Salmonella Typhi shedding in stool was assessed using daily self-collected samples, cultured according to national standard operating procedures [14 ]. Blood (10 mL or 5 mL at typhoid diagnosis) was cultured daily by direct inoculation into broth (BACTEC Plus Aerobic vials, BD) and subsequent automated growth detection (BACTEC FX System, BD), in accordance with standard methods [15 ]. Salmonella Typhi growth and serotype were confirmed by biochemical profile (API-10S, bioMérieux, France) or slide agglutination according to the Kauffman-White classification, respectively [16 ].
Quantitative blood culture was performed at typhoid diagnosis by inoculation of 10 mL blood into an ISOLATOR 10 tube (a commercial lysis-centrifugation system; Alere, UK). After centrifugation, the resulting pellet was directly plated onto XLD agar (Oxoid, UK). Quantitative stool culture was performed by suspending 1 g of stool in sodium selenite, followed by subculturing onto XLD agar (Oxoid). Blood- or stool-inoculated plates were then incubated (37°C for 24 hours) prior to identification and counting.
Quantitative blood culture was performed at typhoid diagnosis by inoculation of 10 mL blood into an ISOLATOR 10 tube (a commercial lysis-centrifugation system; Alere, UK). After centrifugation, the resulting pellet was directly plated onto XLD agar (Oxoid, UK). Quantitative stool culture was performed by suspending 1 g of stool in sodium selenite, followed by subculturing onto XLD agar (Oxoid). Blood- or stool-inoculated plates were then incubated (37°C for 24 hours) prior to identification and counting.