Persistence of sulphonamide resistance in Escherichia coli in the UK despite national prescribing restriction

BACKGROUND

There is a clear association between heavy antimicrobial consumption within a population and the frequent recovery of resistant bacteria, but whether a reduction in antimicrobial use can reverse this process is less clear. We investigated the effect of a national restriction of sulphonamide prescribing in the UK on the prevalence of sulphonamide resistance in Escherichia coli.

METHODS

Consecutive clinical isolates of E coli were collected at the Royal London Hospital in 1991 and 1999. These collections, each of more than 350 isolates, were compared. Minimum inhibitory concentrations of sulphamethoxazole and eight other antimicrobials were determined. The presence and locations of sulphonamide-resistance genes were examined by PCR, plasmid extraction, Southern hybridisation, and transconjugation.

FINDINGS

Despite a huge decrease in sulphonamide prescriptions (from 3,208,000 [corrected] prescriptions per year in 1991 to 77,000 [corrected] in 1999), the frequency of resistance remained high in 1999 (165/359 [46.0%] vs 143/360 [39.7%] in 1991; difference 6.2% [95% CI 20.9 to 13.3]). Integron-borne sulI was present in 16.4% of isolates in 1991 and 17.5% in 1999. The prevalence of sulII increased from 26.7% in 1991 to 36.5% in 1999 (difference 9.8% [3.1 to 16.5] p=0.0046). SulII was located on large plasmids, at least some of which were conjugative multiresistance determinants.

INTERPRETATION

These results show that a huge decrease in antibiotic prescribing does not necessarily reduce resistance within a useful time. The main reason seems to be the genetic linkage of the index resistance to other resistance determinants.

Codon usage can affect efficiency of translation of genes in Escherichia coli

By inserting synthetic oligonucleotides into a highly expressed gene in E. coli it has been shown that unfavourable codon usage can reduce the maximum translation rate of a protein. However, in the case of the codon used (AGG), a significant effect on translation was only seen at very high transcription rates from a gene containing multiple copies of the unfavourable codon.

Exploitation of gene(s) involved in 2,4-diacetylphloroglucinol biosynthesis to confer a new biocontrol capability to a Pseudomonas strain

Tn5 mutagenesis and complementation analysis were used to clone a 6-kb genomic fragment required for biosynthesis of 2,4-diacetylphloroglucinol (Phl) from fluorescent Pseudomonas sp. strain F113. A recombinant plasmid, pCU203, containing this region partially complemented a Phl production-negative mutant (F113G22) derived from strain F113. When sugar beet seeds were sown into an unsterilized soil, in which sugar beet was subject to damping-off by Pythium ultimum, the emergence of sugar beet seeds inoculated with strain F113 was significantly greater than that of seeds inoculated with F113G22. Transfer of pCU203 into eight other Pseudomonas strains conferred the ability to synthesize Phl in only one of these strains, Pseudomonas sp. strain M114. Strain M114(pCU203) showed enhanced antagonism towards P. ultimum in vitro and significantly increased the emergence of sugar beet seeds in the same soil compared with emergence induced by the parent strain M114.

Trends in prescribing and utilization of statins and other lipid lowering drugs across Europe 1997-2003

AIMS

To describe trends in utilization and prescribing of statins and other lipid lowering drugs across Europe from data in routine administrative databases.

METHODS

Observational study in EU member states and Norway. Comparison of annual utilization data for lipid lowering agents by class and drug from national administrative databases for reimbursement over the period 1997-2003, measured in DDDs per 1000 inhabitants/day. Prescribed daily doses (PDD) of statins obtained from a commercial database (IMS Health) for 2000 and 2003, and used to calculate numbers of "patient treatment days" (PTD) in each country in each year. Analysis of PTD to explain increased utilization of statins.

RESULTS

Use of lipid lowering agents varied among countries (in 2003, highest in Ireland and Norway, and lowest in Italy), but increased in all countries studied (between 2000 and 2003 by 274% in Ireland and by 56% in France). This increase was entirely due to increases in statin use. Prescribed daily doses of statins increased in all countries for which data was available between 2000 and 2003, but still usually fell below the doses used in the major trials of statins. As a result, the numbers of PTDs increased to a lesser extent than suggested by utilization (e.g. by 192% in Ireland and by 35% in France). One-third of the total rise in utilization was explained by increased PDD, and two-thirds by an increase in numbers of PTDs. Statins dominated the markets in all countries, although fibrates remained strong in France and Belgium (approximately 25% of all lipid lowering agents) and to a lesser extent Germany (10%).

