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Y A Chabbert

Publications and source records attributed to Y A Chabbert.

18 recordsLinked to original sources
PubMed1979

Reversible translocation of antibiotic resistance determinants in Salmonella ordonez.

Salmonella ordonez (BM 2000) codes for kanamycin (Km, aphA), ampicillin (Ap), streptomycin (SmSp:aadA and Sm:aphC), chloramphenicol (Cm), tetracycline (Tc) and sulfonamide (Su) resistances and for production of colicin Ib (Cib). Genetical analysis by incompatibility testing, conjugation, transformation and physical studies using electron microscopy, agarose gel electrophoresis, led us to associate the Km and Cib characters to a 98.7 kilobase (kb) IncI1 plasmid (pIP565), and the Sm (aphC) and Su determinants to a 8.3 kb plasmid (pIP605). The ApCmSmSp(aadA)SuTc determinants were not associated in BM2000 S. ordonez with a plasmid structure. Following conjugation of S. ordonez to E. coli, the ApCmSmSpSuTc determinants were found stably associated with a single plasmid structure (pIP173, 127.5 kb) belonging to IncI1 group. Agarose gel electrophoresis of plasmid DNA restriction endonuclease digests and electron microscopy heteroduplex analysis showed that the acquisition of the ApCmSmSpSuTc determinants resulted from the insertion into pIP565 of a 28.8 kb DNA sequence. This sequence coding for ApCmSmSpSuTu resistances in S. ordonez could be translocated either to pIP565 plasmid or to several IncI1 plasmids but never to plasmids belonging to IncW, IncP or IncFII, suggesting the existence of specific sequences on the IncI1 receptor plasmids. Moreover, R-determinants were translocated back "en bloc" from pIP173 to the chromosome of a susceptible S. ordanez. The results were consistent with the presence in BM2000 S. ordonez chromosomal DNA of an integrated translocatable sequence encoding ApCmSmSpSuTc resistances. Such a structural association could account for the stability of these resistances in the Salmonella ordonez serotype.

Ampicillin↗
PubMed1979

Plasmid epidemics.

Explore the source record for details and available documents.

Aminoglycosides↗
PubMed1978

Taxonomy and epidemiology of gram-negative bacterial plasmids studied by DNA-DNA filter hybridization in formamide.

Phylogenetic and epidemiological relatedness among transferable plasmids belonging to the IncC, IncM and IncH incompatibility groups has been studied by DNA-DNA filter hydridization. Hybridization was carried out on nitrocellulose microfilters, at low temperature, in formamide and under paraffin oil. The degree of hybridization among plasmids belonging to the IncC and IncM groups supported the conclusions drawn from genetic classification. Studies on relatedness among plasmids belonging to the IncH group allowed their classification into three phylogenetic sub-groups. Comparison of DNA sequences of three plasmids sharing the same genetic properties and isolated from different bacterial species suggested an epidemiological spread of the same plasmid.

Base Sequence↗
PubMed1978

Molecular studies and possible relatedness between R plasmids from groups B and D streptococci.

Resistance plasmids isolated from Streptococcus agalactiae (group B) and S. faecalis (group D) have been compared in regard to resistance markers, molecular weight, and DNA-DNA homology. Three of them (pIP501, pIP612, and pIP613) have been found to confer identical (or very similar) resistance patterns (erythromycin, lincomycin, and streptogramin B, respectively) and to have similar molecular weights (19.8 x 10(6), 22.7 x 10(6), and 17.6 x 10(6), respectively) and a high level of DNA-DNA homology in hybridization experiments (90 to 100%). These results are compatible with the view that these plasmids may derive from one common ancestor, and/or that they can be transferred between unrelated Streptococcus strains belonging to the same or different groups.

Anti-Bacterial Agents↗
PubMed1978

HR 756, the syn isomer of a new methoxyimino cephalosporin with unusual antibacterial activity.

