Prevention of Group B Streptococcal Colonization with Topically Applied Lipoteichoic Acid in a Maternal-Newborn Mouse Model

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Abstract
Summary: An animal model of maternal-newborn transmission of group B streptococci (GBS) was developed. Pregnant Swiss-Webster mice were colonized by applying 108 GBS to the oral cavity, vagina, and nipples daily for 3 days before delivery. Lipoteichoic acid (LTA) from type III GBS or phosphate buffered saline was applied topically to the oral cavity, perineum or nape of newborn mice. Cultures of newborn mice at 3 days of age revealed 35 of 75 (47%) controls and 0 of 79 animals given 2 doses of LTA (2 mg/ml) were positive for GBS at one or more sites. One to two% of control and LTA-treated mice remained culture positive at 7 days of age. None developed GBS disease and no obvious toxicity was noted. This is the first in vivo evidence that colonization with GBS can be prevented by interfering with their adherence to epithelial surfaces. LTA also prevented colonization by 60,000 GBS in the oral cavity of 1-day-old newborn mice. A minimum concentration of 0.5 mg LTA/ml was required and similar dose response curves were obtained in preventing maternal-newborn transmission or oral newborn colonization. LTA from type III GBS also protected against types Ia and II. Only 6 of 15 (40%) vaginally colonized, nonpregnant mice became noncolonized 3 days after LTA treatment. Speculation: Topically applied lipoteichoic acid from group B streptococci may be a useful method of preventing GBS colonization and/or disease in human infants at birth if it is nontoxic. The method avoids the problems associated with antibiotic prophylaxis and vaccine development.