Vertical transmission of methicillin-resistant Staphylococcus aureus at
delivery and its clinical impact: an observational, prospective cohort
study
Abstract
Objectives: To accurately assess the vertical transmission rate of
Methicillin-resistant Staphylococcus aureus (MRSA) and its clinical
impacts on pregnant mothers and neonates. Design: A prospective
observational cohort study. Setting: Japan. Population: 898 pregnant
women and their 905 neonates delivered in gestation week >
32+0 at Toyooka Hospital from August 2016 to December 2017. Methods:
MRSA was cultured from the nasal and vaginal samples taken from mothers
at enrollment and the nasal and umbilical samples taken from neonates
immediately after their birth. We examined the vertical transmission
rate of MRSA in mother-neonate pairs. We used multivariable logistic
regression to identify maternal/neonatal adverse outcomes associated
with maternal MRSA colonization. Main outcome measures: The frequency of
maternal/neonatal MRSA colonization and adverse outcomes. Results: The
prevalence of maternal MRSA colonization was 6.1% (55/898), and that of
neonates was 0.8% (8/905). The prevalence of neonatal MRSA was 12.7%
(7/55 mother-neonate pairs) in the MRSA-positive mothers, whereas it was
only 0.12% (1/843 pairs) in the MRSA-negative mothers (OR: 121, 95%
CI: 14.6-1000). When the maternal vaginal-MRSA was positive, the
vertical transmission rate was 44.4% (4/9). Skin and soft tissue
infections (SSTIs) developed significantly more frequently in neonates
born to the MRSA-positive mothers (OR: 7.47, 95% CI: 2.50-22.3).
Conclusions: The prevalence of MRSA in pregnant women was approximately
6%. The vertical transmission rate of vaginal MRSA was as high as
44.4%. Maternal MRSA colonization is associated with increased
development of neonatal SSTIs via vertical transmission.