CONCLUSIONS

Use of statins across Europe has increased hugely over the study period. Some of the increase in use is due to higher prescribed daily doses, but two-thirds is due to increases in numbers of patient days of treatment, either due to more patients treated or less likely to better compliance.

Assessment of bacterial viability status by flow cytometry and single cell sorting

Rapid bacterial detection and viability measurements have been greatly enhanced by recent advances in the use of fluorescent stains in cytometry. It has previously been shown that four physiological states can be distinguished: reproductively viable, metabolically active, intact and permeabilized. Previous sorting experiments have shown that not all intact cells readily grow, but some intact cells can grow even when they fail to show metabolic activity, as determined by esterase turnover. To circumvent the limitations imposed by active dye extrusion or cell dormancy on viability measurements used to date (e.g., enzyme activity or cell polarization), a fast triple fluorochrome staining procedure has been developed that takes account of these problems. This allows further cellular characterization of intact cells by: active exclusion of ethidium bromide (EB) (metabolically active cells), uptake of EB but exclusion of bis-oxonol (BOX) (de-energized but with a polarized cell membrane) and uptake of both dyes (depolarized). Permeabilized cells were identified by propidium iodide (PI) uptake. The method was validated using an electronically programmable single cell sorter (EPICS Elite) and aged Salmonella typhimurium cells. Reproductive viability was determined by sorting single cells to their staining pattern directly onto agar plates. Most polarized cells could be recovered as well as a significant fraction of the depolarized cells, demonstrating that depolarization is a sensitive measure of cell damage but a poor indicator of cell death.

Increased prescribing trends of paediatric psychotropic medications

Psychotropic medication use by children in the USA has increased. We used the IMS MIDAS Prescribing Insights to examine prescribing trends in nine countries between the years 2000 and 2002. Trends in seven countries rose significantly from year 2000 to 2002; the UK had the highest increase (68%).

A model of psychosocial hypertension showing reversibility and progression of cardiovascular complications

The sequence of pathophysiological changes that can result from the stimulating effects of a sustained disturbance of the social environment was studied in ten colonies of socially deprived mice. Sixteen formerly isolated males were placed with 16 normal females in population cages consisting of seven intercommunicating boxes. Six of these socially disturbed 32-member colonies were terminated after periods of interaction ranging from 2 days to 9 months. The remaining four were terminated a month or more after the males had been returned to individual isolation. Indirect blood pressure measurements, body and heart weights, and sections of hearts and aortas were studied in the males. Following the shorter exposures, blood pressure reverted to normal in a few days. Exposure of 6 months or more were associated with unchanged body weights and sustained increases in heart weight and blood pressure readings. In addition, there was a significant development of aortic arteriosclerosis and myocardial fibrosis. These changes persisted despite prolonged return to isolation.

Skin and oral fibroblasts exhibit phenotypic differences in extracellular matrix reorganization and matrix metalloproteinase activity

BACKGROUND

Oral mucosal wounds are characterized by rapid re-epithelialization and remodelling. In vitro, oral mucosal fibroblasts exhibit a fetal phenotype with increased extracellular matrix reorganizational ability, migration and experimental wound repopulation when compared with skin fibroblasts.

OBJECTIVES

To investigate whether phenotypic differences in the expression and production of matrix metalloproteinase (MMP) -2 and tissue inhibitors of metalloproteinases (TIMPs) could play an important part in mediating these in vitro differences.

METHODS

Skin and oral mucosal fibroblast MMP-2, TIMP-1 and TIMP-2 mRNA expression and protein production were studied in three-dimensional collagen lattices using quantitative competitive reverse transcriptase-polymerase chain reaction (QCRT-PCR), enzyme-linked immunosorbent assay (ELISA), zymography and reverse zymography.

RESULTS

Oral mucosal fibroblasts exhibited increased levels of the 62-kDa active form of MMP-2 and lattice contraction when compared with skin fibroblasts. Oral mucosal and skin fibroblast MMP-2 gene expression and synthesis of the 72-kDa pro-MMP-2 was similar as assessed by QCRT-PCR, zymography and ELISA. Differential MMP-2 activation was, however, related to phenotypic differences in TIMP activity between the skin and oral mucosal fibroblasts, as assessed by reverse zymography.

