R-plasmid transfer in vivo: a prospective study

Abstract

Summary. Two hundred and eighty-seven coliform bacteria were isolated from 1 16 rectal swabs or faecal specimens obtained from 113 patients. By means of plasmid analysis and resistance transfer (R-transfer) Escherichia coli was found to differ from other enteric genera in plasmid distribution. Criteria were proposed that enabled invivo "R-transfer potential" and in-vivo "R-transfer rate" to be calculated. From each of 22 of the 1 13 patients numerous coliforms were isolated, of which at least one per patient contained one or more self-transmissible R-plasmids potentially transferable to 43 other coliforms. Evidence indicated that R-plasmid transfer had occurred in vivo on two of the 43 potential occasions. These results are discussed in the context of plasmid ecology in the human host.

Restriction enzyme fingerprinting of enterobacterial plasmids: a simple strategy with wide application

“…This situation occurred with 2 E. coli, 2 Proteus, and 1 of the 96 strains of S. typhimurium (Table 1). With regard to those strains that harbour only small plasmids that were not amenable to cleavage with the enzymes used here, satisfactory fingerprints can often be obtained using Hae III (Platt, Chesham & Kristinsson, 1986;and unpublished).…”

“…Incubation was at 37°C for 4 h (except SmaI which was incubated at 30°C). Electrophoresis was in 0-8 % agarose gels run at 18 mA overnight in tris-borate buffer containing 0 3 ,ug/ml ethidium bromide (Platt, Chesham & Kristinsson, 1986). Each gel was calibrated with a PstI digest of bacteriophage lambda (A) DNA and controlled with a lambda digest of the enzyme under study.…”

“…Individual R-plasmids as transconjugants in Escherichia coli K12 were also studied, and these included representatives of various incompatibility groups. The original sources of both clinical isolates and plasmids are shown in Table 1. DNA preparation and digestion DNA was extracted from 10 ml overnight cultures in Brain Heart Infusion Broth (Oxoid: CM225) as previously described (Platt, Chesham & Kristinsson, 1986) or from about 20 colonies harvested from nutrient agar (Oxoid: CM 3) plates. Purified DNA was dissolved in 60 ,ul of TE buffer (Tris 10 mm, EDTA 1 mM; pH 8 0).…”

“…More recently, this approach has been widely used to study the epidemiology of both plasmids and their host bacteria (Beul et al 1985;Lyon et al 1984; O'Brien et al 1982;Platt, Chesham & Kristinsson, 1986;Rubens et al 1981). The information provided by the application of these techniques is particularly useful for the study of genera for which no established typing scheme is available (Hawkey, Bennett & Hawkey, 1984) and the investigation of cryptic plasmids (Callihan, Young & Clark, 1983).…”

The distribution of plasmids among a representative collection of Scottish strains of salmonellae

“…Since, in addition to phenotypic modification by plasmids, the possession of plasmids confers considerable genetic flexibility upon the host strains , it can be argued that a clearer understanding of plasmid ecology and their behaviour in the natural environment requires the establishment of the relative abundance (and distribution) ofplasmids among defined collections of the enteric genera. Here we report the distribution ofplasmids among a representative collection of salmonellas and defined subgroups of strains and compare the results with those described for Escherichia coli ) and other enteric genera (Platt, Chesham & Kristinsson, 1986).…”