Analysis of plasmid and chromosomal DNA of multidrug-resistant Salmonella enterica serovar typhi from Asia

Abstract

Molecular analysis of chromosomal DNA from 193 multidrug-resistant (MDR) Salmonella enterica serovar Typhi isolates from 1990 to 1995 from Pakistan, Kuwait, Malaysia, Bangladesh, and India produced a total of five major different pulsed-field gel electrophoresis (PFGE) patterns. Even within a particular country MDR S. enterica serovar Typhi DNA was found to be in different PFGE groups. Similar self-transferable 98-MDa plasmids belonging to either incompatibility group incHI1 or incHI1/FIIA were implicated in the MDR phenotype in S. enterica serovar Typhi isolates from all the locations except Quetta, Pakistan, where the majority were of incFIA. A total of five different PFGE genotypes with six different plasmids, based on incompatibility and restriction endonuclease analysis groups, were found among these MDR S. enterica serovar Typhi isolates.

FIG. 1

XbaI RE fragment patterns of representative S. enterica serovar Typhi isolates from various countries. Lanes 1 and 19 (numbering is from left to right), 48.5-kb ladder molecular size standard; lane 2, B1 from Bangladesh in PFGE group C1; lane 3, I1 from India in PFGE group C2; lanes 4 and 5, K1 and K2, respectively, from Kuwait in PFGE group C3; lanes 6, 7, 8, and 9, M1, M2, M3, and M4 from Malaysia in PFGE groups D1, D2, D2, and E1, respectively; lanes 10, 11, 12, 13, and 14, Q1, Q2, Q3, Q4, and Q5 from Quetta, Pakistan, in PFGE groups E2, E1, B1, B2, and A1, respectively; lanes 15, 16, 17, and 18, R1, R2, R3, and R4 from Rawalpindi, Pakistan, in PFGE groups B1, A1, A1, and A2, respectively.