Siderophores and competition for iron govern myxobacterial predation dynamics

Bacterial predators are decisive organisms that shape microbial ecosystems. In this study, we investigated the role of iron and siderophores during the predatory interaction between two rhizosphere bacteria: Myxococcus xanthus, an epibiotic predator, and Sinorhizobium meliloti, a bacterium that establishes nitrogen-fixing symbiosis with legumes. The results show that iron enhances the motility of the predator and facilitates its predatory capability, and that intoxication by iron is not used by the predator to prey, although oxidative stress increases in both bacteria during predation. However, competition for iron plays an important role in the outcome of predatory interactions. Using combinations of predator and prey mutants (non-producers and overproducers of siderophores), we have investigated the importance of competition for iron in predation. The results demonstrate that the competitor that, via the production of siderophores, obtains sufficient iron for growth and depletes metal availability for the opponent will prevail in the interaction. Consequently, iron fluctuations in soils may modify the composition of microbial communities by altering the activity of myxobacterial predators. In addition, siderophore overproduction during predation can alter soil properties, affecting the productivity and sustainability of agricultural operations.

Transcriptomic response of Sinorhizobium meliloti to the predatory attack of Myxococcus xanthus

Bacterial predation impacts microbial community structures, which can have both positive and negative effects on plant and animal health and on environmental sustainability. Myxococcus xanthus is an epibiotic soil predator with a broad range of prey, including Sinorhizobium meliloti, which establishes nitrogen-fixing symbiosis with legumes. During the M. xanthus-S. meliloti interaction, the predator must adapt its transcriptome to kill and lyse the target (predatosome), and the prey must orchestrate a transcriptional response (defensome) to protect itself against the biotic stress caused by the predatory attack. Here, we describe the transcriptional changes taking place in S. meliloti in response to myxobacterial predation. The results indicate that the predator induces massive changes in the prey transcriptome with up-regulation of protein synthesis and secretion, energy generation, and fatty acid (FA) synthesis, while down-regulating genes required for FA degradation and carbohydrate transport and metabolism. The reconstruction of up-regulated pathways suggests that S. meliloti modifies the cell envelop by increasing the production of different surface polysaccharides (SPSs) and membrane lipids. Besides the barrier role of SPSs, additional mechanisms involving the activity of efflux pumps and the peptide uptake transporter BacA, together with the production of H₂O₂ and formaldehyde have been unveiled. Also, the induction of the iron-uptake machinery in both predator and prey reflects a strong competition for this metal. With this research we complete the characterization of the complex transcriptional changes that occur during the M. xanthus-S. meliloti interaction, which can impact the establishment of beneficial symbiosis with legumes.

Guidelines for enhanced recovery after cardiac surgery. Consensus document of Spanish Societies of Anesthesia (SEDAR), Cardiovascular Surgery (SECCE) and Perfusionists (AEP)

The ERAS guidelines are intended to identify, disseminate and promote the implementation of the best, scientific evidence-based actions to decrease variability in clinical practice. The implementation of these practices in the global clinical process will promote better outcomes and the shortening of hospital and critical care unit stays, thereby resulting in a reduction in costs and in greater efficiency. After completing a systematic review at each of the points of the perioperative process in cardiac surgery, recommendations have been developed based on the best scientific evidence currently available with the consensus of the scientific societies involved.

Venous Thromboembolism in Patients With Autoimmune Disorders: Findings From the RIETE Registry

Patients with autoimmune disorders are at an increased risk of venous thromboembolism (VTE), but this association has not been consistently evaluated. We used the RIETE (Registro Informatizado Enfermedad Trombo Embólica) database to compare the rates of VTE recurrences, major bleeding, and death during the course of anticoagulation, according to the presence or absence of autoimmune disorders. Of 71 625 patients with VTE recruited in February 2018, 1800 (2.5%) had autoimmune disorders. Median duration of anticoagulant therapy was slightly longer in patients with autoimmune disorders (median, 190 vs 182 days; P = .001). On multivariable analysis, patients with autoimmune disorders had a similar risk of VTE recurrences (hazard ratio [HR]: 0.93; 95% confidence interval [CI]: 0.68-1.27) or major bleeding (HR: 1.07; 95% CI: 0.82-1.40) and a lower risk to die (HR: 0.66; 95% CI: 0.54-0.81) than those without autoimmune disorders. Patients with giant cell arteritis had the highest rates of major bleeding (8.6 events per 100 patient-years) and the lowest rate of recurrences (zero). In other subgroups, the rates of both events were more balanced. During anticoagulation, patients with or without autoimmune disorders had similar rates of VTE recurrences or major bleeding. However, there were some differences between subgroups of patients with autoimmune disorders.

Sinorhizobium fredii HH103 RirA Is Required for Oxidative Stress Resistance and Efficient Symbiosis with Soybean

Members of Rhizobiaceae contain a homologue of the iron-responsive regulatory protein RirA. In different bacteria, RirA acts as a repressor of iron uptake systems under iron-replete conditions and contributes to ameliorate cell damage during oxidative stress. In Rhizobium leguminosarum and Sinorhizobium meliloti, mutations in rirA do not impair symbiotic nitrogen fixation. In this study, a rirA mutant of broad host range S. fredii HH103 has been constructed (SVQ780) and its free-living and symbiotic phenotypes evaluated. No production of siderophores could be detected in either the wild-type or SVQ780. The rirA mutant exhibited a growth advantage under iron-deficient conditions and hypersensitivity to hydrogen peroxide in iron-rich medium. Transcription of rirA in HH103 is subject to autoregulation and inactivation of the gene upregulates fbpA, a gene putatively involved in iron transport. The S. fredii rirA mutant was able to nodulate soybean plants, but symbiotic nitrogen fixation was impaired. Nodules induced by the mutant were poorly infected compared to those induced by the wild-type. Genetic complementation reversed the mutant's hypersensitivity to H₂O₂, expression of fbpA, and symbiotic deficiency in soybean plants. This is the first report that demonstrates a role for RirA in the Rhizobium-legume symbiosis.

Relationship between peripheral arterial occlusive disease (PAOD) and chronic Chlamydophila (Chlamydia) pneumoniae infection

We carried out a meta-analysis of observational case-control studies published before May 2004 to assess the degree of association between Chlamydophila pneumoniae (Cp) infection and PAOD. A search of the Medline database was performed using atherosclerosis and "Chlamyd* pneumoniae" as keywords. Strict criteria were applied for the selection of case studies, which had to be studies of Cp seroprevalence or of Cp detection in patients versus controls. Forty-three published studies that met these criteria were selected. An association between PAOD and Cp was revealed by immunohistochemical analysis (OR=15.4, 95%CI=5.0–46.9) and nested PCR studies of arterial biopsies (OR=4.3, 95%CI=1.8–10), by PCR study of non-arterial samples (OR=2.9, 95%CI=1.2–7.0), by other direct-detection tests (OR=16.7, 95%CI=7.0–39.8), and by ELISA and MIF tests to detect high IgG (OR=2, 95%CI=1.1–3.5 and OR=1.7, 95%CI=1.0–2.9, respectively) and IgA (OR=1.9, 95%CI=1.1–3.4 and OR=1.5, 95%CI=1.1–2.0, respectively) titers. No significant association was found in simple PCR studies of arterial biopsies, MIF tests to detect low IgG titers or IgM, or ELISA studies to detect IgM. According to this review, the association between Cp infection and PAOD depends on the analytical method adopted. Establishing a relationship between Cp and PAOD will require a case-control study with an adequate number of cases and samples that uses a combination of direct and indirect techniques to identify the presence of the bacterium in different types of sample from the same subjects, correlating the results with the activity of the disease.

