In situ conjugal transfer of plasmid-encoded multiple antibiotic resistance in Escherichia coli isolated from heat

In vitro and in situ conjugal transfer of an R-plasmid among enterobacteriaceae species isolated from meat samples

“…In vitro and in situ R-plasmid transfer in Enterobacteriaceae in other environmental sources have been previously reported in human alimentary tract [16][17][18], animal gastrointestinal tract [19,20], raw sewage [21], sterilized waste water [15,22], botanical environments [14], sterile soil [23], marine sediment [24] and anaerobic digesters [25]. Similar high frequency of plasmid transfer in meat isolates of E. coli harboring transferable R-plasmids, under both in vitro and in situ conditions using a laboratory recipient of E. coli K12 have been reported [8]. The present study expands on these results by using resident recipient strains.…”

“…The sodium dodecyl sulfate (SDS)-alkaline lysis was used to isolate plasmid deoxyribonucleic acid (DNA) [5,8]. Molecular sizes of the plasmids were estimated using a reference strain of E. coli V517 containing multiple plasmids [11], and a restriction sizing and sequence entry program (Molecular Soft-Ware, Inc., Atlanta, GA) operated on an IBM-PC microcomputer.…”

“…In vitro mating was carried out in 3 ml of nutrient broth with 1 ml of donor and respective recipient (approximately 1:1 cell ratio) as described previously [5,8]. Donor and recipients were allowed to mate over a ravage of temperatures for 24 h. In all mating trials carried out at temperatures lower than room temperature, donor, recipients and mating broth were preincubated at the desired temperature prior to mixing.…”

“…Since the discovery of disease outbreaks arising from enteric bacteria carrying transferable, multiple antibiotic resistances, the occurrence and significance of R-plasmids in Enterobacteriaceae in foods of animal origin, particularly Escherichia coli has been well documented [1][2][3][4][5][6][7]. A previous study carried out by Jayaratne et al [8] has shown the ability of multiple antibiotic resistant E. coli isolates from meat to transfer R-plasmids under in situ conditions. Furthermore, Spika et al [9] demonstrated that hamburger products originating from dairy cows can act as a vehicle for transmission of R-plasmids in Salmonella newport infections in humans.…”

Inability to Transfer Antibiotic Resistance in Escherichia coli on Meat Surfaces

“…E. coli was therefore considered a suitable organism to examine first in relation to plasmid transfer in organisms on meat surfaces. The only other such study is that of Jayaratne et al (1987) who demonstrated transfer of Rfactors from a donor strain of E. co/i to strain KIz at temperatures down to 10°C. However, they used ground beef and sausage which was autoclaved, then immersed in a large volume of medium seeded with the two strains; it was thus a highly artificial system and did not resemble the conditions likely to occur on meat.…”