title: Dipstick test for rapid diagnosis of Shigella dysenteriae 1 in bacterial cultures and its potential use on stool samples.
abstract: BACKGROUND
  We describe a test for rapid detection of S. dysenteriae 1 in bacterial cultures and in stools, at the bedside of patients.
  
  
  RESULTS
  The test is based on the detection of S. dysenteriae 1 lipopolysaccharide (LPS) using serotype 1-specific monoclonal antibodies coupled to gold particles and displayed on a one-step immunochromatographic dipstick. A concentration as low as 15 ng/ml of LPS was detected in distilled water and in reconstituted stools in 10 minutes. In distilled water and in reconstituted stools, an unequivocal positive reaction was obtained with 1.6×10⁶ CFU/ml and 4.9×10⁶ CFU/ml of S. dysenteriae 1, respectively. Optimal conditions to read the test have been determined to limit the risk of ambiguous results due to appearance of a faint yellow test band in some negative samples. The specificity was 100% when tested with a battery of Shigella and unrelated strains in culture. When tested on 328 clinical samples in India, Vietnam, Senegal and France by laboratory technicians and in Democratic Republic of Congo by a field technician, the specificity (312/316) was 98.7% (95% CI:96.6-99.6%) and the sensitivity (11/12) was 91.7% (95% CI:59.8-99.6%). Stool cultures and the immunochromatographic test showed concordant results in 98.4 % of cases (323/328) in comparative studies. Positive and negative predictive values were 73.3% (95% CI:44.8-91.1%) and 99.7% (95% CI:98-100%).
  
  
  CONCLUSIONS
  The initial findings presented here for a simple dipstick-based test to diagnose S. dysenteriae 1 demonstrates its promising potential to become a powerful tool for case management and epidemiological surveys.
authors: Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors: Neelam
authors: N
authors: Taneja
authors: Faridabano
authors: F
authors: Nato
authors: Sylvie
authors: S
authors: Dartevelle
authors: Jean Marie
authors: JM
authors: Sire
authors: Benoit
authors: B
authors: Garin
authors: Lan Nguyen
authors: LN
authors: Thi Phuong
authors: Tai The
authors: TT
authors: Diep
authors: Jean Christophe
authors: JC
authors: Shako
authors: François
authors: F
authors: Bimet
authors: Ingrid
authors: I
authors: Filliol
authors: Jean-Jacques
authors: JJ
authors: Muyembe
authors: Marie Noëlle
authors: MN
authors: Ungeheuer
authors: Catherine
authors: C
authors: Ottone
authors: Philippe
authors: P
authors: Sansonetti
authors: Yves
authors: Y
authors: Germani
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001431:Bacteriological Techniques / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D004405:Dysentery, Bacillary / Q000175:diagnosis* / Q000382:microbiology*; D005243:Feces / Q000382:microbiology*; D006801:Humans; D007194:India; D051379:Mice; D008807:Mice, Inbred BALB C; D008875:Middle Aged; D011237:Predictive Value of Tests; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012762:Shigella dysenteriae / Q000302:isolation & purification*; D013997:Time Factors; D055815:Young Adult
chemical_list: D011933:Reagent Kits, Diagnostic