Increase in socioeconomic inequalities in mortality in a Southern European region: a small-area ecological study

BACKGROUND

This study sought to describe the total mortality trend by socioeconomic deprivation (SED) in the Madrid Autonomous Region, by sex and age group.

METHODS

Cross-sectional ecological study by census tract, in two periods: 1994-2000 (P1) with SED of 1996 census and 2001-07 (P2) with SED of 2001 census. We calculated the relative risks (RRs) and their 95% credibility intervals (95% CIs) by SED quintile (Q), taking the quintile of least deprivation as reference. Besag-York-Mollié ecological regression models and the Integrated Nested Laplace Approximation procedure were applied. The absolute differences in age-standardized rates were compared by SED quintile.

RESULTS

Inequalities decreased in young adults: among men aged 20-39 years, the RR in Q5 versus Q1 ranged from 2.73 (95% CI, 2.51-3.02) in P1 to 1.93 (95% CI, 1.76-2.15) in P2, due to the greater improvement in the most underprivileged groups. In contrast, there was an increase in SED-related mortality in the 40-79 age group. Among men aged 40-59 years, the RR in Q5 versus Q1 rose from 1.88 (95% CI, 1.76-2.02) in P1 to 2.29 (95% CI, 2.17-2.43) in P2; the improvement was greater in the most privileged groups.

CONCLUSION

In a context of an economic boom, inequalities were observed to increase among adults by a greater improvement in the most privileged groups.

Lung cancer and urbanization level in a region of Southern Europe: influence of socio-economic and environmental factors

BACKGROUND

This study analysed the distribution of lung cancer deaths in areas with different urbanization levels in the Madrid Region and whether such differences persisted when deprivation and air pollution were considered.

METHODS

This was a population-based cross-sectional study covering lung cancer deaths (2001-07). The exposure indicators were: a deprivation index based on 2001 census data; and the daily mean NO2 measurement (2002-07), both at the census tract level. Analysis was stratified by sex and age group and the Poisson regression models were applied to obtain rate ratios (RRs).

RESULTS

After adjustment for age, deprivation index and NO2, mortality was similar in the city and Greater Madrid areas and lower in the rural area for the over-64 age group (RR: 0.84 in men and RR: 0.66 in women, with respect to the city of Madrid), and significantly lower in the Greater Madrid area (RR: 0.84 in men and RR: 0.74 in women) and in the rural area (RR: 0.73 in men and RR: 0.51 in women) with respect to the city of Madrid for the under-65 age group.

CONCLUSIONS

The most urbanized areas of the Madrid Region are characterized by higher lung cancer mortality.

[Husk of Venezuelan cocoa as raw material of infusions]

In the cocoa bean industry, some by-products go underutilized. Some of these components could provide other innovative products, and such is the case with the husk of the cocoa bean. Previous studies have attributed the husk with a high antioxidant capacity, which added to its relative low cost, makes it an attractive ingredient for the production of infusions. However, prior to promoting it as such, its quality needs to be guaranteed. This study evaluated the chemical composition of the husk of cocoa, its microbiologic quality and other parameters in order to be considered raw material in the preparation of infusions. The cocoa was cultivated in two different states in Venezuela. Moisture, protein, fat, ash, carbohydrates, microbiologic quality and ochratoxin A as well antioxidant properties, content of foreign matter, insoluble ash in HCL and aqueous extract were evaluated in the husk of cocoa seeds. Applied methods were in compliance with national and international norms. Significant differences were determined between the samples through the ANOVA application. A low level in moisture content, but high in ash, along with a microbiologic quality that met the norm, and an absence of ochratoxin A were observed in the totality of the analyzed samples. Low levels of foreign matter, the high value of its aqueous extract and high phenolic compounds content with antioxidant activity allow for the recommendation of the husk of cocoa as raw material for the preparation of infusions.

Studies on variation in fecal reactive oxidative species generation in free-living populations in Guatemala

Among the factors associated with the risk of colorectal cancer and other large bowel diseases are gender, with women having lower incidence than men, and free-radical mediated oxidation. Dietary fiber has been attributed a protective role in human gastro-intestinal health. The main aim of this study was to determine the degree of association between dietary fiber consumption and fecal free-radical production in healthy rural and urban Guatemalan women, moreover, to look for associations between gender and fecal reactive oxidative species (ROS) basal production, a marker of in situ colonic free-radical-based oxidation. For this purpose, we assessed the dietary fiber consumption, using two 24-h recalls, in urban and rural females, and compared the baseline data, i.e., of iron-supplement-free periods, in three previous studies. Two of these trials quantified the fecal ROS generation as total hydroxylated products resulting from free-radical attack on salicylic acid along with residual non-heme iron content in stool samples from 27 Fe-replete men. The third study assessed the same variables in 20 rural and 20 urban women, all consuming their respective habitual diets. The average fiber consumption for females was more than double in the rural group than in the urban population. As for the average ROS responses, a 2.5-fold difference was observed between men and women, with men having the higher concentrations of total hydroxylated products. This difference was sex-linked, unaffected by statistically significant differences in dietary fiber intake, nor by different concentrations of residual fecal non-heme iron between rural and urban women. The difference in background ROS production between men and women suggests a gender-related influence on intraintestinal oxidation that may protect women from harmful effects of dietary oxidants, such as iron.

Chronic liver disease and cirrhosis mortality and social deprivation: a spatial analysis in small areas of Madrid region

OBJECTIVES

To study census-tract distribution of chronic liver disease and cirrhosis mortality in the Madrid Region and its association with socio-economic deprivation.

METHODS

Cross-sectional, ecological (3906 census-tract) study, using mortality data for 1996-2003 and a deprivation index drawn up on the basis of 2001 census data. Standardised mortality ratios were calculated taking Spanish rates for 2001 as reference. Smoothed census-tract relative risks were computed using the Besag-York-Mollie model. Relative risks (RRs) of dying and their 95% credibility intervals (95% CIs) were calculated according to quartiles of the deprivation index (with the fourth quartile -Q- of the indicator being the most unfavourable situation). Maps were plotted depicting the distribution of the posterior probability of RR > 1.

