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Biomedical subjects

D F Brown

Publications and source records attributed to D F Brown.

At least 73 records · Page 4Linked to original sources
PubMed1995

Linkage of vancomycin and high-level gentamicin resistance genes on the same plasmid in a clinical isolate of Enterococcus faecalis.

A transferable 55-MDa plasmid which encoded resistance to both vancomycin and high concentrations of gentamicin was identified in a clinical isolate of Enterococcus faecalis. The plasmid hybridized with probes for the vanB and aac6'aph2" resistance genes. This is the first report of linkage of glycopeptide and high-level aminoglycoside resistance genes in an Enterococcus sp.

Base Sequence↗
PubMed1994

Diabetes: 'tight control' in a comprehensive treatment plan.

Two out of every five older Americans have abnormal glucose homeostasis. Approximately 1 in 5 has diabetes mellitus, but one-half of these persons are undiagnosed. Treatment of diabetes in older adults is usually managed by primary care physicians. A regular exercise program is the cornerstone of management, even in frail patients. Diet, weight loss, and regular patient education are also important. Age should not limit attempts at tight glucose control in older patients who are cognitively intact and otherwise reasonable candidates. The key to successful management is to follow through with a treatment plan that deals with all of the factors that influence glucose metabolism.

Aftercare↗
PubMed1993

Antimicrobial susceptibility testing of enterococci: results of a survey conducted by the United Kingdom National External Quality Assessment Scheme for Microbiology.

Six strains of enterococci were distributed to participants in the United Kingdom National External Quality Assessment Scheme for Microbiology with a request that they be tested for susceptibility to ampicillin/penicillin and vancomycin and for high-level resistance to gentamicin. More than 98% of laboratories correctly reported the resistant strains as resistant to penicillin and ampicillin. However, there was a poorer correlation for the susceptible strains, with only 1-6% and 69-83% of laboratories reporting the strains as susceptible to penicillin and ampicillin respectively. Those laboratories which used 5-25 micrograms ampicillin discs or breakpoint methods reported proportionally more results correctly for the susceptible strains than those using 2 micrograms discs. Participants using Escherichia coli or an enterococcus as a control and those not using a control at all were more likely to report ampicillin-susceptible strains correctly than those using Staphylococcus aureus NCTC 6571 (Oxford strain). For vancomycin-susceptible and high-level vancomycin-resistant strains, 93-96% and 96-99% of reports respectively were correct. For the low-level vancomycin-resistant strains, only 50-54% of reports were correct. Participants using a 5 micrograms vancomycin disc reported proportionally more of the low-level resistant strains correctly than those using 10, 20, 25, 30 or 100 micrograms discs. Participants not using controls were proportionally more likely to report the low-level resistant strains as susceptible than those using an enterococcus or S. aureus NCTC 6571 as a control. For the high-level gentamicin-resistant (HLGR) strains, 96-98% of reports were correct. Depending on the strain, between 12% and 41% of participants also reported high-level resistance for the strains which were not HLGR. Those using low-content discs (< or = 30 micrograms) and breakpoint or MIC methods were more likely to report strains which were not HLGR as HLGR than those using high-content discs. Those using an enterococcus as a control were less likely to report strains which were not HLGR as HLGR than those using either S. aureus NCTC 6571 or E. coli as a control and those not using a control.

Ampicillin Resistance↗
PubMed1993

Development of an internal quality assessment scheme in a clinical bacteriology laboratory.

AIM: To develop an internal quality assessment (IQA) scheme in a clinical bacteriology laboratory. METHODS: Over 24 months, 1230 diagnostic specimens, representing 0.42% of laboratory workload, were anonymised and resubmitted for analysis. Six hundred and twenty one (48.7%) of these gave positive culture results; 44 fecal and upper respiratory specimens were "spiked" (artificially inoculated) to increase the proportion of positive samples. RESULTS: Discrepancies between IQA and clinical sample results occurred in 188 cases (14.8%): 76.6% of these were in culture results, 13.3% in microscopy performance, and 10.1% in clerical recording. The culture discrepancy rate for each positive sample was lowest for wound (17.5%) and urine (18.1%) specimens, and highest for faeces (34.9%) and upper respiratory (37.7%) samples. Discrepancies in several areas responded to staff training and improvement in technical methods. CONCLUSIONS: An IQA programme of this type assesses the reproducibility of tests within a diagnostic laboratory when analysing common specimen types and organisms. It permits blind assessment of many areas of diagnostic work that are not readily amenable to other quality assurance methods, and it raises the awareness of all staff to the importance of quality in every aspect of specimen and data processing.

Bacteriological Techniques↗
PubMed1992

The E-Test challenged with selected strains.

Results with the E-Test minimum inhibitory concentration (MIC) method correlated well with an agar dilution method in tests using a wide range of selected bacteria. Detection of methicillin resistance in Staphylococcus aureus was as reliable as agar dilution and disk diffusion methods. The ease of use of the E-Test makes it particularly suitable for routine clinical microbiology laboratories.

Bacteria↗
PubMed1992

Methods used in the United Kingdom for the culture of micro-organisms from blood.

AIMS: To survey blood culture methods in use in the United Kingdom. METHODS: A questionnaire was distributed to the 415 United Kingdom laboratories participating in the clinical bacteriology subscheme of the UK National External Quality Assessment Scheme for Microbiology. RESULTS: Two hundred and eighty seven laboratories completed the questionnaire. The responses indicated wide variations in methods used including considerable differences among laboratories using the same basic methods. The most widely used techniques were the Bactec and conventional broth systems. CONCLUSIONS: Although many published comparisons have failed to show that any basic method is outstandingly successful in the isolation of all organisms, there is evidence that several factors can contribute to good performance. In some laboratories suboptimal conditions were in use. The variations in technique probably reflect differences in practical suitability of a system for any particular laboratory, costs, and personal preferences.

