NEC.

In the presence of CS, LL is protective against development of NEC in a preterm rabbit model. Future studies are needed that evaluate utilization of prophylactic probiotics in the neonatal intensive care unit to determine if this intervention can successfully decrease rates of NEC in preterm infants.