Integron content of Salmonella enterica serotype Typhimurium strains isolated in Hungary in the years 1997-1999.
The integron content of 52 DT104/U302 phage type strains and 53 non-DT104/U302 strains of Salmonella enterica serotype Typhimurium (S. Typhimurium) was studied in PCR experiments using a 5'-CS/3'-CS primer pair (Lévesque et al., 1995). Forty-three out of 44 streptomycin- and/or ampicillin-resistant DT104 and related phage type strains were found to carry a 1 kb and/or 1.2 kb long integron. The other resistance markers did not affect the number and size of integrons; no integron-free multidrug-resistant (MDR) DT104 strains were found. The two large groups of DT104 strains (Felix-Callow's phage types 2 and 2c) proved to be identical in respect of integron patterns (IPs), supporting the views of those authors who consider DT104 a single clone. Strains of human and animal origin did not differ from each other in their IPs. Within the non-DT104 phage types, ampicillin- and/or streptomycin-resistant, integron-free MDR strains were also found. Based on amplicons varying between 290 and 3500 bp an IP system was suggested. The commonest amplicon sizes in non-DT104 strains were 1450 and 2050 bp. The IPs of DT104 strains and of non-DT104 strains containing an integron of 1 and 1.2 kb size were stable. In contrast, the IPs of other non-DT104 strains showed a varying degree of instability. Integron loss was frequently associated with spontaneous plasmid elimination and changes of R-type among the descendants of a given strain.
National Center for Epidemiology B. Johan, H-1966 Budapest, P.O. Box 64, Hungary.
I
I
Gadó
Judit
J
Pászti
Margit
M
Király
Melinda
M
Jakab
D000818:Animals; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics*; D006801:Humans; D006814:Hungary; D032023:Integrons / Q000235:genetics*; D010957:Plasmids / Q000235:genetics; D012189:Retrospective Studies; D012486:Salmonella typhimurium / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*