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Biomedical subjects

C A Hart

Publications and source records attributed to C A Hart.

At least 361 records · Page 20Linked to original sources
PubMed1988

Occurrence of multiple antibiotic resistance and R plasmids in Enterobacteriaceae isolated from children in the Sudan.

The prevalence of resistance to six commonly-used antimicrobial agents in faecal coliforms from children in Khartoum, Sudan was studied. A relatively high prevalence of resistance was found, ranging from 96% of children with isolates resistant to ampicillin to 70% of children with isolates resistant to chloramphenicol. Seventy-seven percent of children had isolates with high-level resistance to trimethoprim (MIC greater than 1000 micrograms/ml). Twenty-nine different resistance patterns were found. Thirty-nine percent of the children had isolates resistant to all six antibiotics studied, and 80% of children had isolates resistant to at least four. Transfer of resistance to each of the antimicrobials, in varying combinations, was demonstrated, but did not occur for all resistance patterns. Plasmid analysis showed plasmids ranging from 160 MDa to 2.8 MDa and isolates contained from one to five plasmids of different sizes. There were no consistent relationships between resistance pattern and plasmid profile, but multiple resistance transfer was mediated commonly by plasmids with a molecular weight of 62 MDa. The high prevalence of potentially transferable antibiotic resistance in gut commensals of children in the Sudan may be of importance in the management of enteric and other infections requiring antimicrobial treatment.

Ampicillin Resistance↗
PubMed1988

A preliminary investigation of antibiotic resistance in Enterobacteriaceae isolated from children with diarrhoea from four developing countries.

The prevalence of resistance to commonly used antibiotics was investigated in groups of children from four developing countries, Peru, Belize, Zaire and Sudan. Enterobacteriaceae spp. isolated from faeces of children with diarrhoea were tested for sensitivity to ampicillin, tetracycline, sulphonamide, trimethoprim, streptomycin and chloramphenicol. Overall, the highest prevalence of resistance was to sulphonamide (56% of children) and the lowest was to chloramphenicol (19% of children). For individual locations, isolates from Sudan had the highest prevalence of antibiotic resistance, 65% of the isolates being resistant to ampicillin, tetracycline, trimethoprim and streptomycin. Transfer of resistance was studied for some isolates using Escherichia coli Hb101 as recipient.

Belize↗
PubMed1988

C-reactive protein and bacterial meningitis.

We have studied prospectively the C-reactive protein values in the cerebrospinal fluid of 54 patients with bacterial meningitis, tuberculous meningitis, and severe malarial infection and convulsions without infections of the central nervous system. CSF CRP above 1 mg/l was observed in 23 out of 28 patients with bacterial meningitis (sensitivity of 82%). The specificity was 73% at the 1 mg/l level. Five out of 19 patients with severe malarial infection had CSF CRP levels above 1 mg/l. Two patients with TB meningitis were also studied. Both of them had CSF CRP above 1 mg/l. Five patients with febrile convulsions or sepsis without meningitis had CSF CRP below 1 mg/l. It is concluded that CSF CRP would not be used as a useful discriminatory test in areas where malaria and TB meningitis are common.

C-Reactive Protein↗
PubMed1988

Alphaherpesvirus saimiri in rabbits: a model for human encephalitis?

One (KM91) of a series of isolates of alphaherpesvirus saimiri (alpha HVS) produced rapidly fatal encephalitis in rabbits following intradermal infection, whereas the others (KM180, KM322 and KM338) were non-lethal and produced ganglionitis and prolonged latency. Alphaherpesvirus saimiri KM91 initially produced ganglionitis but quickly ascended the spinal cord to the brain causing death 10 days post-infection. Prior infection with any of the three benign isolates or inoculation with beta-propiolactone (beta PL)-inactivated alpha HVS KM91 protected rabbits from lethal encephalitis when they were subsequently challenged with a lethal dose of alpha HVS KM91. Each of 20 rabbits co-inoculated in the same site with a lethal dose of alpha HVS KM91 and either alpha HVS KM322 (1.5 X 10(3) to 1.5 X 10(5) p.f.u.) or beta PL-inactivated alpha HVS KM322 (1 X 10(7) p.f.u. equivalents) survived. In contrast only half of those co-inoculated with alpha HVS KM91 and beta PL-inactivated alpha HVS KM91 (1 X 10(7) p.f.u. equivalents) survived. Co-inoculation of lethal alpha HVS KM91 (75 p.f.u.) and benign alpha HVS KM322 (1.5 X 10(3) p.f.u.) into opposite flanks resulted in protection from encephalitis in one of four rabbits. Alphaherpesvirus saimiri KM91 was shown to have the capacity to become latent in dorsal root ganglia if the rabbit did not die.

