Biomedical subjects

W C Noble

Publications and source records attributed to W C Noble.

At least 37 records · Page 2Linked to original sources

PubMed1994

Mupirocin-resistant Staphylococcus aureus in a specialist school population.

Staphylococcus aureus strains resistant to mupirocin (MIC > 4000 mg l-1) were recovered from children and staff at a school for children with eczema and/or asthma or cystic fibrosis after mupirocin had been used to treat eczematous lesions. At least three distinct strains of S. aureus were involved and resistance was shown to be due in most isolates to a transmissible plasmid. The need for monitoring the extended use of this valuable antibiotic is emphasized.

Adolescent↗

PubMed1994

Cell surface hydrophobicity and adherence to extra-cellular matrix proteins in two collections of methicillin-resistant Staphylococcus aureus.

Non-specific and specific mechanisms of adherence have been examined in two collections of methicillin-resistant Staphylococcus aureus (MRSA). Determination of hydrophobicity by salt aggregation, hydrophobicity indices and of adherence to the extra-cellular matrix proteins fibronectin, vitronectin, laminin and collagen type 1 have failed to reveal any correlation with phage-type, plasmid profile or antibiogram. Further, the strain collections, made over a period of years in two countries, differ markedly in their adherence characteristics; MRSA are heterogeneous in this respect. Such heterogeneity may explain the polarization of views on the epidemicity or 'virulence' of MRSA. With the exception of adherence to collagen a small group of methicillin sensitive S. aureus had characteristics intermediate between the two groups of MRSA.

Agglutination Tests↗

PubMed1994

An investigation of plasmids from Staphylococcus aureus that mediate resistance to mupirocin and tetracycline.

Plasmids conferring mupirocin resistance were prepared from isolates of Staphylococcus aureus obtained from four patients in the same ward. The plasmids are related and in all of them the gene conferring mupirocin resistance (mupA) is flanked by copies of IS257 in direct repeat. In two plasmids mupA and IS257 have been duplicated and in one of these plasmids (pJ3358) a small pT181-like plasmid conferring tetracycline resistance is present flanked by copies of IS257. Filter mating with a strain containing pJ3358 as donor and selection on tetracycline sometimes resulted in transfer of the pT181-like plasmid containing a copy of IS257. Analysis showed that the pT181-like plasmid with the insertion of IS257 is present in high copy number and that the IS257 element is inserted in the copy number control region of the plasmid.

Base Sequence↗

PubMed1994

Rapid identification using pyrolysis mass spectrometry and artificial neural networks of Propionibacterium acnes isolated from dogs.

Curie-point pyrolysis mass spectra were obtained from reference Propionibacterium strains and canine isolates. Artificial neural networks (ANNs) were trained by supervised learning (with the back-propagation algorithm) to recognize these strains from their pyrolysis mass spectra; all the strains isolated from dogs were identified as human wild type P. acnes. This is an important nosological discovery, and demonstrates that the combination of pyrolysis mass spectrometry and ANNs provides an objective, rapid and accurate identification technique. Bacteria isolated from different biopsy specimens from the same dog were found to be separate strains of P. acnes, demonstrating a within-animal variation in microflora. The classification of the canine isolates by Kohonen artificial neural networks (KANNs) was compared with the classical multivariate techniques of canonical variates analysis and hierarchical cluster analysis, and found to give similar results. This is the first demonstration, within microbiology, of KANNs as an unsupervised clustering technique which has the potential to group pyrolysis mass spectra both automatically and relatively objectively.

Animals↗

PubMed1994

Tetracycline resistance genes in staphylococci from the skin of pigs.

Forty-seven tetracycline-resistant staphylococci from the skin of pigs were examined for genes mediating this resistance. Seventeen isolates were also resistant to minocycline and all hybridized with the tet(M) gene; 23 carried the tet(K) gene and 10 the tet(L) gene. Three carried more than one gene and two did not hybridize with any of the three probes tested. Maps were constructed for two plasmids carrying the tet(K) gene, all were very similar in size (4.35-4.7 kb) and structure and closely resembled the plasmid pT181. Four plasmids which bore the tet(L) gene differed in size, ranging from 4.3 to 11.5 kb, and were dissimilar in structure except for the portion bearing the gene.

Animals↗

PubMed1994

Structure and putative origin of a plasmid from Staphylococcus hyicus that mediates chloramphenicol and streptomycin resistance.

The structure and functional organization of Staphylococcus hyicus plasmid pSCGp3EB that mediates chloramphenicol and streptomycin resistance (CmrSmr) is described and compared with another CmrSmr plasmid, pSCS12, from Staphylococcus sciuri. Both plasmids appeared to be formed by co-integrate formation between plasmids that very closely resemble the chloramphenicol resistance (Cmr) plasmid pC221 and the streptomycin resistance (Smr) plasmid pS194. In addition to the established recombination site B (RSB) in pC221 and pS194, another area suitable for recombination immediately downstream of the cat gene in pC221 and upstream of the str gene in pS194 has been identified. Co-integration at these sites would lead to the structures we have observed in the wild-type CmrSmr plasmids pSCGp3EB and pSCS12.

