Investigation into the potential pathogenicity of Staphylococcus felis in a cat.
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Amoxicillin-Potassium Clavulanate Combination↗
Biomedical subjects
W C Noble
Publications and source records attributed to W C Noble.
Co-transfer of plasmids in association with conjugative transfer of mupirocin or mupirocin and penicillin resistance in methicillin-resistant Staphylococcus aureus.
Two distinct strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated from patients in a dermatology ward were also resistant to mupirocin. The mupirocin resistance plasmids from both strains were indistinguishable by EcoRI and HindIII restriction digest analysis, except for the presence of genes apparently mediating penicillinase production in some transconjugants. Conjugative transfer of the plasmid mediating mupirocin resistance from one of these strains to a recipient S. aureus was accompanied in some cases by co-transfer of plasmids mediating resistance to tetracycline or erythromycin; in some instances a plasmid which possessed no apparent resistance markers was also transferred. The second strain demonstrated conjugative transfer of penicillin and mupirocin resistance as well as transfer of a plasmid mediating gentamicin resistance, but transfer of erythromycin resistance was not apparently plasmid-mediated.
Anti-Bacterial Agents↗
Skin bacteriology and the role of Staphylococcus aureus in infection.
Many of the staphylococci and coryneforms that inhabit normal human skin do not cause skin disease. Amongst the remainder the mechanisms of pathogenicity vary widely. For Proteus, Pseudomonas and Brevibacterium species proteolysis is a major determinant. The precise role of Corynebacterium minutissimum in erythrasma and the propionibacteria in acne is not known. Staphylococcus aureus, however, produces a wide range of non-specific agents, such as haemolysins and leucocidins as well as highly specific toxins such as the epidermolytic toxins involved in bullous impetigo and scalded skin syndrome. Most of the current attention, however, is devoted to the role of the enterotoxins and toxic shock toxin as superantigens, with emphasis on their role in atopic dermatitis. Molecularly similar toxins in the streptococci play a similar role and may also have a role in the aetiology of psoriasis.
Corynebacterium Infections↗
Skin and soft tissue infections.
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Editorial↗
Rapid differentiation of closely related Candida species and strains by pyrolysis-mass spectrometry and Fourier transform-infrared spectroscopy.
Two rapid spectroscopic approaches for whole-organism fingerprinting of pyrolysis-mass spectrometry (PyMS) and Fourier transform-infrared spectroscopy (FT-IR) were used to analyze a group of 29 clinical and reference Candida isolates. These strains had been identified by conventional means as belonging to one of the three species Candida albicans, C. dubliniensis (previously reported as atypical C. albicans), and C. stellatoidea (which is also closely related to C. albicans). To observe the relationships of the 29 isolates as judged by PyMS and FT-IR, the spectral data were clustered by discriminant analysis. On visual inspection of the cluster analyses from both methods, three distinct clusters, which were discrete for each of the Candida species, could be seen. Moreover, these phenetic classifications were found to be very similar to those obtained by genotypic studies which examined the HinfI restriction enzyme digestion patterns of genomic DNA and by use of the 27A C. albicans-specific probe. Both spectroscopic techniques are rapid (typically, 2 min for PyMS and 10 s for FT-IR) and were shown to be capable of successfully discriminating between closely related isolates of C. albicans, C. dubliniensis, and C. stellatoidea. We believe that these whole-organism fingerprinting methods could provide opportunities for automation in clinical microbial laboratories, improving turnaround times and the use of resources.
Candida↗
Typing methods for a study of gene transfer in enterococci.
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Bacterial Typing Techniques↗
An apparent outbreak of infection with Acinetobacter calcoaceticus reconsidered after investigation by pyrolysis mass spectrometry.
In a previously reported apparent outbreak of infection due to Acinetobacter calcoaceticus on a Regional Burns Unit in which both clinical and environmental isolates were available for study, investigations of the organisms by electrophoretic typing of surface proteins, plasmid profiling and antibiograms were inconclusive and unable to identify a single epidemic strain of the organism. The same collection of isolates has been analysed for inter-strain comparison by pyrolysis mass spectrometry (PyMS). PyMS analysis suggested that a few isolates were very different from the majority but that most of the collection comprised a group of closely similar but nonetheless distinct isolates. These isolates may well be representatives of a limited variety of strains occupying an ecological niche but not yet a single emergent strain. The ability of PyMS to detect a single epidemic strain of A. calcoaceticus when present in such a collection of isolates was demonstrated by analysis of a "constructed outbreak collection", using some of the original isolates. This study illustrates the versatility of PyMS for inter-strain comparison studies of species not yet amenable to conventional typing methods. The application of rapid, highly discriminatory, high-volume inter-strain comparison methods such as PyMS to apparent outbreaks of nosocomial infection is likely to reveal patterns of organism acquisition other than point-source transmission.
