Comparison of the in vitro activities of delafloxacin and comparators against Staphylococcus epidermidis clinical strains involved in osteoarticular infections: a CRIOGO multicentre retrospective study.

OBJECTIVES: Staphylococcus epidermidis bone and joint infections (BJIs) on material are often difficult to treat. The activity of delafloxacin has not yet been studied on S. epidermidis in this context. The aim of this study was to assess its in vitro activity compared with other fluoroquinolones, against a large collection of S. epidermidis clinical strains. METHODS: We selected 538 S. epidermidis strains isolated between January 2015 and February 2023 from six French teaching hospitals. One hundred and fifty-two strains were ofloxacin susceptible and 386 were ofloxacin resistant. Identifications were performed by MS and MICs were determined using gradient concentration strips for ofloxacin, levofloxacin, moxifloxacin and delafloxacin. RESULTS: Ofloxacin-susceptible strains were susceptible to all fluoroquinolones. Resistant strains had higher MICs of all fluoroquinolones. Strains resistant to ofloxacin (89.1%) still showed susceptibility to delafloxacin when using the Staphylococcus aureus 2021 CA-SFM/EUCAST threshold of 0.25 mg/L. In contrast, only 3.9% of the ofloxacin-resistant strains remained susceptible to delafloxacin with the 0.016 mg/L S. aureus breakpoint according to CA-SFM/EUCAST guidelines in 2022. The MIC50 was 0.094 mg/L and the MIC90 was 0.38 mg/L. CONCLUSIONS: We showed low delafloxacin MICs for ofloxacin-susceptible S. epidermidis strains and a double population for ofloxacin-resistant strains. Despite the absence of breakpoints for S. epidermidis, delafloxacin may be an option for the treatment of complex BJI, including strains with MICs of ≤0.094 mg/L, leading to 64% susceptibility. This study underlines the importance for determining specific S. epidermidis delafloxacin breakpoints for the management of BJI on material.

In transit metastases in children, adolescents and young adults with localized rhabdomyosarcoma of the distal extremities: Analysis of the EpSSG RMS 2005 study.

In-transit metastases (ITM) are defined as metastatic lymph nodes or deposits occurring between the primary tumor and proximal draining lymph node basin. In extremity rhabdomyosarcoma (RMS), they have rarely been reported. This study evaluates the frequency, staging and survival of patients with ITM in distal extremity RMS. METHODS: Patients with extremity RMS distal to the elbow or knee, enrolled in the EpSSG RMS 2005 trial between 2005 and 2016 were eligible for this study. RESULTS: One hundred and nine distal extremity RMS patients, with a median age of 6.2 years (range 0-21 years) were included. Thirty seven of 109 (34%) had lymph node metastases at diagnosis, 19 of them (51%) had ITM, especially in lower extremity RMS. 18F-FDG-PET/CT detected involved lymph nodes in 47% of patients. In patients not undergoing 18F-FDG-PET/CT lymph node involvement was detected in 22%. The 5-yr EFS of patients with ITM vs proximal lymph nodes vs combined proximal and ITM was 88.9% vs 21.4% vs 20%, respectively (p = 0.01) and 5-yr OS was 100% vs 25.2% vs 15%, respectively (p = 0.003). CONCLUSION: Our study showed that in-transit metastases constituted more than 50% of all lymph node metastases in distal extremity RMS. 18F-FDG-PET/CT improved nodal staging by detecting more regional and in-transit metastases. Popliteal and epitrochlear nodes should be considered as true (distal) regional nodes, instead of in-transit metastases. Biopsy of these nodes is recommended especially in distal extremity RMS of the lower limb. Patients with proximal (axillary or inguinal) lymph node involvement have a worse prognosis.

Use of an intravaginal spacer in young girls treated with brachytherapy for bladder neck rhabdomyosarcoma: Dosimetric impact for organs at risk sparing and acute tolerance.

