Recombination of the Phase-Variable spnIII Locus Is Independent of All Known Pneumococcal Site-Specific Recombinases.

Streptococcus pneumoniae is one of the world's leading bacterial pathogens, causing pneumonia, septicemia, and meningitis. In recent years, it has been shown that genetic rearrangements in a type I restriction-modification system (SpnIII) can impact colony morphology and gene expression. By generating a large panel of mutant strains, we have confirmed a previously reported result that the CreX (also known as IvrR and PsrA) recombinase found within the locus is not essential for hsdS inversions. In addition, mutants of homologous recombination pathways also undergo hsdS inversions. In this work, we have shown that these genetic rearrangements, which result in different patterns of genome methylation, occur across a wide variety of serotypes and sequence types, including two strains (a 19F and a 6B strain) naturally lacking CreX. Our gene expression analysis, by transcriptome sequencing (RNAseq), confirms that the level of creX expression is impacted by these genomic rearrangements. In addition, we have shown that the frequency of hsdS recombination is temperature dependent. Most importantly, we have demonstrated that the other known pneumococcal site-specific recombinases XerD, XerS, and SPD_0921 are not involved in spnIII recombination, suggesting that a currently unknown mechanism is responsible for the recombination of these phase-variable type I systems.IMPORTANCEStreptococcus pneumoniae is a leading cause of pneumonia, septicemia, and meningitis. The discovery that genetic rearrangements in a type I restriction-modification locus can impact gene regulation and colony morphology led to a new understanding of how this pathogen switches from harmless colonizer to invasive pathogen. These rearrangements, which alter the DNA specificity of the type I restriction-modification enzyme, occur across many different pneumococcal serotypes and sequence types and in the absence of all known pneumococcal site-specific recombinases. This finding suggests that this is a truly global mechanism of pneumococcal gene regulation and the need for further investigation of mechanisms of site-specific recombination.

Persistent Staphylococcus aureus isolates from two independent cases of bacteremia display increased bacterial fitness and novel immune evasion phenotypes.

Staphylococcus aureus bacteremia cases are complicated by bacterial persistence and treatment failure despite the confirmed in vitro susceptibility of the infecting strain to administered antibiotics. A high incidence of methicillin-resistant S. aureus (MRSA) bacteremia cases are classified as persistent and are associated with poorer patient outcomes. It is still unclear how S. aureus evades the host immune system and resists antibiotic treatment for the prolonged duration of a persistent infection. In this study, the genetic changes and associated phenotypic traits specific to S. aureus persistent bacteremia were identified by comparing temporally dispersed isolates from persistent infections (persistent isolates) originating from two independent persistent S. aureus bacteremia cases with the initial infection isolates and with three resolved S. aureus bacteremia isolates from the same genetic background. Several novel traits were associated specifically with both independent sets of persistent S. aureus isolates compared to both the initial isolates and the isolates from resolved infections (resolved isolates). These traits included (i) increased growth under nutrient-poor conditions; (ii) increased tolerance of iron toxicity; (iii) higher expression of cell surface proteins involved in immune evasion and stress responses; and (iv) attenuated virulence in a Galleria mellonella larva infection model that was not associated with small-colony variation or metabolic dormancy such as had been seen previously. Whole-genome sequence analysis identified different single nucleotide mutations within the mprF genes of all the isolates with the adaptive persistence traits from both independent cases. Overall, our data indicate a novel role for MprF function during development of S. aureus persistence by increasing bacterial fitness and immune evasion.

Recording occupation in general practice--a second cycle audit.

BACKGROUND: An audit of working age patients' records in two Cornish general practices in 2012 found infrequent and inconsistent recording of patients' occupations. A concurrent survey of general practitioners (GPs) in Cornwall found that a majority of them believed it was important to do so. AIMS: To review occupation recording in the same practices a year later and to audit a third practice, following the introduction of the electronic fit note. To repeat the survey of attitudes to recording occupation in GPs in Cornwall. METHODS: We manually checked 300 randomly selected patient records in Practice A and electronically searched all records of working age patients (aged 16-65 years) in Practices B and C for recorded occupation. We sent an electronic survey of attitudes to recording occupation to 202 GPs in Cornwall. RESULTS: Recording of occupation increased from 17 to 30% of records (χ(2) = 15, P < 0.001) in Practice A and from 12 to 14% (χ(2) = 16.5, P < 0.001) in Practice B. In Practice C, 1% of records had occupation recorded and coded. The proportion of GPs in Cornwall who said that it is important to records patients' occupation increased from 70 to 90% (Fisher's exact statistic 0.01, P < 0.05). CONCLUSIONS: Recording of patients' occupation increased in both practices from 2012 to 2013, but remains infrequent and inconsistent and the very low levels in a third practice not previously audited is of concern.

