Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three of 19 strains of Haemophilus ducreyi, isolated during a recent outbreak of chancroid, were found to produce beta-lactamase and to harbor a 6.0 x 10(6)-dalton plasmid. Escherichia coli transformed with this plasmid acquired beta-lactamase-mediated resistance to ampicillin. The guanine-plus-cytosine content of the plasmid was found to be 41 mol%. Restriction endonuclease digestion studies suggest that a relatively large portion of the Tn1 translocon is carried by this plasmid. Whereas this plasmid could not be transferred to H. influenzae by mating on membrane filters, a strain of H. ducreyi was able to receive and donate a 30 x 10(6)-dalton ampicillin resistance plasmid from H. influenzae. The ability of H. ducreyi to receive and donate conjugative plasmids may result in the appearance of multiply resistant strains.
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PMID:Plasmid-mediated ampicillin resistance in Haemophilus ducreyi. 31 18

Intraspecies genotypic heterogeneity among Haemophilus ducreyi isolates was examined by using genomic fingerprints with rRNA from Escherichia coli as a probe. DNA from 44 isolates of H. ducreyi was digested by restriction endonuclease HincII or HindIII, separated by agarose gel electrophoresis, transferred to nylon membranes, and hybridized with 32P-labeled 16S and 23S rRNA. HincII digests yielded four hybridization patterns (ribotypes), whereas HindIII digests yielded eight ribotypes. Four HincII and five HindIII ribotypes were observed among 14 H. ducreyi isolates collected within a period of 1 month in Kenya, where chancroid is endemic. In contrast, one HincII and two HindIII ribotypes were observed among 28 isolates collected during the Orange County, Calif., chancroid epidemic that occurred in 1981 and 1982. The plasmid content, in conjunction with ribotyping, provided additional differentiation among some isolates of H. ducreyi. This study demonstrates that ribotyping of H. ducreyi may be used to study the epidemiology of chancroid.
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PMID:Molecular characterization of Haemophilus ducreyi by ribosomal DNA fingerprinting. 166 18

An Actinobacillus pleuropneumoniae strain contained a plasmid (pHD8.1) conferring resistance to streptomycin and sulfonamide. Restriction endonuclease mapping and DNA-DNA hybridization showed that pHD8.1 is related to RSF1010 from Salmonella panama, which also confers resistance to streptomycin and sulfonamide, and to pHD148 from Haemophilus ducreyi, which confers resistance only to sulfonamide.
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PMID:Characterization of a streptomycin-sulfonamide resistance plasmid from Actinobacillus pleuropneumoniae. 254 56

Haemophilus species have been implicated as the source of plasmid-mediated ampicillin resistance in Neisseria gonorrhoeae. Previous attempts to transfer conjugally the resistance plasmids from Haemophilus species to N. gonorrhoeae have met with limited success. Using both biparental and triparental mating systems, it was found that transfer will occur if the commensal Neisseria species, Neisseria cinerea, is used as a transfer intermediate. This organism stably maintains resistance plasmids of Haemophilus and facilitates transfer of these plasmids to N. gonorrhoeae, in a triparental mating system, at a transfer frequency of 10(-8). Both Haemophilus ducreyi and N. gonorrhoeae carry mobilizing plasmids capable of mediating conjugal transfer of the same resistance plasmids. However, restriction endonuclease mapping and DNA hybridization studies indicate that the mobilizing plasmids are distinctly different molecules. Limited homology is present within the transfer region of these plasmids.
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PMID:Transfer of plasmid-mediated ampicillin resistance from Haemophilus to Neisseria gonorrhoeae requires an intervening organism. 302 Jul 21

Haemophilus ducreyi is the etiologic agent of chancroid, an infection which is endemic in tropical and subtropical areas of the world and which is becoming more prevalent in Europe and North America. Recently, several strains have demonstrated resistance to several antimicrobials by plasmid acquisition and cell envelope alteration making control of the spread of this organism a challenge. Equally challenging is the growth of this organism in the clinical microbiology laboratory because of its in vitro fastidious nature. Currently, the therapy of choice for Haemophilus ducreyi infection is trimethoprim sulfamethoxazole or erythromycin. Plasmid enumeration and restriction endonuclease fingerprinting in addition to outer membrane protein profiles may provide a basis for subtyping which would be useful in epidemiologic studies.
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PMID:Haemophilus ducreyi. 388 2