PURPOSE: Interstitial brachytherapy is indicated as part of a conservative strategy for children with bladder and/or prostate rhabdomyosarcoma (RMS), providing high local control probability with acceptable functional results. Vaginal and/or rectal complications were however reported, due to the close proximity to the implanted volume. We investigated the dosimetric impact of a vaginal spacer in terms of rectal and vaginal doses. METHODS AND PATIENTS: Medical records of 12 consecutive female patients with bladder neck RMS, median age 32 months (range: 1.3-6 years), were reviewed. Five patients were treated prior to 2017 without a vaginal spacer and seven patients treated after 2017 had their brachytherapy delivered with a vaginal spacer placed at time of implant. RESULTS: Minimal doses delivered to the most exposed 2cm3, 1cm3, and 0.5cm3 of the rectum were all statistically significantly lower among patients treated with a vaginal spacer, as compared to those treated without a spacer. Median rectal D2cm3 was 22GyEQD2 versus 38GyEQD2 (P=0.02), D1cm3 was 29GyEQD2 versus 51GyEQD2 (P=0.013), and D0.5cm3 was 32GyEQD2 versus 61GyEQD2 (P=0.017), with and without the vaginal spacer, respectively. The posterior vaginal wall D0.5cm3 dose was also significantly decreased, with median D0.5cm3 of 92GyEQD2 versus 54GyEQD2 (P<0.0001), with and without the spacer, respectively. Acute tolerance was excellent in all patients, with no need for replanning and no acute complication. CONCLUSIONS: The use of vaginal spacers in brachytherapy of female pediatric patients with bladder neck RMS resulted in significantly decreased doses to the rectum and the posterior vaginal wall. Though the clinical impact of such dose reduction remains undemonstrated, routine utilization of a vaginal spacer could be a method to decrease long-term morbidity in these patients.

Minimally invasive surgery for neuroblastic tumours: A SIOPEN multicentre study: Proposal for guidelines.

INTRODUCTION: Surgery plays a key role in the management of Neuroblastic tumours (NB), where the standard approach is open surgery, while minimally invasive surgery (MIS) may be considered an option in selected cases. The indication(s) and morbidity of MIS remain undetermined due to small number of reported studies. The aim of this study was to critically address the contemporary indications, morbidity and overall survival (OS) and propose guidelines exploring the utility of MIS for NB. MATERIALS & METHODS: A SIOPEN study where data of patients with NB who underwent MIS between 2005 and 2018, including demographics, tumour features, imaging, complications, follow up and survival, were extracted and then analysed. RESULTS: A total of 222 patients from 16 centres were identified. The majority were adrenal gland origin (54%) compared to abdominal non-adrenal and pelvic (16%) and thoracic (30%). Complete and near complete macroscopic resection (>95%) was achieved in 95%, with 10% of cases having conversion to open surgery. Complications were reported in 10% within 30 days of surgery. The presence of IDRF (30%) and/or tumour volume >75 ml were risk factors for conversion and complications in multivariate analysis. Overall mortality was 8.5%. CONCLUSIONS: MIS for NB showed that it is a secure approach allowing more than 95% resection. The presence of IDRFs was not an absolute contraindication for MIS. Conversion to open surgery and overall complication rates were low, however they become significant if tumour volume >75 mL. Based on these data, we propose new MIS guidelines for neuroblastic tumours.

Investigation of Serratia marcescens surgical site infection outbreak associated with peroperative ultrasonography probe.

Early postoperative infections due to Serratia marcescens have been reported by both clinicians and microbiologists in our teaching hospital. Here, we present an interlinked clinical, epidemiological, environmental and genomic investigation of this outbreak due to a T-shaped intraoperative probe contaminated by S. marcescens used during peroperative ultrasonography in laparoscopic liver resection.

Modeling uranium and 226Ra mobility during and after an acidic in situ recovery test (Dulaan Uul, Mongolia).

