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Biomedical subjects

J M Hamilton-Miller

Publications and source records attributed to J M Hamilton-Miller.

At least 19 recordsLinked to original sources
PubMed2002

Vancomycin-resistant Staphylococcus aureus: a real and present danger?

The glycopeptide antibiotics, vancomycin and teicoplanin, are the mainstay of therapy for infections involving strains of Staphylococcus aureus that are resistant to methicillin and gentamicin. Durng the last 5 years, clinical isolates of S. aureus showing reduced susceptibility to glycopeptides have been reported from many countries around the world, often associated with prolonged glycopeptide therapy. Detection and monitoring of such strains has been hindered by the fact that vancomycin (or glycopeptide)-intermediate S. aureus (VISA) isolates may be missed on conventional disk sensitivity tests. Effective control measures are required to prevent the increasing occurrence and spread of such strains in both the hospital and community settings. An important aspect of control is promoting the judicious use of glycopeptides. The recent introduction of the alternative antibiotics quinupristin/dalfopristin and linezolid, which are active against S. aureus strains resistant to many other classes of agent, should facilitate this process.

Anti-Bacterial Agents↗
PubMed2001

Identity and antibiotic susceptibility of enterobacterial flora of salad vegetables.

The enterobacterial flora from carrots (organic and non-organic) and salad vegetables has been identified and antibiotic susceptibilities determined. Pseudomonas fluorescens and Pantoea (formerly Enterobacter) agglomerans were the species most commonly found; the former was usually resistant to at least six of the antibiotics under test. Rahnella aquatilis (often producing beta-lactamase) was also found in carrots. There were no clear differences in flora from organic and non-organic carrots. Thus, uncooked vegetables are a potential source of highly resistant opportunistic pathogens.

Anti-Bacterial Agents↗
PubMed2001

Immunopharmacology of antibiotics: direct and indirect immunomodulation of defence mechanisms.

Antibiotics can alter the host's reaction to an infection (itself an immunomodulating event) in various ways. Indirect actions involve killing of bacteria, changing the intestinal flora, intrinsic antigenicity and preventing bacteria making virulence factors. Direct actions are upon phagocytic function, chemotaxis and lymphocyte activities. Immunomodulation can be positive ("pro-host") or negative, and can be quantitated by means of the parameter "immune index". Among the cephalosporins, cefodizime shows the greatest positive immunomodulating activity, due to the unique nature of the 3-sidechain. Cefotaxime has an immunodepressing effect in vitro. The oral cephalosporin cefaclor appears to have a beneficial effect on polymorph function. While immunomodulation by antibiotics may appear marked in in vitro and ex vivo experiments, and in animal models, this phenomenon does not appear to have decisive effects therapeutically.

Adjuvants, Immunologic↗
PubMed2000

Sir Edward Abraham's contribution to the development of the cephalosporins: a reassessment.

This paper is based on an invited lecture given at the 21st International Congress of Chemotherapy in July 1999, as part of a Symposium entitled '50 years of cephalosporins: their use the next 50 years', (Hamilton-Miller JMT, Cephalosporins: from mould to drug. Sardinia to Oxford and beyond, J Antimicr Chemother 1999;44(A):26). Celebration of this Golden Anniversary was made more poignant by the death of the last major participant, Sir Edward Abraham, in May 1999. This history has been told before, but mainly by Sir Edward, who being a very modest man (to which his obituaries graphically attest) consistently underplayed the role that he and Newton had in the discovery of cephalosporin C, that led to all the cephalosporins now in use. I had the privilege of working at the Dunn School from 1967 to 1970, with Abraham and Newton, where I met Brotzu, Florey and Dorothy Hodgkin, all of whom had important roles in this story. Other workers at the Dunn School at that time, e.g. Heatley, Sanders and Jennings (who became Lady Florey), helped develop penicillin. Such a galaxy of stars of the antibiotic firmament will never again be assembled. "Let us now praise famous men... these were honoured in their generation, and were the glory of their times" - Ecclesiasticus XLIV. vv 1.7.

Cephalosporins↗
PubMed2000

Patterns of phenotypic resistance to the macrolide-lincosamide-ketolide-streptogramin group of antibiotics in staphylococci.

