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G de Cespédès

Publications and source records attributed to G de Cespédès.

15 recordsLinked to original sources
PubMed1998

Diversity of structures carrying the high-level gentamicin resistance gene (aac6-aph2) in Enterococcus faecalis strains isolated in France.

Of 24 high-level gentamicin-resistant clinical isolates of Enterococcus faecalis, 20 carried gentamicin resistance (Gmr) plasmids. The plasmids ranged from 65.0 to 80.0 kb in size. Three of these plasmids were nonconjugative, and 17 transferred by conjugation to an E. faecalis recipient at low frequency (10(-5) to 10(-6) transconjugants per donor). The remaining four strains had a nonconjugative chromosomal Gmr determinant. On the basis of restriction enzyme and DNA-DNA hybridization profiles, Tn4001-like alpha elements were located on the chromosome and three types of Tn4001-truncated structures, I, II, and III, were found to be carried by the Gmr plasmids. Structure I lacked IS256 in the right-hand flanking extremity of Tn4001. Structure II was the same as structure I except that it also had a partial deletion of IS256 in the left-hand flanking extremity of Tn4001. Structure III lacked both the right- and left-hand flanking extremities of Tn4001. One of the wild-type strains carried the Gmr determinant both on the chromosome, as a Tn4001-like alpha element, and on a conjugative plasmid, as a Tn4001-truncated type I structure.

Chromosome Mapping↗
PubMed1997

Molecular typing of Enterococcus faecalis strains resistant to high levels of gentamicin and isolated in Romania.

Sixteen Enterococcus faecalis strains resistant to high levels of gentamicin, 15 of which were isolated in the same year in a Romanian hospital, harboured conjugative gentamicin resistance (Gm(r)) plasmids ranging from 55 to 85 kilobases. On the basis of restriction enzyme and DNA-DNA hybridization profiles of these plasmids, as well as of chromosomal SmaI macrorestriction and Tn916 hybridization patterns, clonal relationship was established for seven strains whereas the other strains were considered to be independent. Nine and seven of the Gm(r) plasmids carried Tn4001-like and Tn4001-truncated structures, respectively; the latter structures were truncated in the right-hand flanking extremity of the element.

Chromosomes, Bacterial↗
PubMed1996

Plasmid-borne high-level resistance to gentamicin in Enterococcus hirae, Enterococcus avium, and Enterococcus raffinosus.

Enterococcus hirae, E. avium, and E. raffinosus isolated in Romania, Tunisia, and Portugal harbored plasmids pICC8, pIP1700, and pIP1701, respectively, encoding resistance to high levels of gentamicin (Gmr). The Gmr marker was carried on pIP1700 by a Tn4001-like element and on pICC8 and pIP1701 by Tn4001-truncated structures. pICC8 carried, in addition to Gmr, chloramphenicol, erythromycin, and tetracycline-minocycline (TetM) resistance determinants. The gene tetM of pICC8 was carried on a Tn916-like element.

Drug Resistance, Microbial↗
PubMed1993

Study of heterogeneity of chloramphenicol acetyltransferase (CAT) genes in streptococci and enterococci by polymerase chain reaction: characterization of a new CAT determinant.

An assay based on the utilization of degenerate primers that enable enzymatic amplification of an internal fragment of cat genes known to be present in gram-positive cocci was developed to identify the genes encoding chloramphenicol resistance in streptococci and enterococci. The functionality of this system was illustrated by the detection of cat genes belonging to four different hydridization classes represented by the staphylococcal genes catpC221, catpC194, catpSCS7, and the clostridial gene catP, and by the characterization of a new streptococcal cat gene designated catS. A sequence related to the clostridial catQ gene, which was present in one streptococcal strain, was not detected by this assay. These results reveal that these six cat genes account for chromosomal-borne chloramphenicol resistance in 12 group A, B, and G streptococci tested. By contrast, only three of these six cat genes (catpC221, catpC194, and catpSCS7) were detected on the 10 enterococcal plasmids studied here that encode resistance to chloramphenicol.

Amino Acid Sequence↗
PubMed1992

Natural occurrence of structures in oral streptococci and enterococci with DNA homology to Tn916.

Seventeen oral streptococci and 18 enterococci were tested for the presence of DNA sequences homologous to the conjugative transposon Tn916 encoding tetracycline resistance. All the strains were resistant to tetracyclines, including minocycline, and most of them were resistant to other antibiotics. Tn916-like structures, identified by hybridization of HincII-digested DNA, were found on the chromosomes of 11 oral streptococci and four enterococci and on two plasmids, pIP1549 and pIP1440, one harbored by an Enterococcus hirae strain and the other harbored by an Enterococcus faecalis strain. Sequences homologous to Tn916, only some of which corresponded to its internal HincII structure (Tn916-modified elements), were chromosomally located in three oral streptococci and two enterococci and were plasmid borne in pIP614 harbored by an E. faecalis strain. Nine enterococci and three oral streptococci carried either the Tet M or the Tet O determinant chromosomally, but they carried no other sequences homologous to Tn916.

Anti-Bacterial Agents↗
PubMed1990

Tn3702, a conjugative transposon in Enterococcus faecalis.

Enterococcus faecalis strain D434 was found to carry on its chromosome a determinant encoding tetracycline-minocycline resistance (Tcr-Mnr) and to harbor both an R plasmid and a cryptic conjugative plasmid, pIP1141. The determinant coding for Tcr-Mnr was located on a conjugative transposon, designated Tn3702. The transposition of Tn3702 on to both pIP1141 and the hemolysin plasmid pIP964 yielded different derivatives each of which contained an 18.5-kilobase insert. The structure of Tn3702 is similar to that of the conjugative transposon Tn916.