This article presents the results of groundwater monitoring over a period of six years and the interpretation of these results by a reactive transport model, following an In Situ Recovery (ISR) test on the Dulaan Uul uranium deposit in Mongolia. An environmental monitoring survey was set up using 17 piezometers, from which it has been possible to describe the changes in the water composition before, during and after the ISR test. The water quality before the start of mining activities rendered it unfit for human consumption. During and after the test, a descent of the saline plume was observed, resulting in a dilution of the injection solutions. After a rapid decrease to pH = 1.13 during the production phase of the ISR test, the pH stabilized at around 4 in the production area and 5.5 below the production cell one year after the end of the test. Uranium and radium were being naturally attenuated. Uranium returned to background concentrations (0.3 mg/L) after two years and the measured 226Ra concentrations represent no more than 10% of the expected concentrations during production (75 Bq/L). The modeling of the contaminants of concern mobility, namely pH and concentrations of sulfate, uranium and 226Ra, is based on several key complementary mechanisms: density flow, cation exchange with clay minerals and co-precipitation of 226Ra in the barite. The modeling results show that the observed plume descent and sulfate dilution can only be predicted if consideration of a high-density flow is included. Similarly, the changes in pH and 226Ra concentration are only correctly predicted when the cationic exchanges with the clays and the co-precipitation reaction within the barite using the solid solution theory are integrated into the models. Finally, the proper representation of the changes in water composition at the scale of the test requires the use of a sufficiently fine mesh (1 m × 1 m cell) to take into account the spatial variability of hydrogeological (permeability distribution in particular) and geological (reduced, oxidized and mineralized facies distributions) parameters.

Activity of fosfomycin alone or combined with temocillin in vitro and in a murine model of peritonitis due to KPC-3- or OXA-48-producing Escherichia coli.

Background: Alternative therapeutic regimens are urgently needed against carbapenemase-producing Enterobacteriaceae. Fosfomycin often remains active against KPC and OXA-48 producers, but emergence of resistance is a major limitation. Our aim was to determine whether the association of temocillin with fosfomycin might be useful to treat KPC- or OXA-48-producing Escherichia coli infections. Methods: Isogenic derivatives of E. coli CFT073 with blaKPC-3- or blaOXA-48-harbouring plasmids (named CFT073-KPC-3 and CFT073-OXA-48, respectively) were used. The addition of temocillin to fosfomycin was tested using the chequerboard method and time-kill curves as well as in a fatal peritonitis murine model. Mice were treated for 24 h with fosfomycin alone or in combination with temocillin. Bacterial loads, before and after treatment, were determined in the peritoneal fluid and fosfomycin-resistant mutants were detected. Results: Temocillin MICs were 8, 32 and 256 mg/L for CFT073 (WT), CFT073-KPC-3 and CFT073-OXA-48, respectively. Fosfomycin MIC was 0.5 mg/L for all strains. The chequerboard experiments demonstrated synergy for all three strains. In time-kill curves, combining temocillin with fosfomycin was synergistic, bactericidal and prevented emergence of resistance for CFT073-pTOPO and CFT073-KPC-3, but not CFT073-OXA-48. In vivo, for the three strains, bacterial counts were lower in peritoneal fluid with the combination compared with fosfomycin alone (P < 0.001) and inhibited growth of resistant mutants in all cases. Conclusions: The combination of fosfomycin and temocillin demonstrated a benefit in vitro and in vivo against E. coli strains producing KPC-3 or OXA-48-type carbapenemases. This combination prevented the emergence of fosfomycin resistance and proved to be more bactericidal than fosfomycin alone.

Preservation of future fertility in pediatric patients with cancer.

The cure rate for childhood and adolescent patients with cancer has currently reached almost 80% and protecting future fertility and thereby promoting quality of life have become a major challenge in the care of these patients (Bioethics Law, 2004). Age, sex and associated treatments influence the risk of future subfertility. Certain chemotherapies (particularly alkylating agents) and radiotherapy fields that include the gonads or hypothalamopituitary axis may negatively impact the future fertility of patients. Evaluation of the gonadotoxic potential of therapeutic measures and the utilization of appropriate methods to preserve fertility require the combined efforts of a multidisciplinary team that includes pediatric oncologists, radiotherapists, surgeons, reproductive physicians and biologists and psychologists. Techniques for fertility preservation vary depending on the age of the child and range from surgical transposition of the gonads for pelvic radiotherapy to cryopreservation of the ovary or testicle in case of sterilizing chemotherapy. While scientists still do not yet fully understand the maturation of immature germ cells, these children will be seeking the assistance of Medically Assisted Procreation (MAP) in 20-30 years. In the meanwhile, it is to be hoped that many more advances will be achieved in the utilization of harvested germinal tissue.

[Economic impact of etanercept and adalimumab biosimilars on hospitals scale covered by PharmAlp'Ain, a hospitals grouping of orders for health products]. / Évaluation de l'impact économique des biosimilaires d'étanercept et d'adalimumab à l'échelle des établissements adhérents au groupement de commandes PharmAlp'Ain.

