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J L Brunton

Publications and source records attributed to J L Brunton.

36 records · Page 2Linked to original sources
PubMed1989

Plasmid mediated antimicrobial resistance in Ontario isolates of Actinobacillus (Haemophilus) pleuropneumoniae.

The genetic basis of antimicrobial resistance in Ontario isolates of Actinobacillus (Haemophilus) pleuropneumoniae was studied. Two Ontario isolates of A. pleuropneumoniae were found to be resistant to sulfonamides (Su), streptomycin (Sm) and ampicillin (Amp). Resistance to Su and Sm was specified by a 2.3 megadalton (Mdal) plasmid which appeared to be identical to pVM104, which has been described in isolates of A. pleuropneumoniae from South Dakota. Southern hybridization showed that the 2.3 Mdal Su Sm plasmid was highly related to those Hinc II fragments of RSF1010 known to carry the Su Sm genes, but was unrelated to the remainder of this Salmonella resistance plasmid. Resistance to Su and Amp was specified by a 3.5 Mdal plasmid and appeared identical to pVM105 previously reported. The beta-lactamase enzyme had an isoelectric point of approximately 9.0. Southern hybridization showed no relationship to the TEM beta-lactamase. A third isolate of A. pleuropneumoniae was found to be resistant to chloramphenicol (Cm), Su and Sm by virtue of a 3.0 Mdal plasmid which specified a chloramphenicol acetyl transferase. We conclude that resistance to Su, Sm, Amp and Cm is mediated by small plasmids in A. pleuropneumoniae. Although the Su and Sm resistance determinants are highly related to those found in Enterobacteriaceae, the plasmids themselves and the beta-lactamase determinant are different.

Actinobacillus↗
PubMed1988

Cloning and nucleotide sequence analysis of the genes determining verocytotoxin production in a porcine edema disease isolate of Escherichia coli.

The structural genes determining the edema disease principle were cloned from the total cellular DNA of Escherichia coli strain 412 (O139:K82) isolated from a case of porcine edema disease. An assay for cytotoxicity in Vero cells was used to detect the edema disease principle. A 7.5 kb EcoRI-SalI fragment specifying cytotoxin production was subcloned in pUC18. Sequences which specified production of cytotoxin were localized to a 0.9 kb region by transposon Tn5 mutagenesis. A 2.4 kb EcoRI-BglII fragment encompassing this region was subcloned into pUC18. Using nucleotide sequence analysis, two open reading frames separated by 12 bp were identified. They encoded proteins of 319 (A subunit) and 87 (B subunit) amino acids which both had N-terminal sequences typical of E. coli signal peptides. Comparison of these with the published sequence for the Shiga-like toxin II (SLT-II) showed 91% overall nucleotide sequence similarity. The nucleotide sequence similarity extended to 200 base pairs upstream of the putative A subunit translational start site suggesting a common regulatory mechanism. The deduced amino acid sequences of the processed A and B subunits had 94% and 84% similarity, respectively. These findings confirm the close genetic relationship between SLT-II and edema disease principle.

Amino Acid Sequence↗
PubMed1987

Glycolipid binding of purified and recombinant Escherichia coli produced verotoxin in vitro.

Escherichia coli verotoxin (also known as Shiga-like toxin) has been implicated in the aetiology of the hemolytic uremic syndrome and hemorrhagic colitis. The glycolipid binding specificity of verotoxin purified from E. coli H30 and verotoxin cloned from bacteriophage H19B has been examined. Verotoxin from both sources binds specifically to globotriosyl ceramide containing the carbohydrate sequence galactose alpha 1-4galactose beta 1-4glucose-ceramide. Removal of the terminal galactose or substitution with N-acetylgalactosamine in beta 1-3 linkage deletes toxin binding activity. A ceramide trihexoside species, consistent with a globotriosyl ceramide structure was shown to be the major verotoxin-binding glycolipid of cultured vero cells which are routinely used to measure the cytotoxicity of toxin samples.

Bacterial Toxins↗
PubMed1987

Characterization of a bacteriophage that carries the genes for production of Shiga-like toxin 1 in Escherichia coli.

