EVALUATION OF ALKALINE PHOSPHATASE-LABELED IPAH PROBE FOR DIAGNOSIS OF SHIGELLA INFECTIONS

The presence of many enteropathogens which are not easily detectable b y routine stool culture has led to the development of alternative diag nostic methods. One of these techniques, nucleic acid probe hybridizat ion, has been used to identify Shigella spp. and enteroinvasive Escher ichia coli (EIEC) in stool specimens through the detection of genetic material encoded by a specific large almost-equal-to 200-kbp virulence -related plasmid. In the present study, an alkaline phosphatase-labell ed oligonucleotide probe developed to detect the gene for ipaH, a repe titive genetic sequence thought to be present on both the virulence-re lated plasmid and the chromosomes of all strains of Shigella and EIEC, was tested in a developing-country setting through a prospective clin ical trial. In a group of 219 Peruvian adults and children with acute gastroenteritis, the ipaH probe detected 85% of cases of shigellosis a nd demonstrated a specificity of 95% when compared with simultaneous d etection by several stool culture techniques. Additionally, three case s of EIEC infection which could not be diagnosed by culture methods al one were detected with the ipaH probe and were confirmed by plasmid an alysis and Sereny testing. These preliminary results suggest that, wit h further research, the ipaH probe should prove to be a useful and rap id adjunct in the diagnosis of acute gastroenteritis in developing cou ntries.