Evaluation of a new optical immunoassay for diagnosis of neonatal chlamydial conjunctivitis

Evaluation of the rapid BioStar optical immunoassay for detection of Chlamydia trachomatis in adolescent women

We evaluated the performance of the BioStar Chlamydia OIA (optical immunoassay) in adolescent females (n = 261) from an inner city population. With a reference standard of two different nucleic acid amplification tests, the sensitivity and specificity of the BioStar Chlamydia OIA were 59.4 and 98.4%, respectively. Due to its relatively low sensitivity, the BioStar Chlamydia OIA should only be used in conjunction with more sensitive laboratory tests unless laboratory tests are unavailable or timely return for treatment is unlikely.

Optical immunoassay for snake venom detection

A sensitive and specific optical immunoassay (OIA) has been developed for snake venom detection. The assay is based on the principle of detection of physical changes in thickness of molecular thin film resulting from specific binding events on an optical silicon chip (SILAS-I, ThermoBioStar, Colorado, USA). The reflection of white light through the thin film results in destructive interference of a particular wavelength of the light from gold to purple-blue depending on the thickness of the thin film formed or the amount of venom in the test sample. A prototype test kit for the simultaneous identification of species and semi-quantitative detection of venoms from four medically important snakes of South Vietnam (Trimeresurus albolabris, Calloselasma rhodostoma, Naja kaouthia and Ophiophagus hannah) has been developed. The kit can detect venom analytes in blood, plasma, urine, wound exudates, blister fluid or tissue homogenates. The efficacy of the test kit in snakebite diagnosis has been demonstrated in experimental envenomations and sample analytes taken from snakebite victims in South Vietnam. This rapid snake venom detection kit based on OIA technique is potentially applicable in the clinics as well as in the field.

A new avidin-biotin optical immunoassay for the detection of beta-bungarotoxin and application in diagnosis of experimental snake envenomation

A highly sensitive avidin-biotin optical immunoassay (AB-OIA) has been developed for the detection of beta-bungarotoxin (beta-BuTx), a neurotoxin from the venom of Bungarus multicinctus, in whole blood, plasma, and urine. Affinity purified rabbit IgG anti-beta-BuTx antibody was immobilized on an optically active silicon surface (SILIAS wafer). The test sample was incubated and the antigen-antibody reaction was monitored by the addition of a biotinylated monoclonal antibody (mAb 15) specific to the toxin, avidin-horseradish peroxidase (HRP) and tetramethylbenzidine substrate. The silicon assay surface technology enables us to directly visualize a physical change in the optical thickness of the antibody thin film. The change in thickness is due to the specific capture of the toxin on the surface and when the substrate is added, the binding event is amplified, which then alters the reflected light path and a change in colour is visualized. The assay could detect beta-BuTx levels as low as 16 pg/ml in sample buffer and 100 pg/ml in whole blood or plasma. The AB-OIA is simple, requires only 40 microl of biological fluid and can be performed without specialized equipment. The efficacy of the test for detection of beta-BuTx in blood or plasma obtained from mice during experimental envenomation with B. multicinctus venom was demonstrated. The AB-OIA was also used to quantitate the postmortem level of beta-BuTx in various organs such as brain, liver, and kidney, as well as the tissue at the site of injection. Development of a simple, rapid snake toxin detection kit based on AB-OIA technique potentially applicable in the clinics as well as in the field is discussed.

Evaluation of a rapid assay for detection of Chlamydia trachomatis infections in outpatient clinics in South Kalimantan, Indonesia

A multicenter cross-sectional survey was conducted comparing a commercially available chlamydial optical immunoassay (OIA) to the chlamydial ligase chain reaction (LCR). Endocervical samples from 415 outpatients visiting clinics from three hospitals in South Kalimantan, Indonesia, were evaluated. Relative to the LCR, the overall sensitivity and specificity of the OIA were 31.6 and 98.9%, respectively. The sensitivity of the OIA varied among the three hospital laboratories, ranging from 20 to 50%. The OIA performance was slightly lower on samples from patients attending dermatovenereology clinics than on samples from nondermatovenereology clinic patients. The results indicate that the OIA did not perform well compared to LCR.

[Chlamydia trachomatis conjunctivitis in the newborn]

Infections of the conjunctiva are frequent in the neonatal period. While Neisseria gonorrhoea and chemical agents were considered as the main etiologies of ophtalmiae neonatorum in the past, Chlamydia trachomatis is today a major cause of neonatal conjunctivitis. Thus in a study of 180 uni-or bilateral neonatal conjunctivitis the authors found a prevalence of Chlamydia trachomatis infection of 41%. The importance of the etiological diagnosis of neonatal conjunctivitis is emphasized, in order to define a specific treatment. Etiological diagnosis of Chlamydia trachomatis infection is based upon immunofluorescence and molecular diagnosis techniques (PCR, LCR). Prevention of neonatal Chlamydia trachomatis conjunctivitis relies upon screening and treatment of Chlamydia trachomatis infections in pregnant women and their partners. Treatment requires oral macrolides, the topical treatment being ineffective.