CONCLUSIONS

These studies propose a mechanism by which fibroblast phenotype may contribute directly to the observed preferential remodelling of oral wounds.

A comparison of the ability of intra-oral and extra-oral fibroblasts to stimulate extracellular matrix reorganization in a model of wound contraction

Intra-oral wounds, like wounds in children, demonstrate privileged healing when compared with adult wounds at extra-oral sites. This study investigated whether this preferential healing is related to an increased ability of oral mucosal fibroblasts to reorganize extracellular matrix (ECM) when compared with their dermal counterparts. ECM reorganization was investigated by means of a fibroblast-populated collagen lattice (FPCL) system. The effect of donor age was also investigated in this system. Differences in ECM reorganization and FPCL contraction were evident: FPCL contraction was more rapid by oral mucosal fibroblasts than dermal fibroblasts (p < 0.01). FPCL contraction was also greater in child (donor < 10 years) than adult (donor > 18 years) oral mucosal fibroblasts (p < 0.01). These differences were not related to phenotypic differences in cell viability (p > 0.5), DNA synthesis (p > 0.05), and cell number (p > 0.5) within the FPCLs, or cellular attachment to collagen (p > 0.07). FPCL contraction was not stimulated by the addition of conditioned medium from oral mucosal or dermal fibroblasts (p > 0.05). These data show that the significantly increased ability of oral mucosal fibroblasts to reorganize ECM in vitro, when compared with dermal fibroblasts, represents a distinct phenotypic contractile difference, rather than differences in their production of soluble mediators or cell attachment to ECM.

Temperature dependence of cell-cell fusion induced by the envelope glycoprotein of human immunodeficiency virus type 1

We investigated cell-cell fusion induced by the envelope glycoprotein of human immunodeficiency virus type 1 strain IIIB expressed on the surface of CHO cells. These cells formed syncytia when incubated together with CD4-positive human lymphoblastoid SupT1 cells or HeLa-CD4 cells but not when incubated with CD4-negative cell lines. A new assay for binding and fusion was developed by using fluorescent phospholipid analogs that were produced in SupT1 cells by metabolic incorporation of BODIPY-labeled fatty acids. Fusion occurred as early as 10 min after mixing of labeled SupT1 cells with unlabeled CHO-gp160 cells at 37 degrees C. When both the fluorescence assay and formation of syncytia were used, fusion of SupT1 and HeLa-CD4 cells with CHO-gp160 cells was observed only at temperatures above 25 degrees C, confirming recent observations (Y.-K. Fu, T.K. Hart, Z.L. Jonak, and P.J. Bugelski, J. Virol. 67:3818-3825, 1993). This temperature dependence was not observed with influenza virus-induced cell-cell fusion, which was quantitatively similar at both 20 and 37 degrees C, indicating that cell-cell fusion in general is not temperature dependent in this range. gp120-CD4-specific cell-cell binding was found over the entire 0 to 37 degrees C range but increased markedly above 25 degrees C. The enhanced binding and fusion were reduced by cytochalasins B and D. Binding of soluble gp120 to CD4-expressing cells was equivalent at 37 and 16 degrees C. Together, these data indicate that during gp120-gp41-induced syncytium formation, initial cell-cell binding is followed by a cytoskeleton-dependent increase in the number of gp120-CD4 complexes, leading to an increase in the avidity of cell-cell binding. The increased number of gp120-CD4 complexes is required for fusion, which suggests that the formation of a fusion complex consisting of multiple CD4 and gp120-gp41 molecules is a step in the fusion mechanism.

Extracellular matrix metabolites as potential biomarkers of disease activity in wound fluid: lessons learned from other inflammatory diseases?

The new era of pharmacogenetics has identified a potential for individuals to receive customized treatments for a variety of disease states. For such individualized treatments to fulfil their potential, it will be essential for clinicians to be able to monitor disease activity, ideally in a rapid, noninvasive fashion. The accessibility of the skin offers much potential to develop noninvasive tests of metabolic and disease activity for clinical use. Impaired human wound healing in the skin is a chronic inflammatory disorder in which the development of such tests has considerable potential, aiding clinical decision making and monitoring responses to treatment. This review article discusses how studies in other human diseases have highlighted potential biochemical markers (biomarkers) of disease activity in secreted biofluids, as aids to determining disease and metabolic activity within tissues. Using, as examples, lessons learned in the study of disease activity and prognosis of other chronic inflammatory conditions, such as osteoarthritis and periodontal disease, this review highlights the potential of dermal extracellular matrix (ECM) components (collagens, proteoglycans, hyaluronan and glycoproteins) for such uses. The limitations of currently utilized techniques and the concept that analysis of ECM components in wound fluid may represent useful biomarkers of disease activity are also discussed.

