The ability to rapidly identify the potential for perinatal infections requires diagnostic tools that are highly sensitive, specific, inexpensive, easy to use, and located in primary care settings. Group B streptococcus (GBS) is a leading cause of early-onset sepsis and pneumonia in newborn babies. The major risk factor for early-onset disease is maternal colonization at time of delivery. It has been calculated that the screening-based strategy can reduce early-onset neonatal GBS disease by as much as 78%. Screening accuracy in predicting GBS carriage at delivery is higher if the cultures are collected within 5 weeks before delivery, and when both vaginal and rectal samples are examined. Microbiological culture methods include direct plating on solid media and the use of selective broth media. New techniques have been developed to increase sensitivity or to decrease the time for GBS detection. However, such techniques typically have higher costs and require skills and technologies not universally available for routine testing. The proposed project is focused on developing a point-of-care diagnostic for GBS that is rapid, easy to use, highly sensitive and specific, while being cost-effective. The proposed sensor, invented at Michigan State University, uses a conductimetric detection technique and has been demonstrated in the lab to produce qualitative results in 6 to 10 min with a lower detection limit of 79 cells/ml for E. coli. The overall aim of the Phase I program is to demonstrate the feasibility of the biosensor technology as a single pathogen assay for GBS detection in inoculated vaginal swab samples. Specifically, using methods from preliminary studies, single-target biosensors will be fabricated for detection of S. agalactiae in broth (pure) cultures. Then, protocols will be developed in collaboration with University of Michigan for the processing and preparation of vaginal swab samples prior to testing with the biosensor. Feasibility of the biosensor for use with vaginal swab-based samples will thus be demonstrated. Combined sample preparation and test time is aimed at less than 30 minutes. The Phase II research will focus on the sensor design modifications needed to improve biosensor sensitivity, optimize dynamic detection range of the biosensor for rapid diagnosis of GBS in vaginal as well as rectal swabs, enable mass production of the sensor strips, and develop a sample handling and processing module to facilitate point-of-care use with minimal labor needed. Industrial partnerships are already in place for the Phase II work. Following Phase II, clinical trials will be conducted, and FDA approvals for the diagnostic device will then be sought.
The proposed biosensor is inexpensive and ideally-suited to the task of rapidly detecting GBS in swab samples. This will help healthcare providers quickly identify the potential for perinatal infections just prior and during delivery of new-born infants, and aid appropriate targeted antibiotic treatment. This will also prevent increase in resistance of GBS to antibiotics resulting from indiscriminate use of antibiotics, and reduce health costs and man-hours lost associated with misdiagnosed illnesses and unnecessary hospitalizations. Commercialization of the conductimetric sensor technology will enable improvement in the overall quality of human life all over the world.
