Development And Performance Evaluation Of A Novel Lateral Flow Test Strip For Group B Streptococcus

Background:Group B streptococcus?GBS?,also known as Streptococcus agalactiae,which is a gram positive streptococcus and conditional pathogen,often parasitic in the human body's lower digestive tract and urogenital tract.GBS can cause urinary tract infection in perinatal women,leading to adverse pregnancy outcomes,such as neonatal sepsis,meningitis,pneumonia,etc.In recent years,it also has received extensive attention from domestic clinicians and researchers.At present,the commonly used methods to detect GBS in clinical include microbial culture,immunology,molecular biology and so on^[1].Immunology belongs to the rapid detection method,which can detect the antigen or corresponding antibody of bacteria.This method is rapid,but the sensitivity and specificity are slightly lower.In this study,fluorescence resonance energy transfer?FRET?and time-resolved fluorescence immunoassay?TRFIA?technologies were combined with colloidal gold chromatography,respectively,to explore whether the two new test strips could improve the sensitivity and specificity of the test strips,and to evaluate their clinical feasibility.Objective:Fluorescence resonance energy transfer?FRET?and time-resolved fluorescence immunoassay?TRFIA?were applied to the improvement of colloidal gold immunochromatographic strip labeling technology of GBS,so as to achieve the purpose of rapid detection of GBS,by color and fluorescence double-reading method.Methods:?1?FITC-labeled GBS antibody and Eu³⁺-labeled GBS antibody were separately prepared into a novel immunochromatographic test strip.The detection specificity and sensitivity were evaluated,and the relationship between the concentration of GBS and the fluorescence intensity value was initially explored.?2?In clinical,vaginal discharge samples were collected from high-risk women,at 35to 37 weeks gestation.And microbiological culture,RT-PCR as well as two new immunochromatographic strips were used for the detection.With reference to the positive rate of culture method and RT-PCR method,the positive rate of the two new immunochromatographic strips was analyzed to see whether they were better than the traditional colloidal gold method.Results:?1?There was no cross reaction with Lactobacillus acidophilus,Staphylococcus aureus,Streptococcus pneumoniae and Group A streptococcus.The minimum detected concentration of GBS was 10⁵CFU/ml.There was a good correlation between GBS concentration and fluorescence intensity in the range of 10³-10⁹CFU/ml.?2?The test results of clinical specimens showed that there was no significant difference in the positive detection rate of the two new tomographic strips,and no significant difference in the positive detection rate,compared with the microbial culture method and RT-PCR method.Conclusions:The two new immunochromatographic test strips are convenient and fast to use,which can not only realize rapid diagnosis and screening,but also realize quantitative analysis.This design idea is also applicable to the detection and research of other pathogenic microorganisms on the test strip platform.