HR 756, the syn derivative of 7-[(2-(2-amino-4-thiazolyl)-2-methoxyimino)acetamido]cephalosporanic acid, is a new semisynthetic cephalosporin. It was 80 times more active than the anti derivative against beta-lactamase-producing strains of gram-negative bacteria. The range of inhibitory concentrations of HR 756 against gram-negative bacteria, including Haemophilus influenzae, susceptible or resistant to penicillins and cephalosporins was from 0.01 to 0.1 mug/ml. This activity was consistently higher than those observed with cephalothin, cephaloridine, cephalexin, and cefazolin. Nevertheless, some strains of Enterobacter cloacae were resistant. HR 756 showed very similar activity to that of ampicillin against group A streptococci and Streptococcus pneumoniae.

Ampicillin↗
PubMed1978

Determination of the ID50 values of antibacterial agents in agar.

Microorganisms were plated on agar plates containing various concentrations of an antimicrobial drug and inhibition of growth was determined at each drug concentration. The ID50 value and the gradient of the line were calculated by the least square method. When 200 approximately 800 bacterial cells were inoculated on an agar plate, growth inhibition corresponded linearly with the log concentration of a drug within range of 5 approximately 95% inhibition. The ID50 value and the gradient obtained were reproducible and reliable using microorganisms at stationary phase of growth with all tested bacterial species and all tested antimicrobial agents. It was found that the ID50 values of drugs were more reproducible and may be more reliable than the MIC (minimum inhibitory concentration) values of the drugs.

Agar↗
PubMed1978

[Occurrence of R plasmids belonging to incompatibility group incC in Aeromonas hydrophila strains isolated from sewage water (author's transl)].

The susceptibility to antimicrobial agents of 321 strains of Aeromonas hydrophila was studied: 319 strains were found to be resistant to one or several antibiotics. Transfer of resistance markers was obtained from 24 strains. Five plasmids from these strains were classified into incompatibility group incC. Epidemiological consequences of R plasmid diffusion in water bacteria are discussed.

Aeromonas↗
PubMed1977

[Trimethoprim resistance plasmids: transferability and incompatibility groups (author's transl)].

Over a three year period, 119 strains of enterobacteria isolated from patients have been found resistant to trimethoprim (TMP) and sulfonamides (Su); 11 strains were resistant to TMP only. MIC of TMP were between 32 and 2048 microng/ml. Three groups of strains are described: (1) thymineless variants (2 strains); (2) TMP resistance non-transferable into Escherichia coli K12 (95 strains); (3) TMP resistance transferable into E. coli K12 (33 strains). TMP marker and Su marker have been transferred independantly from 13 strains; they were cotransferred from 20 strains. The incompatibility group of 31 plasmids has been determined: 10 belong to the fi+ type, group FII; 21 belong to the fi--type, group 6, group 7, group 10, group N and group I1. Epidemiological implications of such a wide range of incompatibility groups among a small number of plasmids specifying TMP resistance are discussed.

Drug Resistance, Microbial↗
PubMed1976

R plasmids in Streptococcus agalactiae (group B).

Two plasmids determining resistance to tetracycline (RIP500) and to chloramphenicol, erythromycin, lincomycin, and pristinamycin I (RIP501) were isolated from a strain of Streptococcus agalactiae. The frequency-of-resistance loss is very low for RIP500 (<3 x 10(4)) but higher for RIP501 (the efficiency was dependent upon the curing agents and incubation temperature and varied between 0.5 and 96%). Derivatives susceptible to all drugs were also obtained. RIP500 and RIP501 have similar molecular weights (17.9 x 10(6) and 20 x 10(6), respectively) and represent different percentages of total deoxyribonucleic acid (0.4 and 4%, respectively). The number of copies of RIP500 and RIP501 per cell is different, and these plasmids are likely replicated under different kinds of control (stringent and/or relaxed). No plasmid deoxyribonucleic acid was found in a derivative of strain B96 susceptible to all drugs.

Centrifugation, Density Gradient↗
PubMed1976

Chelocardin-inducible resistance in Escherichia coli bearing R plasmids.