Conjugation, Genetic↗
PubMed1990

Presence of chromosomal elements resembling the composite structure Tn3701 in streptococci.

Tn3701, carried by Streptococcus pyogenes A454, is the first chromosomal composite element to be described; it contains in its central region Tn3703, a transposon similar to Tn916. A comparison by DNA-DNA hybridization of Tn3701 with omega(cat-tet) and Tn3951, carried by Streptococcus pneumoniae BM6001 and by Streptococcus agalactiae B109, respectively, revealed that the two latter structures are also Tn3701-like composite elements. The DNAs of 27 other antibiotic-resistant group A, B, C, and G streptococci and of S. pneumoniae BM4200 showed sequence homologies to Tn3701 (14 strains, including BM4200), to the regions of Tn3701 outside of Tn3703 (5 strains), and to Tn916 alone (8 strains). The DNAs of five strains did not detectably hybridize with any probe. The tetM gene was identified in most chromosomal genetic elements coding for tetracycline-minocycline resistance. Since Tn3701-like elements are widely disseminated among antibiotic-resistant streptococci (47% of the 34 strains studied), we propose that Tn3701 be considered the prototype of chromosomal composite elements.

Chromosome Mapping↗
PubMed1988

Heterogeneity of chromosomal genes encoding chloramphenicol resistance in streptococci.

The DNA of 21 chloramphenicol-resistant plasmid-free streptococci was tested for sequence homology with the genes encoding chloramphenicol acetyltransferase (cat) of the staphylococcal plasmids pC194 and pC221. Homology to the cat gene of pC194 was detected in 11 strains, including the 8 strains of Streptococcus pneumoniae examined, and homology to cat of pC221 was found in 3 strains. The DNA of 7 strains did not detectably hybridize with either probe.

Acetyltransferases↗
PubMed1988

Molecular analysis of a composite chromosomal conjugative element (Tn3701) of Streptococcus pyogenes.

The plasmid-free Streptococcus pyogenes A454 contains a conjugative element, Tn3701, encoding resistance to erythromycin (Emr), tetracycline (Tcr), and minocycline (Mnr). We have mapped a 50-kilobase (kb) chromosomal region of A454 corresponding to the internal part of Tn3701. Tn3701 includes a 19.7-kb structure, designated Tn3703, on which the Emr Tcr Mnr determinants were localized. Tn3703 was very similar in structure to Tn916. Translocation of the Emr Tcr Mnr markers from A454 onto pIP964, an Enterococcus faecalis hemolysin plasmid, yielded different pIP964 derivatives. When the inserts of four of these derivatives were aligned with the 50-kb region of Tn3701, three of them were found to result from the transposition of Tn3703 and one resulted from the insertion of a 44.0-kb portion of Tn3701, including Tn3703. Tn3701 inserted, apparently without changing its structure, in the chromosomes of various streptococcal transconjugants, as well as in one of the 12 E. faecalis transconjugants studied. Tn3703 inserted at different chromosomal sites in four E. faecalis transconjugants, and one copy of Tn3701 plus an additional copy of Tn3703 were detected in the chromosomes of seven transconjugants.

Cloning, Molecular↗
PubMed1987

Location of antibiotic resistance markers in clinical isolates of Enterococcus faecalis with similar antibiotypes.

Eight wild-type strains of Enterococcus faecalis, resistant to chloramphenicol (Cmr), erythromycin (Emr), tetracycline (Tcr), and minocycline (Mnr), were examined for the genetic basis of their antibiotic resistance, Five of the strains transferred all of their antibiotic resistance markers by conjugation, while the other three strains transferred only Tcr and Mnr. Cmr and Emr determinants were localized by DNA-DNA hybridization experiments, in which the Cmr gene of plasmid pIP501, of group B Streptococcus origin, and the Emr gene of transposon Tn917, of E. faecalis origin, served as probes. A chromosomal location was found for the nonconjugative Cmr and Emr markers of one wild-type strain. In two strains these markers were carried by nonconjugative plasmids, and in the other strains they were carried by plasmids that transferred by conjugation. Plasmids isolated from three transconjugants resistant to tetracycline but susceptible to minocycline bore nucleotide sequences homologous to the tetL gene. Nucleotide sequences homologous to conjugative transposon Tn916, of E. faecalis origin, were detected by hybridization in the tetracycline-minocycline-resistant transconjugants. Three of these transconjugants were plasmid free, while four harbored conjugative cryptic plasmids. Sequences homologous to Tn916 were also found on two conjugative plasmids, one of which appeared to be a conjugative cryptic plasmid that had acquired chromosomal Tcr Mnr markers during transfer.

Chloramphenicol Resistance↗
PubMed1986

Dispersal of a plasmid-borne chloramphenicol resistance gene in streptococcal and enterococcal plasmids.

Plasmids coding for chloramphenicol resistance, five isolated from streptococci of groups A, B, and G, ten from enterococci (Enterococcus faecalis, Enterococcus faecium), and two from staphylococci, were tested for sequence homology with the chloramphenicol resistance gene of pIP501, a 30-kb plasmid originally isolated from a group B Streptococcus. The 6.3-kb HindIII fragment of pIP501, known to carry the chloramphenicol resistance gene, was cloned into pBR322. A 1.6-kb portion of the cloned fragment, which included most of the chloramphenicol resistance gene, was used as probe in DNA-DNA hybridization experiments. Sequence homology was detected between the probe and four of the streptococcal, seven of the enterococcal, and one of the staphylococcal plasmids. The absence of hybridization between this probe and one plasmid isolated from a group B Streptococcus, as well as three isolated from E. faecalis, indicated that there are at least two different plasmid-borne chloramphenicol resistance determinants in the streptococci and in the enterococci.

Chloramphenicol↗