The Shiga-like toxin 1-converting bacteriophage H-19B was recently shown to carry the structural genes for the toxin and was shown to have DNA sequence homology with phage lambda. We present evidence that the linear genome of bacteriophage H-19B has cohesive termini which become covalently associated during prophage integration. Integration occurs through a site on a 4-kilobase-pair EcoRI fragment located near the center of the bacteriophage chromosome. The relationship between bacteriophages H-19B and lambda was examined by Southern hybridization. Homologous regions were mapped on the respective chromosomes which corresponded to the regions of the J gene, the int-xis area, and the O and P genes of phage lambda. The H-19B tox genes were mapped to the right of the O and P gene homology, which was far away from the phage attachment site. We concluded that H-19B is a lambdoid bacteriophage. Unlike other toxin-converting bacteriophages, the toxin genes were not located adjacent to the phage attachment site. It appeared that the Shiga-like toxin 1 genes were not picked up by a simple imprecise prophage excision. H-19B could, however, have acquired chromosomally located toxin genes by a series of events involving deletion and duplication followed by aberrant excision.

Bacterial Toxins↗
PubMed1986

Cloning and expression of the genes specifying Shiga-like toxin production in Escherichia coli H19.

Some strains of Escherichia coli produce a protein which is cytotoxic for Vero cell and HeLa cell monolayers. This toxin is very similar to the toxin of Shigella dysenteriae 1 and has been named verotoxin or E. coli Shiga-like toxin. It has been shown that toxin conversion is due to a group of bacteriophages, one of which has been designated H-19B. In this study we report hybridization experiments showing that part of the H-19B genome is homologous to phage lambda. We have cloned a 1.7-kilobase BalI-BglII fragment from the genome of H-19B into pUC18. The recombinant plasmid confers the ability to produce high levels of Shiga-like toxin on transformed E. coli cells. We demonstrate using an in vitro transcription/translation system that the cloned fragment specifies the two verotoxin subunit peptides which have masses of 31 and 5.5 kilodaltons. The identity of peptides was confirmed by immunoprecipitation with verotoxin antiserum and protein A-Sepharose beads.

Animals↗
PubMed1986

In vitro studies of plasmid-mediated penicillinase from Streptococcus faecalis suggest a staphylococcal origin.

A strain of Streptococcus faecalis with plasmid-mediated penicillinase production was studied further. Partially purified penicillinase from the S. faecalis strain hydrolyzed penicillin, ampicillin, and ureido-penicillins but not penicillinase-resistant semisynthetic penicillins, cephalosporins, or imipenem; hydrolysis was inhibited by clavulanic acid. Hydrolysis of a given antibiotic correlated with a marked increase in the minimal inhibitory concentration (MIC) of that drug when a high inoculum was used. As with most enterococci, the MICs of cephalosporins and penicillinase-resistant semisynthetic penicillins were too high for clinical usefulness, although these agents did not show an inoculum effect. Based upon hybridization under stringent conditions of plasmid DNA from the S. faecalis strain to cloned penicillinase genes from Staphylococcus aureus, it appears that these resistance determinants are highly homologous and suggests that this enzyme was introduced into streptococci from staphylococci.

Anti-Bacterial Agents↗
PubMed1984

Q fever: hazard from sheep used in research.

The recent recognition that Q fever is endemic in Ontario and the known occupational risk of Q fever to research personnel working with sheep prompted a study to determine the prevalence of antibodies to the causative organism, Coxiella burnetti, in animals and staff at a Toronto animal research institute. Of 37 sheep 34 (92%) were found to be seropositive--that is, to have a titre of complement-fixing antibody to the phase II antigen of 1:8 or greater. Of 331 staff members tested, 18% were found to be seropositive, compared with 0.6% of a random sample of Toronto blood donors. The highest rate of seropositivity, 68%, was in the 28 animal attendants tested. Seropositivity was associated with working with sheep or fetal lamb tissue (p less than 0.0001) and with visiting the animal facility (p less than 0.001). Of the 59 seropositive staff members 63% had had no direct contact with sheep. There were 12 clinically apparent cases of Q fever, 2 of which required admission to hospital. Q fever remains a serious occupational hazard to staff working in research laboratories using sheep, even to those with indirect exposure to infected animals.

Adult↗
PubMed1983

Evolution of antibiotic resistance plasmids in Neisseria gonorrhoeae and Haemophilus species.

