title: Detection of Shigella by a PCR assay targeting the ipaH gene suggests increased prevalence of shigellosis in Nha Trang, Vietnam.
abstract: Shigella spp. are exquisitely fastidious gram-negative organisms which frequently escape detection by traditional culture methods. To get a more complete understanding of the disease burden caused by Shigella in Nha Trang, Vietnam, real-time PCR was used to detect Shigella DNA. Randomly selected rectal swab specimens from 60 Shigella culture-positive patients and 500 Shigella culture-negative patients detected by population-based surveillance of patients seeking care for diarrhea were processed by real-time PCR. The target of the primer pair is the invasion plasmid antigen H gene sequence (ipaH), carried by all four Shigella species and enteroinvasive Escherichia coli. Shigella spp. could be isolated from the rectal swabs of 547 of 19,206 (3%) patients with diarrhea. IpaH was detected in 55 of 60 (93%) Shigella culture-positive specimens, whereas it was detected in 87 of 245 (36%) culture-negative patients free of dysentery (P < 0.001). The number of PCR cycles required to detect a PCR product was highest for culture-negative, nonbloody diarrheal specimens (mean number of cycles to detection, 36.6) and was lowest for children with culture-positive, bloody diarrheal specimens (mean number of cycles, 25.3) (P < 0.001). The data from real-time PCR amplification indicate that the culture-proven prevalence of Shigella among patients with diarrhea may underestimate the prevalence of Shigella infections. The clinical presentation of shigellosis may be directly related to the bacterial load.
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
authors.forename: Dinh Thiem
authors.initials: DT
authors.lastname: Vu
authors.forename: Orntipa
authors.initials: O
authors.lastname: Sethabutr
authors.forename: Lorenz
authors.initials: L
authors.lastname: Von Seidlein
authors.forename: Van Tung
authors.initials: VT
authors.lastname: Tran
authors.forename: Gia Canh
authors.initials: GC
authors.lastname: Do
authors.forename: Trong Chien
authors.initials: TC
authors.lastname: Bui
authors.forename: Huu Tho
authors.initials: HT
authors.lastname: Le
authors.forename: Hyejon
authors.initials: H
authors.lastname: Lee
authors.forename: Huo-Shu
authors.initials: HS
authors.lastname: Houng
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Hale
authors.forename: John D
authors.initials: JD
authors.lastname: Clemens
authors.forename: Carl
authors.initials: C
authors.lastname: Mason
authors.forename: Duc Trach
authors.initials: DT
authors.lastname: Dang
mesh_terms: D000293:Adolescent; D000328:Adult; D000942:Antigens, Bacterial / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000235:genetics; D004405:Dysentery, Bacillary / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D005814:Genes, Viral; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods*; D012760:Shigella / Q000235:genetics* / Q000302:isolation & purification*; D014744:Vietnam / Q000453:epidemiology
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C063500:ipaH protein, Shigella flexneri