Use of molecular techniques to study microbial diversity in the skin: chronic wounds reevaluated

The skin is colonized by an array of microorganisms which form its natural microflora. Disruption to the normal barrier function of the skin (due to trauma or disease) may result in invasion of the dermis by opportunistic bacteria. To date, these organisms, which may contribute to the chronicity of skin wounds, have been analyzed solely by culture methods. It is increasingly realized that standard culture methods of analysis do not accurately reflect the full diversity of complex microflora. This review discusses the limitations of traditional culture approaches and reviews recent advances in molecular microbiological techniques which facilitate a more comprehensive characterization of the microflora within clinical samples. The currently available technologies and techniques are described, as is their use in clinical practice and their potential for diagnostic screening. Chronic venous ulceration of the lower limbs is an important skin disorder in which the microflora invading the dermal tissues contribute to the observed delayed healing. Using chronic leg ulcers as a working example, we show how strict culture and molecular microbiological techniques may be employed, for the first time in combination, to definitively characterize the invading microbial community of the dermis.

Anaerobic cocci populating the deep tissues of chronic wounds impair cellular wound healing responses in vitro

BACKGROUND

Anaerobic cocci are estimated to be present in the deep tissues of over 50% of chronic skin wounds. While the part they play in the chronicity of these wounds is uninvestigated, anaerobic cocci have previously been shown to be involved in other chronic inflammatory human conditions.

METHODS

In this study the anaerobic microflora of the deep tissues of 18 patients with refractory chronic venous leg ulcers (mean age 80.3 years; mean duration > 24 months) was characterized using strict anaerobic culture conditions. The effect of the anaerobic organisms isolated from these tissues on extracellular matrix (ECM) proteolysis and cellular wound healing responses was studied using in vitro models.

RESULTS

Anaerobic organisms were present in the deep tissues of 14 of 18 wounds and were principally Peptostreptococcus spp. The effects of three Peptostreptococcus spp. isolated from these wounds (P. magnus, P. vaginalis and P. asaccharolyticus) on cellular wound healing responses were compared with those of two pathogenic organisms also isolated from these wounds (Pseudomonas aeruginosa and Citrobacter diversus). While the direct ECM proteolytic activity exhibited by the Peptostreptococcus spp. was limited, they did significantly inhibit both fibroblast and keratinocyte proliferation, but only at high concentrations. However, at lower concentrations peptostreptococcal supernatants profoundly inhibited keratinocyte wound repopulation and endothelial tubule formation. The magnitude of these effects varied between strains and they were distinct from those demonstrated by Pseudomonas aeruginosa and Citrobacter diversus.

CONCLUSIONS

These studies confirm the importance of anaerobic organisms in chronic wounds and demonstrate an indirect, strain-specific mechanism by which these microorganisms may play a part in mediating the chronicity of these wounds.

Molecular analysis of the microflora in chronic venous leg ulceration

There is growing evidence to suggest that the resident microflora of chronic venous leg ulcers impairs cellular wound-healing responses, thereby playing an important role in maintaining the non-healing phenotype of many of these wounds. The significance of individual species of bacteria will remain unclear until it is possible to characterize fully the microflora of such lesions. The limitations and biases of culture-based microbiology are being realized and the subsequent application of molecular methods is revealing greater diversity within mixed bacterial populations than that demonstrated by culture alone. To date, this approach has been limited to a small number of systems, including the oral microflora. Here, for the first time, the comprehensive characterization of the microflora present in the tissue of a chronic venous leg ulcer is described by the comparison of 16S rDNA sequences amplified directly from the wound tissue with sequences obtained from bacteria that were isolated by culture. The molecular approach demonstrated significantly greater bacterial diversity than that revealed by culture. Furthermore, sequences were retrieved that may possibly represent novel species of bacteria. It is only by the comprehensive analysis of the wound microflora by both molecular and cultural methods that it will be possible to further our understanding of the role of bacteria in this important condition.

