Plasmids in Listeria monocytogenes in relation to cadmium resistance

Abstract

One hundred and seventy-three unrelated Listeria monocytogenes strains isolated from humans, animals, the environment, and food were analyzed for the presence of plasmids. Extrachromosomal DNA was found in 28% of the strains. Plasmid DNA was extracted more frequently from L. monocytogenes serogroup 1 strains (35%) than from serogroup 4 strains (15%). Among strains from food and the environment, 40%YV and 29%Yo, respectively, harbored plasmids, whereas only 13% of the strains from humans and animals with listeriosis bore plasmids. We also investigated the susceptibility of 90 strains to seven antibiotics and four heavy-metal salts. No antibiotic resistance could be detected, but 95.3% of the plasmid-positive strains and only 12.7% of the plasmid-negative strains were resistant to cadmium. The plasmid-determined genetic basis of cadmium resistance was proven by conjugation between strains of L. monocytogenes and by cure of the plasmid. This is the first time that plasmids of L. nwnocytogenes have been shown to be associated with cadmium resistance.

Subtyping of Listeria monocytogenes on the basis of plasmid profiles and arsenic and cadmium susceptibility

“…tested. In the remaining culture (serovar 1/2b), plasmid DNA was detected in only two of the five replicates which had been Our findings confirm those of Lebrun et al (1992) in that, where plasmid DNA was detected, this was present in the grown in FDA broth and subcultured onto both Oxford and PALCAM agars ; plasmid DNA was detected in all replicates majority of cultures as a single similarly-sized entity. Further molecular characterization of the components of the plasmids grown in PALCAM broth.…”

“…The testing of susceptibilities to arsenic and cadmium The presence and carriage rates of plasmid DNA in wildtype L. monocytogenes has been reported previously as 0% together with the method for plasmid profiling described here offer simple techniques which can be easily applied in (Fistrovici andCollins-Thompson 1990), 14% (Pérez-Díaz et al 1982), 20% (Peterkin et al 1992), 24% (Flamm et al laboratories without a specialized expertise in dealing with this bacterium. Together with serogrouping (which can be 1984), 28% (Lebrun et al 1992), 77% (Kolstad et al 1992) and 79% (Dykes et al 1994). Plasmid DNA in wild-type L.…”

“…Further molecular characterization of the components of the plasmids grown in PALCAM broth. (Lebrun et al 1992(Lebrun et al , 1994b) might further extend the discriminatory power of this technique, although the additional…”

“…applicable to the work of non-specialist laboratories. monocytogenes have included serotyping (Seeliger and Höhne Plasmid DNA has been detected in L. monocytogenes but, 1979), phage typing (McLauchlin et al 1986), DNA restricbecause of both the relatively rare occurrence of plasmids and tion fragment analysis (Nocera et al 1990 ;Graves et al 1991 ; their similarity in size when detected (Pérez-Díaz et al 1982 ;Jacquet et al 1992 ;Ridley 1995) including pulsed field gel Peterkin et al 1992 ;Lebrun et al 1992), plasmid profile electrophoresis (Brosch et al 1991), random amplification of typing has not been widely utilized for the subtyping of this polymorphic DNA analysis (Mazurier and Wernars 1992) organism. and multilocus enzyme electrophoresis (Bibb et al 1990 ; Resistance to arsenic (Buchanan et al 1991) and cadmium Piffaretti et al 1989).…”

“…and multilocus enzyme electrophoresis (Bibb et al 1990 ; Resistance to arsenic (Buchanan et al 1991) and cadmium Piffaretti et al 1989). Although a combination of these (Lebrun et al 1992) has been described ; however, the susmethods offers typing systems of high discrimination (No Ârceptibilities to these agents have not been fully evaluated for rung and Gerner-Smidt 1993 ;McLauchlin 1996) there is the purpose of epidemiological subtyping. a considerable investment required in time, personnel and…”