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Exploring the Pregnant Guinea Pig as a Model for Group B Streptococcus Intrauterine Infection
Maria I Harrell1, Kellie Burnside1, Christopher Whidbey1,2
1Department of Pediatrics, University of Washington and Seattle Children's Research Institute, Seattle, Washington, United States of America.
Insights
The guinea pig effectively models in utero Group B Streptococci (GBS) infections, showing bacterial spread to fetal organs. This model aids research into preventing pregnancy infections and related newborn complications.
Area of Science:
- Obstetrics and Gynecology
- Infectious Diseases
- Animal Models
Background:
- Intrauterine infections cause preterm birth, stillbirth, and neonatal infections.
- Current therapies are lacking due to inadequate animal models for studying in utero infections.
- Existing mouse, rat, and nonhuman primate models have limitations in recapitulating human pregnancy.
Purpose of the Study:
- To evaluate the pregnant guinea pig as a feasible animal model for studying in utero infections.
- To investigate the utility of the guinea pig model for Group B Streptococci (GBS) infections during pregnancy.
Main Methods:
- Intrauterine inoculation of pregnant guinea pigs with wild-type and hyperhemolytic Group B Streptococci (GBS).
- Assessment of bacterial invasion and dissemination to maternal and fetal tissues.
- Comparison of GBS dissemination patterns in guinea pigs with existing data from other animal models.
Main Results:
- Intrauterine GBS inoculation led to bacterial invasion and spread to the placenta, amniotic fluid, and fetal organs.
- Hyperhemolytic GBS strains exhibited increased dissemination into amniotic fluid and fetal tissues like the lung and brain.
- Observed dissemination patterns in guinea pigs mirrored findings in mouse and nonhuman primate models.
Conclusions:
- The pregnant guinea pig serves as a valuable and appropriate model for studying in utero GBS infections.
- This model can advance understanding of mechanisms leading to pregnancy infections and associated comorbidities.
- Findings support the guinea pig model for developing strategies to prevent and treat intrauterine GBS infections.
Abstract:
Infection of the amniotic cavity remains a major cause of preterm birth, stillbirth, fetal injury and early onset, fulminant infections in newborns. Currently, there are no effective therapies to prevent in utero infection and consequent co-morbidities. This is in part due to the lack of feasible and appropriate animal models to understand mechanisms that lead to in utero infections. Use of mouse and rat models do not fully recapitulate human pregnancy, while pregnant nonhuman primate models are limited by ethical considerations, technical constraints, and cost. Given these limitations, the guinea pig is an attractive animal model for studying pregnancy infections, particularly as the placental structure is quite similar to the human placenta. Here, we describe our studies that explored the pregnant guinea pig as a model to study in utero Group B Streptococci (GBS) infections. We observed that intrauterine inoculation of wild type GBS in pregnant guinea pigs resulted in bacterial invasion and dissemination to the placenta, amniotic fluid and fetal organs. Also, hyperhemolytic GBS such as those lacking the hemolysin repressor CovR/S showed increased dissemination into the amniotic fluid and fetal organs such as the fetal lung and brain. These results are similar to those observed in mouse and non-human primate models of in utero infection, and support use of the guinea pig as a model for studying GBS infections in pregnancy.