Pneumonia
in children (< 5 years of age) contributes to about 15% of total child
mortality and the major pathogen causing the disease in Streptococcus
pneumoniae. The currently available detection methods for S. pneumoniae are tedious, time
consuming, and few protocols lack sensitivity in children. Due to complicated
steps involved in currently available procedures for Streptococcus
detection, it is quite essential to design a user-friendly point of care format
to detect the pathogen enabling child pneumonia diagnosis. In this context, we aimed
to develop a gold nanoparticle based immunochromatographic dipstick device to
detect pneumolysin - a protein released by invasive S. pneumoniae in the urine
of children suffering from pneumonia. We developed the protocol as follows. Monoclonal
anti pneumolysin antibody was first coupled to Gold nanoparticles. The dipstick
was fabricated by attaching nitrocellulose membrane and absorbent pad on
plastic backing card. Test spot (polyclonal anti pneumolysin antibody) and
Control spot (anti mouse IgG) were applied on nitrocellulose membrane and were
allowed to dry. Pneumolysin (commercially available) at various concentrations
in running buffer were mixed with antibody conjugated gold nanoparticles followed
by incubation of reaction mixture for 15 minutes at room temperature. The dipstick was dipped into the reaction
mixture to observe test and control spots when the mixture moves up through
nitrocellulose membrane by capillary action. Test and control spots were
visible on the dipstick when pneumolysin was used at 50ng and 100ng
concentrations. The efficacy of the device to detect pneumolysin in urine
samples of pneumonic children is being currently evaluated. We believe that, the
device can be used for quick detection of S.
pneumoniae in children suffering from pneumonia and treatment options can
be selected accordingly by health professionals.