OBJECTIVES: To evaluate the economic impact of future prescriptions of etanercept and adalimumab biosimilars at the territorial scale covered by PharmAlp'Ain, a hospitals grouping of orders for health products. METHODS: Determination of the number and status of patients (naive or in continuation of treatment) from the National Database "Datamart de Consommation Inter-Régimes" of health insurance, concerned by a dispensation in a pharmacy of etanercept or adalimumab in 2015. Calculation of potential savings in case of biosimilar requirements according to 3 hypotheses: 63% (rate observed in a previous study) of initiations are treated with biosimiliaries and the others by princeps (H1); all initiations under biosimilars and continuation therapy with the princeps (H2) or all patients are treated with biosimilars (H3). RESULTS: The annual savings are estimated at 237,000 € with the H1 hypothesis. In the case of H2, the expected savings would be 376,200 € per year. In the case of H3, savings for the community could reach almost 1,282,800 € per year. CONCLUSION: The arrival of biosimilars allows significant savings for medicines market. According to the French recommendations in 2016, the expected savings are between the H1 and H2 hypothesis. The rate of penetration of biosimilars depends on many factors such as the involvement of health professionals, patient adherence, or health authority recommendations.

Biological cost of fosfomycin resistance in Escherichia coli in a murine model of urinary tract infection.

Prevalence of fosfomycin resistance in E. coli clinical isolates from UTIs remains very low. Our hypothesis was that fosfomycin resistance may be associated with a biological cost. Three groups of strains of E. coli belonging to the B2 phylogenetic group were used: clinical wild-type (WT) isolates, clinical multidrug-resistant isolates and in vitro fosfomycin-resistant derivatives from the uropathogen clinical strain E. coli CFT073. In each group fosfomycin-susceptible and -resistant isolates were compared. In vitro, we found a significantly decreased growth rate for fosfomycin-resistant strains as compared with susceptible strains in the WT group. In a murine model of ascending UTI, there was a significant reduction in infection rates with fosfomycin-resistant isolates as compared with susceptible ones, in all 3 study groups, ranging from 28 to 39% (P<0.03). All fosfomycin-susceptible clinical strains were virulent in vivo (13/13), while fosfomycin-resistant clinical strains were either virulent (2/7) or non-virulent (5/7) (P<0.002). This difference was not explained by the number of virulence factors or pathogenicity-associated islands. In conclusion, fosfomycin resistance appears to carry some biological cost in E. coli, which may explain in part the apparent paradox of the low prevalence of fosfomycin resistance despite a high rate of spontaneous mutants.

Hepatocellular carcinoma in a patient with congenital porto-systemic shunt.

Congenital porto-caval shunt is a rare anomaly that can result in direct shunt-related complications (encephalopathy, pulmonary hypertension) or indirect complications such as the development of benign or malignant hepatic neoplasms. Treatment consists of management of the complications and occlusion of the porto-caval shunt in one or two stages by either a surgical or an interventional radiology approach.

Methane and nitrous oxide annual emissions from an old eutrophic temperate reservoir.

Two greenhouse gases -methane (CH4) and nitrous oxide (N2O) - were monitored monthly during one year (2011) at the Eguzon Reservoir in France. The objective of the study was to quantify for the first time in a temperate area the total emissions of these gases through the main emission pathways (diffusion and bubbling from the reservoir, degassing and downstream diffusion). The reservoir was impounded in 1926 and had, in 2011, a eutrophic status promoting high organic matter degradation and nitrification-denitrification, all favouring CH4 and N2O production. CH4 and N2O emissions were dominated by diffusion from the reservoir surface (respectively 78.0% and 92.3%). Ebullition was only observed for CH4 and accounted for 14.0% of total CH4 emissions. Downstream degassing and diffusion represented 8.1% of the total CH4 emissions and 7.7% of the total N2O emissions.

Activity of temocillin in a lethal murine model of infection of intra-abdominal origin due to KPC-producing Escherichia coli.

