The role of broth enrichment in Staphylococcus aureus cultivation and transmission from the throat to newborn infants: results from the Swedish hygiene intervention and transmission of S. aureus study

Eur J Clin Microbiol Infect Dis. 2013 Dec;32(12):1593-8. doi: 10.1007/s10096-013-1917-6. Epub 2013 Jul 2.


Staphylococcus aureus is detected by direct plating, whereas incubation in enrichment broth prior to plating to increase the proportion of positive samples has not been fully evaluated. S. aureus throat colonization has been suggested to be more common than colonization of the anterior nares, but no data are available on the transmission of S. aureus from the throat. Swab samples were collected from the anterior nares and umbilicus from newborn infants (n = 168), anterior nares, throat, skin lesions, and vagina from parents (n = 332), and anterior nares, throat, and skin lesions from healthcare workers (n = 231) at three maternity wards. spa typing was used to elucidate the transmission routes of S. aureus. The use of enrichment broth prior to plating increased the proportion of positive samples by 46%. The prevalence of S. aureus colonization in adults was 58%. Throat colonization (47%) was significantly more common than colonization in any of the other screened sites (p < 0.001). In total, 103 out of 168 (61%) newborn infants were colonized during their hospital stay. Overall, 124 S. aureus transmissions to newborn infants were detected. Although we detected an increased risk of transmission from the nares as compared to the throat, with an odds ratio of 4.8 [95% confidence interval (CI) 1.8-12.7], we detected a transmission rate of 7 % from the throat. We show that S. aureus throat colonization is more common than colonization in any of the other sites among the parents and staff. We also show evidence of transmission from the throat.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bacteriological Techniques / methods*
  • Carrier State / microbiology*
  • Carrier State / transmission
  • Cluster Analysis
  • Female
  • Humans
  • Infant, Newborn
  • Nasal Cavity / microbiology
  • Pharynx / microbiology*
  • Prevalence
  • Staphylococcal Infections / microbiology*
  • Staphylococcal Infections / transmission
  • Staphylococcal Protein A / genetics
  • Staphylococcus aureus / genetics
  • Staphylococcus aureus / growth & development*
  • Staphylococcus aureus / isolation & purification*
  • Umbilicus / microbiology
  • Vagina / microbiology


  • Staphylococcal Protein A