Biomedical subjects
Publications and source records attributed to D S Tompkins.
Experiments were conducted to investigate the microaerobic culture of Helicobacter pylori in a liquid medium by using gas-permeable Lifecell tissue culture flasks. Growth in Lifecell tissue culture flasks was 1.2 to 1.6 log units greater than that in glass control bottles. These results were comparable to those reported by the use of gyrated media.
The systemic immune response to Helicobacter pylori was examined in 69 children with recurrent abdominal pain and upper gastrointestinal symptoms. Twenty one (30%) children were histologically positive for H pylori. Eighteen of the 21 positive subjects and two H pylori negative subjects (one with normal mucosa, one with lymphocytic gastritis) were positive for H pylori IgG antibodies by enzyme linked immunosorbent assay (ELISA) (86% sensitivity, 98% specificity). In children with H pylori associated gastritis, there was a significant positive correlation (p less than 0.05) between IgG antibody titres and patient age. Intra-assay comparison of sera from histologically negative adults with those of histologically negative children showed that the cut off for positivity in the ELISA for adults was greater than that for children. Immunoblotting showed IgG positivity in 20 of the 21 patients with H pylori infection (95% sensitivity). Both ELISA and immunoblotting for IgA and IgM H pylori antibodies had poor discriminatory value for determining infection. Serological detection of H pylori IgG antibodies seems to be valuable in the assessment of children presenting with recurrent abdominal pain and other gastrointestinal symptoms, but assays must first be validated in paediatric populations.
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Ascorbic acid, the reduced form of vitamin C, may protect against gastric cancer. Accordingly, this study assessed the variability of ascorbic acid and vitamin C in the gastric juice of 77 patients with dyspepsia. There was a vitamin C concentration gradient from gastric juice down to plasma in subjects with normal gastric mucosa, but not in those with chronic gastritis. Patients with chronic gastritis had significantly lower gastric concentrations of vitamin C and ascorbic acid, and ascorbic acid concentrations were especially low in subjects with hypochlorhydria. The presence of the concentration gradient suggests that a mechanism for the secretion of vitamin C into the stomach exists. This is compromised by chronic gastritis. The very low ascorbic acid concentrations in hypochlorhydria may be a consequence of oxidation by bacterial nitrite. Those patients who by the Correa model are at greatest risk for gastric cancer have the lowest gastric levels of ascorbic acid.
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Patients' dresses were washed at 40 degrees C using an ordinary detergent for 1 week and a novel detergent with added 'Triclosan' for the following 2 weeks. The bacterial load on the finished laundry was acceptably low using either detergent. The killing of residual bacteria on washed clothing by drying in a tunnel finisher was demonstrated. This preliminary study did not show any benefits to be gained from the addition of 'Triclosan' to detergent for the low-temperature laundering of patients' clothing.
Gastric campylobacter-like organisms (CLO) were isolated from gastric tissues removed at sacrifice from 17 mature ferrets; all animals were colonized, but no macroscopic mucosal lesions or histological features of chronic gastritis were seen. The isolates resembled Campylobacter pylori in many cultural and biochemical characteristics, and produced substantial urease activity, but there were sufficient differences from C. pylori to suggest that ferret gastric CLO represents a separate species. Comparison of human C. pylori and ferret gastric CLO may help to elucidate the pathogenicity of the former in patients with gastritis, and the ferret may serve as a useful animal model for the study of C. pylori infection.
Agarose gel isoelectric focusing was used to determine the isoelectric points of ureases from strains of gastric campylobacterlike organisms isolated from ferrets (pI 5.4), baboons (pI 5.7), and pigs (pI 5.9) and from isolates of Campylobacter pylori in humans (pI 5.9). This technique may help differentiate these closely related bacteria.
beta-Lactamase production was demonstrated in four of nineteen strains of intestinal spirochaetes isolated from human subjects. The enzyme was preferentially active against penicillins and was inhibited by clavulanic acid; it was membrane bound and non-inducible. No plasmids were detected in the intestinal spirochaetes and the beta-lactamase-production characteristic was not transferable to non-producing strains.
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Faeces or rectal swabs from 1527 subjects were examined for the presence of intestinal spirochaetes by anaerobic culture on blood agar incorporating spectinomycin (400 mg/l). Twenty three specimens (1.5%) were positive, and only one of these came from a patient with diarrhoea. All positive specimens came from either Asians or known homosexuals. Comparative tests showed a close phenotypic similarity between the human isolates and non-pathogenic porcine intestinal spirochaetes. These organisms differ from Brachyspira aalborgi, a spirochaete isolated from subjects with histologically confirmed intestinal spirochaetosis.
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One hundred and seventeen specimens of cerebrospinal fluid from 94 patients were examined for the presence of pneumococcal and Haemophilus influenzae type b antigens using counterimmunoelectrophoresis and coagglutination tests. The coagglutination method using Phadebact reagents was as sensitive as counterimmunoelectrophoresis, but culture was a more sensitive diagnostic procedure than either test. A meningococcus coagglutination reagent, included in a prototype meningitis diagnostic kit, was also found to be as sensitive as counterimmunoelectrophoresis when tested on culture-positive cerebrospinal fluid specimens. Coagglutination tests for the detection of bacterial antigen are useful supportive tests when used in conjunction with direct microscopy and culture for bacterial pathogens.
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The Phadebact Gonococcus Test, a coagglutination procedure for the confirmation of identity of presumptive N gonorrhoeae isolates, was evaluated under normal working conditions in a routine diagnostic laboratory and compared with an immunofluorescence technique. Of 166 isolates of N gonorrhoeae from urogenital, rectal, and pharyngeal sites, 164 gave a positive coagglutination reaction, and one of the two negative isolates gave a positive reaction on retesting after subculture. There were no cross-reactions with other organisms tested. This was in contrast with the immunofluorescence technique; with this method, three of 46 isolates of N meningitidis fluoresced brightly, and a further 17 isolates of N meningitidis gave reactions that were difficult to interpret. The coagglutination test is rapid, simple and a more specific alternative to immunofluorescence.