Development of immunochromatographic colloidal gold test strip for rapid detection of Haemophilus influenzae in clinical specimens.

ABSTRACT

AIMS: A simple and fast test strip for simultaneous detection of Haemophilus influenzae, based on the theory of colloidal gold immunochromatography was developed. METHODS AND RESULTS: In this study, monodispersional colloidal gold and gold-labelled polyclonal antibody (AbP6Line) specific to the linear antigenic determinant OMP6 of H. influenzae were prepared, and identified by UV-visible spectroscopy (200-700 nm) and transmission electron microscopy. The test strip was assembled on a plastic backing containing a sample pad, a conjugate pad, an absorbent pad and a nitrocellulose membrane, on which test and control lines were stuck. The strip showed us specific recognization of H. influenzae and did not identify other common respiratory pathogens such as Streptococcus pneumoniae, Mycoplasma pneumoniae, Moraxella catarrhalis and Legionella pneumophila. It was shown that the detection limit of the test strip was as low as 1 × 106 CFU per ml and the whole process can be completed within 10 min. The strips could be stored at 4°C for at least 6 months without losing sensitivity or specificity. CONCLUSIONS: The test strip was specific, simple and convenient for rapid detection of H. influenzae presenting good stability and reproducibility. SIGNIFICANCE AND IMPACT OF THE STUDY The test strip provides a simple, convenient and specific tool for the on-site surveillance and diagnosis of H. influenzae infection in clinical samples.