Apyrase-based colorimetric test for detection of Shigella and enteroinvasive Escherichia coli in stool.
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.
Sankaran
Krishnan
K
Centre for Biotechnology, Anna University, Chennai, India. ksankran@yahoo.com
Banerjee
Sanchari
S
Pavankumar
Asalapuram R
AR
Jesudason
Mary
M
Reissbrodt
Rolf
R
Williams
Peter H
PH
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
D001426:Bacterial Proteins; D011756:Diphosphates; D001081:Apyrase