We know that prolonged antibiotic use in preterm babies increase their chance of later developing NEC. The assumption being that the disturbance of the intestinal flora leads to the increase in susceptibility. Here is some more direct evidence to support that assumption.
Greenwood C, Morrow AL, Lagomarcino AJ, Altaye M, Taft DH, Yu Z, Newburg DS, Ward DV, Schibler KR: Early empiric antibiotic use in preterm infants is associated with lower bacterial diversity and higher relative abundance of enterobacter. The Journal of pediatrics 2014(0).
There were 74 babies under 33 weeks studied, who had their microbiomic analysis performed weekly, 3 times. They divided the babies into those who had antibiotics for 0 days, 1-4 days, or 5-7 days.
All of the antibiotic use was empiric, defined as treatment based solely on clinical suspicion of infection without a positive culture result.
RESULTS: Infants who received 5-7 days of empiric antimicrobial agents in the first week had increased relative abundance of Enterobacter (P = .016) and lower bacterial diversity in the second and third weeks of life. Infants receiving early antibiotics also experienced more cases of necrotizing enterocolitis, sepsis, or death than those not exposed to antibiotics.
The table 2 in that article requires a bit of explanation, it took me a while to realize that the row labelled ‘cases’ means those babies who had the combined outcome of death, NEC or sepsis.
The message to me is clear, prematurity is not in itself a septic event. You don’t have to have antibiotics just because you are admitted to an NICU! If you do have an indication for expectant antibiotic therapy, they should be stopped if the cultures are negative unless you have a very good reason.
Of course the other method is that all babies develop a microbiome, we can wreck it by giving antibiotics, and we can nudge it in the right direction by administering probiotics.