Animals↗
PubMed1988

Trophoblast membrane infusion for unexplained recurrent miscarriage.

A novel protocol is described which has been developed for immunotherapy in unexplained recurrent miscarriage. This is based on a single intravenous infusion with isolated placental trophoblast plasma membrane vesicle preparations. Clinical experience gained with this approach is described. A total of 16/21 (76%) patients who subsequently had pregnancies have now achieved a live birth or are currently pregnant at greater than 28 weeks gestation.

Abortion, Habitual↗
PubMed1988

Plasmid-mediated conjugative transfer of Klebsiella sp. rcs genesable to induce colanic acid capsular polysaccharide biosynthesis in Escherichia coli.

Regulation of capsular biosynthesis (rcs) genes, encoding the ability to induce the production of a colanic acid polysaccharide capsule, were transferred to Escherichia coli by conjugation with Klebsiella pneumoniae (aerogenes) of capsular serotype K36. Transfer was mediated by a 58.4-MDa conjugative plasmid of incompatibility group IncM, which carried a copy of Tn7 (specifying resistance to trimethoprim and streptomycin) together with determinants for several further resistances. This plasmid did not carry the rcs genes itself, but mediated the conjugative recA-dependent transfer of part of the Klebsiella chromosome to E. coli. Once resident in E. coli, the rcs gene(s) could not be mobilised to other strains of E. coli, and the mobilising plasmid could be cured from capsulate transconjugants without loss of the ability to produce colanic acid. All such cured transconjugants contained an insertion of Tn7 in the chromosome, suggesting that the transposon might be involved in mobilisation of the rcs genes from Klebsiella sp. to E. coli. These findings explain previous observations that the ability to manufacture capsular polysaccharide could be transferred by plasmids between Klebsiella sp. and E. coli.

Conjugation, Genetic↗
PubMed1988

Acute transient myositis due to Toxocara.

Two children presented with spontaneous, isolated swelling of the lower half of the left leg; this was diagnosed as acute myositis of unknown aetiology. Further investigations showed antibodies to Toxocara. The symptoms resolved within 72 hours and the children were discharged on no treatment.

Animals↗
PubMed1988

Rapid identification of bacterial antigen in blood cultures and cerebrospinal fluid.

The ability of antibody coated latex particle suspensions to aid the diagnosis of septicaemia and meningitis in children was assessed in 272 blood culture sets and 85 cerebrospinal fluid specimens. This was also assessed in cases caused by Neisseria meningitidis group B infection. The method was 100% sensitive and 99% specific, with good predictive values (range 63% to 100%) and provided valuable support to the routine bacteriological examination of blood culture and cerebrospinal fluid.

Antigens, Bacterial↗
PubMed1988

Ciprofloxacin treatment of chlamydial infections of urogenital tracts of women.

Ciprofloxacin was evaluated in chlamydial infections of the urogenital tracts of women treated with a dosage regimen of 500 mg orally twice a day for seven days. Of the 40 women evaluated, 30 were infected with Chlamydia trachomatis only, two were infected with Neisseria gonorrhoeae only, and a further eight had combined gonococcal and chlamydial infections. Ten were found to be harbouring Chlamydia trachomatis in the urethra as well as the cervix. Neisseria gonorrhoeae was eradicated from all patients with or without concomitant chlamydial infection. The overall chlamydial reisolation rates were 14% (5/35) four weeks after treatment and 23% (6/26) 11 weeks after treatment. The organism was not reisolated from the urethra of any of the patients after treatment. Ciprofloxacin was effective against Mycoplasma hominis, but almost completely ineffective against Ureaplasma urealyticum.

Chlamydia Infections↗
PubMed1988

Lectin-induced damage to the enterocyte brush border. An electron-microscopic study in rabbits.

