ANTIBIOTIC-RESISTANT SALMONELLA-TYPHI FROM 2 OUTBREAKS - FEW RIBOTYPES AND IS200 TYPES HARBOR INC HI1 PLASMIDS

To investigate factors that could be involved in the emergence of anti biotic resistant S. typhi, we characterized R plasmids and antibiotic resistant S. typhi strains from two outbreaks of typhoid in Peru and C hile. Differences in the Inc HI1 plasmids of Peruvian and Chilean stra ins were identified by conjugation and incompatibility studies and pla smid DNA characterization. Antibiotic-resistant S. typhi harboring Inc HI1 plasmids belonged to a reduced number of Pst1 and Cla1 ribotypes and IS200 types, in contrast to the high genetic diversity found among epidemic antibiotic-susceptible S. typhi.(15) The low diversity of an tibiotic-resistant S. typhi suggests that they may express properties that are related to both their ability to harbor Inc HI1 R plasmids an d to disseminate.