Acinetobacter Infections↗
Potential for gene transfer among enterococci from a single patient and the possibility of confounding typing results.
The results of typing methods used in a study of the epidemiology of enterococci in burn patients showed inconsistencies. The possibility that these inconsistencies were the result of gene acquisition or loss was investigated by using 12 isolates of Enterococcus faecalis from a single patient. In vivo and in vitro exchange and loss of genes were observed. The study showed that the typing results for isolates from this patient can be modified by known and demonstrated genetic elements; as a result, the isolates could be divided into between three and seven strains. In the present study, the SmaI digestion patterns gave the most consistent results, correctly identifying the transconjugants as indistinguishable from recipient strain 196R.
Bacterial Typing Techniques↗
Antibiotic resistance in the staphylococci.
There has been much interest in the media, international as well as national, on the potential for the development of "superbugs' by which is usually meant pathogenic bacteria resistant to all available antibiotics. Two of the genera most often thought to fall into this category are the staphylococci (MRSA or Methicillin Resistant Staphylococcus aureus) and the enterococci (VRE or Vancomycin Resistant Enterococci) and although this article concentrates on the staphylococci the two share much in the way of transmissible genes.
DNA Mutational Analysis↗
Gentamicin resistance gene transfer from Enterococcus faecalis and E. faecium to Staphylococcus aureus, S. intermedius and S. hyicus.
Transfer of gentamicin resistance from Enterococcus faecalis and E. faecium to Staphylococcus aureus, S. hyicus and S. intermedius was accomplished by filter mating. Transfer from E. faecalis was plasmid mediated and a probe to the gentamicin resistance gene aac(6')-aph(2") hybridized to HindIII fragments of various sizes (7.5, 6.2 and 4.7 kbp) of these plasmids. Transfer from E. faecium was apparently to the chromosome in 9 of 10 instances with HindIII fragments of 3.3 or 3.0 kbp hybridizing to the probe. These results are consistent with transposon mediated resistance. Plasmid transfers to S. intermedius were at much lower frequencies than to S. aureus or to S. hyicus but presumed transposon transfer direct to the chromosome was equal in all three species.
Burns↗
Sub-species discrimination, using pyrolysis mass spectrometry and self-organising neural networks, of Propionibacterium acnes isolated from normal human skin.
Curie-point pyrolysis mass spectra were obtained from 30 Propionibacterium acnes strains isolated from the foreheads of six healthy humans. Multivariate analyses and Kohonen artificial neural networks (KANNs), employing unsupervised learning, were used successfully to discriminate between the P.acnes isolates from different individual hosts. The classification of the isolates by KANNs was compared with the more classical multivariate techniques of canonical variates analysis and hierarchical cluster analysis and found to give similar groupings. The combination of pyrolysis mass spectrometry with these numerical methods also showed that more than one strain of P.acnes had been isolated from three of the human hosts.
Adult↗
Antimicrobial activities in vitro and in vivo of transition element complexes containing gold(I) and osmium(VI).
Metal compounds have been used as antibacterial agents for centuries. The in-vitro activity of two metal containing complexes, one gold, the other osmium, was investigated using a panel of clinically isolated bacteria and Candida albicans. Twenty strains of each organism were used and MIC and MBC values determined using the agar plate dilution method. Protein binding effects on the activity of the compounds were also investigated using media supplemented with 5% human blood. In-vivo activity of the two compounds was subsequently determined in a hairless-obese mouse skin-surface activity model. Both compounds were highly active against the Gram-positive organisms and Candida albicans in vitro. The gold compound had some Gram-negative activity but the osmium complex was inactive against these organisms. Both were extensively protein bound. In the in-vivo experiment the gold compound achieved a 2-3 log reduction for all the test organisms and was at least as good as or superior to mupirocin in its eradication rate. The osmium compound was inactive.
Animals↗
The staphylococcal insertion sequence IS257 is active.
The plasmid pJ3356 confers high-level mupirocin resistance on a strain of Staphylococcus aureus isolated from a hospital. The plasmid also carries two copies of IS257. Recombination of an IS257-containing plasmid conferring erythromycin resistance, pOX7-IS, into either of the IS257s of pJ3356 has been observed. The co-integration of pJ3356 and a small plasmid, pOX7, is also reported and involves duplication of one of the IS257s from pJ3356 together with 8 bp of pOX7 at the site of integration. Thus IS257 has been shown to be an active mobile genetic element.
