Methods: From November 1, 2014 to April 30, 2015 stool swabs were collected from NICU patients at The Hospital for Sick Children. Infants were included in the study if they received any dose or duration of the following antibiotics: ampicillin and tobramycin (AT), ampicillin and cefotaxime (AC), or ampicillin, tobramycin, and metronidazole (ATM). DNA was extracted from stool swabs and subject to Illumina sequencing of the V4 hypervariable region of the 16S rRNA gene. Infants were stratified by gestational age (term or preterm). The first samples taken within one week after antibiotic exposure were analysed for diversity measures, taxonomic composition and anaerobe relative abundance.
Results: A total of 64 NICU infants were included in the study, 46 (71.9%) received AT, 7 (10.9%) received AC, and 11 (17.2%) received ATM. Term infants received either AT (19/46; 41.3%) or AC (7/7; 100%), whereas preterm infants received either AT (27/46; 58.7%) or ATM (11/11; 100%). Shannon diversity was not statistically significant between term infants receiving AT and AC or preterm infants receiving AT and ATM. However, the relative abundance of anaerobes was significantly decreased after exposure to ATM in comparison to preterm infants receiving AT (p<0.005)
Within one week after ATM therapy, the relative abundance of gut anaerobes in preterm infants were significantly decreased in comparison to preterm infants receiving a course of AT. Therefore, limiting the use of ATM in preterm infants may protect the developing gut microbiota.
M. Science, None
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