The emergence of beta-lactamase producing strains of Haemophilus influenzae and Neisseria gonorrhoeae has required fundamental changes in the antimicrobial therapy of disease caused by these organisms. Ampicillin resistance in both organisms is caused by plasmid mediated production of TEM beta-lactamase. This enzyme is specified by a sequence of mol. wt 3.2 X 10(6) which is capable of inserting itself at multiple sites in DNA replicons without the requirement for significant base sequence homology between donor and recipient replicon. Further, it does so without requirement for conventional recombination enzymes. Analysis of beta-lactamase specifying plasmids of H. influenzae show that they generally have a molecular mass in the order of 30 X 10(6) and contain the complete TnA sequence. They are conjugative but are incapable of mobilizing smaller beta-lactamase plasmids. Previous studies have presented evidence suggesting that these plasmids may have evolved by insertion of the TnA sequence (perhaps introduced from enteric bacteria) into a phenotypically cryptic plasmid of mol. wt 27 X 10(6) resident in rare strains of H. influenzae. In this study, we review data showing a high degree of homology between the small (3--7 X 10(6) mol. wt), nonconjugative beta-lactamase specifying plasmids of N. gonorrhoeae, H. parainfluenzae and H. ducreyl and present new evidence that cryptic plasmids highly homologous to the beta-lactamase plasmids are present in many strains of H. parainfluenzae. This suggests that the small beta-lactamase specifying plasmids of H. parainfluenzae, H. ducreyi and N. gonorrhoeae may have arisen by insertion of TnA into phenotypically cryptic plasmids present in H. parainfluenzae.

Ampicillin↗
PubMed1982

Primary and secondary healing in infected wounds. An experimental study.

The beneficial effects of delayed closure of contaminated wounds are recognized, but not well defined. Rats with abdominal incisions were infected with Staphylococcus aureus or Escherichia coli and then subgrouped for primary or secondary healing. Noninfected rats served as controls. Between seven and 119 days later, the wounds were subjected to breaking-strength determination, hydroxyproline analysis, and light and scanning electron microscopy. In the controls, secondary closure gave stronger wounds than primary closure. In those infected with S aureus the wounds were stronger than in the primary-closure control group, regardless of the closure method. Of the E coli-infected wounds those primarily closed were weaker than those secondarily closed. Secondary closure gave infected wounds fewer complications. Biochemical and microscopic examination did not explain these findings.

Abdominal Muscles↗
PubMed1982

Plasmid-mediated sulfonamide resistance in Haemophilus ducreyi.

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.

Endonucleases↗
PubMed1982

Haemophilus influenzae: comparison of respiratory tract isolates with genitourinary tract isolates.

Haemophilus influenzae isolates recovered from the genitourinary (GU) tract were shown to have a significantly different biotype distribution compared with respiratory tract isolates. Biotype IV strains were recovered more commonly from the GU tract, and most strains were non-serotypable. Antibiotic-susceptible strains isolated from the GU tract more frequently harbored plasmids of less than 10 megadaltons than did antibiotic-susceptible respiratory tract strains. One 2.8-megadalton plasmid resident in a GU tract isolate and one 1.8-megadalton plasmid resident in a respiratory tract isolate were shown to be related to the small ampicillin resistance plasmids previously described in H. influenzae, Haemophilus parainfluenzae, Haemophilus ducreyi, and Neisseria gonorrhoeae. This supports the suggestion that these ampicillin resistance plasmids originated by transposition or recombination of the ampicillin transposon (TnA) with cryptic endogenous Haemophilus plasmids.

Anti-Bacterial Agents↗
PubMed1979

A prospective controlled investigation of prophylactic trimethoprim/sulfamethoxazole in hospitalized granulocytopenic patients.

Oral trimethoprim/sulfamethoxazole (TMP/SMZ) therapy was investigated in the prophylaxis of infections in granulocytopenia. Hospitalized granulocytopenic patients were allocated at random to receive TMP/SMZ (group 1) or to a control group (group 2). The percentage of febrile granulocytopenic days was significantly reduced in group 1, 19 per cent compared to 39 per cent in group 2 (P less than 0.01). In group 1, there were no bacteremias in 59 episodes of granulocytopenia (909 days). In group 2, there were nine bacteremias in 52 episodes of granulocytopenia (796 days)(P = 0.001). Disseminated candidiasis developed in two patients in each group. Candida occurred in similar numbers in surveillance cultures in both groups; Staphylococcus aureus and Pseudomonas aeruginosa were slightly decreased, and Enterobacteriaceae resistant to TMP slightly increased in group 1. This study suggest that oral prophylactic TMP/SMZ therapy is an effective, well tolerated, easily administered alternative to "gut sterilization" with nonabsorbable antibiotics.

