title: A quantitative polymerase chain reaction assay for rapid detection of 9 pathogens directly from stools of travelers with diarrhea.
abstract: OBJECTIVE
  Every year, 80 million tourists traveling to tropical and subtropical areas contract traveler's diarrhea (TD). Forty percent to 80% of cases are caused by bacteria, yet clinical diagnostic tests are available to identify only a few of the strains that cause TD. We aimed to develop a quantitative polymerase chain reaction (qPCR) assay to identify all major pathogens in stool samples.
  
  
  METHODS
  We developed a low-cost, high-throughput, multiplex qPCR assay for simultaneous detection of 9 bacterial pathogens in stool samples: Salmonella, Yersinia, Campylobacter, and Vibrio cholerae, as well as Shigella or enteroinvasive Escherichia coli, enterohemorrhagic E coli, enterotoxigenic E coli (ETEC), enteroaggregative E coli (EAEC), and enteropathogenic E coli (EPEC). The assay was validated using positive (n = 245) and negative (n = 243) control strains, as well as preselected positive and negative stool samples. In addition, stool samples were collected from 96 returning travelers with TD. The findings were compared with those from routine diagnostic tests.
  
  
  RESULTS
  The assay detected the bacterial strains with 100% sensitivity and specificity, compared with results from the reference tests. Of all stool samples collected from travelers with TD, EPEC was found in 47%, EAEC in 46%, ETEC in 22%, enterohemorrhagic E coli in 7%, Campylobacter in 6%, Shigella or enteroinvasive E coli in 2%, and Salmonella in 2%. Multiple pathogens were found in 37% of all samples.
  
  
  CONCLUSIONS
  We developed a low-cost, high-throughput qPCR assay for use in routine diagnostic analysis and research. It detects the pathogenic bacteria most commonly associated with TD in stool samples with 100% sensitivity and specificity, compared with reference methods. The assay requires 4 hours, whereas current detection methods require 1 to 7 days. At least 1 TD pathogen was identified in stool samples from 76% of returning travelers, whereas conventional methods found a pathogen in only 17%. The most commonly detected bacteria were EPEC, EAEC, and ETEC.
authors: Helsinki University Hospital Laboratory, Department of Bacteriology, Helsinki, Finland.
authors: Jenni
authors: J
authors: Antikainen
authors: Anu
authors: A
authors: Kantele
authors: Sari H
authors: SH
authors: Pakkanen
authors: Tinja
authors: T
authors: Lääveri
authors: Jukka
authors: J
authors: Riutta
authors: Martti
authors: M
authors: Vaara
authors: Juha
authors: J
authors: Kirveskari
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification*; D001424:Bacterial Infections / Q000175:diagnosis* / Q000382:microbiology; D001431:Bacteriological Techniques / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D003967:Diarrhea / Q000175:diagnosis* / Q000382:microbiology; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods; D060888:Real-Time Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D014195:Travel; D057236:Travel Medicine / Q000379:methods*; D055815:Young Adult
keywords: EAEC; EHEC; EPEC; ETEC; Fecal Sample; Gastroenteritis; PCR; PCR Assay; TD; Tourist; enteroaggregative Escherichia coli; enterohemorrhagic Escherichia coli; enteropathogenic Escherichia coli; enterotoxigenic Escherichia coli; polymerase chain reaction; qPCR; quantitative polymerase chain reaction; traveler’s diarrhea