909. Increased Risk of Antibiotic Resistance in Neonatal Early-Onset Sepsis with Maternal Antibiotic Exposure: A Case-Cohort Study
Session: Poster Abstract Session: Antimicrobial Utilization and Resistance in Children
Saturday, October 22, 2011
Room: Poster Hall B1

Antibiotic exposure increases the risk of antibiotic resistance (AR) in maternal flora and may put neonates at increased risk of AR early-onset sepsis (AR-EOS). We asked whether AR-EOS was more likely if mothers had received antibiotics during pregnancy.


A case-cohort study was performed using all neonates with confirmed or probable bacterial infections in the first 14 days of life at Mount Sinai Hospital, Toronto, between January 1, 2008 and May 30, 2010. Resistance was defined as resistance to at least 1 empiric antibiotic used in our NICU for EOS during this time. Chart review was performed to identify demographic and medical information including antibiotic exposure; telephone interviews to confirm antibiotic exposure. In situations with >1 infection (e.g. triplets with 2+ infants infected), only 1 case was counted and it was classified as AR if at least 1 infection was AR.


There were 64 episodes of EOS with 60 eligible episodes for analysis. The most common positive culture site was blood (49, 82%), while the most common bacteria were Escherichia coli (18, 30%), Group B streptococcus (13, 22%), and K. pneumoniae (11, 18%). The most common antibiotic was erythromycin (34/122 courses) and the most common indication was preterm premature rupture of membranes (PPROM; 53/122 courses; 176/510 antibiotic days). 32 episodes of EOS were due to AR bacteria while 28 were antibiotic-sensitive. AR-EOS was more likely in neonates born to mothers given antibiotics during pregnancy (OR 4.6, 95% CI 1.1-19.1, p=.05). The trend was similar if only sterile sites were analyzed (OR 4.7; 95% CI 0.9-24.8, p=.08). Prematurity (32/32 v 17/28 neonates, p<.01), gestational age (27.2 v 34.5 weeks, p<.01), hospitalization (25/32 v 11/28 mothers, p<.01), and PPROM (30/32 v 14/28 mothers, p<.01) were also associated with AR. 98% of mothers with PPROM, 94% of premature neonates, and 94% of mothers hospitalized in pregnancy were exposed to antibiotics such that it was not possible to identify the true causal factor in this study.


Antibiotic exposure, prematurity, hospitalization, and PPROM were associated with AR-EOS in our population. These factors can be used to identify neonates at risk of AR if they get EOS and to optimize empiric antibiotic choices.

Subject Category: P. Pediatric and perinatal infections

Alissa Wright, MD1, Sharon Unger, MD2, Brenda Coleman, PhD3, Po-Po Lam, MSc3 and Allison McGeer, MD3, (1)Department of Medicine, Division of Infectious Disease, University of British Columbia, Vancouver, BC, Canada, (2)Department of Neonatology, University of Toronto, Toronto, ON, Canada, (3)Department of Microbiology, University of Toronto, Toronto, ON, Canada


A. Wright, None

S. Unger, None

B. Coleman, None

P. P. Lam, None

A. McGeer, None

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