Enteric Infections and Diagnostic Testing
Enteric Infections and Diagnostic Testing
Purpose of Review: Gastrointestinal pathogens profoundly affect human health and well being. The provider's ability to render optimal care often highly depends on diagnostic microbiologic support. We aim to provide a clinically pertinent assessment of the current state of our ability to diagnose human gastrointestinal pathogens and describe (and decry) the unsophistication of many current diagnostic methods and strategies.
Recent Findings: Recent advances involve improved stool polymerase chain reaction assays and application of this technology to a broader panel of pathogens, stool antigen assays, and improved culture techniques, but there is little penetration of such diagnostic advances into clinical practice. Many such techniques remain limited to research or epidemiologic use and are not typically available in the clinical laboratory.
Summary: Multiple clinical and laboratory factors need to be considered when attempting to diagnose the wide variety of gastrointestinal pathogens afflicting humans. Careful interpretation of diagnostic tests with attention to the population studied and the characteristics of each test is necessary.
The World Health Organization has estimated that diarrhea causes or is a major contributor to approximately one-quarter of all postneonatal childhood deaths. The Centers for Disease Control and Prevention estimate that 1.4 episodes of diarrhea occur per person per year in the USA. Gastrointestinal infections that are not manifest as diarrhea are also common, such as chronic intestinal helminthic infestations, Helicobacter pylori infection, and infectious esophagitis. Gastrointestinal infections clearly cause major problems worldwide.
Diagnosis underlies all good medical therapy, and yet our abilities to diagnose enteric infections remain limited, outmoded, and expensive. The decision to even seek microbiologic diagnosis depends on geographic-specific epidemiology, laboratory resources, microbiologic expertise, providers' preconceived notions about the need for and choice of such tests, the nuisance of specimen collection and transport, and the low likelihood that a patient's illness will be beneficially affected by the results. In most such cases, acute gastrointestinal infections are self-limited, whether or not the causative agent is found. Most cases of chronic diarrhea are also not attributable to an identifiable organism. Supportive care, symptomatic relief, and assiduous attention to hydration and nutrition are usually sufficient. It is, therefore, understandable that diagnostic enteric microbiology remains so problematic.
This contribution will review various diagnostic situations and considerations regarding microbiologic assessment. We will also provide an overview of recent developments in diagnostic technology for specific pathogens or classes of pathogens. The articles chosen for review, necessarily, extend backwards beyond the customary 12-18 month interval for Current Opinions articles, because there is a paucity of practical, broadly helpful recent literature in the field. Most current contributions to the field consist of rapid technologies to identify specific pathogens in polymicrobial substances, including food and stool, but describe advances that currently have little bearing on clinical practice.
Abstract and Introduction
Abstract
Purpose of Review: Gastrointestinal pathogens profoundly affect human health and well being. The provider's ability to render optimal care often highly depends on diagnostic microbiologic support. We aim to provide a clinically pertinent assessment of the current state of our ability to diagnose human gastrointestinal pathogens and describe (and decry) the unsophistication of many current diagnostic methods and strategies.
Recent Findings: Recent advances involve improved stool polymerase chain reaction assays and application of this technology to a broader panel of pathogens, stool antigen assays, and improved culture techniques, but there is little penetration of such diagnostic advances into clinical practice. Many such techniques remain limited to research or epidemiologic use and are not typically available in the clinical laboratory.
Summary: Multiple clinical and laboratory factors need to be considered when attempting to diagnose the wide variety of gastrointestinal pathogens afflicting humans. Careful interpretation of diagnostic tests with attention to the population studied and the characteristics of each test is necessary.
Introduction
The World Health Organization has estimated that diarrhea causes or is a major contributor to approximately one-quarter of all postneonatal childhood deaths. The Centers for Disease Control and Prevention estimate that 1.4 episodes of diarrhea occur per person per year in the USA. Gastrointestinal infections that are not manifest as diarrhea are also common, such as chronic intestinal helminthic infestations, Helicobacter pylori infection, and infectious esophagitis. Gastrointestinal infections clearly cause major problems worldwide.
Diagnosis underlies all good medical therapy, and yet our abilities to diagnose enteric infections remain limited, outmoded, and expensive. The decision to even seek microbiologic diagnosis depends on geographic-specific epidemiology, laboratory resources, microbiologic expertise, providers' preconceived notions about the need for and choice of such tests, the nuisance of specimen collection and transport, and the low likelihood that a patient's illness will be beneficially affected by the results. In most such cases, acute gastrointestinal infections are self-limited, whether or not the causative agent is found. Most cases of chronic diarrhea are also not attributable to an identifiable organism. Supportive care, symptomatic relief, and assiduous attention to hydration and nutrition are usually sufficient. It is, therefore, understandable that diagnostic enteric microbiology remains so problematic.
This contribution will review various diagnostic situations and considerations regarding microbiologic assessment. We will also provide an overview of recent developments in diagnostic technology for specific pathogens or classes of pathogens. The articles chosen for review, necessarily, extend backwards beyond the customary 12-18 month interval for Current Opinions articles, because there is a paucity of practical, broadly helpful recent literature in the field. Most current contributions to the field consist of rapid technologies to identify specific pathogens in polymicrobial substances, including food and stool, but describe advances that currently have little bearing on clinical practice.
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