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Biomedical subjects

R Bayston

Publications and source records attributed to R Bayston.

At least 19 recordsLinked to original sources
PubMed1992

Infection of cerebrospinal fluid shunts in infants: a study of etiological factors.

The aim of this study was to find reasons for the high incidence of cerebrospinal fluid shunt infections seen in neonates. Four-hundred sixty-six consecutive shunt operations were analyzed retrospectively in 294 children, and 60 children were studied prospectively by quantitative sampling of skin bacteria before surgery and by sampling open wounds, shunt catheters, surgical gloves, and airborne bacteria. In total, 110 strains of coagulase-negative Staphylococcus isolated from the skin of 53 children before surgery were then tested for bacterial adherence. Retrospectively, the infection rate for infants younger than 6 months old was 15.7% (28 of 178 procedures), compared with 5.6% (16 of 288 procedures) for older children (p = 0.0005). Of all infections, 67% were due to coagulase-negative Staphylococcus. Age was the only major factor influencing the infection rate. Three of the 60 children studied prospectively developed postoperative shunt infections. All were younger than 6 months and all had high skin bacterial densities before surgery. Contamination during surgery was generally low, but correlated with the preoperative skin bacterial density. Strains of coagulase-negative Staphylococcus with high bacterial adherence were more commonly found in neonates than in older children. High skin bacterial density in neonates before surgery was a risk factor for infection in this study. These results also suggest that there is selection of more virulent strains of coagulase-negative Staphylococcus on the skin of neonates. Prevention of shunt infections in this high-risk group could be facilitated by the reduction of skin bacterial density before surgery using chlorhexidine shampoos and by the elimination of contamination by skin bacteria during surgery using packs soaked in an antiseptic agent to isolate wound edges and glove-changing before handling the shunt.

Adolescent↗
PubMed1991

Pneumococcal meningitis in a child with a ventriculo-peritoneal shunt.

A case of pneumococcal meningitis in an infant with a ventriculo-peritoneal shunt is reported. There was initial failure of treatment with penicillin and cefotaxime in full dosage. Eradication of infection without shunt removal was eventually achieved by adding rifampicin to the antibiotic regime.

Cefotaxime↗
PubMed1991

The Doppler pulsatility index as a screening test for blocked ventriculo-peritoneal shunts.

Doppler ultrasound studies have demonstrated a raised Gosling pulsatility and Pourcelot resistance index in untreated hydrocephalus. The application of transcranial Doppler ultrasound to the diagnosis of blocked ventriculoperitoneal shunts was studied by comparing the Gosling pulsatility indices of 63 children with symptoms of shunt malfunction with a reference range derived from 248 asymptomatic shunted children. An abnormally raised pulsatility index predicted a blocked shunt with a sensitivity of 56% and a specificity of 97%. The pulsatility index correlated with intracranial pressure in patients with confirmed shunt blockage.

Adolescent↗
PubMed1991

Determination of C reactive protein: an evaluation of three methods.

Two semi-quantitative methods--a latex kit and a precipitin test--and a quantitative turbidometric technique were compared to determine the concentration of C reactive protein in serum. Neither of the semi-quantitative tests was found superior in respect of performance or rapidity to the turbidometric method. The cost of capital equipment needed for the latter is high, but it may also be used for a range of other rapid quantitative determinations.

Adolescent↗
PubMed1990

A prospective randomised controlled trial of antimicrobial prophylaxis in hydrocephalus shunt surgery.

Despite attempts to reduce their incidence, shunt infections remain a major complication of the treatment of hydrocephalus. Various forms of antimicrobial prophylaxis are in use, but no controlled, statistically valid trial has been conducted to assess their efficacy. Such a trial was therefore carried out and its design is described here. After a 1-year retrospective and prospective study by members of the United Kingdom Hydrocephalus Group to establish feasibility and infection rates, a statistical study showed that at least 712 patients would be required. Six centres were enrolled to fulfil these requirements, and ethical committee approval was obtained at each. The chosen prophylactic regimen was 10 mg vancomycin administered into the ventricular system during surgery. Adults and children undergoing insertion or revision of ventriculoperitoneal shunts were included unless they were receiving therapeutic antimicrobials. Randomisation was by computer-generated numbers. Controls received the antimicrobial regimen, if any, currently used in that centre, the only difference between the two groups being intraventricular vancomycin in the test group. Diagnosis of shunt infection included accepted clinical and microbiological criteria reinforced by measurement of serum C-reactive protein levels. Follow-up was for at least six months. After 2.5 years only 158 patients had been enrolled in the trial, 80 controls and 78 tests. There were 5 preventable infections in the control group and 2 in the test group. In view of the small total the planned statistical analysis was not possible. Therefore, while no problems were encountered with toxicity, the trial failed to enroll enough patients to answer the question of efficacy of antimicrobial prophylaxis in shunt surgery and the reasons for this are discussed.