Acute Disease↗
PubMed1979

Plasmid-mediated ampicillin resistance in Haemophilus ducreyi.

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.

Ampicillin↗
PubMed1979

Cytotoxic enterotoxin produced by Aeromonas hydrophila: relationship of toxigenic isolates to diarrheal disease.

Ninety-six Aeromonas hydrophila isolates were tested for cytotoxin and hemolysin production. Sixty-six (69%) of the isolates were both cytotoxic and hemolytic, whereas the rest produced neither cytotoxin nor hemolysin. No evidence of a separate cytotonic activity could be found in any of the isolates. Cytotoxin activity correlated with enterotoxic activity. Of four cytotoxin-producing strains tested in the isolated rabbit ileal loop, three were definitely positive and one was borderline, whereas two nontoxigenic strains were negative. Cytotoxin activity appeared to be a stable property and could not be assoicated with any common identified plasmid; only 10 of 21 cytotoxin-producing strains could be shown to have any plasmid by agarose gel electrophoresis. Cytotoxin production correlated with a positive lysine decarboxylase phenotype (98%) or a positive Voges-Proskauer phenotype (94%), compared to 27% lysine decarboxylase-positive and 23% Voges-Proskauer-positive, cytotoxin-negative isolates (P less than 0.001 for both). In fecal samples, cytotoxin production correlated with diarrheal disease; of 40 diarrheal isolates, 32 (80%) were toxigenic compared to 9 (41%) of 22 nondiarrheal isolates (P = 0.004). It appears that A. hydrophila can be a cause of diarrhea and that this enteropathogenic potential is mediated by a cytotoxic enterotoxin.

Aeromonas↗
PubMed1978

Granulocytopenia in hospitalized patients: I. Prognostic factors and etiology of fever.

The clinical course of 126 hospitalized patients during 192 episodes of granulocytopenia and fever was studied. Fever was a regular accompaniment of granulocytopenia, occurring in 94 per cent of granulocytopenic episodes. The mean duration of granulocytopenia (less than 1,000/mm3) was 18 days, with fever (temperature greater than 38 degrees C) being present during 44 per cent of those days. Fever was present during 69 per cent of days with a granulocyte count less than 10/mm3. A presumed infection was present in 86 of 128 febrile granulocytopenic episodes in adults and in 19 of 64 febrile granulocytopenic episodes in children. A fungal infection was found in 11 patients; a viral infection in 23 patients. Bacteremia occurred during 44 granulocytopenic episodes with 16.8 bacteremias/1,000 days of granulocytopenia in adults and 12.7 bacteremias/1,000 days in children. The mortality was 33 per cent per granulocytopenic episode in adults and only 8 per cent per episode in children.

Adolescent↗
PubMed1978

Granulocytopenia in hospitalized patients. II. A prospective comparison of two antibiotic regimens in the empiric therapy of febrile patients.

The results of empiric antibiotic therapy in 126 hospitalized patients with fever during 192 episodes of granulocytopenia were studied. Febrile granulocytopenic patients were randomly allocated to receive either carbenicillin, methicillin and gentamicin, or carbenicillin and cephalothin. The response rate for the two antibiotic regimens was similar, 49 (60 per cent) of 81 responded to the former and 42 (54 per cent) of 78 to the latter. The response rate in patients receiving other antibiotics because of specific indications or counterindications was 19 (58 per cent) of 33. Thirty-nine (35 per cent) of 110 patients who responded to initial antibiotic therapy had an increase in circulating granulocytes of one log10 or more compared to only 10 (12 per cent) of 79 nonresponders with such an increase. The mortality rate in adult patients receiving carbenicillin, methicillin and gentamicin was eight (16 per cent) of 51, compared to 18 (37 per cent) of 49 in those receiving cephalothin and carbenicillin (P less than 0.05). The significance of this difference in the initial response rate or mortality rate between patients treated with the two antibiotic regimens when only patients with documented bacterial infection were considered. Patients who responded to their initial antibiotic regimen, and patients for whose fever no explanation was found, had the best prognosis.

Adolescent↗