RESULTS

Census tracts with a high risk of mortality were detected, mostly located in the centre and on the eastern, south-eastern and south-western fringes of the city of Madrid. Mortality increased with deprivation. RRs of mortality according to quartíles of the deprivation index were: Q2 = 1.5 (CI: 1.3-1.6), Q3 = 1.9 (CI:1.7-2.2) and Q4 = 2.5 (CI:2.2-2.8) for men; and Q2 = 1.3 (CI:1.1-1.5), Q3 = 1.5 (CI:1.3-1.7) and Q4 = 1.6 (CI:1.3-1.8) for women.

CONCLUSIONS

This small-area study enabled census tracts with excess mortality eligible for a special public health intervention to be identified, and their association with socio-economic deprivation to be confirmed.

Census tract socioeconomic and physical environment and cardiovascular mortality in the Region of Madrid (Spain)

BACKGROUND

Features of the area might contribute to differences in cardiovascular mortality. The census tract distribution of ischaemic heart disease (IHD) and cerebrovascular disease mortality in the Region of Madrid and its association with deprivation and environmental variables were examined in this study.

METHODS

Cross-sectional, ecological study covering 3906 census tracts (median of around 1000 inhabitants), using mortality data (population aged <75 years) for 1996-2003, as well as socioeconomic deprivation and other environmental indicators (subjective perceptions of pollution, background noise, lack of green spaces and delinquency) drawn from the 2001 census. Standardised mortality ratios were calculated. Smoothed census tract relative risks were calculated using the Besag-York-Mollié model. Relative risks (RRs) of dying and their 95% credibility intervals (95% CI) were calculated according to the indicators considered (with the fourth quartile, Q, being the most unfavourable situation). Maps were plotted depicting the distribution of the posterior probability of RR>1.

RESULTS

Census tracts with excess mortality were mostly located in the city of Madrid. Mortality increased with deprivation: RRs of IHD and stroke mortality in Q4 with respect to Q1 were 1.42 (95% CI 1.31 to 1.54) and 1.66 (95% CI 1.45 to 1.88) for men, and 1.54 (95% CI 1.33 to 1.79) and 1.52 (95% CI 1.29 to 1.76) for women respectively. Associations with deprivation decreased only slightly when perceived lack of green spaces and delinquency were included in the model. In men, subjective perceptions of areas remained associated with cardiovascular mortality after adjustment for deprivation.

CONCLUSION

Deprivation and subjective perceptions of physical environmental characteristics are ecologically associated with cardiovascular disease mortality.

Rituximab in systemic lupus erythematosusA systematic review of off-label use in 188 cases

The complexity of the therapeutic approach in systemic lupus erythematosus (SLE) is increased by the large number of patients who do not respond to the first-line therapies and by relapses after initial clinical remission. In these patients, second-line drugs are often prescribed according to individual clinical decisions. The emergence of biological therapies has increased the therapeutic armamentarium available in these complex situations, but their use is limited by the lack of licensing. Available data on the use of rituximab in SLE rely on a large number of case reports and some observational studies. We analyzed current evidence on the therapeutic use of rituximab in adult SLE patients by a systematic review of reports included in the PubMed database between 2002 and 2007. A total of 188 SLE patients treated with rituximab were identified; 171 (91%) patients showed a significant improvement in one or more of the systemic SLE manifestations. There were 103 patients with lupus nephritis, with an overall rate of therapeutic response of renal involvement of 91%. Adverse events were reported in 44 (23%) patients; the most frequent were infections (19%). Although it is not yet possible to make definite recommendations, the global analysis of all cases reported to date support the off-label use of rituximab in severe, refractory SLE cases, whereas its use as a first-line therapy or in patients with a predominantly mild form of the disease is not advised.

The tep1 gene of Sinorhizobium meliloti coding for a putative transmembrane efflux protein and N-acetyl glucosamine affect nod gene expression and nodulation of alfalfa plants

Background

Soil bacteria collectively known as Rhizobium, characterized by their ability to establish beneficial symbiosis with legumes, share several common characteristics with pathogenic bacteria when infecting the host plant. Recently, it was demonstrated that a fadD mutant of Sinorhizobium meliloti is altered in the control of swarming, a type of co-ordinated movement previously associated with pathogenicity, and is also impaired in nodulation efficiency on alfalfa roots. In the phytopathogen Xanthomonas campestris, a fadD homolog (rpfB) forms part of a cluster of genes involved in the regulation of pathogenicity factors. In this work, we have investigated the role in swarming and symbiosis of SMc02161, a S. meliloti fadD-linked gene.

Results

The SMc02161 locus in S. meliloti shows similarities with members of the Major Facilitator Superfamily (MFS) of transporters. A S. meliloti null-mutant shows increased sensitivity to chloramphenicol. This indication led us to rename the locus tep1 for transmembrane efflux protein. The lack of tep1 does not affect the appearance of swarming motility. Interestingly, nodule formation efficiency on alfalfa plants is improved in the tep1 mutant during the first days of the interaction though nod gene expression is lower than in the wild type strain. Curiously, a nodC mutation or the addition of N-acetyl glucosamine to the wild type strain lead to similar reductions in nod gene expression as in the tep1 mutant. Moreover, aminosugar precursors of Nod factors inhibit nodulation.

Conclusion

tep1 putatively encodes a transmembrane protein which can confer chloramphenicol resistance in S. meliloti by expelling the antibiotic outside the bacteria. The improved nodulation of alfalfa but reduced nod gene expression observed in the tep1 mutant suggests that Tep1 transports compounds which influence nodulation. In contrast to Bradyrhizobium japonicum, we show that in S. meliloti there is no feedback regulation of nodulation genes. Moreover, the Nod factor precursor, N-acetyl glucosamine reduces nod gene expression and nodulation efficiency when present at millimolar concentrations. A role for Tep1 in the efflux of Nod factor precursors could explain the phenotypes associated with tep1 inactivation.

[Renal failure and insulin resistance: effect of the dialysis dose]

BACKGROUND

The main cause of death in patients undergoing hemodialysis are cardiovascular events. We have analyzed the association between intradialysis fractional clearance of urea or Kt/V index in patients with chronic renal failure in hemodialysis as an indicator of adequate dialysis and the classical factors of cardiovascular risk.

PATIENTS AND METHODS

A total of 47 patients with chronic renal failure on hemodialysis were included. Diabetes mellitus was considered an exclusion criteria. Optimization of dialysis was analyzed by Kt/v index in accordance with the Daugirdas formula. The cardiovascular risk factors evaluated were: insulin resistance, calculated according to the HOMA method, total cholesterol, LDL-cholesterol, triglycerides, arterial hypertension, obesity and metabolic syndrome. The relationship between cardiovascular risk factors and Kt/V index was analyzed with the variant and multivariant analysis.

RESULTS

The HOMA median (interquartile range) of the patients was 1.16 (0.53-5.77). HOMA was correlated with triglycerides and HDL-cholesterol levels. HOMA was significantly greater in those who had less adapted dialysis (Kt/V < 1.4) (1.9 +/- 1.3 vs 1.0 +/- 0.3, p = 0.02). Furthermore, a negative correlation was found between HOMA and Kt/V. The multivariant analysis of the factors associated to HOMA demonstrated that the only associated parameters were Kt/V greater than 1.4, body mass index and age.

