Integrons and Gene Cassettes in the Enterobacteriaceae

Abstract

Integrons were detected in 59 of 120 (49%) urinary isolates of Enterobacteriaceae by PCR using degenerate primers targeted to conserved regions of class 1, 2, and 3 integrase genes. PCR sequencing analysis of the cassette arrays revealed a predominance of cassettes that confer resistance to the aminoglycosides and trimethoprim.

Diagnostic Accuracy of Class 1 Integron PCR Method in Detection of Antibiotic Resistance in Salmonella Isolates from Swine Production Systems

“…As described previously (10,16,17,26), a strong association of class 1 integrons (1,000, 1,000 and 1,200, and 1,600 bp) with identified resistance to specific antibiotics was demonstrated and attributed in part to the existence of resistance genes (aadA for streptomycin and spectinomycin, aadB for gentamicin and kanamycin, and ␤-lactamase for ampicillin) within these integrons. The gene sequencing and associated antibiotic resistance profiles of each integron group suggest that the 1,600-bp integron in part shares a common ancestor with the 1,000-bp integron plus additional genetic material containing the aadB gene.…”

“…Class 1 integrons can capture genes from the environment and incorporate them by site-specific recombination. When they are part of the genome of pathogenic organisms such as Salmonella (10,8,9,17), Klebsiella (13,26), Yersinia (23), and Escherichia coli (16), integrons may be responsible for the horizontal transfer of antibiotic resistance among other pathogenic bacteria. The presence of genes within integrons coding for antibiotic resistance and the association of antibiotic resistance phenotypes with the presence of integrons have been well documented (10,16,17,25,26).…”

Characteristics of aac(6′)-Ib-cr Gene in Extended-Spectrum β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Isolated from Chungnam Area

“…Gene cassette arrays of the integron-positive isolates were identified using multiplex PCR; subsequently, these cassettes were amplified and fully sequenced [15].…”

Integron content of Salmonella enterica serotype Typhimurium strains isolated in Hungary in the years 1997-1999

“…The integrase encoded by an intI gene of 5'-CS builds in the cassettes by site-specific recombination (Hall et al, 1991). Four classes of integrons were described till now, having different integrase genes (White et al, 2001). Most of the integrons in the clinical isolates of the family Enterobacteriaceae belong to class 1 (Brown et al, 1996).…”