Affiliation:
1. Department of Bacteriology, University of California, Davis, California 95616
Abstract
Antibiotic resistance carried on R factors was transferred by conjugation from
Escherichia coli
B/r and
Shigella flexneri
1a to
Erwinia
spp. Tetracycline resistance (TetR) carried on R factor R100
drd-56
was transferred from
E. coli
B/r to strains of
Erwinia amylovora, E. aroideae, E. atroseptica, E. chrysanthemi, E. cytolytica, E. dissolvens, E. herbicola, E. nigrifluens
, and
E. nimipressuralis
, but not to strains of
Erwinia carotovora, E. carnegieana, E. dieffenbachiae, E. oleraceae
, and
E. quercina
. Multiple antibiotic resistance (chloramphenicol, streptomycin, tetracycline; ChlR-StrR-TetR) carried on R factor SR1 was transferred from a clinical isolate of
S. flexneri
1a to strains of
E. aroideae, E. chrysanthemi, E. herbicola
, and
E. nigrifluens
, but not to strains of other
Erwinia
spp. The frequency of this transfer was low with receptive cultures of
Erwinia
spp. and
E. coli
(F
−
strain). Antibiotic resistance in the exconjugants showed varying degrees of stability in the presence or absence of acridine orange, depending on the strain tested. The frequencies of segregation to drug susceptibility in the presence of acridine orange, though low, suggest that the elements exist as plasmids in the majority of the
Erwinia
exconjugants. Multiple antibiotic resistance (ChlR-StrR-TetR) was found to segregate into various resistance classes (ChlR-StrR, StrR-TetR, TetR, StrR, and none) in these exconjugants. The exconjugants of
E. amylovora, E. herbicola
, and
E. nigrifluens
, to which R100
drd-56
was transferred from
E. coli
B/r, were sensitive to the male (F)-specific phage M13. There was a positive correlation between the susceptibility of exconjugants to the F-specific phage M13 and their ability to transfer R100
drd-56
to the recipient cultures of
Escherichia coli, Erwinia herbicola, Salmonella typhimurium
, and
Shigella dysenteriae
. Exceptions were, however, noted with
Erwinia dissolvens
and
E. nimipressuralis
exconjugants harboring R100
drd-56
; these exconjugants, although not susceptible to M13, transferred R100
drd-56
to the recipient cultures. The frequency of transfer of R100
drd-56
and the levels of resistance to tetracycline in
Erwinia
exconjugants were found to differ markedly depending upon the strain employed. Transfer of multiple antibiotic resistance (ChlR-StrR-TetR) from
Erwinia
exconjugants was not obtained in preliminary trials with an
E. coli
F
−
strain as the recipient culture.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
46 articles.
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