Twelve Months of Routine HIV Screening in 6 Emergency Departments in the Paris Area: Results from the ANRS URDEP Study

Objective

In October 2009 the French National Authority for Health recommended that HIV testing be proposed at least once to all persons aged 15 to 70 years in all healthcare settings. We examined whether routine HIV screening with a rapid test in emergency departments (EDs) was feasible without dedicated staff, and whether newly diagnosed persons could be linked to care.

Methods

This one-year study started in December 2009 in 6 EDs in the Paris area, using the INSTI™ test. Eligible individuals were persons 18 to 70 years old who did not present for a vital emergency, for blood or sexual HIV exposure, or for HIV screening. Written informed consent was required.

Results

Among 183 957 eligible persons, 11 401 were offered HIV testing (6.2%), of whom 7936 accepted (69.6%) and 7215 (90.9%) were tested (overall screening rate 3.9%); 1857 non eligible persons were also tested. Fifty-five new diagnoses of HIV infection were confirmed by Western blot (0.61% (95% CI 0.46–0.79). There was one false-positive rapid test result. Among the newly diagnosed persons, 48 (87%) were linked to care, of whom 36 were not lost to follow-up at month 6 (75%); median CD4 cell count was 241/mm³ (IQR: 52–423/mm³).

Conclusions

Screening rates were similar to those reported in opt-in studies with no dedicated staff. The rate of new diagnoses was similar to that observed in free anonymous test centres in the Paris area, and well above the prevalence (0.1%) at which testing has been shown to be cost-effective.     

Chemical Communication between the Endophytic Fungus Paraconiothyrium Variabile and the Phytopathogen Fusarium oxysporum

Paraconiothyrium variabile, one of the specific endophytic fungi isolated from the host plant Cephalotaxus harringtonia, possesses the faculty to inhibit the growth of common phytopathogens, thus suggesting a role in its host protection. A strong antagonism between the endophyte P. variabile and Fusarium oxysporum was observed and studied using optic and electronic microscopies. A disorganization of the mycelium of F. oxysporum was thus noticed. Interestingly, the biological effect of the main secondary metabolites isolated from P. variabile against F. oxysporum did not account for this strong antagonism. However, a metabolomic approach of pure fungal strains and confrontation zones using the data analysis tool XCMS were analyzed and pointed out a competition-induced metabolite production by the endophyte in the presence of the phytopathogen. Subsequent MS/MS fragmentations permitted to identify one of the induced metabolites as 13-oxo-9,11-octadecadienoic acid and highlighted a negative modulation of the biosynthesis of beauvericin, one of the most potent mycotoxin of F. oxysporum, during the competition with the endophyte.     

Hydrous and photosynthetic adaptations of common and durum wheat to saline stress

Seven varieties of bred wheat and seven varieties of durum wheat were cultivated in three different sites from the area of Errachidia (southeastern Morocco). These sites differ by the degree of salinity in the irrigation water. Results obtained showed that the reduction in leaf area is the principal strategy that makes it possible to attenuate the effects of the reduction in the availability of water under saline stress. Bread wheat, which limited the reduction in the leaf area, with the risk to undergo some hydrous problems, seems to better preserve its photosynthetic potentialities and grain productivity.     

Capsular polysaccharides secreted by building façade colonisers: characterisation and adsorption to surfaces

Abstract

Exopolymers secreted by algal and cyanobacterial strains isolated from building façades were imaged by microscopy techniques. They were extracted and characterised to investigate their possible contribution to interactions with solid surfaces. The polymers were polysaccharides, with anionic and hydrophobic properties varying between the various strains. Capsular polysaccharides extracted from a strain of Klebsormidium flaccidum adsorbed in higher amounts on hydrophobic than on hydrophilic surfaces. These results tend to confirm the hypothesis that exopolymers are important in the colonisation process of microorganisms to surfaces.     

Optimal exploitation for a commercial fishing model

A two non-linear dynamic models, first one in two state variables and one control and the second one with three state variables and one control, are presented for the purpose of finding the optimal combination of exploitation, capital investment and price variation in the commercial fishing industry. This optimal combination is determined in terms of management policies. Exploitation, capital and price variation are controlled through the utilization rate of available capital. A novel feature in this model is that the variation of the capital depends on the income.     

Cell Division Inhibition in Salmonella typhimurium Histidine-Constitutive Strains: an ftsI-Like Defect in the Presence of Wild-Type Penicillin-Binding Protein 3 Levels