Two plasmid-linked tetracycline resistance characters, tet A and tet B, were distinguishable in part, according to the level of resistance they conferred to minocycline (<3 mug/ml for tet A; >6 mug/ml for tet B). Escherichia coli K-12 strains that harbored the tet B character were also resistant to tetracycline but susceptible to chelocardin. In such tet B strains, subinhibitory concentrations of tetracycline could induce resistance to chelocardin as well as to otherwise inhibitory concentrations of tetracyclines. Chelocardin itself was ineffective as an inducer and therefore could be used to select constitutively resistant mutants. E. coli K-12 strains harboring the tet A character were also resistant to tetracycline and susceptible to chelocardin; tetracycline did not induce resistance to chelocardin in these strains.

Drug Antagonism↗
PubMed1976

[Instability of group FII plasmids in "Salmonella panama" (author's transl)].

Almost all Salmonella panama isolated in France only harbour R plasmids of incompatibility groups I1 (K Col Ib) and N (T). Reference R plasmids belonging to 11 incompatibility groups have been introduced into S. panama. All are stable after 50 generations except those of group FII. FII instability cannot be explained either by the presence of a group FII cryptic plasmid or by restriction enzymes in S. panama.

Conjugation, Genetic↗
PubMedDate not supplied

[Genetic map and structure in "Escherichia coli" K12 of a resistance plasmid isolated from "Salmonella ordonez" (author's transl)].

A resistance plasmid called R IP173 has been transferred into E. coli K12 from a multiresistant strain of S. ordonez isolated during an epidemic in Dakar. This plasmid mediates for colicine Ib production and resistance to ampicillin, streptomycin, spectinomycin, kanamycin, chloramphenicol, tetracycline and sulfonamides. It is transducible "en bloc" by the phage P1-kc between strains of E. coli K12. Compatibility studies have shown that R IP173 belongs to the fi- class, I1 group. It is transferred "en bloc" in conjugation experiments between E. coli K12 strains. But during transfers from S. ordonez into E. coli, incomplete variants are obtained, lacking different markers. A deletion map was obtained after analysis of 19 different variants, and it is suggested that the loss of markers results from the loss of genetic material during transfer. In this particular case, the deletions observed in transduction or conjugation experiments lead to identical genetic maps.

Ampicillin↗
PubMedDate not supplied

[Characteristics of "Streptococcus mutans" from endocarditis and susceptibility to antimicrobial agents (author's transl)].

Strains of Streptococcus mutans were isolated from blood cultures of ten patients with endocarditis. Nine of these patients had a typical clinical picture of subacute bacterial endocarditis, with fever, weakness, heart murmur and multiple positive blood cultures. All the patients had previous valvular heart diseases; only in three cases the initiating event involved some type of dental manipulations which where supposed as the source of infection. The major criteria for recognizing S. mutans were colony morphology on blood agar, characteristic extracellular polysaccharide production in 5% sucrose broth, acid formation in mannitol and sorbitol broth, and the failure of antigenic extracts of S. mutans to react with streptococcal group antisera. The susceptibility to antimicrobial agents was tested by the diffusimetric method with susceptibility disks. All the strains were susceptible to penicillin G, erythromycin, pristinamycin, lincomycin and tetracycline, and resistant to streptomycin and gentamicine.

Endocarditis, Subacute Bacterial↗
PubMedDate not supplied

[R plasmids incompatibility groups in epidemic Salmonella (author's transl)].

The susceptibility to antimicrobial agents of 410 strains belonging to six serotypes of epidemic Salmonella (S. wien, S. saint-paul, S. panama, S. heidelberg, S. isangi and S. brandenburg) was studied. Resistance to one or more antibiotics was shown for 228 of these strains. Study of resistance transfer was investigated for 25 multiresistant strains of different epidemic origin. Resistance was coded for by conjugative R plasmids except in the case of S. brandenburg. From 20 strains of Salmonella, 39 plasmids were transferred to E. coli K12. Twenty-nine of these plasmids were classified into 7 incompatibility groups: IncFI, FII, I1, I2, N, C, M. These same groups were also found for 84 R plasmids from different enterobacteria. The "epidemic character" of these Salmonella serotypes does not seem to be associated with carriage of any particular R plasmid.

Anti-Bacterial Agents↗