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Biomedical subjects

W C Noble

Publications and source records attributed to W C Noble.

At least 73 records · Page 4Linked to original sources
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

Onchodermatitis--correlation between skin disease and parasitic load in an endemic focus in Ecuador.

Onchocerciasis is a chronic parasitic infection in which infiltration of the skin by microfilariae has been associated with a number of different pathological changes. This survey compared the prevalence of different forms of skin disease in two villages, one of which was located within the endemic zone for onchocerciasis (Zapallo Grande), in a lowland rain forest area of western Ecuador. The commonest skin diseases in both villages were scabies, pyoderma and pityriasis versicolor. In addition changes closely correlated with the presence of microfilariae in skin snips were found in Zapallo Grande--such as atrophic gluteal changes, and acute and chronic papular dermatitis. The only other skin disease associated with onchocerciasis was widespread tinea corporis due to T. rubrum. The Amerindians in the endemic onchocerciasis area were more likely than Negroes to have generalized atrophic changes of the skin, whereas in the latter group significant numbers of individuals had no obvious skin lesions but large numbers of microfilariae were detected in skin snips. Acute papular dermatitis was common in both groups and in biopsied lesions microfilariae could usually be identified within the epidermis or close to the dermo-epidermal junction. One patient had developed severe reactive onchodermatitis (Sowda). Swabs taken from onchocercal skin lesions showed no evidence of skin surface carriage of Staphylococcus aureus. Changes classically associated with onchocerciasis such as pretibial hypopigmentation (leopard skin) and hanging groin were notably absent in this population.

Adolescent↗
PubMed1989

The preservation of micro-organisms in biological specimens stored at-70 degrees C.

The preservation of micro-organisms that may be found on the skin was studied by storage in liquid media at--70 degrees C. In the first part of the study the performance of 12 varieties of suspending media was evaluated with pure cultures of 17 species of micro-organisms maintained in the laboratory. After storage for 1 year the best medium (Oxoid Nutrient Broth with 15% glycerol) showed a mean survival for all organisms studied of 83.8%, with no significant differences between organisms. Even the worst medium (distilled water) permitted greater than 40% survival at 1 year. No changes in the characteristics of these micro-organisms were detected after 6 months storage in glycerol broth. In the second part of the study nose swabs were suspended in one representative medium (Bacto Nutrient Broth containing 7% glycerol). The mean percentage survival of staphylococci in these suspensions after 1 year's storage at - 70 degrees C was 75.4%. These results indicate that coagulase-negative coagulase-negative staphylococci in samples of skin flora may be stored under these conditions for long periods, greatly reducing the work-load in epidemiological studies of infection.

Cryopreservation↗
PubMed1989

Studies on antagonism between porcine skin bacteria.

Strains of Staphylococcus warneri, Staph. epidermidis and Aerococcus viridans isolated from porcine skin were shown to produce substances that inhibited the growth of Staph. hyicus. Studies of interactions between the inhibitor-producing bacteria and Staph. hyicus on cellulose acetate membranes demonstrated a significant reduction (P less than 0.001) of the Staph. hyicus population at various stages of its growth cycle, depending on the inhibitor used. Inhibitor production profiles in batch culture showed a change in production with culture growth. Trypsin and an extracellular substance from Staph. hyicus had similar effects in reducing inhibitor production. Staphylococcus hyicus was shown to produce varying amounts of a proteolytic enzyme during growth in batch culture. Such in vitro models of bacterial interaction enable potential mechanisms of disease control using inhibitor-producing organisms to be investigated and provide a basis for studies in vivo.

Animals↗
PubMed1989

SDS-PAGE protein patterns of yeasts from human sources.

Protein patterns of Candida species and other yeasts have been studied by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Although differences in patterns occur which tend to separate the species, variability between replicate samples is sometimes high. The method cannot be used for speciation of common yeasts from medical sources.

Candida↗
PubMed1989

Staphylococcus aureus nasal carriage, exit-site infection and catheter loss in patients treated with continuous ambulatory peritoneal dialysis (CAPD).

