title: Apyrase-based colorimetric test for detection of Shigella and enteroinvasive Escherichia coli in stool.
abstract: For lack of simple inexpensive early detection methods for Shigella spp. and enteroinvasive Escherichia coli (EIEC), bacillary dysentery remains a major cause of childhood mortality and morbidity in India and other developing countries. Rapid stool testing for apyrase, a specific periplasmic enzyme essential for the pathogen's intracellular spread, may provide a solution. We have developed a whole-cell colorimetric pyrophosphate hydrolysis assay based on cheap, stable, and locally available reagents. An innovative filtration-cum-inoculation step eliminates interfering stool solids and ensures sufficient bacterial growth and apyrase expression in 6 to 7 h at 37 degrees C. In a limited double-blind study of 57 clinical isolates of common enterobacteria, the test showed 100% sensitivity and 80% specificity for Shigella spp. and EIEC. Requiring only widely available equipment and inexpensive consumables, this affordable test is readily adaptable for determining antibiograms and for surveillance of food and water samples for the presence of Shigella and EIEC.
authors.affiliation: Centre for Biotechnology, Anna University, Chennai, India. ksankran@yahoo.com
authors.forename: Krishnan
authors.initials: K
authors.lastname: Sankaran
authors.forename: Sanchari
authors.initials: S
authors.lastname: Banerjee
authors.forename: Asalapuram R
authors.initials: AR
authors.lastname: Pavankumar
authors.forename: Mary
authors.initials: M
authors.lastname: Jesudason
authors.forename: Rolf
authors.initials: R
authors.lastname: Reissbrodt
authors.forename: Peter H
authors.initials: PH
authors.lastname: Williams
mesh_terms: D001081:Apyrase / Q000032:analysis*; D001426:Bacterial Proteins / Q000032:analysis*; D001431:Bacteriological Techniques / Q000379:methods*; D003124:Colorimetry / Q000379:methods*; D011756:Diphosphates / Q000378:metabolism; D004405:Dysentery, Bacillary / Q000175:diagnosis* / Q000382:microbiology; D004926:Escherichia coli / Q000201:enzymology / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000175:diagnosis* / Q000382:microbiology; D005243:Feces / Q000382:microbiology*; D005516:Food Microbiology; D007194:India; D008826:Microbial Sensitivity Tests; D012680:Sensitivity and Specificity; D012760:Shigella / Q000201:enzymology / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D011756:Diphosphates; D001081:Apyrase