Detection of Shigella by a PCR assay targeting the ipaH gene suggests increased prevalence of shigellosis in Nha Trang, Vietnam.
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.
Vu
Dinh Thiem
DT
National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
Sethabutr
Orntipa
O
Von Seidlein
Lorenz
L
Tran
Van Tung
VT
Do
Gia Canh
GC
Bui
Trong Chien
TC
Le
Huu Tho
HT
Lee
Hyejon
H
Houng
Huo-Shu
HS
Hale
Thomas L
TL
Clemens
John D
JD
Mason
Carl
C
Dang
Duc Trach
DT
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
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C063500:ipaH protein, Shigella flexneri