FLAGELLAR SEROTYPES OF SALMONELLA-TYPHI IN INDONESIA - RELATIONSHIPS AMONG MOTILITY, INVASIVENESS, AND CLINICAL ILLNESS

While the H1-d flagellar serotype of Salmonella typhi has been found w orldwide, the H1-j serotype occurs only in Indonesia. A cross-sectiona l survey in Indonesia compared epidemiologic, clinical, and pathogenet ic characteristics of these two serotypes. S. typhi isolates were coll ected from patients with acute typhoid fever in four Indonesian cities . Flagellar serotype was determined by polymerase chain reaction ampli fication of the fliC locus of the flg gene. Of 321 isolates, 51 (15.9% ) were H1-j. Patients with H1-j infection were older than those with H 1-d (P < .001). Among 30 patients with known clinical outcomes, H1-j i nfection was associated with milder clinical illness than H1-d (P = .0 6). In vitro, H1-j isolates were both less motile on semi-solid agar p lates (P = .004) and less invasive of HEp-2 cells (P = .002) than H1-d isolates. The association of decreased severity of illness with decre ased motility and invasiveness suggests that flagellar properties are a component of S. typhi's virulence.