Caffeine as an intensifier of stress-induced hormonal and pathophysiologic changes in mice

Psychosocially stressed male mice competing in a Henry-Stephens complex population cage develop hypertension, cardiovascular damage, and chronic interstitial nephritis. Their plasma renin, noradrenaline, corticosterone, and adrenal-catecholamine synthetic enzymes are increased and they die prematurely. Adding 3.3 mg of caffeine a day per kilogram of mouse body weight (the equivalent of 20 micrograms/ml decaffeinated coffee) to their drinking water significantly intensifies most of these changes. A dose of 90 mg/kg of caffeine (the equivalent of 560 micrograms/ml, i.e., brewed tea or coffee) further increases the effects. The drug-induced enhancement of competitive social stimulation of the neuroendocrine system resulted in a further increase of plasma renin and corticosterone levels as well as blood pressure and adrenal weight. These effects together with accelerated mortality and increased pathology indicate that chronic consumption of caffeinated liquids adds to the risks of psychosocial stress.

Bi-allelic inactivation is more prevalent at relapse in multiple myeloma, identifying RB1 as an independent prognostic marker

The purpose of this study is to identify prognostic markers and treatment targets using a clinically certified sequencing panel in multiple myeloma. We performed targeted sequencing of 578 individuals with plasma cell neoplasms using the FoundationOne Heme panel and identified clinically relevant abnormalities and novel prognostic markers. Mutational burden was associated with maf and proliferation gene expression groups, and a high-mutational burden was associated with a poor prognosis. We identified homozygous deletions that were present in multiple myeloma within key genes, including CDKN2C, RB1, TRAF3, BIRC3 and TP53, and that bi-allelic inactivation was significantly enriched at relapse. Alterations in CDKN2C, TP53, RB1 and the t(4;14) were associated with poor prognosis. Alterations in RB1 were predominantly homozygous deletions and were associated with relapse and a poor prognosis which was independent of other genetic markers, including t(4;14), after multivariate analysis. Bi-allelic inactivation of key tumor suppressor genes in myeloma was enriched at relapse, especially in RB1, CDKN2C and TP53 where they have prognostic significance.

KIM127, an antibody that promotes adhesion, maps to a region of CD18 that includes cysteine-rich repeats

A series of fusion proteins have been generated between human and mouse CD18. These proteins have been used to carry out preliminary mapping studies on a number of anti-CD18 antibodies including KIM127 an antibody that promotes CD18-dependent adhesion. This antibody maps to a region of the CD18 molecule between amino acids 406 and 570 in a region containing cysteine-rich repeats.

Constitutional translocation breakpoint mapping by genome-wide paired-end sequencing identifies HACE1 as a putative Wilms tumour susceptibility gene

BACKGROUND

Localisation of the breakpoints of chromosomal translocations has aided the discovery of several disease genes but has traditionally required laborious investigation of chromosomes by fluorescent in situ hybridisation approaches. Here, a strategy that utilises genome-wide paired-end massively parallel DNA sequencing to rapidly map translocation breakpoints is reported. This method was used to fine map a de novo t(5;6)(q21;q21) translocation in a child with bilateral, young-onset Wilms tumour.

METHODS AND RESULTS

Genome-wide paired-end sequencing was performed for approximately 6 million randomly generated approximately 3 kb fragments from constitutional DNA containing the translocation, and six fragments in which one end mapped to chromosome 5 and the other to chromosome 6 were identified. This mapped the translocation breakpoints to within 1.7 kb. Then, PCR assays that amplified across the rearrangement junction were designed to characterise the breakpoints at sequence-level resolution. The 6q21 breakpoint transects and truncates HACE1, an E3 ubiquitin-protein ligase that has been implicated as a somatically inactivated target in Wilms tumourigenesis. To evaluate the contribution of HACE1 to Wilms tumour predisposition, the gene was mutationally screened in 450 individuals with Wilms tumour. One child with unilateral Wilms tumour and a truncating HACE1 mutation was identified.

CONCLUSIONS

These data indicate that constitutional disruption of HACE1 likely predisposes to Wilms tumour. However, HACE1 mutations are rare and therefore can only make a small contribution to Wilms tumour incidence. More broadly, this study demonstrates the utility of genome-wide paired-end sequencing in the delineation of apparently balanced chromosomal translocations, for which it is likely to become the method of choice.