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Viruses 2018, 10(10), 552;

Potential Application of Bacteriophages in Enrichment Culture for Improved Prenatal Streptococcus agalactiae Screening

School of Veterinary Medicine, Azabu University, Kanagawa 252-5201, Japan
Kitasato Institute for Life Sciences, Kitasato University, Tokyo 108-8641, Japan
Research Institute of Molecular Genetics, Kochi University, Kochi 783-8502, Japan
Kochi Medical School, Kochi University, Kochi 783-8505, Japan
Author to whom correspondence should be addressed.
Received: 9 August 2018 / Revised: 24 September 2018 / Accepted: 9 October 2018 / Published: 10 October 2018
(This article belongs to the Special Issue Biotechnological Applications of Phage and Phage-Derived Proteins)
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Vertical transmission of Streptococcus agalactiae can cause neonatal infections. A culture test in the late stage of pregnancy is used to screen for the presence of maternal S. agalactiae for intrapartum antibiotic prophylaxis. For the test, a vaginal–rectal sample is recommended to be enriched, followed by bacterial identification. In some cases, Enterococcus faecalis overgrows in the enrichment culture. Consequently, the identification test yields false-negative results. Bacteriophages (phages) can be used as antimicrobial materials. Here, we explored the feasibility of using phages to minimize false-negative results in an experimental setting. Phage mixture was prepared using three phages that specifically infect E. faecalis: phiEF24C, phiEF17H, and phiM1EF22. The mixture inhibited the growth of 86.7% (26/30) of vaginal E. faecalis strains. The simple coculture of E. faecalis and S. agalactiae was used as an experimental enrichment model. Phage mixture treatment led to suppression of E. faecalis growth and facilitation of S. agalactiae growth. In addition, testing several sets of S. agalactiae and E. faecalis strains, the treatment with phage mixture in the enrichment improved S. agalactiae detection on chromogenic agar. Our results suggest that the phage mixture can be usefully employed in the S. agalactiae culture test to increase test accuracy. View Full-Text
Keywords: phage; Enterococcus faecalis; Streptococcus agalactiae; culture enrichment phage; Enterococcus faecalis; Streptococcus agalactiae; culture enrichment

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Uchiyama, J.; Matsui, H.; Murakami, H.; Kato, S.-I.; Watanabe, N.; Nasukawa, T.; Mizukami, K.; Ogata, M.; Sakaguchi, M.; Matsuzaki, S.; Hanaki, H. Potential Application of Bacteriophages in Enrichment Culture for Improved Prenatal Streptococcus agalactiae Screening. Viruses 2018, 10, 552.

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