A clinical isolate of Haemophilus ducreyi was found to harbor three plasmids: a 23.5-megadalton (Mdal) phenotypically cryptic plasmid, a 7.0-Mdal ampicillin resistance plasmid, and a 4.0-Mdal sulfonamide resistance plasmid. The two smaller plasmids were transferable by conjugation to Haemophilus recipients, but only if the donor cell harbored the 23.5-Mdal plasmid as well, indicating that this large plasmid had mobilizing capabilities. Transfer was also possible to Escherichia coli recipients. Haemophilus influenzae transconjugants which had acquired both the 23.5-Mdal plasmid and one of the R-plasmids could subsequently retransfer the R-plasmid to other Haemophilus recipients at higher frequencies. A derivative of the 23.5 Mdal plasmid was isolated which was shown by restriction endonuclease analysis to contain an ampicillin resistance transposon and to have retained its conjugative ability.
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PMID:Mobilization of nonconjugative antibiotic resistance plasmids in Haemophilus ducreyi. 627 68

Clinical isolates of Haemophilus ducreyi from patients with chancroid were shown to have one or more 4.9- to 7.0-megadalton non-self-transferable plasmids and to have in vitro resistance to sulfonamides. Transformation of Escherichia coli to sulfonamide resistance was associated with the acquisition of a 4.9-megadalton plasmid, which did not confer linked resistance to streptomycin. The guanine-plus-cytosine content of this plasmid was found to be 57%. Filter-blot hybridization and restriction endonuclease digestion studies suggested a relationship of this plasmid to RSF1010. Electron microscope heteroduplex analysis confirmed this relationship. The identification in H. ducreyi of a plasmid closely related to plasmids found in enteric species, rather than transposition of a resistance determinant to an indigenous plasmid, suggests that further dissemination of the enteric plasmid pool to this genus is possible since plasmid transfer between certain Haemophilus species is readily demonstrated.
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PMID:Plasmid-mediated sulfonamide resistance in Haemophilus ducreyi. 628 5

Seven strains of Haemophilus ducreyi from diverse geographic origins were analyzed for their plasmid content. All strains were multiply resistant, but only resistance to ampicillin was transferred to Escherichia coli by transformation. The H. ducreyi plasmids encoding for ampicillin resistance were 7.4, 5.7, and 3.6 megadaltons and encoded for part or all of TnA, and ampicillin transposon. The relatedness of these plasmids was examined by restriction endonuclease digestion and DNA-DNA homology with isolated DNA fragments from TnA.
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PMID:Characterization of ampicillin resistance plasmids from Haemophilus ducreyi. 628 12

Restriction endonuclease maps of the ampicillin resistance plasmids of Haemophilus ducreyi and Neisseria gonorrhoeae show marked structural similarities. Transfer frequencies obtained by mobilization correlated with physical structure and were enhanced by increased homology with the conjugative plasmid. The origin of transfer of each plasmid was located within a specific restriction fragment.
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PMID:Characterization of ampicillin resistance plasmids of Haemophilus ducreyi and Neisseria gonorrhoeae with regard to location of origin of transfer and mobilization by a conjugative plasmid of Haemophilus ducreyi. 631 3

Clinical isolates of Haemophilus ducreyi were shown to be resistant to tetracycline. Resistance was associated in some strains with a 30-megadalton plasmid capable of transferring resistance in conjugative matings with other strains of H. ducreyi and other species of Haemophilus. Restriction endonuclease digestion patterns suggest a relationship between H. ducreyi plasmids and other tetracycline resistance plasmids in Haemophilus. The presence of plasmid-mediated resistance to the tetracyclines limits the use of these agents for the treatment of chancroid.
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PMID:Plasmid-mediated tetracycline resistance in Haemophilus ducreyi. 632 65


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