The ultrastructural effects of 11 lectins on the intestinal brush border were examined by means of an in vitro rabbit ileal mucosal explant culture system. Five of the lectins that bind to oligosaccharides containing either N-acetylglucosamine (phytohaemagglutinin, Euonymus europaeus lectin, pokeweed mitogen, and wheat germ agglutinin) or N-acetylneuraminic acid (Mycoplasma gallisepticum lectin) all had a specific effect on microvilli. The effects varied in accordance with the lectin and included lengthening, distortion, and vesiculation of the microvilli. In contrast, lectins binding specifically to galactose, glucose, mannose, and N-acetylgalactosamine had no effect. Incubation of mucosal fragments with the divalent cation ionophore A23187 did not mimic the effect of the lectins. This apparent relationship between lectin damage and receptor specificity may reflect either accessibility of appropriate binding sites or a differential response to binding.

Animals↗
PubMed1988

Impaired neutrophil killing in a patient with defective degranulation of myeloperoxidase.

A case of recurrent, superficial abscesses in an 18 year old girl, is described. Staphylococcus aureus was the pathogen most often implicated and on several occasions the abscesses required surgical drainage. Defects in humoral immunity, neutrophil chemotaxis or opsonophagocytosis were not observed. However, her neutrophil's ability to kill ingested S. aureus in vitro was impaired. This was associated with impaired luminol-dependent chemiluminescence in response to stimulation by either latex beads, or the chemotactic peptide FMLP plus cytochalasin B. Oxygen uptake and superoxide anion production were normal but release of myeloperoxidase by this patient's neutrophils occurred more slowly and to a lower extent than in control cells. These data suggest that the recurrent infections and diminished in vitro neutrophil bactericidal activity observed in this patient are associated with impaired degranulation of myeloperoxidase.

Abscess↗
PubMed1988

Myeloperoxidase secretion during phagocytosis: a case of a patient with impaired bactericidal activity.

We describe a case of a 5-year-old male patient with prolonged and extensive osteomyelitis of the left femur. Staphylococcus aureus was grown from blood cultures taken upon admission and also from pus drained from an incised hip joint. A defect in immune function was suspected and neutrophil function was assessed. Chemotaxis and phagocytosis were normal, but phagocytosed S. aureus were not killed as efficiently as in control neutrophils. No inherent defect in the ability of these neutrophils to generate reactive oxidants was observed, but an unusual luminol-dependent chemiluminescence response was obtained during phagocytosis of latex beads or opsonized S. aureus: This was characterized by an initial rapid, but transient increase occurring within 1 min of addition of phagocytic stimulus. Whereas during phagocytosis of latex beads by control neutrophils less than 1% of the total myeloperoxidase activity was detected extracellularly, up to 15% was released from the patient's neutrophils. We propose that release of myeloperoxidase from the patient's neutrophils during phagocytosis reduces the intraphagosomal concentration of this enzyme and thus impairs the efficiency of intracellular killing of S. aureus.

Chemotaxis, Leukocyte↗
PubMed1988

Viral redskins.

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Humans↗
PubMed1987

Oxidative inactivation of myeloperoxidase released from human neutrophils.

Within 1 min of stimulation of human neutrophils by the chemotactic peptide (N-formyl-L-methionyl-L-leucyl-L-phenylalanine) plus cytochalasin B, myeloperoxidase (together with other granule enzymes) was secreted and detected extracellularly. In contrast with the other granule constituents assayed (vitamin B12-binding protein and beta-glucuronidase), the activity of released myeloperoxidase rapidly decreased, so that, by 10 min after stimulation, only about 5% of the total cellular activity was detected. This inactivation was shown to be dependent on oxidant generation during the respiratory burst, since inactivation was not observed (a) after stimulation of anaerobic suspensions or (b) after release from neutrophils from a patient with chronic granulomatous disease; purified myeloperoxidase was rapidly inactivated after incubation with H2O2, presumably owing to the formation of an inactive enzyme-H2O2 complex. These results show that experiments designed to assess the role of myeloperoxidase in neutrophil functions which utilize assays based on peroxidase activity will grossly underestimate this enzyme if oxidant generation during the respiratory burst has also been activated.

Granulomatous Disease, Chronic↗
PubMed1987

Genome isomerism in two alphaherpesviruses: Herpesvirus saimiri-1 (Herpesvirus tamarinus) and avian infectious laryngotracheitis virus. Brief report.

Genome isomerism of avian infectious laryngotracheitis virus (ILT) and Herpesvirus saimiri-1 (HVS-1) (formerly H. tamarinus) was investigated using restriction endonuclease analysis and scanning densitometry. ILT DNA was found to have 2 isomers with a molecular weight of 109 X 10(6). HVS-1 DNA was found to have four isomers with a molecular weight of 102 X 10(6).

Animals↗