CONCLUSIONS

In patients with chronic renal failure, adapted dialysis, determined by the Kt/V index, correlated negatively with insulin resistance. Based on these data, we suggest the need for longitudinal studies that consider this index as a predictive variable of cardiovascular events in this type of patients.

D-dimer levels correlate with mortality in patients with acute pulmonary embolism: Findings from the RIETE registry

OBJECT

Few studies have addressed the prognostic implications of D-dimer in patients with pulmonary embolism. The aim of this study was to investigate the correlation between D-dimer levels and mortality in patients with pulmonary embolism.

DESIGN

Observational study.

SETTING

Hospitals participating in the Registro Informatizado de la Enfermedad Tromboembólica (RIETE).

PATIENTS

A total of 588 consecutive patients with symptomatic pulmonary embolism who were included in the RIETE between March 2001 and December 2004.

INTERVENTIONS

Quantitative D-dimer measurement was performed on admission using an automated latex agglutination test (IL Test D-dimer). All patients underwent clinical follow-up for 3 months.

MEASUREMENTS AND MAIN RESULTS

Overall mortality rate was 10.5%. The cause of death was pulmonary embolism in 18 patients (3.0%), fatal bleeding in one patient (0.2%), and other causes in 43 patients (7.3%). There were 28 (4.8%) nonfatal venous thromboembolism recurrences and 35 (6.0%) nonfatal bleeding episodes. The incidence of D-dimer 500-2499 ng/mL, D-dimer 2500-4999 ng/mL, and D-dimer >or=5000 ng/mL was 47.8%, 26.0%, and 20.4%, respectively. Compared with patients with D-dimer 500-2499 ng/mL, the relative risk (odds ratio) of overall mortality was 1.91 (95% confidence interval 0.91-4.09) and 2.94 (95% confidence interval 1.42-6.25) in patients with D-dimer 2500-4999 ng/mL and D-dimer >or= 5000 ng/mL, respectively (p = .032). Patients with D-dimer >or=5000 ng/mL showed higher risk of death from fatal pulmonary embolism (odds ratio 4.4, 95% confidence interval 0.5-33.0) than death from other causes (odds ratio 2.1, 95% confidence interval 0.7-6.0). Elevated D-dimer levels were associated with more severe disease, as assessed by clinical features.

CONCLUSIONS

In patients who present with pulmonary embolism, D-dimer concentration is an independent predictive factor associated with all-cause and pulmonary embolism-related death. D-dimer >or=5000 ng/mL occurs in about one in five patients and is associated with a 2.9-fold increased risk of overall mortality. These results suggest that D-dimer quantification could be a useful biomarker and help determine initial therapies.

High presence of extended-spectrum β-lactamases and resistance to quinolones in clinical isolates of Escherichia coli

A study was conducted to detect the presence of extended-spectrum beta-lactamases (ESBLs) in 706 isolates of Escherichia coli, largely from outpatients (75.2%). The Clinical and Laboratory Standards Institute (formerly NCCLS)-recommended disk diffusion procedure was used to detect ESBL presence; the VITEK 2 system (bioMérieux, Marcy L'Etoile, France) was used to determine the susceptibility to antibiotics of clinical interest, and the ESBLs were characterized by biochemical study, determining the isoelectric point, and by molecular study with PCR. Clonal distribution was studied in eight hospital isolates. There were 115 ESBL-producing isolates (16.3%), with a predominance of CTX-M9 type (58.3%). We draw attention to the high resistance to quinolones (>70%) in CTX-M9 and SHV enzyme producing isolates and the lower aminoglycoside activity in the latter.

Meta-analysis of studies analyzing the relationship between bladder cancer and infection by human papillomavirus

PURPOSE

Studies have been done of the possibility that infection by human papillomavirus is a risk factor contributing to bladder cancer but no definite conclusions have yet been drawn. We performed a meta-analysis of observational studies published until July 2005 to ascertain the degree of association between bladder cancer and human papillomavirus infection.

MATERIALS AND METHODS

The MEDLINE database was searched using the key words bladder cancer and virus. Strict criteria were applied to select studies revealing the prevalence in serum of human papillomavirus infection or its direct detection in patients. A total of 44 articles with these methodological criteria were chosen.

RESULTS

In 39 studies the investigators determined the presence of human papillomavirus DNA, and found a prevalence of between 0% and 100% and significant homogeneity analysis (p <0.001). Pooled estimation of the presence of the infection was 16.0% (95% CI 12.8 to 19.1). Pooled OR estimation was 2.3 (95% CI 1.3 to 4.1) with no significant publication bias. In 7 studies human papillomavirus infection was studied by detecting the antigen or antibodies and a prevalence of between 14% and 60% was found with significant homogeneity analysis (p <0.001). Pooled estimation of the prevalence of infection was 32.4% (95% CI 17.0 to 47.8). Pooled OR estimation was 2.9 (95% CI 1.7 to 5.3).

CONCLUSIONS

Finding a relationship between bladder cancer and human papillomavirus depends on the method used. In the literature examined there are insufficient cases and samples compared to controls and studies rely on a combination of various microbiological techniques in the same patient and sample, making it difficult to draw any definite conclusion.

Effects of endogenous salicylic acid on nodulation in the model legumes Lotus japonicus and Medicago truncatula

The exogenous addition of salicylic acid (SA) was previously shown to inhibit indeterminate but not determinate-type nodulation. We sought to extend these results by modulating endogenous levels of SA through the transgenic expression of salicylate hydroxylase (NahG) in both stably transformed Lotus japonicus and composite Medicago truncatula plants. NahG expression in L. japonicus resulted in a marked reduction of SA levels. This reduction correlated with an increase in the number of infections and mean nodule number when compared to controls. However, a complicating factor was that NahG-expressing plants had greater root growth. Spot inoculations of NahG-expressing L. japonicus plants confirmed increased nodulation in these plants. Consistent with the reported inhibitory effects of exogenous SA on indeterminate-type nodulation, NahG expression in M. truncatula plants led to enhanced nodulation and infection. These data point to an important role for SA-mediated plant defense pathways in controlling nodule formation on both determinate and indeterminate nodule-forming hosts.

Evaluation of two automated systems for detection of bacteriuria

The Utiscreen-CORAL Biomedical system and ROBOBACT system were tested against conventional uroculture in blood agar and MacConkey agar as a reference method to determine the bacteriuria from 400 samples. For the Utiscreen-CORAL Biomedical system, a sensitivity of 92.5% was obtained. However, by the ROBOBACT system, the sensitivity was 69.9%.

Descripción de inmunógenos de Chlamydia pneumoniae reconocidos por el suero de sujetos con enfermedad arterial periférica

BACKGROUND AND OBJECTIVE

The relationship between antibodies to C. pneumoniae and presence of the bacteria was studied in individuals with peripheral arterial disease.