OBJECTIVES: Temocillin is a 6-α-methoxy derivative of ticarcillin that shows in vitro activity against Enterobacteriaceae producing Klebsiella pneumoniae carbapenemase (KPC). Our objective was to assess in vivo temocillin activity against KPC-producing Escherichia coli. METHODS: Isogenic derivatives of the WT E. coli CFT073 producing KPC-2, KPC-3 or OXA-48 were constructed. An experimental murine model of intra-abdominal infection with sepsis was used. Mice were treated subcutaneously with temocillin 200 mg/kg every 2 h for 24 h, reproducing the duration of time that the free serum concentration of temocillin exceeded the MIC in humans with a regimen of 2 g every 12 h or 2 g every 8 h. Blood, peritoneal fluid (PF) and spleen were collected; 24 h survival and sterility rates were assessed. RESULTS: Temocillin MICs were 8, 16, 32, and 256 mg/L for the susceptible strain and KPC-2-, KPC-3-, and OXA-48-producing strains, respectively. In mice treated with temocillin, significant bacterial reduction was obtained in PF, blood, and spleen for the susceptible strain and KPC-2- and KPC-3-producing strains (P < 0.001) but not for the OXA-48-producing strain. Sterility rates in PF were 53%, 10%, 0% and 0% (P < 0.001) and sterility rates in blood were 77%, 40%, 3% and 0% (P < 0.001), while survival rates were 97%, 97%, 57%, 0% (P < 0.001) for mice infected with the susceptible strain and KPC-2-, KPC-3- and OXA-48-producing strains, respectively. CONCLUSIONS: In a lethal-infection model with bacteraemia from intra-abdominal origin, temocillin retained significant activity in PF, blood and spleen and prevented death in mice by effectively working against KPC-producing E. coli with temocillin MICs ≤16 mg/L.

In vitro antimicrobial susceptibility of Helcococcus kunzii and molecular analysis of macrolide and tetracycline resistance.

Thanks to the recent advent of matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) technology, Helcococcus kunzii is now easily identifiable and considered as an opportunistic pathogen. However, data about antimicrobial susceptibilities remain very limited. The aim of the study was, then, to assess its in vitro susceptibility to 18 antimicrobial agents and to investigate the genetic basis of macrolide and tetracycline resistance. Thirty-nine human clinical isolates of H. kunzii collected from 2008 to 2013 were studied, as well as the type strain ATCC 51366(T). Minimum inhibitory concentrations (MICs) of penicillin G, amoxicillin, cefotaxime, imipenem, gentamicin, erythromycin, clindamycin, quinupristin-dalfopristin, ciprofloxacin, levofloxacin, tetracycline, tigecycline, vancomycin, teicoplanin, linezolid, daptomycin, cotrimoxazole and rifampin were determined by the microdilution method. Screening for macrolide [erm(A) including erm(TR), erm(B), erm(C), erm(F), erm(T), erm(X), msr(A) and mef(A)] and tetracycline [tet(L), tet(M) and tet(O)] resistance genes was performed, as well as the detection of mutations in 23S rRNA. Except for one strain resistant to cefotaxime, all strains were categorised as susceptible to ß-lactams, glycopeptides, linezolid, daptomycin and tigecycline. Whereas ciprofloxacin and gentamicin exhibited limited activity, 95% of strains were categorised as susceptible to levofloxacin. Concerning erythromycin, a bimodal distribution was observed, with 29 'wild-type' strains (MICs from 0.25 to 2 mg/L) and 11 'resistant' strains (MICs ≥ 256 mg/L), including ten harbouring erm(TR). Two isolates exhibited acquired tetracycline resistance (MICs of 16 mg/L) by the production of tet(M). This large study on the in vitro antimicrobial susceptibility of H. kunzii suggests that ß-lactams (especially penicillins) should be preferred for the treatment.

Bridgehead invasion of a monomorphic plant pathogenic bacterium: Xanthomonas citri pv. citri, an emerging citrus pathogen in Mali and Burkina Faso.