A biobank analysis of prognostic biomarkers of the systemic inflammatory response in patients presenting with malignancy of undefined primary origin.

BACKGROUND: Survival prediction in patients presenting with malignancy of undefined primary origin (MUO) is challenging, with a lack of validated prognostic tools. Biomarkers of the systemic inflammatory response independently predict survival in other cancer types, but their role in MUO is unclear. The aim of this study was to assess biomarkers of the systemic inflammatory response in patients presenting with MUO. PATIENTS AND METHODS: A biobank of 1049 patients presenting with MUO referred to a regional oncology service in Scotland was analysed. Key inflammatory biomarkers (white cell count, neutrophil count and C-reactive protein combined with albumin [to give the modified Glasgow Prognostic Score {mGPS}]) were examined. The relationship between these and survival was examined using Kaplan-Meier and Cox regression methods. RESULTS: Data were available for 1049 patients. Median survival was 4.3 months (interquartile range: 1.7-16.0 months). On multivariate analysis mGPS was independently associated with survival and stratified survival from 13.6 months (mGPS: 0) to 2.3 months (mGPS: 2) (p < 0.001). The mGPS was predictive of survival on multivariate analysis in patients found to have a non-cancer diagnosis (p = 0.034), an identified primary cancer (0.002), cancer of unknown primary (CUP) (p = 0.011), those for whom biopsy was not done (MUO) (p = 0.036), those found to have an identified primary cancer (0.002) and even those found to have a non-cancer diagnosis (p = 0.034) after further detailed investigations. In patients with CUP mGPS predicted survival regardless of the recognised clinicopathological prognostic subgroup (p < 0.001). CONCLUSIONS: The results of the present study demonstrate that biomarkers of the systemic inflammatory response are reliable prognostic factors in patients presenting with MUO. These simple, objective, routine clinical tests may inform clinical management.

Consequence of neo-antigenicity of the 'altered self'.

Post-translational modifications play a central role in determining the function of proteins. Such protein modifications come in a great variety of guises, and include phosphorylation, proteolysis, glycosylation, citrullination and oxidative modifications. In relation to inflammatory autoimmune diseases, some post-translational modifications appear to result in the generation of new antigens, and hence autoantibodies. Examples include: the induction of peptide immunogenicity by the spontaneous conversion of aspartic acid residues to isoaspartic acid; granzyme B-mediated cleavage of SLE autoantigens; the oxidative modification--on the surface of apoptotic cells--of lipids and proteins, rendering them immunogenic; and the presence of antibodies to oxidatively modified type II collagen and C1q in RA and SLE patients, respectively. The measurement of autoantibodies to citrullinated proteins has been verified as a very useful diagnostic tool in RA. Proteomics techniques, in principle, allow the detection of all types of in vivo protein modifications, and the increasing application of such technologies to the study of rheumatological diseases will further our understanding of autoantigenicity.

Contralateral hyperalgesia and allodynia following intradermal capsaicin injection in man.

OBJECTIVES: Contralateral responses to unilateral stimuli have been well described in animal models. These range from central sensitization to peripheral inflammatory responses. Our aim was to test for contralateral responses following unilateral intradermal capsaicin injection in man. METHODS: Three groups were investigated. A healthy volunteer group (1) was injected with capsaicin into the volar aspect of one forearm. A group of patients with RA (2) was also injected with capsaicin. A control group of healthy volunteers (3) was not injected with capsaicin. All groups were tested for hyperalgesia and allodynia every 10 min for 1 h following the injection using quantitative sensory testing. RESULTS: A total of 9/14 healthy volunteers (Group 1) and 10/14 patients with RA (Group 2) demonstrated contralateral sensitization that subsided within 1 h following intradermal capsaicin injection. A total of 2/23 control subjects (Group 3) demonstrated positive responses with the monofilaments. The frequency of the contralateral responses in the experimental groups compared with the control group is significant (P < 0.05). The peak hyperalgesia was relatively delayed contralaterally compared with the ipsilateral side (35 min vs 15 min). The area of sensitization, where present, was reduced compared with the ipsilateral side (5-50%). CONCLUSIONS: This is the first demonstration of a contralateral response following a unilateral stimulus in man. Bilateral neural pathways mediating contralateral responses may have a role in the pathophysiology of chronically painful or inflammatory diseases and a confounding influence on using the contralateral limb as a control experimentally. We did not find that a systemic inflammatory disease sensitized for this phenomenon.