PATIENTS AND METHOD

An observational analytical, case-control study was performed in 118 patients (68 cases, 50 controls) to investigate immunoglobulin (Ig) G and A against C. pneumoniae in serum, using Western-blot (commercial and no commercial methods), ELISA and MIF; DNA of the bacteria in vascular tissue biopsy specimens was studied by polymerase chain reaction.

RESULTS

Using commercial Western-blot, significant presence of IgG anti-39 kDa and anti-54 kDa was found in cases and was related to MIF results and C. pneumoniae DNA findings; IgA anti-LPS, anti-92 kDa and anti-Hsp60 kDa were also found and related to DNA presence. Using no commercial Western-blot, significant presence of 128.8 and 9.2 kDa bands for IgG was detected in cases and associated with DNA presence; 70.8, 58.9, 47.9, 47.5, 18.4, 12.1, 10.6, 8.1, and 7.6 kDa bands for IgG were found in cases; and DNA was present when 54.6 and 1.1 kDa bands for IgG and 79.4, 50.1, and 18.4 kDa bands for IgA were also detected.

CONCLUSIONS

Using Western-blot, a greater serologic response was found against certain proteins of the bacteria in individuals with peripheral arterial disease. This may reflect an initial stage with presence of DNA and specific IgG. Subsequently, even in absence of the bacteria, an immunomediated disease may develop with presence of IgA and IgG.

Comparison of the SYBR Green and the hybridization probe format for real-time PCR detection of HHV-6

A comparative study was conducted of a novel real-time quantitative PCR test (LightCycler System) with FastStart DNA Master(PLUS) SYBR Green I dye to detect DNA of human herpes virus 6 (HHV-6). Results were compared with those of a real-time quantitative PCR with hybridization probe (HP) formats using the fluorescence resonance energy transfer method, and with those of a single qualitative PCR test. The detection limit of the test with SYBR Green I dye was 20 copies of the virus, similar to that of the other two tests. The reproducibility was satisfactory. The new test has the same advantages as real-time PCR with HP formats and offers a greater versatility at lower cost.

Phosphorus-free membrane lipids of Sinorhizobium meliloti are not required for the symbiosis with alfalfa but contribute to increased cell yields under phosphorus-limiting conditions of growth

The microsymbiont of alfalfa, Sinorhizobium meliloti, possesses phosphatidylglycerol, cardiolipin, phosphatidylethanolamine, and phosphatidylcholine as major membrane phospholipids, when grown in the presence of sufficient accessible phosphorus sources. Under phosphate-limiting conditions of growth, S. meliloti replaces its phospholipids by membrane lipids that do not contain any phosphorus in their molecular structure and, in S. meliloti, these phosphorus-free membrane lipids are sulphoquinovosyl diacylglycerols (SL), ornithine-containing lipids (OL), and diacylglyceryl-N,N,N-trimethylhomoserines (DGTS). In earlier work, we demonstrated that neither SL nor OL are required for establishing a nitrogen-fixing root nodule symbiosis with alfalfa. We now report the identification of the two structural genes btaA and btaB from S. meliloti required for DGTS biosynthesis. When the sinorhizobial btaA and btaB genes are expressed in Escherichia coli, they cause the formation of DGTS in this latter organism. A btaA-deficient mutant of S. meliloti is unable to form DGTS but can form nitrogen-fixing root nodules on alfalfa, demonstrating that sinorhizobial DGTS is not required for establishing a successful symbiosis with the host plant. Even a triple mutant of S. meliloti, unable to form any of the phosphorus-free membrane lipids SL, OL, or DGTS is equally competitive for nodule occupancy as the wild type. Only under growth-limiting concentrations of phosphate in culture media did mutants that could form neither OL nor DGTS grow to lesser cell densities.

[D-dimer levels in venous thromboembolism]

Venous thromboembolism (VTE) is associated with substantial morbidity and mortality. The clinical signs and symptoms are unspecific, widely varying from asymptomatic to sudden death. The diagnostic algorithm of VTE is an evolving field, in which D-dimers (DD) determination has been used as one of the preferred screening tests. Clinical management studies are clarifying the role of DD in the diagnostic paradigm of VTE. Published reports support the use of plasma DD determination in patients with a low clinical probability of VTE. Patients with moderate or high clinical probability of VTE show a higher probability of false negative plasma DD values. This fact forces the clinician to use more complex diagnostic test in order to either confirm or exclude VTE. A variety of different qualitative and semi-quantifiable assays are available for plasma DD determination. There is a wide variation in performance and there are discrepancies in the comparability of the different assays. Therefore, in order to both appropriately incorporate plasma DD determination in the diagnostic strategies of VTE and to reduce unnecessary investigations, clinicians should ensure that they are familiar with the diagnostic performance of the assay used in their own institution allowing a safer and cost-effective procedure.

Acceptable performance of VITEK 2 system to detect extended-spectrum β-lactamases in clinical isolates of Escherichia coli: a comparative study of phenotypic commercial methods and NCCLS guidelines

The disk approximation method, Etest (AB Biodisk, Solna, Sweden), and VITEK 2 system (bioMérieux, Marcy l'Etoile, France) were used to study 399 extended-spectrum beta-lactamase (ESBL)-producing (115 strains) and non-ESBL-producing (284 strains) clinical isolates of Escherichia coli after recommended procedures. Comparative study of the phenotypic findings yielded data on the sensitivity, specificity, and positive and negative predictive values and performance of each method. The sensitivity (100% using 2 substrates), specificity (99.3-100%), and predictive values of the disk approximation, Etest, and VITEK 2 methods were similar.

[Relationship between the peripheral arterial occlusive disease and the infection by Chlamydophila pneumoniae]

BACKGROUND AND OBJECTIVE

The relationship between peripheral arterial occlusive disease (PAOD) and Chlamydophila pneumoniae infection was studied by analyzing clinical samples from 95 patients with PAOD (cases) and 100 controls.

PATIENTS AND METHOD

The following investigations were conducted: IgG and IgA against lipopolysaccharide (LPS) and against purified C. pneumoniae-specific antigens from elementary bodies (EB) with ELISA; anti-EB IgG, with MIF; C. pneumoniae DNA in arterial biopsy and peripheral blood leukocyte cells (PBLCs) with heminested PCR; LPS with ELISA; and bacteria culture in HEp-2 cells from arterial biopsy.

RESULTS

The percentage of positive results in cases and controls groups for anti-LPS IgG was: 21% and 14%, respectively, with no differences; nor were there any differences with IgA (22 and 21%, respectively). However, differences were seen in the anti-EB IgG between cases (74% and 72%, for ELISA and MIF, respectively) and controls (31% and 34%). There were no differences in anti-EB IgA. Bacterial DNA was detected in 67% of atheromatous plaques (cases) vs. 12% of pudendal arteries (controls) (p = 0.0001). No C. pneumoniae DNA and LPS was detected in PBLCs and biopsic samples, respectively; and no C. pneumoniae strain could be recovered by cell culture from cases.

