14th ICID - Poster Abstracts - International Society for Infectious ...

When citing these abstracts please use the following reference:
Author(s) of abstract. Title of abstract [abstract]. Int J Infect Dis 2010;14S1: Abstract number.
Please note that the official publication of the International Journal of Infectious Diseases 2010, Volume 14, Supplement 1
is available electronically on http://www.sciencedirect.com
Final Abstract Number: 77.028
Session: Gram-positives & Miscellaneous Pathogens
Date: Friday, March 12, 2010
Time: 12:30-13:30
Room: Poster & Exhibition Area/Ground Level
Type: Poster Presentation
Association of breast milk Lactobacilli and Staphylococcus aureus in women with mastitis using
quantitative PCR
U. srinivasan, N. Shrivastwa, S. Ponnaluri, J. Debusscher, C. Barbossa-Cesnik, C. F. Marrs, B.
Foxman
University of Michigan, Ann Arbor, MI, USA
Background: Staphylococcus aureus is the most common causative agent of lactation mastitis;
an infection of the breast that affects up to 30% of lactating women and often requires treatment
with antibiotics. Commensal breast milk Lactobacilli inhibit pathogenic Staphylococcus growth in
vitro; whether this is true in vivo is not known. We will test Staphylococcus and Lactobacillus
levels in mastitis and healthy breast milk collected from a study of lactating mothers in Brazil and
determine the association of Staphylococcus and Lactobacilli levels in breast milk.
Methods: Breast milk samples were collected from 72 healthy mothers and mothers suffering
from mastitis in Brazil. Bacterial genomic DNA from breast milk was purified from breast milk
samples and quantitative PCR assays were designed to measure the amounts of
Staphylococcus, Lactobacilli and total bacteria. Primers for Staphylococcus aureus assays were
based on the Staphylococcus aureus specific nuc gene, while Lactobacilli specific 16S ribosomal
gene regions were used to design primers specific to Lactobacillus genus. Total bacteria were
determined in quantitative PCR assays using universal bacterial primers based on conserved
regions of the 16S ribosomal gene.
Results: Preliminary quantitative PCR results of 24 samples indicate that Staphylococcus aureus
was present in roughly 47% (n=11) of milk and Lactobacilli was present in 82% (n=19) of milk
samples. Lactobacilli levels varied between 70 - 103 copies / ul while Staphylococcus aureus
levels were higher (102-106 copies/ul).
Conclusion: Our results suggest that Lactobacilli are more common in breast milk than
previously reported in literature. We will investigate whether Lactobacilli levels in breast milk are
related to Staphylococcus aureus levels in healthy and mastitis milk. If the levels of commensal
Lactobacilli and pathogenic Staphylococcus aureus are related, this suggests that microbial milk
composition is an important determinant of breast milk health and indicates the need to
investigate whether probiotic supplementation with Lactobacilli can help reduce the risk of
mastitis in women.