Are you better? A multi-centre study of patient-defined recovery from Complex Regional Pain Syndrome.

BACKGROUND: Complex Regional Pain Syndrome (CRPS) symptoms can significantly differ between patients, fluctuate over time, disappear or persist. This leads to problems in defining recovery and in evaluating the efficacy of therapeutic interventions. OBJECTIVES: To define recovery from the patients' perspective and better understand their priorities for treatment approaches. METHODS: Establishing an international consortium, we used a 2-Round Delphi-based study in eight countries across Europe and North America. Participants ≥18 years who met, or had met, Budapest clinical criteria were included. Round 1 participants completed the statement: 'I would/do consider myself recovered from CRPS if/because…' alongside demographic and health questionnaires. Data were thematically organised and represented as 62 statements, from which participants identified and ranked their recovery priorities in Round 2. RESULTS: Round 1 (N = 347, 80% female, 91% non-recovered) dominant ICF themes were: activities of daily living; bodily functions; external factors; participation and personal factors. The top five priority statements in Round 2 (N = 252) were: no longer having (1) CRPS-related pain, (2) generalised pain and discomfort, (3) restricted range of movement, (4) need for medication, (5) stiffness in the affected limb. With very few exceptions, priorities were consistent, irrespective of patient demographics/geography. Symptoms affecting daily activities were among those most frequently reported. CONCLUSIONS: Our data showed a small number of themes are of highest importance to CRPS patients' definition of recovery. Patients want their pain, movement restriction and reliance on medication to be addressed, above all other factors. These factors should therefore be foremost concerns for future treatment and rehabilitation programmes. SIGNIFICANCE: Those with longstanding CRPS may no longer meet diagnostic criteria but still be symptomatic. Defining recovery is therefore problematic in CRPS. Our study has identified patients' definition of recovery from CRPS, in order of priority, as relief from: their CRPS-related pain, generalised pain, movement restriction, reliance on medication, and stiffness.

An in vitro transposon system for highly regulated gene expression: construction of Escherichia coli strains with arabinose-dependent growth at low temperatures.

Placing a gene of interest under the control of an inducible promoter greatly aids the purification, localization and functional analysis of proteins but usually requires the sub-cloning of the gene of interest into an appropriate expression vector. Here, we describe an alternative approach employing in vitro transposition of Tn Omega P(BAD) to place the highly regulable, arabinose inducible P(BAD) promoter upstream of the gene to be expressed. The method is rapid, simple and facilitates the optimization of expression by producing constructs with variable distances between the P(BAD) promoter and the gene. To illustrate the use of this approach, we describe the construction of a strain of Escherichia coli in which growth at low temperatures on solid media is dependent on threshold levels of arabinose. Other uses of the transposable promoter are also discussed.

Effect of glucocorticoids on alpha 1-adrenergic receptor binding in rat vascular smooth muscle.

Glucocorticoids are known to have marked effects on blood pressure regulation, predominantly through altering cardiovascular sensitivity to noradrenaline. However, the molecular mechanisms underlying this action remain unclear. As part of our studies into these we have measured alpha 1-adrenergic receptor binding using the ligand [3H]prazosin in plasma membrane fractions of aortas prepared from control, adrenalectomized and dexamethasone-treated adrenalectomized rats. In controls there were 50 +/- 8 (S.E.M.; n = 6) fmol alpha 1-adrenergic receptors/mg membrane protein (Bmax) with a dissociation constant (Kd) of 0.52 +/- 0.10 nM (n = 6). Adrenalectomy 8 days before tissue preparation caused a 40% decrease in Bmax and a 60% decrease in Kd. Dexamethasone replacement after adrenalectomy returned these values close to those of controls. Noradrenaline competed for the [3H]prazosin-binding sites. Computer analysis by a non-linear curve-fitting program (LIGAND) showed that noradrenaline binding was to a heterogeneous population of high- and low-affinity receptors with Kd values of 1.87 +/- 0.73 microM and 0.48 +/- 0.12 mM (n = 5) respectively. Guanosine thiotriphosphate (GTP[S]) caused the conversion of high-affinity to low-affinity binding, consistent with the model of the high-affinity sites being coupled to a G protein. After adrenalectomy, noradrenaline binding was to a homogeneous population of low-affinity receptors; hence, the effect of GTP[S] was no longer apparent, suggesting that under these conditions the alpha 1-adrenergic receptors were unable to couple to a G protein. The two-site model of binding and GTP[S] effect was returned by dexamethasone treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucocorticoids regulate the amount of G proteins in rat aorta.

