Integron-Containing IncU R Plasmids pRAS1 and pAr-32 from the Fish Pathogen Aeromonas salmonicida

Abstract

A 45-kb R plasmid, pRAS1, that confers resistance to tetracyclines, trimethoprim, and sulfonamides was isolated in 1989 from an atypical strain of the fish pathogen Aeromonas salmonicida. This plasmid could be transferred by conjugation to Escherichia coli with a high degree of efficiency (frequency, 0.48). The following year pRAS1 was isolated from A. salmonicida subsp. salmonicida in the same area. Incompatibility group U plasmid pRAS1 contained a drug resistance-determining region of 12 kb consisting of a class 1 integron similar to In4 of Tn1696 but with a dfrA16 gene cassette inserted. Close to IS6100 at the right end of Tn4 was a truncated Tn1721. Restriction enzyme analysis showed that R plasmid pAr-32, isolated from A. salmonicida in Japan in 1970, had the same backbone structure as pRAS1, while the drug resistance-determining region contained a complex class 1 integron with an aadA2 cassette; the chloramphenicol resistance gene catA2, as in In6 of pSa; and a duplicate of the 3 conserved segment of the integron.

Organization of lin Genes and IS 6100 among Different Strains of Hexachlorocyclohexane-Degrading Sphingomonas paucimobilis : Evidence for Horizontal Gene Transfer

“…vesicatoria, where it was shown to increase the expression of the streptomycin resistance genes strA and strB (35). Similarly, IS6100 has been found in Salmonella enterica serovar Typhimurium (5), in plasmid pACM1 from Klebsiella oxytoca (27), in plasmid pTET3 in Corynebacterium glutamicum (36), and in plasmid pRASI in Aeromonas salmonicida (34). There has been no previous report of IS6100 elements in any strain of S. paucimobilis, and using Southern blot hybridization, we were unable to detect IS6100 elements in S. paucimobilis ATCC 29837 T and S. chlorophenolica DSM 7098 T .…”

Antibiotic Resistance in the Environment, with Particular Reference to MRSA

“…Fluit and Schmitz (2004) resistance (Bass et al, 1999;Sorum et al, 2003). A recent study (Nemergut et al, 2004) has shown evidence of a gene cassette encoding nitroaromatic catabolism, a group of compounds associated with mining activity, this highlights the fact that other selective pressures other than antibiotics may also co-select for resistance genes.…”

Antibiotic resistance due to an unusual ColE1-type replicon plasmid in Aeromonas salmonicida

“…This resistance was first believed to be caused by a plasmid like pAsa4, pAB5S9b, pSN254b or pAr-32 (Reith et al, 2008;Sørum et al, 2003;Vincent et al, 2014). To solve this point and determine the nature of the unusual plasmidic profile, the total DNA of isolate JF3791 was sequenced by NGS (see Methods).…”

“…This bacterium has a notable plasmidome involved in antibiotic resistance in several isolates (Adams et al, 1998;L'Abee-Lund & Sørum, 2002;Piotrowska & Popowska, 2015;Reith et al, 2008;Sørum et al, 2003;Vincent et al, 2014), leading to a bottleneck in the effectiveness of antibiotic treatments. More precisely, pAsa4 (166.7 kbp), pSN254b (152.2 kbp), pAB5S9b (25.5 kbp) and pAr-32 (~47 kb) are plasmids conferring resistance to chloramphenicol (CHL) in A. salmonicida subsp.…”

“…For both pSN254b and pAB5S9b, the resistance is due to the floR gene, which encodes an efflux pump (Vincent et al, 2014). In the case of pAsa4 and pAr-32, the CHL resistance is produced by a cat gene, which encodes a CHL acetyltransferase (CAT) (Reith et al, 2008;Sørum et al, 2003).…”