Base Sequence↗
Labile antibiotic resistance in Staphylococcus aureus.
Twenty-two isolates of Staphylococcus aureus, recovered from patients over a period of about one year, exhibited low level resistance to mupirocin, developed a salmon pink colour on culture and 21 had the same phage-type. However the plasmid profiles and associated antibiotic resistances differed. Digestion of cellular DNA with SmaI showed that two isolates from a single patient had a markedly different pattern to the remainder, and that six others differed by one band, though these formed groups of one and five isolates. This episode apparently represents a small outbreak of colonization or infection, which would have been missed but for the unusual pigmentation of the isolates recovered, and illustrates the difficulties of relying on a single typing system.
Anti-Bacterial Agents↗
Chloramphenicol resistance in Staphylococcus intermedius from a single veterinary centre: evidence for plasmid and chromosomal location of the resistance genes.
A total of seven Staphylococcus intermedius cultures isolated from cases of canine pyoderma were investigated for the genetic basis of chloramphenicol resistance (Cmr). All of these S. intermedius isolates mediated Cmr via the expression of the Cm-inactivating enzyme chloramphenicol acetyltransferase (CAT); the respective cat genes were found to be located on small multicopy plasmids of 3.1 to 4.1 kb in four of the seven cultures. The four Cmr plasmids, designated pSCS20-23, differed upon restriction endonuclease mapping. Hybridization experiments identified all of them to belong to the pC221-family of staphylococcal Cmr plasmids. The expression of all four plasmid-encoded cat genes was inducible with chloramphenicol. The remaining three S. intermedius isolates also harboured an inducible cat gene of the pC221-type which, however, was found to be located in the chromosomal DNA. These differences in the subcellular localisation and consequently in the number of cat gene copies per S. intermedius cell had no influence on the MIC values of Cm exhibited by the respective S. intermedius isolates.
Animals↗
Production and use of monoclonal antibodies to Microsporum canis.
Microsporum canis NCPF 179 and M. canis NCPF 177 dermatophyte cytoplasmic extracts (DCEs) were used as antigens to generate monoclonal antibodies (mAbs). Hybridomas with supernatants of optical density (OD) > 1 for homologous dermatophyte cytoplasmic extracts (CE) and OD < 0.5 for heterologous CE of Candida albicans tested by the enzyme-linked immunosorbent assays (ELISA) were selected for cloning. mAbs secreted by cloned hybridoma lines were screened against CE of M. canis, M. gypseum, M. equinum, M. distortum, Trichophyton verrucosum, C. albicans, Malassezia pachydermatis and Aspergillus fumigatus. The ELISA performed on clone supernatants identified a variety of different activities between the dermatophyte and other fungal CEs. The selected mAbs were used for immunoblotting of native and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) gels. Immunoblots with some of the mAbs tested allowed the differentiation of strains belonging to different dermatophyte species and isolates belonging to the M. canis.
Animals↗
Adherence characteristics of coagulase-negative staphylococci isolated from patients with infective endocarditis.
Coagulase-negative staphylococci isolated from patients with endocarditis were divided according to whether the infection was of native or of prosthetic valves and was acquired either in the community or in hospital. Comparisons were made with strains from intravenous line-associated bacteraemias. All strains were examined by direct and indirect adherence tests. Line-associated bacteraemia strains were more likely to produce slime and were more hydrophilic but were less likely to attach HEp2 tissue culture cells than were endocarditis strains, and almost equally likely to adhere to plastic and extracellular matrix proteins. Amongst the endocarditis strains, there was little difference in slime production but hospital-acquired or prosthetic-valve strains were more hydrophobic and more likely to adhere to silicone than were the native-valve or community-acquired strains. Exposure of extracellular matrix proteins on native valves due to a pre-existing non-infective heart condition may account for the selection of strains able to adhere to fibronectin or laminin.
Bacteremia↗
In vitro indices of tissue adherence in Staphylococcus intermedius.
In vitro indices of adherence showed that strains of Staphylococcus intermedius from lesions of canine pyoderma differed from strains isolated from normal carrier sites in that a significantly greater proportion of pyoderma strains adhered to extracellular matrix proteins whilst fewer adhered to polystyrene. Slime production and a hydrophobicity index did not differ between the groups. This suggests that exposure of extracellular matrix proteins due to underlying disease may result in the selection of a narrower spectrum of strains from amongst those at carrier sites.
Animals↗