Extended-spectrum β-lactamase-producing Enterobacteriaceae among pregnant women in Norway: prevalence and maternal-neonatal transmission.
OBJECTIVE
To study (i) the prevalence and risk factors for carriage of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) in pregnant women, (ii) the maternal-neonatal transmission rate of ESBL-E at birth and (iii) the prevalence of ESBL-E in expressed breast milk of colonized mothers.


METHODS
In this cross-sectional, population-based study with case follow-up on maternal-neonatal transmission of ESBL-E, women were screened for rectal ESBL-E colonization at 36 weeks of pregnancy and delivery. Possible risk factors for colonization were studied by logistic regression. Infants of ESBL-E-positive mothers were screened for ESBL-E during their first weeks of life. ESBL-encoding genes were detected by PCR and clonal relatedness was investigated by pulsed-field gel electrophoreses.


RESULTS
In total, 26 out of 901 (2.9%) women were colonized by ESBL-producing Escherichia coli at 36 weeks of pregnancy. One of the women carried an additional ESBL Klebsiella pneumoniae strain. Adjusted for traveling, African or Asian nationality was a risk factor for colonization; OR=5.62 (2.21, 14.27) (LR-p=0.003). Fourteen women remained ESBL-E carriers at delivery. ESBL-E strains indistinguishable from the strains isolated from their respective mothers were detected in 5 (35.7%) infants during their first days of life (median day 3; range=2 to 8). A total of 146 expressed milk samples were cultured from 25 out of 26 colonized mothers, all were ESBL-E negative.


CONCLUSIONS
The prevalence of ESBL-E carriage among pregnant women was low in our region, but the high maternal-neonatal transmission rate suggests that colonized mothers represent a substantial risk for infant colonization.
Department of Pediatrics, Stavanger University Hospital, Stavanger, Norway.
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Rettedal
Department of Medical Microbiology, Stavanger University Hospital, Stavanger, Norway.
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Löhr
Department of Medical Microbiology, Stavanger University Hospital, Stavanger, Norway.
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Bernhoff
Department of Medical Microbiology, Stavanger University Hospital, Stavanger, Norway.|Department of Infection Control, Stavanger University Hospital, Stavanger, Norway.
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Natås
Department of Medical Biology, University of Tromsø, Stavanger, Norway.|Norwegian National Advisory Unit on Detection of Antimicrobial Resistance, University Hospital of North Norway, Tromsø, Norway.
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Sundsfjord
Department of Pediatrics, Stavanger University Hospital, Stavanger, Norway.|Department of Clinical Science, University of Bergen, Bergen, Norway.
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Øymar
D000328:Adult; D002353:Carrier State / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004755:Enterobacteriaceae / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000175:diagnosis / Q000201:enzymology / Q000635:transmission*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical / Q000706:statistics & numerical data*; D016015:Logistic Models; D009664:Norway / Q000453:epidemiology; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis* / Q000453:epidemiology; D011263:Pregnancy Trimester, Third; D011296:Prenatal Diagnosis; D015995:Prevalence; D018570:Risk Assessment; D001618:beta-Lactamases / Q000378:metabolism*
D001618:beta-Lactamases