Cerebrospinal Fluid Shunts↗
PubMed1990

Morbidity and outcome of shunted hydrocephalus.

Over an eighteen month period 50 children with hydrocephalus of different aetiologies were treated with a ventriculo-peritoneal shunt during the first year of life. The morbidity associated with their shunts and their outcome were reviewed after 10 years. During the 10 year follow-up period 82% required a shunt revision. The number of hospitalisations varied widely (range 0-13, median 3). 28% suffered from a shunt infection at some time during the 10 years. Shunt revisions and shunt infections had no significant effect on long-term outcome. 72% of the infants had a good outcome and the sub-group of infants with post-haemorrhagic hydrocephalus fared as well as the rest.

Cerebrospinal Fluid Shunts↗
PubMed1990

Production of extra-cellular slime by Staphylococcus epidermidis during stationary phase of growth: its association with adherence to implantable devices.

A method of optimising slime production produced by Staphylococcus epidermis and its quantitative assay was developed, which gave a preliminary indication of its identity and an assessment of the correlation between slime production and adherence of the organism to implants. After inducing vigorous growth in brain heart infusion broth to stationary phase, all nutrients were removed by washing and the organisms resuspended in sterile deionised water with added magnesium. After further incubation the culture was centrifuged and the supernatant reacted with alcian blue in 50 mM magnesium chloride/sodium acetate solution, and the amount of bound dye was measured spectrophotometrically at 620 nm after its resolubilisation using sodium dodecyl sulphate. Large quantities of slime were produced by some, but not all, strains. Preliminary electrophoresis of the slime showed mobility and staining similar to that of the glycosaminoglycans. Adherence was tested by growing strains in wells of tissue culture plates and aspirating the supernatant after incubation. After fixation and staining of adherent growth the amount of bound stain was determined spectrophotometrically after its elution with ethanol. In this series of organisms there was no correlation between the result of tests for adherence or production of extracellular slime, and no correlation between either of these and the clinical source of the organisms.

Bacterial Adhesion↗
PubMed1989

Surgery, sepsis, and nonspecific immune function in neonates.

An audit of 143 neonatal surgical operations identified low birth weight infants as being at particular risk of developing post-operative sepsis following major surgical trauma. Activity of the nonspecific immune system was examined pre- and post-operatively in order to elucidate the susceptibility to post-operative sepsis of these infants. A chemiluminescence micro-method was developed specifically for this purpose. Neonatal plasma was shown to have significantly impaired opsonising activity, and activity was further reduced in low birth weight infants. Levels of immunoglobulin and complement factors were also reduced, particularly in the low birth weight infant. Following major surgical trauma polymorph activity was significantly lower in low birth weight infants than in mature neonates.

Anti-Bacterial Agents↗
PubMed1989

The epidemiology of peritonitis caused by coagulase-negative staphylococci in continuous ambulatory peritoneal dialysis.

The epidemiology of 10 episodes of CAPD peritonitis caused by coagulase-negative staphylococci was studied. The infecting micro-organism was found in prospective skin swabs in six episodes, widely distributed and as the predominant, or equally predominant, organism at each site but was not detected in swabs taken more than 12 weeks before the episode of peritonitis; this suggests recent acquisition. Infecting strains were no more likely to be adherent or to produce slime than non-infecting strains, nor had they any other characteristic detected in our typing scheme that might lead to their detection before peritonitis developed.

Bacterial Adhesion↗
PubMed1989

Prevention of hydrocephalus shunt catheter colonisation in vitro by impregnation with antimicrobials.

A process is described by which hydrocephalus shunt catheters can be impregnated with antimicrobials. The processed catheters showed antimicrobial activity at their surfaces for long periods and could be sterilised by autoclaving. When tested in vitro in a model of catheter colonisation using large challenge doses of Staphylococcus epidermidis and prolonged perfusion, some antimicrobials failed to protect against colonisation whereas others protected against one or two challenges. A combination of rifampicin and clindamycin gave best results, protecting against three successive challenges over a 28 day perfusion period. Resistant organisms did not develop. The process is likely to be useful in prevention of hydrocephalus shunt infection.

Anti-Bacterial Agents↗
PubMed1988

Haemophilus influenzae meningitis in the presence of cerebrospinal fluid shunts.

Haemophilus influenzae is an uncommon pathogen in shunted patients and there is uncertainty about optimal management. We report here two cases which were managed differently, with different outcomes. The first case was treated with chloramphenicol and the shunt was not removed. Although there were subsequent episodes of respiratory infection, the outcome was satisfactory. The second case was treated with cefuroxime and the shunt was exteriorized. Re-shunting was followed by relapse and further shunt removal. This and other case reports suggest that in Haemophilus meningitis in shunted patients treatment need not involve shunt removal, but that this is so only if appropriate antimicrobials such as chloramphenicol are used.

Cefuroxime↗