title: Transmission of Staphylococcus aureus from mothers to newborns.
abstract: BACKGROUND
  The study objective was to define the risk factors and the route of Staphylococcus aureus transmission between mother and newborn.
  
  
  METHODS
  Women at late pregnancy were screened for nasal and vaginal S. aureus colonization. Newborns were screened for nasal, auricular, umbilical, and rectal colonization at birth and before discharge. Carrier mothers and their newborns were rescreened at 1 month. Pulse-field gel electrophoresis was used to assess strain genetic relatedness.
  
  
  RESULTS
  Of the 208 women screened, 34% were colonized with S. aureus. Overall, by 72-100 hours after birth, the cumulative incidence of S. aureus acquisition was 42.6/100 newborns of carrier mothers versus 7.4/100 newborns of noncarrier mothers (adjusted risk ratio = 5.7; 95% confidence interval [CI], 2.3-13.9). The risk to acquire a maternal strain was significantly higher than nonmaternal strain (adjusted risk ratio = 1.5; 95% CI, 1.3-1.9); Newborns to carrier mothers were also at a risk to acquire nonmaternal S. aureus strains compared with newborns to noncarrier mothers (adjusted risk ratio = 2.9; 95% CI, 1.6-5.4). The cumulative incidence of S. aureus acquisition was similar among newborns delivered by cesarean versus vaginal delivery (24.5 vs. 23.0/100 cases). At 1-month follow-up, the cumulative incidence of S. aureus acquisition reached 69.7/100 newborns of carrier mothers.Genetically identical strains were isolated in 32/40 (80%) mother-newborn pairs, among these, the source of the newborn strain was a maternal nasal strain in 29/32 (90%).
  
  
  CONCLUSIONS
  Newborns of carrier mothers are at risk to acquire S. aureus colonization. Most newborns of carrier mothers are colonized within the first month of life. Horizontal transmission from the mother is probably the major source for S. aureus carriage in newborns.
authors.affiliation: Infectious Diseases Unit, The Chaim Sheba Medical Center, Tel Hashomer and the Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Eyal
authors.initials: E
authors.lastname: Leshem
authors.forename: Ayala
authors.initials: A
authors.lastname: Maayan-Metzger
authors.forename: Galia
authors.initials: G
authors.lastname: Rahav
authors.forename: Mordechai
authors.initials: M
authors.lastname: Dolitzki
authors.forename: Jacob
authors.initials: J
authors.lastname: Kuint
authors.forename: Yulia
authors.initials: Y
authors.lastname: Roytman
authors.forename: Aviva
authors.initials: A
authors.lastname: Goral
authors.forename: Ilya
authors.initials: I
authors.lastname: Novikov
authors.forename: Ronen
authors.initials: R
authors.lastname: Fluss
authors.forename: Nathan
authors.initials: N
authors.lastname: Keller
authors.forename: Gili
authors.initials: G
authors.lastname: Regev-Yochay
mesh_terms: D000328:Adult; D002353:Carrier State / Q000382:microbiology / Q000635:transmission; D016000:Cluster Analysis; D004423:Ear / Q000382:microbiology; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical; D017720:Molecular Epidemiology; D058889:Molecular Typing; D009666:Nose / Q000382:microbiology; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious; D012007:Rectum / Q000382:microbiology; D013203:Staphylococcal Infections / Q000382:microbiology* / Q000635:transmission*; D013211:Staphylococcus aureus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D014472:Umbilicus / Q000382:microbiology; D014621:Vagina / Q000382:microbiology