Rapid testing kit for bedside diagnosis and treatment of maternal infections on expectant mothers

Summary

Maternal mortality is unacceptably high worldwide, with an estimated 300,000 women dying in 2017; about 200,000 of these were in sub-Saharan Africa. Maternal bacterial infections are poorly diagnosed, which leads to adverse pregnancy outcomes such as premature delivery and stillbirths. Jesse and his team have developed a simple and fast diagnostic tool for prompt and rapid detection of harmful maternal infections for timely intervention.

Background

Maternal health refers to the health of women during pregnancy, childbirth and the postpartum period. The major causes of maternal mortality include haemorrhage, infection, high blood pressure, unsafe abortion, and obstructed labour.

Bacterial infections have been implicated as the leading cause of poor pregnancy outcomes such as premature deliveries, still births, maternal and newborn infection and death. It is estimated that up to 18% of deliveries in some African countries are premature, contributing to about 35% of neonatal mortality while premature delivery is the leading cause of mortality in children under five years.

Maternal bacterial infections (MBIs) have an indolent subclinical course and are mostly asymptomatic, hence are poorly diagnosed. A significant proportion of these infections cause chronic subclinical inflammation of the maternal/foetal unit, compromising fetal wellbeing and triggering premature labour, premature delivery and stillbirths. Antenatal care clinics in Kenya, like in other developing countries, have adopted the WHO-recommended syndromic management of MBIs where clinical symptoms are used for diagnosis in the absence of laboratory confirmation.  While this approach compensates for the lack of equipment and trained personnel for detection of causative pathogens in such settings, it is deficient in timing, sensitivity and specificity. Inability to diagnose MBIs and predict the risk of adverse pregnancy outcomes prevents timely interventions that may include available and inexpensive solutions such as use of prenatal steroids, antibiotics or well-planned newborn care. Moreover, existing strategies to test for MBIs are not sensitive enough, do not necessarily indicate current infection and require sophisticated infrastructure.

Study description

Two different technical strategies were used for rapid and sensitive detection of select maternal bacterial infections. The first was applied to Group B Streptococcus (GBS); the second was applied to Chlamydia trachomatis and Neisseria gonorrhoea. We analysed the results in a cohort of 234 pregnant women at the antenatal follow up clinic at Thika Level 5 Hospital, Kenya. Our study employs innovative assays to develop point-of-care diagnostics that have the potential to mainstream testing for subclinical maternal infections that cause adverse maternal outcomes.

Study outcomes

Our group, in collaboration with the Klapperich lab at Boston University in the USA and the Pamme lab at the University of Hull in the UK and others, developed and evaluated molecular- and cellular-based assays and tests for point-of-care diagnosis for maternal bacterial infections. Evaluation of the first group demonstrated more than 95% sensitivity and specificity for detection of Chlamydia trachomatis and Neisseria gonorrhoea. We also evaluated the lab-in-a-chip devise, employing immune-magnetic separation which enabled rapid isolation and detection of GBS with capture efficiency of 80% in less than 20 minutes. These results will facilitate further clinical evaluation of these strategies and potentially enable utilisation of these low-cost technologies in routine antenatal clinics for prompt diagnosis and treatment of affected women. Currently, most molecular assays, though highly sensitive and specific, when performed in low resource settings, require cold chain storage for sample collection and transportation and for reagent delivery and storage. Rapid diagnostic tests based on antibody/antigen detection have variable reliability while culture methods may not be appropriate in the targeted settings due to the need for electricity, incubators and skilled personnel.

We have developed a diagnostic for GBS for use in the antenatal period and evaluated the use of a highly sensitive molecular Helicase-dependent isothermal amplification (HDA) assay with paper-based read out. Unlike PCR, HDA assay takes place at a constant temperature and utilizes helicase enzyme to unwind the DNA and the polymerase to amplify the DNA. This makes HDA assay a suitable technique for use in resource limited settings. We also developed a polarizing anisotropy detection system that enables rapid result read out. These innovations have the potential for clinical use by enabling prompt rapid detection of asymptomatic yet harmful infections for timely intervention.

Lessons

Further development of innovations that have the potential to enable rapid and highly sensitive testing of maternal bacterial infections is needed. Our group and others in this space are working to hasten delivery of reliable, affordable and field deployable tools to strengthen the fight against adverse pregnancy outcomes caused by subclinical, undiagnosed and harmful infections in pregnancy. These tools, which detect curable sexually transmitted infections that cause adverse pregnancy outcomes, are needed to enable same-day treatment in low resource settings and reduce the burden of prematurity and stillbirths. These tests can easily be mainstreamed into routine antenatal care clinics and be useful in any trimester.

Impact

We explored a simple and fast system for GBS detection from urine samples for the first time using IFAST/ATP assays. Isolation and assays were combined in one chip, and results were obtained within 20 minutes. Although it was limited by sensitivity to background microflora, the device showed potential when implemented with real patient urine samples. Future investigations will focus on overcoming these challenges. Once fully developed, the microfluidic IFAST/ATP assay approach could be implemented for point-of-care diagnosis of pathogenic bacteria.  Additionally, we evaluated the use of point-of-care molecular testing using the isothermal Helicase Dependent Assay with paper read out, which showed high reliability. We aim to drive this work further to clinical trials and scale-up clinical usage.

About Jesse Gitaka

Jesse Gitaka is a Kenyan Physician Scientist and Researcher at Mount Kenya University. He is a grantee of the Grand Challenges Africa programme (GC Africa), which promotes Africa-led scientific innovations to help countries achieve the UN’s Sustainable Development Goals (SDGs) by awarding seed and full grants to develop innovative solutions. GC Africa is implemented through the Alliance for Accelerating Excellence in Science in Africa (AESA), a funding, agenda-setting, programme management initiative of the African Academy of Sciences (AAS), the African Union Development Agency (AUDA-NEPAD), founding and funding global partners, and through a resolution of the summit of African Union Heads of Governments. GC Africa is supported by the Bill & Melinda Gates Foundation, Swedish International Development Cooperation Agency (Sida), and the German Federal Ministry of Education and Research (BMBF).