CONCLUSIONS

On the basis of our results, PAOD is significantly associated with C. pneumoniae infection through the detection of anti-EB IgG from serum and bacterial DNA from arterial biopsy.

High incidence of extended-spectrum β-lactamases among outpatient clinical isolates of Escherichia coli: a phenotypic assessment of NCCLS guidelines and a commercial method

The production of extended-spectrum beta-lactamases (ESBLs) among 357 clinical isolates of Escherichia coli and 175 of Klebsiella spp. was studied using both the National Committee for Clinical Laboratory Standards disk diffusion method and the semiautomated Wider system. We highlight the predominance of E. coli (50, 92.6%) among positive samples and the largely outpatient origin of these (40, 80%), including 39 samples of urine (97.5%) and one of urethral exudate. There were only four ESBL-producing isolates of Klebsiella spp. (7.4%), and three were in outpatient urine samples (75%, 2 K. oxytoca and 1 K. pneumoniae). The positive and negative predictive values for the Wider system were 81% and 98.5%, respectively. We stress the high incidence of ESBL in our setting, the predominance of cases in the outpatient setting, and the acceptable detection of ESBL by means of the Wider system in E. coli and Klebsiella spp.

Identification of functional mob regions in Rhizobium etli: evidence for self-transmissibility of the symbiotic plasmid pRetCFN42d

An approach originally designed to identify functional origins of conjugative transfer (oriT or mob) in a bacterial genome (J. A. Herrera-Cervera, J. M. Sanjuán-Pinilla, J. Olivares, and J. Sanjuán, J. Bacteriol. 180:4583-4590, 1998) was modified to improve its reliability and prevent selection of undesired false mob clones. By following this modified approach, we were able to identify two functional mob regions in the genome of Rhizobium etli CFN42. One corresponds to the recently characterized transfer region of the nonsymbiotic, self-transmissible plasmid pRetCFN42a (C. Tun-Garrido, P. Bustos, V. González, and S. Brom, J. Bacteriol. 185:1681-1692, 2003), whereas the second mob region belongs to the symbiotic plasmid pRetCFN42d. The new transfer region identified contains a putative oriT and a typical conjugative (tra) gene cluster organization. Although pRetCFN42d had not previously been shown to be self-transmissible, mobilization of cosmids containing this tra region required the presence of a wild-type pRetCFN42d in the donor cell; the presence of multiple copies of this mob region in CFN42 also promoted conjugal transfer of the Sym plasmid pRetCFN42d. The overexpression of a small open reading frame, named yp028, located downstream of the putative relaxase gene traA, appeared to be responsible for promoting the conjugal transfer of the R. etli pSym under laboratory conditions. This yp028-dependent conjugal transfer required a wild-type pRetCFN42d traA gene. Our results suggest for the first time that the R. etli symbiotic plasmid is self-transmissible and that its transfer is subject to regulation. In wild-type CFN42, pRetCFN42d tra gene expression appears to be insufficient to promote plasmid transfer under standard laboratory conditions; gene yp028 may play some role in the activation of conjugal transfer in response to as-yet-unknown environmental conditions.

A new microimmunofluorescence test for the detection ofChlamydia pneumoniae specific antibodies

To evaluate a microimmunofluorescence (MIF) test (Chlamydia pneumoniae IgG, Vircell, Spain) that detects IgG against Chlamydophila pneumoniae (Cp), MRL Diagnostics MIF was used as reference test. Cross-reactivity against Chlamydia trachomatis (Ct) and Chlamydophila psittaci (Cps) was investigated. Eighty sera were analysed from 22 subjects with vascular disease, 38 with multiple sclerosis and 20 healthy individuals. Vircell and MRL MIF tests assessed 58.75% and 60% of the samples as positive, respectively, and their results coincided (positive/negative) in 98.75% of samples. One major (>1 IgG titre) and 32 minor (1 titre) discrepancies were observed. Correlation between tests was significant. Vircell MIF test demonstrated 97.9% sensitivity and 100% specificity. Differences in simultaneous reactivity to Ct and Cps between the tests were not significant. Vircell MIF test showed a good performance to detect the IgG against Cp.

[A study of clinical response to antibiotic treatment in subjects with chronic bacterial prostatitis]

A study was carried out on the clinical response to antibiotics in 105 patients with chronic bacterial prostatitis. Two groups of patients were compared in a retrospective study. The results of rectal examination, ultrasound scan, microbiological analysis, and response to different antibiotic therapy regimens were compared. There was a high incidence of perineal-testicular pain and sexual potency reduction; prostate congestion and pain on rectal examination were frequently reported. All the patients had positive microbial cultures, with Gram-negative microorganisms being predominantly isolated. Following the administration of different antibiotic therapy regimens, symptoms either disappeared or diminished, irrespective of whether positive cultures remained. A poorer clinical response was observed in patients with positive prostate ultrasound and rectal examination, and with isolated Gram-negative bacilli. No differences were observed between either group in clinical response to different antimicrobial regimens.

ELISA test to detect Chlamydophila pneumoniae IgG

A new ELISA test (Chlamydophila pneumoniae IgG, Vircell, Spain) to detect Chlamydophila pneumoniae IgG was evaluated. The micro-immunofluorescence (MIF) test was used as reference method. Chlamydia trachomatis and Chlamydophila psittaci elementary bodies were also assayed. Two hundred and sixteen sera were included in the study: 66 from patients with peripheral arterial occlusive disease (Panel 1), 68 from adults with pneumonia (Panel 2), 44 from healthy adults (Panel 3) and 38 from patients with a sexuality transmitted disease by C. trachomatis (Panel 4). In Panel 1, 51 sera (77%) had antibody titres between 32 and 128; 4 out of 15 sera with IgG titres < 32 were positive by ELISA test and 2 sera with 32 IgG titres were uncertain by ELISA; the remaining 60 sera were correctly classified, giving a 91% concordance between the techniques. In Panel 2, 55 sera (81%) had IgG titres between 32 and 512; 2 out of 13 sera with IgG titres < 32 were positive by ELISA and 2 sera with 32 titres were uncertain by ELISA; the remaining 64 sera were correctly classified, giving a 97% concordance. In Panel 3, 22 sera (50%) had IgG titres between 32 and 64; only 1 out of 22 sera with IgG titres < 32 was positive by ELISA, giving a 97% concordance between the techniques. In Panel 4, there were 24 (63%) negative, 10 (26%) uncertain and 4 (10%) positive results by ELISA, giving an 86% concordance. The C. pneumoniae ELISA test demonstrated 100% sensitivity and 85% specificity. The IgG ELISA test demonstrated a good concordance with the MIF test without the drawbacks associated with the latter assay. We conclude that the ELISA test could be an alternative to the MIF test.

