Variability of IncHI1 plasmids from Salmonella typhi with special reference to Peruvian plasmids encoding resistance to trimethoprim and other antibiotics

Abstract

In spite of extensive DNA homology among IncHI1 plasmids, ApaI and XbaI restriction digests of plasmids from Peruvian Salmonella typhi varied considerably from other IncHI1 plasmids isolated previously. IncHI1 plasmids appear to be undergoing a process of modular evolution, probably by sequential acquisition of resistance determinants.

Use of plasmid profiles in epidemiologic surveillance of disease outbreaks and in tracing the transmission of antibiotic resistance

“…Because plasmids can elaborate their own system for selftransfer between bacteria, it is not unexpected that antibiotic resistance in bacteria has become a major problem. For example, in 1972 trimethoprim resistance (Tpr) in Entero-bacteriaceae was associated only with incompatibility group W plasmids, but by 1980 Tpr was found on incompatibility group W, B, C, D, I, FII, N, P, and X plasmids (28,49,185).…”

Does chloramphenicol remain the drug of choice for typhoid?

“…However, two other plasmid compatibility groups were identified in the remaining three strains with plasmid-mediated resistance -F1me (2 strains), and FII (1 strain). Thus the claims that plasmid-mediated chloramphenicol resistance in S. typhi is almost invariably encoded by Inc H1 plasmids (Farrar, 1985;Taylor et al 1985) are incorrect, although H1 plasmids have been reported on several occasions when chloramphenicol-resistant S. typhi have caused epidemics (Anderson, 1975). In the five strains with chromosomal resistance, the low levels of resistance are consistent with alterations in the permeability of the cell wall and not with the production of antibiotic-inactivating enzymes.…”

Restriction endonuclease characterization of resistant plasmids in Enterobacteriaceae isolated from children in the Sudan

“…and is likely to be highly conserved (22), it may be regarded as a marker of common evolutionary origin (23). However, the exchange of DNA within plasmids, both by acquisition and loss of transposons, and by gene mutation and deletions (24) results in plasmids of the same incompatibility group having diverse total DNA. Various studies have demonstrated DNA variability within incompatibility groups by restriction endonuclease digests and DNA hybridization (25)(26)(27)(28).…”

“…As part of a study of antibiotic resistance in enteric flora isolated from children in Khartoum, Sudan, we have investigated the use of restriction endonuclease digestion to characterize resistant transconjugant plasmids. Resistance pattern pKc [1][2][3][4][5][6][7][8] Ap Su Tm Sm pKc9,10 TcC pKcl11 Ap Tm pKc [12][13][14][15] Tm pKc 16 Ap Tc PKc 17 Ap Su Tm Sm C pKc 18,19 ApTcSuTmSm pKc 20 Ap Su Tm pKc 21 Ap Tc Su Tm Sm C pKc 22 Ap Tc C pKc 23,24 Ap PATIENTS AND METHODS…”