Glucocorticoids are known to influence cardiovascular sensitivity to catecholamines but the molecular mechanisms are undefined. We recently showed that glucocorticoids control the coupling of adrenergic receptors to G protein. Alterations in the amount of G protein is one mechanism by which receptor-G protein coupling may be controlled. Therefore, we set out to measure the levels of G proteins in aorta from normal, adrenalectomized and dexamethasone-treated adrenalectomized rats. G proteins were measured in plasma membrane preparations by immunoblotting and horseradish peroxidase staining. After adrenalectomy there was 53% (n = 5) decrease in the density of staining for Gi (ANOVA; P less than 0.05 compared to controls). Conversely, there was a 210% (n = 5) increase in the density of staining for Gs. The levels of Go and the beta-subunit of G proteins were not changed by adrenalectomy. Dexamethasone-replacement treatment after adrenalectomy returned Gi and Gs close to control values. Go remained unaltered compared to controls but was 24% (n = 3) less than the adrenalectomized values (ANOVA; P less than 0.05). The levels of beta-subunit after dexamethasone replacement were significantly greater (ANOVA; P less than 0.05) than both the controls and adrenalectomized values. These results show that glucocorticoids can differentially regulate the amounts of G proteins in rat aorta as in other tissues. This may be an important mechanism by which steroids control receptor-G protein coupling and hence transmembrane signalling pathways in vascular smooth muscle.

GnRH antagonists: a new generation of long acting analogues incorporating p-ureido-phenylalanines at positions 5 and 6.

A series of antagonists of gonadotropin-releasing hormone (GnRH) of the general formula Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph/4Amf(P)-D4Aph/D4Amf(Q)-Leu-ILys-Pro-DAla-NH2 was synthesized, characterized, and screened for duration of inhibition of luteinizing hormone release in a castrated male rat assay. Selected analogues were tested in a reporter gene assay (IC50 and pA2) and an in vitro histamine release assay. P and Q contain urea/carbamoyl functionalities designed to increase potential intra- and intermolecular hydrogen bonding opportunities for structural stabilization and peptide/receptor interactions, respectively. These substitutions resulted in analogues with increased hydrophilicity and a lesser propensity to form gels in aqueous solution than azaline B [Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(Atz)-D4Aph(Atz)-Leu-ILys-Pro-DAla-NH2 with Atz = 3'-amino-1H-1',2',4'-triazol-5'-yl, 5], and in some cases they resulted in a significant increase in duration of action after subcutaneous (s.c.) administration. Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(L-hydroorotyl)-D4Aph(carbamoyl)-Leu-ILys-Pro-DAla-NH2 (acetate salt is FE200486) (31) and eight other congeners (20, 35, 37, 39, 41, 45-47) were identified that exhibited significantly longer duration of action than acyline [Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(Ac)-D4Aph(Ac)-Leu-ILys-Pro-DAla-NH2] (6) when administered subcutaneously in castrated male rats at a dose of 50 microg in 100 microL of phosphate buffer. No correlation was found between retention times on a C18 reverse phase column using a triethylammonium phosphate buffer at pH 7.0 (a measure of hydrophilicity) or affinity in an in vitro human GnRH report gene assay (pA2) and duration of action. FE200486 was selected for preclinical studies, and some of its properties were compared to those of other clinical candidates. In the intact rat, ganirelix, abarelix, azaline B, and FE200486 inhibited plasma testosterone for 1, 1, 14, and 57 days, respectively, at 2 mg/kg s.c. in 5% mannitol (injection volume = 20 microL). Based on the information that 31, 33, 35 and 37 were significantly shorter acting than acyline or azaline B after intravenous administration (100 microg/rat), we surmised that the very long duration of action of the related FE200486 (for example) was likely due to unique physicochemical properties such as solubility in aqueous milieu, comparatively low propensity to form gels, and ability to diffuse at high concentrations in a manner similar to that described for slow release formulations of peptides. Indeed, in rats injected s.c. with FE200486 (2 mg/kg), plasmatic concentrations of FE200486 remained above 5 ng/mL until day 41, and the time after which they dropped below 3 ng/mL and plasma LH levels started rising until full recovery was reached at day 84 with levels of FE200486 hovering around 1 ng/mL. Additionally, FE200486 was less potent at releasing histamine from isolated rat mast cells than any of the GnRH antagonists presently described in preclinical reports.