An evaluation of a polyantigenic ELISA to detect Epstein-Barr virus reactivation

The diagnostic reliability of the Enzygnost EBV test (DadeBehring, Germany) for the detection of IgG and IgA antibodies in the diagnosis of Epstein-Barr virus (EBV) recurrent disease was investigated. Of 81 serum samples examined there were fourteen asymptomatic patients without EBV infection, 46 with past EBV infection, and 21 patients with EBV reactivation. The Enzygnost EBV test was based on an enzyme-linked immunosorbent assay with a pool of viral antigens. The reliability of IgG at >650 IU/ml, and IgA for the diagnosis of reactivation or chronic persistent EBV infection gave 100% sensitivity, 83.3% and 98.3% specificity, respectively. The data indicated that the appearance of EBV IgA was associated with EBV reactivation together with clinical manifestations.

A fadD mutant of Sinorhizobium meliloti shows multicellular swarming migration and is impaired in nodulation efficiency on alfalfa roots

Swarming is a form of bacterial translocation that involves cell differentiation and is characterized by a rapid and co-ordinated population migration across solid surfaces. We have isolated a Tn5 mutant of Sinorhizobium meliloti GR4 showing conditional swarming. Swarm cells from the mutant strain QS77 induced on semi-solid minimal medium in response to different signals are hyperflagellated and about twice as long as wild-type cells. Genetic and physiological characterization of the mutant strain indicates that QS77 is altered in a gene encoding a homologue of the FadD protein (long-chain fatty acyl-CoA ligase) of several microorganisms. Interestingly and similar to a less virulent Xanthomonas campestris fadD(rpfB) mutant, QS77 is impaired in establishing an association with its host plant. In trans expression of multicopy fadD restored growth on oleate, control of motility and the symbiotic phenotype of QS77, as well as acyl-CoA synthetase activity of an Escherichia coli fadD mutant. The S. meliloti QS77 strain shows a reduction in nod gene expression as well as a differential regulation of motility genes in response to environmental conditions. These data suggest that, in S. meliloti, fatty acid derivatives may act as intracellular signals controlling motility and symbiotic performance through gene expression.

Characterization of typical pepper-isolates of PVY reveals multiple pathotypes within a single genetic strain

Potato virus Y (PVY) isolates originally coming from infected pepper plants, were biologically and genetically characterized, especially in comparison with PVY potato-isolates. Pepper PVY isolates could be differentiated from potato isolates in their host range, aphid transmission efficiencies, Mab serology, and genetic status. The genetic distances estimated for PVY pepper-isolates, based on their restrictotypes with five restriction enzymes and on their coat protein gene sequences, indicated that they form a single genetic strain with different pathotypic properties. This situation is essentially different to that of PVY potato-isolates.

Time-course of lipoxygenase, antioxidant enzyme activities and H2 O2 accumulation during the early stages of Rhizobium-legume symbiosis

•  The involvement of lipoxygenase and antioxidant enzyme activities as well as hydrogen peroxide (H₂ O₂ ) accumulation are reported during early infection steps in alfalfa (Medicago sativa) roots inoculated either with a wild type Sinorhizobium meliloti or with a mutant defective in Nod-factor synthesis (Nod C^- ). •  Compatibility between M. sativa and Rhizobium correlates, at least in part, with an increase in the activities of these enzymes, particularly catalase and lipoxygenase, during the preinfection period (up to 12 h). The mutant strain, defective in Nod-factor biosynthesis, showed a decrease in all enzyme activities assayed, and an increase in H₂ O₂ accumulation. •  Enhancement of scavenging activities for several reactive oxygen species correlated with compatibility of the S. meliloti-alfalfa symbiosis, whereas the Nod C^- strain triggered a defence response. Nod factors were essential to suppress this response. •  Increase in lipoxygenase and lipid hydroperoxide decomposing activities, observed during the first hours after inoculation with a compatible strain, could be related to tissue differentiation and/or the production of signal molecules involved in autoregulation of nodulation by the plant.

Construction and environmental release of a Sinorhizobium meliloti strain genetically modified to be more competitive for alfalfa nodulation

Highly efficient nitrogen-fixing strains selected in the laboratory often fail to increase legume production in agricultural soils containing indigenous rhizobial populations because they cannot compete against these populations for nodule formation. We have previously demonstrated, with a Sinorhizobium meliloti PutA- mutant strain, that proline dehydrogenase activity is required for colonization and therefore for the nodulation efficiency and competitiveness of S. meliloti on alfalfa roots (J. I. Jiménez-Zurdo, P. van Dillewijn, M. J. Soto, M. R. de Felipe, J. Olivares, and N. Toro, Mol. Plant-Microbe Interact. 8:492-498, 1995). In this work, we investigated whether the putA gene could be used as a means of increasing the competitiveness of S. meliloti strains. We produced a construct in which a constitutive promoter was placed 190 nucleotides upstream from the start codon of the putA gene. This resulted in an increase in the basal expression of this gene, with this increase being even greater in the presence of the substrate proline. We found that the presence of multicopy plasmids containing this putA gene construct increased the competitiveness of S. meliloti in microcosm experiments in nonsterile soil planted with alfalfa plants subjected to drought stress only during the first month. We investigated whether this construct also increased the competitiveness of S. meliloti strains under agricultural conditions by using it as the inoculum in a contained field experiment at León, Spain. We found that the frequency of nodule occupancy was higher with inoculum containing the modified putA gene for samples that were analyzed after 34 days but not for samples that were analyzed later.

The disruption of a gene encoding a putative arylesterase impairs pyruvate dehydrogenase complex activity and nitrogen fixation in Sinorhizobium meliloti

Nitrogen-fixing Sinorhizobium meliloti cells depend upon dicarboxylic acids as carbon and energy sources. The metabolism of these intermediate compounds of the trichloroacetic acid cycle is dependent upon the availability of acetyl-coenzyme A (CoA). In bacteroids, the combined activities of malic enzymes and pyruvate dehydrogenase (PDH) have been proposed to be responsible for the anaplerotic synthesis of acetyl-CoA. We obtained a S. meliloti mutant strain, PD3, in which a Tn5 insertion led to a significant decrease in the overall PDH activity. The genetic characterization of this mutant revealed that the transposon is located at the 3' end of a gene (ada) encoding a putative arylesterase. The mutant PD3 is deficient in nitrogen fixation, which strengthens the physiological importance of PDH activity in the symbiosis of S. meliloti with alfalfa plants.

Sinorhizobium meliloti putA gene regulation: a new model within the family Rhizobiaceae

Proline dehydrogenase (PutA) is a bifunctional enzyme that catalyzes the oxidation of proline to glutamate. In Sinorhizobium meliloti, as in other microorganisms, the putA gene is transcriptionally activated in response to proline. In Rhodobacter capsulatus, Agrobacterium, and most probably in Bradyrhizobium, this activation is dependent on an Lrp-like protein encoded by the putR gene, located immediately upstream of putA. Interestingly, sequence and genetic analysis of the region upstream of the S. meliloti putA gene did not reveal such a putR locus or any other encoded transcriptional activator of putA. Furthermore, results obtained with an S. meliloti putA null mutation indicate the absence of any proline-responsive transcriptional activator and that PutA serves as an autogenous repressor. Therefore, the model of S. meliloti putA regulation completely diverges from that of its Rhizobiaceae relatives and resembles more that of enteric bacteria. However, some differences have been found with the latter model: (i) S. meliloti putA gene is not catabolite repressed, and (ii) the gene encoding for the major proline permease (putP) does not form part of an operon with the putA gene.