Phenotypes of resistance to the macrolide-lincosamide-ketolide-streptogramin (MLKS) group of antibiotics have been determined in 540 clinical isolates of staphylococci (210 Staphylococcus aureus and 330 coagulase-negative species). Results of disc diffusion tests using erythromycin A, oleandomycin, rokitamycin, clindamycin, telithromycin, quinupristin and dalfopristin delineated four main groups corresponding to those defined classically using erythromycin and clindamycin only, but with sub-divisions. Resistance to erythromycin was more common in coagulase-negative strains (56%) than in S. aureus (16%); telithromycin, clindamycin, quinupristin-dalfopristin and rokitamycin were active against >97% of S. aureus strains and >88% of the coagulase-negative strains. The commonest resistance phenotype was 'inducible MLS(B)' (12% in S. aureus, 31% in coagulase-negative strains); this group could be divided in terms of the different inducing abilities of erythromycin and oleandomycin. 'Constitutive MLS(B)' and 'MS' phenotypes were more often found in coagulase-negative strains (11 and 13%, respectively) than in S. aureus (2 and 1%). Novel phenotypes were found during the isolation of constitutively resistant mutants from inducible strains, and of resistant mutants from 'MS' strains. This extended phenotyping scheme has revealed further complexities and evolutionary possibilities in patterns of resistance to this group of antibiotics.

Anti-Bacterial Agents↗
PubMed1999

Disorganization of cell division of methicillin-resistant Staphylococcus aureus by a component of tea (Camellia sinensis): a study by electron microscopy.

A component of aqueous extracts of green tea (Camellia sinensis), known to reverse methicillin-resistance in staphylococci, causes extensive morphological changes in methicillin-resistant but not in methicillin-sensitive Staphylococcus aureus. Clumps of partly divided cocci, consisting of up to 14 individuals, with thickened internal but normal external cell walls were seen by electron microscopy in cultures of methicillin-resistant S. aureus grown in the presence of the active principle. The morphological changes observed were consistent with selective inhibition of penicillin-binding proteins.

Anti-Bacterial Agents↗
PubMed1999

Susceptibility testing of linezolid by two standard methods.

To determine to what extent methodological differences affect susceptibility testing parameters for linezolid, MICs and disk inhibition zones were compared using the methods described by the National Committee for Clinical Laboratory Standards and the British Society for Antimicrobial Chemotherapy for 198 strains of gram-positive cocci. Zones were 4-5 mm larger by the British Society for Antimicrobial Chemotherapy method, but MICs did not differ, except for pneumococci, which were more sensitive when the British Society for Antimicrobial Chemotherapy method was used. This is because incubation in CO2 depresses the activity of linezolid against this species only. Breakpoints for linezolid may need adjusting when testing is by other than National Committee for Clinical Laboratory Standards methods.

Acetamides↗
PubMed1999

Public health issues arising from microbiological and labelling quality of foods and supplements containing probiotic microorganisms.

OBJECTIVE: To assess the accuracy and helpfulness of labelling on products containing probiotic bacteria. DESIGN AND SETTING: 52 such products - 44 from the UK (21 supplements, 15 fermented functional foods, eight 'health-care' products) and eight from continental Europe - have been tested for microbiological content, and results compared to the information available on their labels. Products were stored in the dark at 4 degrees C and analysed before their expiry or sell-by date. Careful note was taken of wording on labels, package inserts, packaging, promotional literature and catalogue descriptions, as applicable. Products were cultured on appropriate bacteriological media, and organisms grown were counted and identified. RESULTS: Bioyoghurts gave no indication of numbers, and only five accurately described their bacterial content; results of culture were usually satisfactory. 'Healthcare' products (mostly intended for the bowel) usually indicated the presence of bacteria, but the numerical content was hard to ascertain, and cultural results fell short of label claims. Supplements were sometimes incorrectly labelled in bacteriological terms, and often contained markedly reduced numbers and/or had extraneous strains and/or strains specified on the label were missing. Products from continental Europe (that were sold for specific medical indications) seemed of a higher microbiological standard. The potential pathogen Enterococcus faecium was found in nine products. The most successful of the new functional foods in Britain now contain probiotics, and probiotic preparations are prominent among the expanding range of nutritional supplements presently available to consumers. CONCLUSIONS: Our findings have public health implications, and suggest that improvements are needed in labelling and quality assurance procedures for products containing probiotic organisms. The presence of the potential pathogen Enterococcus faecium (intentionally or as a contaminant) in some products calls for a review of the value of this species as a probiotic.

Dietary Supplements↗