Biomedical subjects
Publications and source records attributed to E J Shaw.
The proposed flow microcalorimetric method for the diagnosis of bacteriuria has been extended to include antibiotic sensitivity testing. Sensitive organisms rapidly (4-8 min) show thermal responses to the added antibiotics over the normal range of concentrations (1 x, 2x, MIC value).
A test is described for assessing the sanitizing effect of napkin treatment products on naturally urine-wetted and faecally-contaminated napkins. This test defines in-use conditions which closely resemble typical domestic situations. One napkin treatment product ('Napisan'), tested at two different concentrations and with challenges of different numbers of babies' napkins, performed satisfactorily under the conditions used.
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We have assessed the bacteriological safety of a system of intravenous feeding by culturing catheters on removal, swabs taken from the catheter's skin entry sites, and samples of infusion fluid. Among 38 treatment periods using 51 catheters over 1551 patient days, septicaemia due to Staphylococcus aureus was observed in one treatment period and bacteraemias due to Staphylococcus albus and Diphtheroid species in two others. The Staph. aureus and the diphtheroids probably gained access via the skin entry site along the outside of the catheter. The origin of the Staph. albus was uncertain. Parenteral nutrition over extended periods can be a safe procedure if aseptic precautions are taken. The importance of the catheter's skin entry site as a source of contaiminating organisms is emphasised.
The results of Gram stains and cultures from 145 women with uncomplicated ano-genital gonorrhoea are presented. The site which gave the highest yield of gonococci was the cervix. Equally good results were obtained with Stuart's transport medium and direct plating in the clinic. Positive results from rectal specimens alone were obtained from 8.4% of the 119 women in whom the rectum was examined. In 89 women the results of rectal specimens taken through a proctoscope were compared with those of swabs passed blindly up the anal canal. When Stuart's transport medium was used swabs taken through a proctoscope gave better results than the swabs taken blindly; the latter gave more positive results when direct plating was used. Thus when Stuart's medium is used a proctoscope is essential for the collection of rectal samples. Up to three sets of investigations were carried out where necessary, but 95% of the 145 cases were diagnosed on the results of the first set. However, only 54% of those patients diagnosed at their first visit had positive Gram-stain results. Further refinement of culture results is unlikely to improve diagnostic yield; what is needed is better, rapid diagnosis in the clinic.
We describe the continuous-flow automation of a quenching fluoroimmunoassay for determination of the antibiotic gentamicin in serum. In the flow system, sample is mixed with fluorescein-labeled gentamicin, followed by antiserum, and after a short incubation the fluorescence is measured. The intrinsic blank signal of each sample is corrected for during its single passage through the system by pumping antiserum discontinuously, so as to divide the final stream into sections corresponding to conventional separate assay and blank mixtures. Analyses time for each sample is 6 min, and 20 samples can be run per hour. Sensitivity, precision, and accuracy are adequate for clinical purposes, and assays of patients' samples correlate satisfactorily with the results of manual quenching and polarization fluoroimmunoassays, and plate diffusion bioassay.
Two hundred strains of Staphylococcus aureus isolated from outpatients with infections of the skin and subcutaneous tissues were tested for sensitivity to penicillin, erythromycin, tetracycline, sodium fusidate, methicillin, clindamycin, chloramphenicol, and gentamicin. One hundred and sixty-three (81.5%) of the strains were resistant to penicillin and 16 (8%) resistant to tetracycline. Incidence of resistance to other antibiotics was low. No strain was resistant to chloramphenicol, gentamicin, or methicillin. When compared with results of earlier studies, there was an increase in the incidence of resistance to penicillin and tetracycline, but no appreciable increase in resistance to other antibiotics.
In controlled experiments intraperitoneal povidone-iodine significantly reduced the mortality of mice (p less than 0.01) and rats (p less than 0.01) with induced peritonitis. Povidone-iodine irrigation of the rat colon before and after anastomosis did not interfere with healing or inhibit peritoneal adhesion formation. However, a newly formulated povidone-iodine solution containing increased PVP significantly reduced adhesion formation in a controlled study in rats.
