Higher intake of coagulase-negative staphylococci from maternal milk promotes gut colonization with mecA -negative Sta p hylococcus e p idermidis in preterm neonates

We aimed to determine factors associated with gut colonization of preterm neonates with coagulase-negative staphylococci (CoNS) from maternal milk (MM). CoNS isolated from weekly collected stool and MM of hospitalized preterm (n = 49) and healthy term neonates (n = 20) were genotyped. Colonization-related factors were determined by Cox proportional hazards regression. Gut colonization with mecA-negative Staphylococcus epidermidis from MM was less prevalent (40.8% vs. 95%) and delayed (median age 15.5 vs. 2 days) in preterm compared with term neonates. Enhanced colonization was associated with higher intake of CoNS from MM (hazard ratio (95% confidence interval) 1.006 (1.00–1.01) for 106 colony-forming units), lower proportion of mecA-positive predominant NICU strains in gut (0.09 (0.01–0.49) for 1%) and lower incidence of late-onset CoNS sepsis (5% vs. 34% in those without colonization). Enteral feeding with larger proportion of unpasteurized MM and limiting spread of predominant strains may promote colonization with CoNS from MM.