Clinical utility of a competitive ELISA to detect antibodies against Treponema pallidum

Screening for Treponema pallidum infection is carried out on a large human population. To reduce costs, fewer tests which still offer adequate sensitivity and specificity could be performed. We studied the reliability of a novel indirect ELISA method to test for this infection. Several panels of sera were used that corresponded to 40 primary infections (group 1), 13 recurrences (group 2), 348 latent infections (group 3), 5 samples with anticardiolipin antibodies (group 4), 15 samples from patients with Lyme borreliosis (group 5), and 400 samples from blood donors and healthy pregnant women (group 6). The ELISA showed a global sensitivity and specificity of 100 and 99.5%, respectively. Our evaluation shows that Enzygnost Syphilis is a sensitive, specific, and simple test to screen for this infection.

Antibodies to Borrelia burgdorferi in European populations

We compared the antibodies to B. burgdorferi in three different populations in order to evaluate the diagnostic reliability of Lyme borreliosis serologic analysis. The subjects included 25 patients with Lyme borreliosis (Group 1); 50 patients with diseases of unknown cause, B. burgdorferi ELISA-positive in serum and without B. burgdorferi infection (Group 2); and 1,251 individuals without Lyme borreliosis (Group 3). All samples were tested for B. burgdorferi B31 and B. afzelii antigens using ELISA. The positive results of the ELISA B. burgdorferi B31 assay were confirmed with Western blot for the same strain. In Group 3, 162 (12.9%) patients were ELISA positive for B. burgdorferi B31, while only 6 (0.6%) patients had IgG ELISA antibodies to B afzelii. Bands in WB were detected in 104 (8.4%) of the Group 3 subjects. The bands found to be most reliable for the identification of strain B. burgdorferi B31 by IgG WB were those representing the 93, 39, 34, and 23-kDa proteins. Our results show that serologic diagnosis of Lyme borreliosis is far from clearly established. To date, the only reliable criteria are clinical ones correlated with laboratory evidence.

Comparison of several ELISA tests for detecting the presence of IgG and IgM against herpes simplex viruses

Four enzyme-linked immunosorbent assays designated test 1 (ETI-HSVK-G 1/2); test 2 (ETI-HSVK-M 1/2); test 3 (ETI-HSVK-G 2), and test 4 (BioElisa HSV2 IgG) were studied to evaluate different stages of herpes simplex virus (HSV) infection. Samples (50 sera and 14 cerebrospinal fluid) were included in four groups. Group 1 consisted of samples from patients with primary HSV infections; group 2 comprised samples from patients with recurrent HSV infections; group 3 were samples nonreactive to HSV; and group 4 were samples from patients with infections by other herpes viruses (4a, chickenpox; 4b, herpes zoster; and 4c, infectious mononucleosis by Epstein-Barr virus). The percentages of agreement between tests 1 and 2 were 100 and 72.1%, respectively. The total diagnostic values of tests 1 and 2 were: 100 and 50% sensitivity, respectively; and 100 and 89% specificity, respectively. Few positive results for HSV-2 infection were found, and so, tests 3 and 4 were not evaluated. The results of tests 3 and 4 for a chickenpox patient, and a herpes zoster patient were not in agreement.

ISRm4-1 and ISRm9, two novel insertion sequences from Sinorhizobium meliloti

Two novel insertion sequences, ISRm4-1 and ISRm9 have been identified in Sinorhizobium meliloti. ISRm4-1 is 936-bp in length, flanked by 17-bp putative terminal inverted repeats and a putative target duplication of 3-bp. ISRm4-1 is a member of the IS5 family of insertion sequences, closely related to ISRm4. ISRm9 is 2797-bp in length and carries 25-bp inverted repeats with target duplication of 7-bp: ISRm9 belongs to the IS21 family of insertion elements. On the non-pSym plasmid pRmeGR4b from S. meliloti strain GR4, a copy of ISRm4-1 is interrupted at nucleotide 150 from its 5'-end by a copy of ISRm9. Whereas ISRm4-like elements are widespread in S. meliloti, the distribution of ISRm9 appears to be correlated to that of pRmeGR4b-type plasmids.

Characterization of a Rhizobium meliloti proline dehydrogenase mutant altered in nodulation efficiency and competitiveness on alfalfa roots

Rhizobium meliloti strain GRM8 is able to transform ornithine into proline by means of an ornithine cyclodeaminase and, therefore, has the ability to use either of these amino acids as its sole carbon and nitrogen source. By Tn5 insertion mutagenesis we obtained a GRM8 mutant derivative strain (LM1) unable to catabolize either ornithine or proline. DNA hybridization studies showed that the LM1 mutant carries a single Tn5 insertion within a chromosomally located gene that, as deduced from a partial nucleotide sequence, encodes a proline dehydrogenase (ProDH). Enzymatic assays confirmed the lack of ProDH activity in cell extracts of strain LM1 and revealed that production of this enzyme is inducible in the parental strain by proline and ornithine. Ultrastructural nodule microscopy analysis, acetylene reduction assays, and dry-weight determinations of nodulated alfalfa plants showed no obvious defect in the nitrogen fixation process of the ProDH- mutant LM1. However, nodulation tests and competition assays demonstrated that in R. meliloti ProDH is required for nodulation efficiency and competitiveness on alfalfa roots.

Identification of a novel Rhizobium meliloti nodulation efficiency nfe gene homolog of Agrobacterium ornithine cyclodeaminase

The nfe genes located on the large plasmid pRmeGR4b are involved in the nodulation efficiency and competitiveness of Rhizobium meliloti GR4 on alfalfa roots. One hundred twenty-eight base-pairs downstream of nfe2 gene we found an open reading frame designated ORFC, 970 bp long and potentially coding for a 320 amino acid long protein. The amino acid sequence of the putatively encoded ORFC product shows similarity with ornithine cyclodeaminase (OCD) of Agrobacterium tumefaciens an unusual enzyme that converts ornithine into proline. The gene product of ORFC was identified as a 37-kDa protein by in vitro-coupled transcription-translation and in vivo by the T7 RNA polymerase/promoter system. DNA hybridization studies showed that strain GR4 carries a single copy of the ocd-like gene. No homologous sequences to GR4 ORFC DNA were found in other R. meliloti strains or Rhizobium spp. assayed. Furthermore, a GR4 derivative mutant obtained by plasmid disruption of ORFC showed an impaired nodulation efficiency as compared to that of the wild-type strain GR4. Thus, the former locus should be considered a novel nfe gene. We propose to rename the nfe genes, nfe1, 2 and ORFC as nfeA, B, and D, respectively.