Rapid and sensitive detection of using fluorescent microspheres as label for immunochromatographic test strip.

Background: Bacillary dysentery caused by genus is a major cause of morbidity and mortality worldwide. In China, the popular strain was mainly (). Therefore, fluorescent microspheres (FMs)-based immunochromatographic test strip (ICTS), as a novel, reliable, sensitive and uncomplicated method, was evaluated to detect .

Methods: Sixty-three clinical samples of were collected in this paper. Polymerase chain reaction (PCR) combined with FMs-ICTS based on magnetic purification assay was developed for the quantitative detection of . And the genus-specific gene of and drug resistant gene of from Shigella were selected to investigate the potential of this new method. The sensitivity and specificity of this method were demonstrated by classical microbiological methods (API Coryne System), PCR assay based on agarose gel electrophoresis (PCR-GE) and the real-time fluorescent quantitative PCR (RTFQ-PCR) method.

Results: Under optimized conditions, the lower detection limits of PCR-ICTS, PCR-GE and RTFQ-PCR were 2.5×10, 2.5×10 and the 3.2×10 ng/µL, respectively. Experiments demonstrated the PCR-ICTS has a diagnostic agreement of 100% with conventional PCR and RTFQ-PCR on detection of clinical samples and could correctly recognize and non- from different microbial samples. After the purification of PCR products with Silicon coated magnetic nanoparticles (Si-MNPs), the false positive results were removed because of the strong screening ability of the purification process. Our results showed that FM-based ICTS was promising for measurable and sensitive detection of S. within 3 h.

Conclusions: The results from immunochromatographic test were agreement with those from API Coryne system and RTFQ-PCR. Hence, this developed method might be useful for screening and monitoring clinical sample of , due to its speed, non-poisonous, simplicity and low-cost and helpful for promoting the prevention and control of communicable diseases caused by enteric pathogens such as .