Molecular epidemiology studies further our understanding of migrations of phytopathogenic bacteria, the major determining factor in their emergence. Asiatic citrus canker, caused by Xanthomonas citri pv. citri, was recently reported in Mali and Burkina Faso, a region remote from other contaminated areas. To identify the origin and pathways of these emergences, we used two sets of markers, minisatellites and microsatellites, for investigating different evolutionary scales. Minisatellite typing suggested the introduction of two groups of strains in Mali (DAPC 1 and DAPC 2), consistent with microsatellite typing. DAPC 2 was restricted to Bamako district, whereas DAPC 1 strains were found much more invasive. The latter strains formed a major clonal complex based on microsatellite data with the primary and secondary founders detected in commercial citrus nurseries and orchards. This suggests that human activities played a major role in the spread of DAPC 1 strains via the movement of contaminated propagative material, further supported by the frequent lack of differentiation between populations from geographically distant nurseries and orchards. Approximate Bayesian Computation analyses supported the hypothesis that strains from Burkina Faso resulted from a bridgehead invasion from Mali. Multi-locus variable number of tandem repeat analysis and Approximate Bayesian Computation are useful for understanding invasion routes and pathways of monomorphic bacterial pathogens.

Non-carbapenem therapy of urinary tract infections caused by extended-spectrum ß-lactamase-producing Enterobacteriaceae.

PURPOSE: We determined the prevalence of ESBL Enterobacteriaceae in urinary tract infections among inpatients, identified risk factors of acquisition, and evaluated the effectiveness of alternatives to carbapenems. METHODS: The clinical, microbiological, and therapeutic data as well as the outcomes were recorded for all ESBL-E positive urine samples for three months. RESULTS: Thirty-one (4%) of the 762 Enterobacteriaceae positive cultures were ESBL producers. The predisposing conditions for being infected with those strains were: immunodepression (61%), recent hospitalization (52%), recent antibiotic therapy (52%), and urinary catheterization (61%). 19% of infections were community acquired. The seven cases of acute pyelonephritis and five of prostatitis were treated with piperacillin-tazobactam (5), fluoroquinolones (4), ceftazidime (2), or carbapenems (only 1) after specialized advice. Four (33%) patients relapsed at week 10: three were immunodepressed and three presented with bacteremia. CONCLUSIONS: Alternatives to carbapenems (especially piperacillin-tazobactam) seem to be a good option for non-bacteremic UTI in immunocompetent patients.

Meso-Rex bypass for extrahepatic portal vein obstruction in children.

BACKGROUND: Meso-Rex bypass (MRB) and portosystemic surgical shunt (PSS) are both used to treat extrahepatic portal vein obstruction (EHPVO) in children. The aim of this study was to analyse the outcome of MRB and PSS to select patients who could benefit from a prophylactic MRB. METHODS: This single-centre retrospective study of children who underwent either MRB or PSS for EHPVO was conducted between 1996 and 2010. Details of patient demographics and preoperative evaluation were collected. Success rates, defined as shunt patency after a minimum of 6 months and clearance of varices or symptoms, were compared. Determinants of outcomes were explored. RESULTS: Sixty-nine patients underwent a MRB or PSS. Median (interquartile range, i.q.r.) age at surgery was 6.6 (4.0-10.6) years. Twenty-four patients (35 per cent) had had a neonatal umbilical catheter (NUC) placed previously and 47 (68 per cent) had experienced an upper gastrointestinal bleed. Imaging assessment of the intrahepatic left portal vein was considered favourable in 40 patients. Of 43 MRBs attempted, 11 failed during surgery and four patients had persistent thrombosis after a median of 55 (i.q.r. 18-107) months. The success rate of MRB was 60 per cent (26 of 43) compared with 100 per cent (26 of 26) for PSS (P < 0.001). It was lower among patients in whom a NUC had been used (2 of 10 versus 24 of 33; P = 0.004), for procedures undertaken early in the series (6 of 16 versus 20 of 27; P = 0.020) and when the imaging pattern was unfavourable (0 of 5 versus 26 of 38; P = 0.006). On multivariable analysis, only a previous history of NUC predicted failure (P = 0.016). CONCLUSION: Prophylactic MRB seems a good treatment option for EHPVO in children, but should be done only by an experienced team in patients with favourable imaging and without a previous history of NUC.

First Report of Xanthomonas citri pv. citri Causing Asiatic Citrus Canker in Burkina Faso.