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Human cell membranes acquired an antigenic substance from the bovine serum in culture medium. The antigen was named the heterologous membrane antigen (HM Ag). Cross-reactive antigen was found in sera of all mammals tested, except for man. The distribution of the HM Ag serologically distinguished man from other mammals.
The intraperitoneal instillation of noxythiolin in the treatment of peritonitis is widespread in clinical practice despite contradictory evidence as to its efficacy. In this light the value of noxythiolin was reappraised by studying its effect in guinea-pigs and mice with induced bacterial peritonitis. Treatment with a 1% solution of noxythiolin reduced the mortality rate of mice by 14% (P less than 0.1). The guinea-pig model proved unreliable giving inconsistent mortality rates throughout. Further studies are required to determine the optimum dose and concentration of noxythiolin while the search for more effective intraperitoneal antiseptics should continue.
Water beds in use in this hospital were found to be contaminated with Pseudomonas aeruginosa. The addition of sodium hypochlorite, giving a final concentration of 200 parts/10(6) available chlorine, was found to be effective in preventing microbial contamination over a 6-month study period.
A new type of non-isotopic immunoassay, applied to the determination of serum gentamicin, is reported. The method is based on partial quenching of fluorescence observed when fluorescein-labelled gentamicin is bound by anti-gentamicin serum. The fluorescence intensity of the labelled gentamicin in an unseparated immunoassay incubation mixture therefore serves to indicate the extent of binding, which is related to the amount of competing unlabelled gentamicin present. Precision and accuracy are shown to be similar to those of the best existing methods for gentamicin, while the new assay is more rapid and technically simpler, and avoids the use of expensive radio-chemicals with their attendant health hazard. Assays of patient samples correlate with established bioassay and polarisation fluoroimmunoassay methods.
A double blind comparison of two regimens of amoxycillin plus probenecid in the treatment of uncomplicated anogenital gonorrhoea is reported. Forty-three (86-0%) of 50 patients treated with 1 g amoxycillin plus 1 g probenecid and followed-up for 14 days were regarded as cured, and 51 (94-4%) of 54 patients treated with 3 g amoxycillin plus 1 g probenecid were regarded as cured. Fifty-nine per cent of 69 isolates of Neisseria gonorrhoeae were sensitive to amoxycillin (minimum inhibitory concentration less than or equal to 0-05 mg/ml). Although there was no statistical difference between the results of the two regimens it is concluded that the larger dose of amoxycillin plus probenecid is required where only 60% of gonococci are sensitive to amoxycillin.
A wild type strain of E. coli which produced an invertase capable of hydrolysing sucrose and raffinose transmitted this ability at high frequency to a recipient strain. E. coli C. The ability to ferment both sucrose and raffinose was lost both in the wild type parent and recombinant strains by treatment with ethidium bromide.
Analysis of blood-cultures done at St. Bartholomew's Hospital over the decade 1966-75 has revealed a five-fold increase in the incidence of bacteraemia. This increase was particularly prominent in patients with non-malignant disease. The predominance of bacteraemia caused by gram-negative organisms declined in recent years, whereas bacteraemia due to gram-positive organisms, anaerobes, and Candida spp. increased. A recent increase in the number of blood-cultures performed was associated with the introduction of commercially prepared bottles. This led to a higher rate of investigation of patients who ultimately proved to have negative results, and also to a higher incidence of contamination which exceeded the positivity-rate.
A polarisation fluoroimmunoassay has been developed for the routine determination of gentamicin levels in serum. The method employs fluorescein-labelled gentamicin which is easily, reproducibly and economically prepared and has excellent shelf-life. The assay is fast (minimum incubation time 2 min) and requires 1.25 mul of serum. There is no separation step prior to readout of results. Recovery experiments reveal no serum effects. Intra- and inter-assay coefficients of variation are of the order of 10% or less. Estimations of gentamicin levels in patient serum samples correlate closely with those obtained by bioassay (r = 0.93) and radioimmunoassy (r = 0.97).