Enhancement of noradrenaline-induced inositol polyphosphate formation by glucocorticoids in rat vascular smooth muscle cells.

Glucocorticoids are known to regulate the contractility of vascular smooth muscle by increasing its response to noradrenaline. The molecular mechanisms for achieving this remain unclear. Recent results in our laboratory have demonstrated that glucocorticoids affect both alpha 1-adrenoceptor number and coupling to G proteins. Whether this leads to an increase in second-messenger production has to be established. The present experiments, therefore, report the effects of dexamethasone on inositol polyphosphate production in vascular smooth muscle cells in culture. Noradrenaline induced the release of inositol polyphosphates from prelabelled [3H]inositol phosphoinositides in the membrane in a dose-dependent manner. The concentration of noradrenaline which caused half-maximal response was 1.26 mumol/l. Prazosin inhibited noradrenaline-induced inositol monophosphate formation to 10.26 +/- 3.67% (mean +/- S.E.M.; P less than 0.01, n = 5) of control value whereas yohimbine reduced it to only 61.74 +/- 11.82% (P less than 0.05, n = 5), suggesting an action primarily through alpha 1-adrenergic receptors. Dexamethasone (100 nmol/l, 48 h) enhanced noradrenaline-induced inositol monophosphate, bisphosphate and trisphosphate formation up to twofold (P less than 0.001, n = 5). The enhancement of the response occurred despite the fact that dexamethasone reduced [3H]inositol prelabelling of membrane phosphoinositides by 49.5 +/- 9.9% (P less than 0.05, n = 3). The present results suggest that the potential action of glucocorticoids on vascular smooth muscle contractility is, at least in part, through controlling alpha 1-adrenoceptor-mediated second-messenger production.

Phantoms in rheumatology.

This paper examines rheumatology pain and how it may relate to amputee phantom limb pain (PLP), specifically as experienced in rheumatoid arthritis, fibromyalgia and complex regional pain syndrome (CRPS). Clinical findings, which suggest cortical sensory reorganization, are discussed and illustrated for each condition. It is proposed that this sensory reorganization generates pain and altered body image in rheumatology patients in the same manner as has previously been hypothesized for amputees with PLP; that is via a motor/sensory conflict. The correction of this conflict through the provision of appropriate visual sensory input, using a mirror, is tested in a population of patients with CRPS. Its analgesic efficacy is assessed in those with acute, intermediate and chronic disease. Finally, the hypothesis is taken to its natural conclusion whereby motor/sensory conflict is artificially generated in healthy volunteers and chronic pain patients to establish whether sensory disturbances can be created where no pain symptoms exists and exacerbated when it is already present. The findings of our studies support the hypothesis that a mismatch between motor output and sensory input creates sensory disturbances, including pain, in rheumatology patients and healthy volunteers. We propose the term 'ominory' to describe the central monitoring mechanism and the resultant sensory disturbances as a dissensory state.

Symmetry, T cells and neurogenic arthritis.

Symmetry in clinical disease occurs more commonly than expected by chance and is unexplained. In this paper we focus on symmetry in arthritis and describe the neurogenic hypothesis. Neuropeptides are anatomically relevant to systemic arthritis and have been shown to have modulating effects on both the immune and circulatory systems. Neural networks project bilaterally and are involved in the development and propagation of inflammatory disease. These putative pathological neuro-feedback loops may derive from the existence of biologically protective symmetrical mechanisms.

Synthesis and properties of amphiphilic networks 2: a differential scanning calorimetric study of poly(dodecyl methacrylate-stat-2,3 propandiol-1-methacrylate-stat-ethandiol dimethacrylate) networks and adhesion and spreading of dermal fibroblasts on these materials.