Amino Acid Sequence↗

PubMed1993

A comparison of lincomycin hydrochloride and clindamycin hydrochloride in the treatment of superficial pyoderma in dogs.

Thirty dogs with superficial pyoderma were randomly allocated to treatments with either lincomycin hydrochloride (22 mg/kg twice daily) or clindamycin hydrochloride (11 mg/kg once daily), initially for three weeks. Samples were taken from pustules, from adjacent apparently uninvolved skin, and from the nares. These were submitted for bacterial culture and sensitivity testing. The dogs were re-examined after three weeks treatment and samples for bacteriology were taken from the nares, from any pustules that were present or from skin in the area that was previously affected; the treatment was extended if necessary. Seventy-one per cent of the dogs given lincomycin hydrochloride responded within three weeks compared with 81 per cent of the dogs treated with clindamycin hydrochloride. The overall response rates, including those given longer courses of treatment were 93 per cent for those treated with lincomycin hydrochloride and 94 per cent for those treated with clindamycin hydrochloride, and there was no statistically significant difference between the groups either after three weeks treatment or after extended treatment. The microbiological results demonstrated that Staphylococcus intermedius was present on the skin adjacent to pustules and suggested that the nasal carriage of S intermedius was a result of cutaneous colonisation.

Administration, Oral↗

PubMed1993

Distribution of genes encoding erythromycin ribosomal methylases and an erythromycin efflux pump in epidemiologically distinct groups of staphylococci.

Erythromycin-resistant staphylococci can be divided into two phenotypic classes based on their pattern of cross-resistance to other macrolides, lincosamides and type B streptogramins. Strains inducibly or constitutively resistant to all MLS antibiotics possess erythromycin ribosomal methylase (erm) genes, whereas strains inducibly resistant to only 14 and 15-membered ring macrolides and type B streptogramins harbour msrA, which encodes an ATP-dependent efflux pump. Dot-blot hybridization was used to study the distribution of ermA, ermB, ermC and msrA in five epidemiologically distinct groups of staphylococci. The most widely-distributed resistance determinant was ermC, which was detected in 112 (50.6%) of 221 isolates, alone in 106 isolates and in combination with a second erythromycin resistance determinant in six strains. MsrA was detected in 73 (33%) of isolates, alone in 65 and in combination with a methylase gene in eight strains. This determinant was responsible for erythromycin resistance in over one-third (36.4%) of clinical isolates of coagulase-negative staphylococci. ErmA and ermB were present in only a minority of isolates (5.9 and 7.2% of strains, respectively). The resistance determinants present in ten strains did not hybridize to any of the four probes although, in all cases, their resistance phenotype was consistent with the possession of a methylase gene. Interestingly, ermB was found exclusively in animal isolates of Staphylococcus intermedius, Staphylococcus xylosus and Staphylococcus hyicus, but not in coagulase-negative staphylococci of human origin. This determinant has previously only been found in a small number of epidemiologically related strains of Staphylococcus aureus.

Animals↗

PubMed1993

Characterisation of Staphylococcus intermedius isolates from canine pyoderma and from healthy carriers by SDS-PAGE of exoproteins, immunoblotting and restriction endonuclease digest analysis.

Ten Staphylococcus intermedius isolates from cases of canine pyoderma and 10 from healthy carriers were examined by SDS-PAGE of exoproteins, immunoblotting and restriction endonuclease digest analysis. Similarities between banding patterns of the isolates were calculated as Dice coefficients for all three methods. For SDS-PAGE and immunoblotting, no significant differentiation was found between the pyoderma and "healthy" groups. Analysis of DNA digested with BglII indicated that S. intermedius is genetically heterogeneous; Dice coefficients for the pyoderma group were distinct from those for the healthy group (p < 0.001), and cluster analysis confirmed that the pyoderma isolates (9) formed a group separate from the majority (6 of 9) of the normal isolates.

Animals↗

PubMed1993

Probes for the study of mupirocin resistance in staphylococci.

Probes constructed from a 4.05-kb EcoRI digest fragment of a mupirocin resistance plasmid and a 751-bp internal part of this fragment hybridised with DNA from all of 36 independent high-level mupirocin-resistant staphylococci tested from seven centres; most were Staphylococcus aureus. In most instances the probes detected an EcoRI digest fragment of approximately 4 kb. Probes did not hybridise to DNA from low-level resistant strains, nor from strains sensitive to mupirocin.

DNA Probes↗

PubMed1993

Mupirocin resistance in coagulase-negative staphylococci.

