Anaerobic Antimicrobial Therapy After Necrotizing Enterocolitis in VLBW Infants

Julie Aut­mizguine, et al, PEDIATRICS , Vol. 135 No. 1 Jan­u­ary 1, 2015 pp.e117 – e125    

OBJECTIVE: To eval­u­ate the effect of anaer­o­bic antimi­cro­bial ther­a­py for necro­tiz­ing ente­ro­col­i­tis (NEC) on clin­i­cal out­comes in very low birth weight (≤1500 g) infants.

METHODS: We iden­ti­fied very low birth weight infants with NEC from 348 US NICUs from 1997 to 2012. Anaer­o­bic antimi­cro­bial ther­a­py was defined by antibi­ot­ic expo­sure on the first day of NEC. We matched (1:1) infants exposed to anaer­o­bic antimi­cro­bial ther­a­py with infants who were not exposed by using a propen­si­ty score strat­i­fied by NEC sever­i­ty (med­ical and sur­gi­cal). The pri­ma­ry com­pos­ite out­come was in-hos­pi­tal death or intesti­nal stric­ture. We assessed the rela­tion­ship between anaer­o­bic antimi­cro­bial ther­a­py and out­come by using a con­di­tion­al logis­tic regres­sion on the matched cohort.

RESULTS: A total of 1390 infants exposed to anaer­o­bic antimi­cro­bial ther­a­py were matched with 1390 infants not exposed. Mean ges­ta­tion­al age and birth weight were 27 weeks and 946 g, respec­tive­ly, and were sim­i­lar in both groups. We found no sig­nif­i­cant dif­fer­ence in the com­bined out­come of death or stric­tures, but stric­tures as a sin­gle out­come were more com­mon in the anaer­o­bic antimi­cro­bial ther­a­py group (odds ratio 1.73; 95% con­fi­dence inter­val, 1.11–2.72). Among infants with sur­gi­cal NEC, mor­tal­i­ty was less com­mon with anaer­o­bic antimi­cro­bial ther­a­py (odds ratio 0.71; 95% con­fi­dence inter­val, 0.52–0.95).

CONCLUSIONS: Anaer­o­bic antimi­cro­bial ther­a­py was not asso­ci­at­ed with the com­pos­ite out­come of death or stric­tures but was asso­ci­at­ed with an increase in intesti­nal stric­tures. This high­er inci­dence of intesti­nal stric­tures may be explained by the fact that death is a com­pet­ing out­come for intesti­nal stric­tures, and mor­tal­i­ty was slight­ly low­er in the anaer­o­bic cohort. Infants with sur­gi­cal NEC who received anaer­o­bic antimi­cro­bial ther­a­py had low­er mor­tal­i­ty.