A series of amphiphilic networks was prepared by radical copolymerisation of dodecyl methacrylate, 2,3-propandiol-1-methacrylate and ethandiol dimethacrylate. DSC studies on these materials, swollen in water. revealed that only materials containing more than 27 wt% of water displayed melting endotherms due to the melting of ice-like structures of water (freezing water). In materials that did produce a melting endotherm the peak was generally bimodal. Changing thermal history and heating rate did not effect the shape of the two peaks, nor the relative contribution of each peak to the total endothermic response. These observations and the narrow peak width of the low temperature endotherm suggested that the bimodality was an artefact of the DSC experiment and may be due to the promotion of the glass transition once a fraction of the water has frozen. The morphology of transformed human dermal fibroblasts grown on these materials was then examined by scanning electron microscopy. Compositions that contained only non-freezing water were found to allow cell adhesion and spreading. Cells with well-spread morphologies were obtained on materials containing small fractions of freezing water and dodecyl methacrylate. These fibroblasts displayed surface features such as microvilli and filapodia. However, all compositions of poly(2,3-propandiol-1-methacrylate-co-ethandiol dimethacrylate) (i.e. hydrogels that do not contain dodecyl methacrylate repeat units) were poor substrates for cell growth and examination of these materials showed that very few cells had adhered and those that did were highly rounded.

Synthesis and properties of amphiphilic networks. 1: the effect of hydration and polymer composition on the adhesion of immunoglobulin-G to poly(laurylmethacrylate-stat-glycerolmonomethacrylate-stat-ethylene-gly col-dimethacrylate) networks.

A series of hydrogels composed of varying fractions of dodecyl methacrylate (DM) and 2,3-dihydroxypropyl methacrylate (GM) were prepared using ethylene glycol dimethacrylate (EGDMA) as the cross-linking agent. The study found that for a series of gels with the same monomer ratio, bulk hydration could be controlled by adjusting the cross-link density. The ability to control cross-link density allowed the preparation of gels with the same bulk hydration but different ratios of the two monomers. The adsorption of IgG to the gels was investigated using ELISA. The aim of the project was to investigate the effect of the bulk hydration and polymer composition on IgG adsorption. The results show that for a series of gels with the same monomer ratio, there is a clear trend towards a reduction in protein adsorption as the bulk hydration and accompanying chain mobility of the gel increases. Studies on gels of the same bulk hydration but differing ratios of monomer show higher protein adsorption as the proportion of GM increases.

Carbon dioxide regulated secretion of the EaeB protein of enteropathogenic Escherichia coli.

An eaeA mutant (intimin deficient) of enteropathogenic Escherichia coli stimulated phosphorylation of several host cell proteins, showing that intimate adherence is not required to activate signal transduction pathways in enteropathogenic E. coli-infected cells. Growth of enteropathogenic E. coli in tissue culture medium in 5% CO2, in the presence or absence of cultured cells, resulted in the secretion of several bacterial proteins. Two of these, 36 kDa and 20 kDa in size, were expressed at significantly lower levels in air. N-terminal sequencing and analysis of secreted proteins of an eaeB mutant indicated that the 36 kDa secreted protein was EaeB, previously implicated in the stimulation of signalling pathways in enteropathogenic E. coli-infected cells.

Stimulation of bacterial growth by heat-stable, norepinephrine-induced autoinducers.

The ability of norepinephrine to increase the growth of Escherichia coli in a serum-based medium has previously been shown to be due to the production of an autoinducer of growth during early log phase. Seventeen Gram-negative and 6 Gram-positive clinical isolates were examined for a similar ability to respond to norepinephrine, and to synthesise autoinducer. The majority of Gram-negative strains both produced and responded to heat-stable norepinephrine-induced autoinducers of growth. Most of these autoinducers showed a high degree of cross-species activity, suggesting the existence of a novel family of Gram-negative bacterial signalling molecules. In contrast, although a number of Gram-positive strains were able to respond to norepinephrine, the majority failed to produce autoinducers in the presence of norepinephrine.

Catecholamine inotropes as growth factors for Staphylococcus epidermidis and other coagulase-negative staphylococci.

Drugs commonly used in intensive care settings were assayed for their ability to affect the growth of Staphylococcus epidermidis in a minimal salts medium containing 30% serum. Of 28 compounds tested, the inotropic catecholamines adrenaline, dobutamine, dopamine, isoprenaline and noradrenaline significantly stimulated bacterial growth. These drugs, but not structurally similar compounds lacking a dihydroxybenzoyl moiety (such as tyramine, phenylephrine and salbutamol), were able to remove iron from iron-saturated transferrin and to supply transferrin-bound 55Fe to S. epidermidis cells. Similar results were observed with a range of coagulase-negative staphylococci associated with line infections, but not with Staphylococcus aureus (including MRSA).