Immunochromatographic strip test for detection of genus Cronobacter

• Published in: Biosensors & bioelectronics Vol. 26; no. 6; pp. 2828 - 2834
• Main Authors: Blažková, Martina, Javůrková, Barbora, Fukal, Ladislav, Rauch, Pavel
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.02.2011; Elsevier
• Subjects: Bacterial Typing Techniques - methods; Base Sequence; Biological and medical sciences; Biosensing Techniques - methods; Biotechnology; Chromatography - methods; Cronobacter sakazakii - classification; Cronobacter sakazakii - genetics; Cronobacter sakazakii - isolation & purification; Cronobacter sakazakii - pathogenicity; Cronobacter spp; DNA Primers - genetics; DNA, Bacterial - genetics; DNA, Bacterial - isolation & purification; Enterobacter sakazakii; Enterobacteriaceae - classification; Enterobacteriaceae - genetics; Enterobacteriaceae - isolation & purification; Enterobacteriaceae - pathogenicity; Food Microbiology; Food-borne pathogen; Fundamental and applied biological sciences. Psychology; Humans; Immunochromatographic test; Infant; Infant Formula; Polymerase Chain Reaction - methods; Rapid detection; RNA, Bacterial - genetics; RNA, Ribosomal, 16S - genetics; Cronobacter spp; Food-borne pathogen; Enterobacter sakazakii; Infant formula; Rapid detection; Immunochromatographic test; Foodstuff; Rapid technique; Enterobacter; Pathogenic; Bacteria; Detection; Enterobacteriaceae
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2010.10.001

Members of the genus Cronobacter are opportunistic pathogens formerly known as Enterobacter sakazakii, which induce severe meningitis and sepsis in neonates and infants, with a high fatality rate. In this work, a simple and rapid immunochromatographic strip test for the detection of this pathogen was developed. Following the shortened bacteria cultivation and isolation of DNA, a specific gene sequence targeting 16S rRNA from Cronobacter spp. was amplified by PCR using 5′-end labelled specific primers. The PCR product, amplicon labelled with digoxigenin on one side and biotin on the other side, was directly added to the immunochromatographic strip test, composed of nitrocellulose membrane with bound antibody against digoxigenin in the test line. The visualization was mediated by colloidal carbon conjugated to neutravidin, and the appearance of grey/black line was indicative of the presence of specific amplicon. Colour intensity of the test line in pathogen-positive assay was visually distinguishable from that of negative sample within 10min. The visual detection limit of PCR product was 8ng. The specificity of the developed method was confirmed by standard microbiological techniques. Whole detection procedure with the incorporated immunostrip was applied to analysis of infant formulae samples, contaminated with less than 10 cells of Cronobacter spp. per 10g. The results from immunochromatographic test indicated the absolute agreement with those from standard microbiological methods. Moreover, the developed procedure considerably reduced the total analysis time to 16h whereas the reference microbiological method needs 6–7 days.