Biomedical subjects
R Bayston
Publications and source records attributed to R Bayston.
Immunoblot fingerprinting of coagulase negative staphylococci.
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Catheter colonisation: a laboratory model suitable for aetiological, therapeutic and preventive studies.
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Intraventricular vancomycin for treatment of shunt-associated ventriculitis.
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Intraventricular vancomycin in the treatment of ventriculitis associated with cerebrospinal fluid shunting and drainage.
The results of treatment of 50 cases of ventriculitis associated with the use of cerebrospinal fluid shunts or external ventricular drains, and treated with intraventricular vancomycin, are reported. While the overall cure rate was 66% with four cases lost to follow-up, in those cases where treatment involved shunt removal, 20 mg vancomycin daily intraventricularly, and another appropriate systemic antibiotic, 22 of 24 cases were cured with two cases lost to follow-up. In those cases where the shunt was left in during treatment, results were poor and revision for blockage of the distal catheter of ventriculoperitoneal shunts was required in 44% of these. All five patients whose ventriculitis followed external ventricular drainage were cured. Despite relatively high trough levels of vancomycin in the cerebrospinal fluid, no evidence of toxicity was seen.
Enterocolitis in Hirschsprung's disease: a controlled study of the etiologic role of Clostridium difficile.
Cytopathic toxin neutralized by Clostridium sordellii antiserum was found in the feces of seven out of 13 children with Hirschsprung's disease complicated by enterocolitis (54%). Clostridium difficile was isolated from ten of these 13 children (77%). The frequency of fecal toxin positivity, the magnitude of toxin titers, and the isolation rate of C difficile were all significantly greater in children with Hirschsprung's enterocolitis than in children whose Hirschsprung's disease was not complicated by enterocolitis or in children without Hirschsprung's disease. It is suggested that C difficile may be causally related to enterocolitis in Hirschsprung's disease, but the age distribution of positive results indicates that the major etiologic role is confined to children under three years of age. Vancomycin was found to be an effective form of treatment in the children with enterocolitis in whom it was employed.
Bacterial colonisation of the upper pouch in neonates with oesophageal atresia.
The bacterial flora in the upper oesophageal pouch of forty neonates with oesophageal atresia was studied at daily intervals preoperatively. Of the twenty-nine infants whose oesophagus was anastomosed within 24 hours of admission, no organisms were isolated in sixteen, despite the fact that only nine of these patients had antibiotics. The remaining thirteen grew oropharyngeal organisms. Of eleven infants having delayed anastomosis eight received antibiotics. All eleven grew organisms in the upper pouch. Pseudomonas and serratia grew only in those receiving antibiotics. These results suggest that prophylactic antibiotics are rarely indicated. Efficient continuous aspiration of the pouch is probably more important.
Biochemical and cultural characteristics of "JK" coryneforms.
Antibiotic resistant coryneforms (group JK) have increasingly been reported as causes of serious sepsis in the immunosuppressed and in patients with implants. Their cultural and biochemical characteristics were examined in an attempt to provide a simple scheme for their recognition in the clinical laboratory. Their susceptibilities to a range of antimicrobials were determined, and an enriched selective medium was developed for their isolation from normally non-sterile sites. The JK coryneforms fell into a fairly homogeneous group, producing colonial morphology and biochemical profiles identical with reference strains, which allowed their recognition and differentiation from other coryneforms. All strains were resistant to penicillin and susceptible to vancomycin, but there was considerable variation with respect to other antimicrobials. There is scope for further rationalisation of biochemical tests for the recognition of these organisms.
Hydrocephalus shunt infections and their treatment.
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Detection of antibodies to Staphylococcus epidermidis in infected total hip replacements by an enzyme linked immunosorbent assay.
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A model of catheter colonisation in vitro and its relationship to clinical catheter infections.