High-level mupirocin resistance in coagulase-negative staphylococci isolated from patients undergoing peritoneal dialysis was investigated by transfer of the resistance determinants, usually in the form of a plasmid, to Staphylococcus aureus strains, cleavage of the plasmid by restriction endonuclease and hybridisation with a probe comprising a 4.05 kb EcoRI fragment of a plasmid from a S. aureus strain. In most instances the mupirocin-resistant staphylococci isolated from each patient were different according to the species, antibiogram and plasmid profile data. The mupirocin resistance determinant was carried on various plasmids as judged by EcoRI restriction fragment length polymorphisms. All hybridised at about 4 kb with the S. aureus probe.

Animals↗

PubMed1993

Superantigenic exotoxin-secreting potential of staphylococci isolated from atopic eczematous skin.

Although the deleterious effect of Staphylococcus aureus on atopic eczema is well recognized, the mechanism of this effect may be more complex than pyogenic infection alone. We have shown that the majority of S. aureus cultures isolated from atopic eczema produced exotoxins with superantigenic properties, although this was no more frequent than in a control group, and was not restricted to one particular superantigen. However, the widespread nature of staphylococcal infections in atopic eczema indicates that sufficient superantigen may be released to cause T-lymphocyte activation, cytokine release, and mast cell degranulation. These mechanisms could, in part, explain the exacerbations of atopic eczema associated with S. aureus infection.

Antigens, Bacterial↗

PubMed1993

Analyses of skin surface lipid in patients with microbially associated skin disease.

The composition of the total skin surface lipid, free fatty acids and fatty acid of triglyceride was used in discriminant analyses to classify patients with severe acne vulgaris (AV), pityriasis versicolor (PV), seborrhoeic dermatitis (SD) and atopic dermatitis (AD). It was not possible to discriminate between the PV and SD patients but all the lipid groups gave a satisfactory separation between AV, PV + SD and AD patients. A similar separation was obtained when the sex of the patient was studied but not when both sex and disease were taken into account. The results suggest that there are fundamental differences in the composition of skin lipid between patients with microbially associated diseases, but the precise role of the organisms has not been ascertained.

Adolescent↗

PubMed1993

Gram-negative bacterial skin infections.

The gram-negative bacilli are a very diverse group of organisms with varied antimicrobial resistance patterns and degrees of pathogenicity. In consequence, it is difficult to make confident statements on appropriate therapies. Here the most common types of infections, or infecting organisms, are described together with reported successful therapies.

Anti-Bacterial Agents↗

PubMed1992

Co-transfer of vancomycin and other resistance genes from Enterococcus faecalis NCTC 12201 to Staphylococcus aureus.

Conjugative transfer, in the apparent absence of plasmid DNA, of high-level vancomycin resistance from Enterococcus faecalis NCTC 12201 to Staphylococcus aureus B111 has been demonstrated in vivo and in vitro. Selection of transconjugants on media containing erythromycin or chloramphenicol may result in the transfer of resistance to erythromycin, chloramphenicol, gentamicin, streptomycin and vancomycin though these are capable of separate transfer. Vancomycin resistance has not been transmitted from staphylococcus to staphylococcus though transfer of erythromycin and of chloramphenicol resistance has been achieved.

Conjugation, Genetic↗

PubMed1992

Staphylococci on the skin of pigs: isolates from two farms with different antibiotic policies.

Staphylococci isolated from pigs on two farms were identified and their antibiotic resistance and plasmid profiles were examined. A highly resistant Staphylococcus hyicus was epidemic on one of the farms which was also that at which antibiotic-containing feedstuffs were used most often. Staphylococci from this farm were more often resistant to two or more antibiotics than were the strains from the other farm. The many plasmids present in these staphylococci prevented the determination of the genetic nature of the antibiotic resistance.

Animals↗

PubMed1992

Antibiotic resistance and plasmids in Staphylococcus aureus from normal populations.

Antibiotic resistance, plasmid profiles and plasmid structures were examined in nasal Staphylococcus aureus collected from a random sample of normal individuals in the mid 1960s and from women at an antenatal clinic in 1989. The results were generally similar except for an increase in the resistance to penicillin in the later sample. The plasmid population had changed little though more uncategorized plasmids were evident in the 1960s samples.

Drug Resistance, Microbial↗

PubMed1992

Characterization of aerobic non-lipophilic coryneforms from human feet.

Aerobic coryneform bacteria from human feet have been studied by analysis of the cell-wall sugars, lipids and diamino acids and by phenotypic tests. Although many isolates studied fall into the established genus Brevibacterium at least two previously unreported taxa of coryneform have been identified bringing the number of aerobic, non-lipophilic taxa known on skin to four. Simple tests can be used to distinguish between these taxa. Studies on the human skin flora continue to reveal the diversity of organisms present.

Actinomycetales↗