Over a three-year period, 217 episodes of bacterial peritonitis occurred in 183 patient years. Thirty-seven episodes were due to Staphylococcus aureus and 19 (51%) of these required removal of the catheter to eradicate infection. This compared with catheter loss in 4/63 (6.3%) coagulase negative staphylococci infections (p less than 0.001); 7/67 (9.5%) culture negative peritonitis (p less than 0.001); and 10/30 (33.3%) episodes due to gram-negative organisms (p less than 0.05). Over half (51.3%) the episodes due to S. aureus were associated with exit-site infections, and this rose to 100% (10/10) with recurrent peritonitis (p less than 0.01). A prospective analysis of nasal carriage and exit-site infections due to S. aureus was carried out in 87 patients. Exit-site infections were present in 21 (24%), almost entirely due to different strains as judged by sensitivity patterns and phage typing. Nasal carriage, defined as two positive swabs within the study period, was present in 20 (23%) patients. Fourteen (70%) of these had exit-site infections due to the same strain as that isolated from the nose, whereas no patient grew different strains from either site. Nasal carriage increased the risk of infection sixfold (p less than 0.001).

Catheters, Indwelling↗
PubMed1988

A study of the value of electrophoretic and other techniques for typing Acinetobacter calcoaceticus.

Forty-four isolates of Acinetobacter calcoaceticus var anitratus collected during hospital outbreaks were studied using polyacrylamide gel electrophoresis (PAGE), plasmid analysis, antibiograms and biochemical tests to determine their degree of similarity. Reproducibility tests were also carried out on the PAGE and biochemical techniques to determine their validity when used to compare bacteria of the same type isolated intermittently. PAGE data was analysed densitometrically and isolates compared using a similarity matrix. All methods were able to subdivide the isolates, but results did not always correlate well between methods. Reproducibility data indicated that careful attention to technique is required when organisms are examined by PAGE sequentially. Results suggest that no single biotyping technique is likely to be adequate and that electrophoretic, biochemical and antibiogram data may complement one another and other epidemiological data in the typing of these organisms.

Acinetobacter↗
PubMed1988

Outbreak of staphylococcal scalded skin syndrome among neonates.

Over a period of 2 months, 12 babies born in the maternity unit at Guy's Hospital developed staphylococcal scalded skin syndrome in two distinct outbreaks. Staphylococci isolated from the babies, together with those from the mothers and attending medical staff were phage-typed. All isolates from the babies were of type 3A/3C. During the first outbreak only one carrier of the epidemic strain (a paediatrician) was found but a further 12 persons were identified as possible carriers during the second outbreak. In order to confirm the link between outbreaks, all phage group II isolates were subjected to reverse phage-typing, testing for metal-ion resistance, plasmid profiling and in-vivo testing for production of epidermolytic toxin. It was shown that the same epidemic strain of toxin-producing Staphylococcus aureus was responsible for both outbreaks. The affected neonates responded rapidly to a short course of intravenous flucloxacillin. The outbreak ceased after appropriate treatment of all carriers and the implementation of an extensive disinfection policy within the maternity unit.

Carrier State↗
PubMed1988

Plasmids in coryneform bacteria of human origin.

A study of plasmids in coryneform bacteria isolated from human sources is reported. Seventy of 269 strains possessed a total of 89 plasmids. These were shown to be of varying sizes and in some cases of varying structures by endonuclease restriction digest. In six of 20 strains antibiotic resistance was cured with loss of the plasmid. The diversity of plasmids is emphasized.

Actinomycetales↗
PubMed1988

Plasmids in Staphylococcus hyicus.

Fifty-one strains of Staphylococcus hyicus and six of Staph. chromogenes were collected from porcine and bovine sources in England and Belgium. Antibiotic resistance and plasmid profiles were established. Plasmids associated with resistance to tetracycline, erythromycin and streptomycin were identified in many strains; these plasmids were about the same size as those mediating similar resistances in Staph. aureus of human origin. Many small cryptic plasmids were also seen.

Animals↗
PubMed1988

Seborrheic dermatitis and malignancy. An investigation of the skin flora.

The skin flora of patients with disseminated malignant disease and seborrheic dermatitis has been investigated and compared with controls as well as with otherwise healthy patients suffering from seborrheic dermatitis. Although significant differences were detected in both bacterial and yeast counts between different sites on the body, no significant qualitative or quantitative differences were found between the three groups of subjects. Whereas abnormalities of the skin flora have been described in seriously ill patients and in individuals subjected to occlusion, we were unable to demonstrate any changes in skin flora in patients with malignant disease and seborrheic dermatitis. Our results do not support the view that increased numbers of Pityrosporum yeasts are important in the pathogenesis of seborrheic dermatitis.

Bacteria, Aerobic↗