A laboratory model for colonisation of silicone-rubber catheters by staphylococci is described. The criteria for true colonisation that involves adhesion of the organisms to the luminal surface are discussed. Light and scanning electron micrographs of the microcolonies produced in the laboratory model suggest that the same mechanisms of adhesion, involving extracellular slime, apply as in clinically colonised catheters. Potential uses of the model, for studying further the mechanisms of colonisation and particularly its prevention and treatment, are discussed.
The use of intraventricular vancomycin in the treatment of CSF shunt-associated ventriculitis.
Ten cases of shunt-associated ventriculitis treated with intraventricular vancomycin are described. Eight were cured of their infection, one of these without shunt removal, though this failed in another instance. There were no toxic or untoward effects except in one case, where intravenous administration of vancomycin produced a histamine-like reaction. Intraventricular vancomycin, preferably combined with oral rifampicin, should be considered in cases of intractable or problematic shunt-associated ventriculitis due to Gram-positive organisms.
Faecal flora in neonates with oesophageal atresia.
The bacteriological findings of a study of intestinal colonisation in 24 neonates with oesophageal atresia are reported. Only five of the patients received antibiotics. When compared with published findings in healthy neonates, the rate of intestinal colonisation in our series was prolonged, with Staphylococcus albus predominating in the first week. Anaerobic colonisation was delayed and bacteroides spp were present in only five patients by the third week. Bifidobacteria were almost completely absent. The onset of intestinal colonisation seemed to be related temporally to enteral feeding. The use of antibiotics in five patients resulted in colonisation by candida in four and clinical thrush in three.
Clostridial toxins in neonatal necrotising enterocolitis.
Clostridium difficile cytopathic toxin was found in the faeces or gut content of five of 39 neonates with necrotising enterocolitis (NEC). Toxin concentrations were uniformly low and did not differ from those found in healthy neonates. C difficile is unlikely to be involved in the pathogenesis of NEC. Stools from 33 babies with NEC were also tested for C perfringens alpha toxin, with negative results.
Bacteriological examination of removed cerebrospinal fluid shunts.
A conventional method of bacteriological examination of removed cerebrospinal fluid shunts was compared with another method which relies on microscopic and cultural examination of intraluminal fluid. Fifty-five shunts were tested. All eight cases of clinical shunt infection gave positive results with the latter method, whereas a further 23 shunts yielded positive cultures by the conventional method in the absence of clinical infection. The consequences of missed infections due to omission of microscopic examination and overdiagnosis using the conventional culture method are discussed.
No tissue reaction to shunt materials in hydrocephalic children.
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Association between Clostridium difficile and enterocolitis in Hirschsprung's disease.
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The sustained release of antimicrobial drugs from bone cement. An appraisal of laboratory investigations and their significance.
The release of gentamicin sulphate, sodium fusidate and diethanolamine fusidate from Palacos and CMW cements was studied using elution and serial plate transfer tests. Further tests were made to assay the drug remaining in the cement after antibacterial activity could no longer be detected by the above methods, to detect the sustained slow release of the residual drug, and to ascertain the mechanism of release. The results confirmed that the release of gentamicin sulphate could be detected for longer from Palacos cement than from CMW cement, but the opposite was true for sodium fusidate. Little difference was found in the case of diethanolamine fusidate. Comparison of elution and serial plate transfer tests, and of results of elution in buffers of different pH, demonstrated that the test method employed had a significant effect on the results, and the omission of details of methodology from some publications made comparison and evaluation of results difficult. Varying quantities of residual drug were found in cement from which antibacterial activity could no longer be demonstrated; further tests for sustained, slow release showed that the antibiotic did not remain fixed in the cement but was released at a rate too slow to be detected in the elution and serial plate transfer tests. It is concluded that antibiotics are released from the cement by a process of diffusion, but tests to determine the mechanism of diffusion were unhelpful. The theory of diffusion of drugs through solid matrices, and the clinical implications of the experimental findings, are discussed.