Citrus canker, caused by Xanthomonas citri pv. citri, is a bacterial disease of economic importance in tropical and sub-tropical citrus-producing areas (EPPO-PQR online database). X. citri pv. citri causes severe infection in a wide range of citrus species, and induces erumpent, callus-like lesions with water-soaked margins leading to premature fruit drop and twig dieback. It has consequently been subjected to eradication efforts and international regulations. It was first described on the African continent in South Africa at the beginning of the 20th century, from which it was eventually eradicated. Since 2006, several outbreaks caused by phylogenetically diverse strains of X. citri pv. citri have been reported from several African countries (Ethiopia, Mali, Senegal, and Somalia). In July 2011, citrus canker in Burkina Faso was suspected in the area adjacent to the Sikassso Province of Mali where X. citri pv. citri has been confirmed. In November and December 2012, leaves of clementine (Citrus clementina), lemon (C. limon), Volkamer lemon (C. volkameriana), sweet orange (C. sinensis), tangelo (C. paradisi× C. reticulata), and mandarin (C. reticulata) were collected from orchards with trees showing symptoms of citrus canker in the Comoé, Houet, and Kénédougou provinces of Burkina Faso. Isolations performed using KC semi-selective medium (4) recovered 45 Xanthomonas-like strains. All Xanthomonas-like strains were tentatively identified as X. citri pv. citri by PCR (4/7 primers) using IAPAR 306 and sterile distilled water as the positive and negative controls, respectively (3). Among these, two strains (LK4-4 and LK4-5) produced a 'fuscans'-like brown diffusible pigment, a phenotype never reported previously for X. citri pv. citri. MultiLocus Sequence Analysis targeting six housekeeping genes (atpD, dnaK, efp, gltA, gyrB, and lepA) (1,2) fully identified seven strains from Burkina Faso (LJ301-1, LJ303-1, LK1-1, LK2-6, LK4-3, LK4-4, and LK4-5) as X. citri pv. citri (and not to any other Xanthomonas pathovars pathogenic to citrus or host range-restricted pathotypes of pathovar citri), and more specifically as sequence type ST2 which is composed mostly of pathotype A strains of X. citri pv. citri (2). The same seven strains were inoculated to at least four leaves of each of grapefruit cv. Henderson, Mexican lime SRA 140 (C. aurantifolia), Tahiti lime SRA 58 (C. latifolia), and sweet orange cv. Washington Navel, using a detached leaf assay (2). All strains developed typical erumpent, callus-like tissue at wound sites on all citrus species inoculated. No lesions developed on the negative control (sterile 10 mM tris buffer). Koch's postulate was fulfilled after reisolation of Xanthomonas-like yellow colonies from symptoms on Mexican lime produced by the seven strains. Boiled bacterial suspensions were assayed by PCR with 4/7 primers (3) and produced the expected 468-bp amplicon in contrast with the PCR negative control. To our knowledge, this is the first report of X. citri pv. citri in Burkina Faso. Citrus canker-free nurseries and grove sanitation should be implemented for reducing the prevalence of Asiatic canker in Burkina Faso and a thorough survey of citrus nurseries and groves in the region should be conducted. References: (1) N. F. Almeida et al. Phytopathology 100:208, 2010. (2) L. Bui Thi Ngoc et al. Int. J. Syst. Evol. Microbiol. 60:515, 2010. (3) J. S. Hartung et al. Phytopathology 86:95, 1996. (4) O. Pruvost et al. J. Appl. Microbiol. 99:803, 2005.

SAXS conformational tracking of amylose synthesized by amylosucrases.

Amylose, a linear polymer of α(1,4)-linked glucosyl units and a major constituent of starch granules, can also be enzymatically synthesized in vitro from sucrose by bacterial amylosucrases. Depending on the initial sucrose concentration and the enzyme used, amylose oligomers (or polymers) are formed and self-associate during synthesis into various semicrystalline morphologies. This work describes for the first time a synchrotron SAXS study of the structure in solution of two amylosucrases, namely, NpAS and the thermostable DgAS, under conditions of polymer synthesis and, simultaneously, the amylose conformation. The structure in solution of both amylosucrases during the reaction was shown to be similar to the known crystallographic structures. The conformation of amylose produced at an early stage consists of a mixture of wormlike chains and double helical cylindrical structures. In the case of NpAS, in a second stage, individual double helices pack into clusters before crystallizing and precipitating. Amylose produced by DgAS never self-associates in such clusters due to the higher temperature used for amylose synthesis. All the dimensions determined for wormlike chains and cylindrical conformations at different times of NpAS synthesis are in very good agreement with structural features usually observed on gels of amylose extracted from starch. This provides new insights in understanding the mechanisms of amylose gelation.