Characterization of a Self-Transferable Plasmid from Salmonella enterica Serotype Typhimurium Clinical Isolates Carrying Two Integron-Borne Gene Cassettes Together with Virulence and Drug Resistance Genes

Abstract

An unusual self-transferable virulence-resistance plasmid (pUO-StVR2) was found in nine multidrugresistant (ACSSuT phenotype) Salmonella enterica serotype Typhimurium clinical isolates that were assigned to four different phage types and a single and distinctive XbaI pulsed-field gel electrophoresis profile. pUOStVR2 is an IncFII plasmid of about 140 kb in length carrying the spvA, spvB, and spvC (Salmonella plasmid virulence) and rck (resistance to complement killing) genes. It also carries the oxa1/aadA1a (ampicillin resistance and streptomycin-spectinomycin resistance) gene cassette configuration located within a class 1 integron with qacE⌬1/sul1 (ammonium antiseptics resistance and sulfadiazine resistance); the transposon genes merA, tnpA, and tnpR (mercury resistance, transposase, and resolvase of Tn21, respectively); and the catA1 (chloramphenicol resistance) and tet(B) (tetracycline resistance) genes. The insertion of resistance genes into a Salmonella virulence plasmid constitutes a new and interesting example of plasmid evolution and presents a serious public health problem.

Isolation of Salmonella enterica serotype choleraesuis resistant to ceftriaxone and ciprofloxacin

“…Some studies pointed out the serious problem that several Salmonella serotypes, including serotype Choleraesuis, could generate different types of hybrid plasmids, which consisted of the serotype-specific virulence plasmid and an array of gene cassettes (36,69,70,93). Most of the gene cassettes contained resistance genes that were responsible for resistance to conventional antibiotics, such as ampicillin, chloramphenicol, gentamicin, oxacillin, spectinomycin, streptomycin, sulfadiazine, tetracycline, trimethoprim, and other materials, including ammonium antiseptics and mercury (36,69,70,93).…”

“…Most of the gene cassettes contained resistance genes that were responsible for resistance to conventional antibiotics, such as ampicillin, chloramphenicol, gentamicin, oxacillin, spectinomycin, streptomycin, sulfadiazine, tetracycline, trimethoprim, and other materials, including ammonium antiseptics and mercury (36,69,70,93).…”

Resistance to -lactams of human and veterinary Salmonella isolates in Egypt and Algeria

“…The exchange of resistance plasmids between members of Enterobacteriaceae will severely limit the treatment options of infections caused by these microorganisms, which are responsible for nearly half of all infections (Fluit, 2005). Many ESBLs-mediated plasmids also contain virulence genes or regulate their expression; this confers survival advantage in an unfavorable drug environment and constitutes a new tool in the bacterial evolution (Guerra et al, 2002;Martinez and Baquero, 2002;Chu and Chiu, 2006).…”

Erratum: Can landscape ecology untangle the complexity of antibiotic resistance?

“…In addition, a QAC-resistance gene cassette …in studies involving complex environments … the ability to quantify the causal relationship accurately becomes extremely difficult… has been found in class I integrons in various bacteria, including Salmonella spp. 52 Consequently, the use of antibiotics or disinfectants is one way to select for antibiotic resistance in the absence of primary selection pressure.…”

“…Mercury-resistance genes can be found in association with mobile genetic elements in bacteria 55 , and these elements commonly possess antibiotic-resistance genes 56 . For example, the transposon Tn21 possesses the mercury resistance (mer) operon and a class 1 integron that often includes antibioticresistance genes 52,57,58 . Copper is another metal that is toxic to many bacteria at high levels.…”