DIAGNOSTIC-TESTS IN GASTROINTESTINAL INFECTIONS

Advances in the basic science technologies (monoclonal antibodies, pol ymerase chain reaction, and molecular genetic techniques) have lead to more sensitive and specific detection systems for gastrointestinal pa thogens. In the past year, two different monoclonal-based, enzyme-link ed immunosorbent assays have been described that specifically detect p athogenic Entamoeba histolytica in stool. A number of different pretre atment methods have been employed to improve polymerase chain reaction detection of pathogens in stool. Two studies have used immunomagnetic beads (ie, monoclonal antibody-coated) to selectively isolate salmone llae and shigellae followed by detection using polymerase chain reacti on-based tests. Spin column chromatography isolation of Norwalk virus allowed for rapid detection of this virus by reverse transcriptase-pol ymerase chain reaction. A Quiagen procedure improved detection of the toxin A gene target for direct detection of Clostridium difficile by p olymerase chain reaction methods. Results of recent evaluations of new commercially available products for detection of Cryptosporidium spp are evaluated. This report emphasizes tests with improved sensitivity, specificity, and utility in the clinical microbiology laboratory.