Bacteria↗
PubMed1991

The effect of alloxan-induced diabetes on triamine lesions in the ventromedial hypothalamus.

It has been demonstrated that the ventromedial hypothalamus (VMH) of alloxan-induced diabetic mice is protected from subsequent gold thioglucose (GTG)-induced lesions. Another compound, 3,3'-methyliminobis-(N-methylpropylamine) (MIMPA), a triamine structurally unrelated to GTG, has been shown to cause similar VMH lesions in mice. We chose to investigate the effect of alloxan-induced diabetes on VMH lesion formation in MIMPA-treated mice. In this study CF-1 female mice were made diabetic by a simple intravenous (IV) injection of alloxan and subsequently treated with MIMPA by subcutaneous injection (SC). Contrary to studies which showed that GTG-induced VMH lesions are insulin dependent, an insulin deficiency did not inhibit MIMPA-induced lesions in the VMH of mice. Our data suggests, albeit GTG is suspected to induce VMH necrosis by attaching to glucoreceptors and insulin-sensitive neurons, MIMPA works by a different and as yet unknown mechanism. We conclude that MIMPA-induced lesions in the VMH of mice are not insulin dependent.

Animals↗
PubMed1991

The pain experience and psychological adjustment to orthodontic treatment of preadolescents, adolescents, and adults.

Age-related changes in psychological measurements of pain and well-being were studied in patients undergoing full fixed appliance orthodontic treatment. A longitudinal series of four questionnaires was used to obtain measurements of these factors after the separation phase of treatment, banding (2 to 7 days after separation), the first adjustment visit (3 to 4 weeks after placement of full fixed appliances), and the second adjustment visit (3-4 months after banding was completed). The results suggest an interaction between the phases of treatment and reported pain and psychological well-being and significant differences in the response profiles of the adolescent age group (14 to 17 years) compared to the preadolescent (11 to 13 years) and adult groups (18 years and older). These findings did not appear to be due simply to group differences in the use of analgesics, class of malocclusion, or type of full fixed appliance used. The profile comparisons indicated that the adolescent age group generally reported lower levels of psychological well-being and higher levels of pain during the phases of treatment examined. Consistent with these results was the finding that the adolescents differed from the preadolescents and adults in the quality of the pain experience reported during treatment. The results indicate an age difference in adjustment to fixed orthodontic therapy, which suggests that adolescents are more vulnerable to undesirable psychological effects of treatment.

Adolescent↗
PubMed1991

Mechanism of nitrofuran resistance in Salmonella enteritidis phage type 4 and interpretation of nitrofuran susceptibility tests.

The mechanism of nitrofuran resistance in Salmonella enteritidis phage type 4 was studied. Nitrofuran reductase activity was inversely related to the furazolidone MIC for the organism. Strains with low-level nitrofuran resistance, typically found in almost all isolates of S. enteritidis PT4, had intermediate nitrofuran reductase activity. Disc diffusion tests with furazolidone, 15 or 50 micrograms discs, and nitrofurantoin, 50 or 300 micrograms discs, failed to distinguish reliably between susceptible populations and those with low-level resistance. In order to detect low-level resistance to nitrofurans a dilution method should be used with a furazolidone breakpoint of 1 mg/l or a nitrofurantoin breakpoint of 16 mg/l.

Drug Resistance, Microbial↗
PubMed1991

Evaluation of the E test, a novel method of quantifying antimicrobial activity.

The 'E test' is a method for measuring MICs of antimicrobial agents against bacteria and is based on diffusion of a pre-formed antibiotic gradient from a plastic strip. The performance of the E test was evaluated by comparison with a conventional agar dilution MIC method in tests with ten agents and a variety of organisms. Correlation between MICs by the agar dilution and E test methods was good, 98.85% results were within 2 log2 dilution steps in a total of 1304 tests. The E test is technically straightforward as tests are set up in the same way as the disc diffusion method. The versatility and ease of use of the E test make the method an attractive alternative to conventional dilution tests.

Anti-Bacterial Agents↗
PubMed1991

Detection of chloramphenicol resistance in Haemophilus influenzae.

An average of 358 (13%) of United Kingdom laboratories failed to detect resistance to chloramphenicol in strains of Haemophilus influenzae distributed by the United Kingdom National External Quality Assessment Scheme for Microbiology. Clear associations between methods used and results obtained show that error rates are minimised by the use of low content (10 micrograms) disc and a sensitive control strain of H influenzae.

Chloramphenicol Resistance↗
PubMed1990

Nitrofurantoin resistance in isolates of Salmonella enteritidis phage type 4 from poultry and humans.

All 38 isolates of Salmonella enteritidis phage type (PT) 4 from chickens and 86 of 89 isolates from human patients were resistant to nitrofurantoin. Resistance to other agents was rare. Thirteen of 16 isolates of S. enteritidis other than PT4 were nitrofurantoin-resistant, and resistance to other agents was slightly more common than with isolates of PT4. Only one third of 83 isolates of other salmonella serotypes were nitrofurantoin-resistant, but resistance to other agents was more common and some isolates were multiply resistant. There was generally cross-resistance between nitrofurantoin and furazolidone although there were discrepancies with isolates that had MICs close to the breakpoint. It may be that use of nitrofurans in the poultry industry has selected for colonization and infection with S. enteritidis PT4. This could explain the prevalence of the organism in poultry and in human enteric infection in the United Kingdom.

Animals↗