PCR mapping of integrons reveals several novel combinations of resistance genes

Abstract

The integron is a new type of mobile element which has evolved by a site-specific recombinational mechanism. Integrons consist of two conserved segments of DNA separated by a variable region containing one or more genes integrated as cassettes. Oligonucleotide probes specific for the conserved segments have revealed that integrons are widespread in recently isolated clinical bacteria. Also, by using oligonucleotide probes for several antibiotic resistance genes, we have found novel combinations of resistance genes in these strains. By using PCR, we have determined the content and order of the resistance genes inserted between the conserved segments in the integrons of these clinical isolates. PCR mapping of integrons can be a useful epidemiological tool to study the evolution of multiresistance plasmids and transposons and dissemination of antibiotic resistance genes.

Novel Class 1 Integrons in Multi-drug Resistant Isolates from Eastern China

“…DNA template was prepared using boiling method [13]. Briefly, overnight bacteria culture (200 lL) was mixed with 800 lL sterile water and then boiled for 10 min.…”

“…The resulting solution was centrifuged at 12,0009g for 2 min and the supernatants were stored at -20°C, which were used as DNA templates. The specific primers for detecting intI genes and variable regions were shown in Table 1 [13][14][15]. To determine whether class 1 integrons contained the entire 3 0 -CS, the primers qacED1-F and sul1-R were used [16].…”

“…To determine whether class 1 integrons contained the entire 3 0 -CS, the primers qacED1-F and sul1-R were used [16]. PCR for amplification of all the genes was performed as previously described [13,15,16]. Allowing amplification of longer products than Taq DNA polymerase, we used EX Taq DNA polymerase (TaKaRa, Japan) for amplification of the variable region.…”

Occurrence and composition of class 1 and class 2 integrons in clinical and environmental O1 and non-O1/non-O139 Vibrio cholerae strains from the Brazilian Amazon

“…Class 1 integrons carrying distinct cassette arrays have been detected in V. cholerae O1 and non-O1/non-O139 strains in Europe and Asia, indicating the heterogeneity in organisation and/or composition of the variable region (Lévesque et al 1995, Dalsgaard et al 2000. Here, clinical V. cholerae O1 strains from the Brazilian cholera epidemic were shown to carry empty class 1 integrons.…”

Detection of Integrons from Escherichia coli Isolates Obtained from Some Selected Animals in Republic of Korea

“…Integrons are natural expression vectors that permit the insertion of antibiotic resistance genes by a site-specific recombinational mechanism. Only a few studies suggested that integrons are widespread in both animal and human clinical bacterial isolates [6][7][8][9]. The purpose of this current study was to determine the incidence of integrons from E. coli isolates obtained from some selected animals in Republic of Korea.…”