Development and evaluation of an enzyme-linked immunosorbent assay for serum Vi antibodies for detection of chronic Salmonella typhi carriers.
An enzyme-linked immunosorbent assay (ELISA) measuring, in serum, immunoglobulin G (IgG), IgM, and IgA to Vi capsular polysaccharide antigen that was tyraminated (Vi-Tyr) to increase its binding efficiency to microtiter plates was compared with the standard passive hemagglutination assay (PHA) as a screening test for chronic Salmonella typhi carriers. Initially, three populations were evaluated: 22 healthy U.S. adults, 17 young Chilean adults with acute typhoid fever, and 51 Chileans who had bacteriologically confirmed S. typhi chronic carriage. IgG-specific Vi-Tyr antibodies were preferentially present in the S. typhi chronic carrier state. A total of 44 of 51 (81%) chronic carriers, 0 of 22 (0%) healthy U.S. adults, and 2 of 17 (12%) Chileans with acute typhoid fever had reciprocal IgG Vi-Tyr ELISA antibody titers in serum of greater than or equal to 200. The IgG Vi-Tyr ELISA was then compared with the PHA as a screening test for chronic carriers in 141 Chilean female food handlers. One woman was serologically incriminated as a carrier by both the IgG ELISA and PHA; her coprocultures were positive for S. typhi. One other woman, identified as a carrier by PHA, was negative by culture and IgG ELISA. The IgG Vi-Tyr ELISA is as sensitive as the PHA (86 versus 76%) and as specific (95 versus 95%) in screening for chronic carriers.
Department of Medicine, University of Maryland School of Medicine, Baltimore 21201.
G A
GA
Losonsky
C
C
Ferreccio
K L
KL
Kotloff
S
S
Kaintuck
J B
JB
Robbins
M M
MM
Levine
D000208:Acute Disease; D000328:Adult; D000907:Antibodies, Bacterial / Q000032:analysis*; D000942:Antigens, Bacterial / Q000276:immunology; D002353:Carrier State / Q000175:diagnosis* / Q000453:epidemiology; D002677:Chile; D002908:Chronic Disease; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006386:Hemagglutination Tests; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D008297:Male; D008875:Middle Aged; D011135:Polysaccharides, Bacterial; D011237:Predictive Value of Tests; D012485:Salmonella typhi / Q000276:immunology*; D014435:Typhoid Fever / Q000175:diagnosis* / Q000453:epidemiology; D014481:United States
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011135:Polysaccharides, Bacterial