Histidine-constitutive (His^c) strains of Salmonella typhimurium undergo cell division inhibition in the presence of high concentrations of a metabolizable carbon source. Filaments formed by His^c strains show constrictions and contain evenly spaced nucleoids, suggesting a defect in septum formation. Inhibitors of penicillin-binding protein 3 (PBP3) induce a filamentation pattern identical to that of His^c strains. However, the His^c septation defect is caused neither by reduced PBP3 synthesis nor by reduced PBP3 activity. Gross modifications of peptidoglycan composition are also ruled out. d-Cycloserine, an inhibitor of the soluble pathway producing peptidoglycan precursors, causes phenotypic suppression of filamentation, suggesting that the septation defect of His^c strains may be caused by scarcity of PBP3 substrate.When histidine-constitutive (His^c) mutants of Salmonella typhimurium were first isolated, the authors noted that high levels of histidine biosynthetic enzymes caused wrinkled colony morphology on 2% glucose plates (25). Wrinkledness reflects cell filamentation (12, 19), which is triggered by overproduction of hisH and hisF gene products (5, 9, 19). A similar response has been described for Escherichia coli (11). HisH and HisF are subunits of the heterodimeric imidazole-glycerol-phosphate synthase (1, 34), which catalyzes the formation of imidazole-glycerol-phosphate (IGP) with release of the purine precursor AICAR (5-aminoimidazole-4-carboxamide ribonucleotide) (17, 26). However, division inhibition does not require metabolic flow through the histidine biosynthetic pathway, suggesting that HisH and HisF trigger filamentation through an activity unrelated to IGP synthesis (10, 19). The involvement of AICAR has been also ruled out (10, 11). In both S. typhimurium and E. coli, the cell division defect of His^c strains is unrelated to the SOS response and does not involve the cell division inhibitor SulA (11, 12). We show below that the cell division defect of S. typhimurium His^c strains is a block in septum formation, as proposed by Frandsen and D’Ari (11). We also describe the unexpected finding that strains that overproduce IGP synthase contain wild-type levels of active penicillin-binding protein 3 (PBP3). These contradictory data are tentatively reconciled by the ability of d-cycloserine to suppress filamentation in His^c mutants. The latter observation suggests that HisHF overproduction may cause a shortage in PBP3 substrate.

Filament formation by His^c strains.

Mid-exponential-phase cultures of strains LT2 (hisO⁺) and TR6753 (hisO1242 [5, 16]) were observed under the microscope by using Hiraga’s fluo-phase combined method, a procedure that permits the simultaneous observation of nucleoids and cells (15). Nucleoid staining was achieved with DAPI (4′,6-diamino-2-phenylindole). The His^c strain formed long filaments which contained evenly spaced nucleoids, indicating that their division defect is unrelated to DNA synthesis or chromosome partition (Fig. ​(Fig.1).1). Moreover, the presence of blunt constrictions indicates that the division block lies beyond the stage of FtsZ action (8). The filaments are similar in morphology and length to those formed by ftsI and ftsA mutants of E. coli (8). The ftsI gene encodes PBP3, an essential cell division protein involved in septum formation (27). FtsA is a membrane-bound protein that interacts with PBP3 (22, 31). A difference is that ftsI and ftsA mutants are conditional (thermosensitive) lethals unable to form colonies under restrictive conditions (3, 18), while the filaments produced by His^c strains of S. typhimurium in the presence of 2% glucose give rise to colonies which are distinctly wrinkled (9, 19, 25). Open in a separate windowFIG. 1Microscopic photographs of cells and filaments prepared with Hiraga’s fluo-phase combined method (15). (A) Filaments formed by the His^c strain TR6753 grown in E medium containing 2% glucose. (B) An isogenic His⁺ strain (LT2) grown under the same conditions does not form filaments. (C) Addition of aztreonam to a culture of strain LT2 in E medium induces filaments identical to those formed by a His^c strain in high-glucose medium (compare panels A and C). Bar, 5 μm.Antibiotics that inhibit PBP3, such as aztreonam and azlocillin, produce phenocopies of ftsI mutants in E. coli (29). Based on this precedent, we investigated whether PBP3 inhibitors were able to reproduce the filamentation phenotype of His^c strains. Addition of aztreonam (1 mg/liter) to a culture of strain LT2 triggered filament formation (Fig. ​(Fig.1C),1C), and the filaments were identical in morphology and length to those formed by the His^c strain TR6753 (Fig. ​(Fig.1A).1A). The same effect was induced by azlocillin (data not shown). At the concentrations used, these antibiotics inhibit specifically PBP3 (21). These observations suggest that His^c strains of S. typhimurium behave as ftsI mutants.Additional evidence against an FtsA-like defect was provided by the failure of a plasmid carrying the E. coli ftsA gene to relieve cell division inhibition when introduced in strain TR6753. If His^c strains were ftsA-like, a plasmid-borne ftsA gene should restore the FtsA/FtsZ ratio (6), thereby causing a certain degree of suppression. However, the actual result was that pMFV26, an ftsA⁺ plasmid provided by Miguel Vicente (CIB-CSIC, Madrid, Spain), failed to relieve septation inhibition. The conclusion that His^c strains behave as ftsI (rather than ftsA) mutants receives further support from the ability of d-cycloserine to suppress filamentation (see below).

HisHF overproduction does not cause reduced synthesis of PBP3.

The levels of PBP3 produced by HisO⁺ and HisO^c strains were compared by using envelope extracts from mid-exponential-phase cultures (optical density at 600 nm, 0.5 to 0.6) in E medium containing 2% glucose (33). Envelope proteins were fractionated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (8% acrylamide) and detected by immunoblotting against a polyclonal anti-PBP3 serum (21). The levels of PBP3 protein are similar in HisO⁺ and HisO^c strains (Fig. ​(Fig.2);2); densitometric analysis (not shown) confirmed the absence of differences. Thus, the cell division defect associated with IGP synthase overproduction is not caused by reduced synthesis of PBP3. An additional observation is that the electrophoretic mobilities of PBP3 are similar in HisO⁺ and HisO^c strains, thereby eliminating the occurrence of gross structural changes in the protein. Open in a separate windowFIG. 2Immunodetection of PBP3 from the wild type (lanes A and C) and the His^c strain TR6753 (lanes B and D). Lanes A and B contain membrane vesicles corresponding to 80 μg of protein in a final reaction volume of 20 μl. Lanes C and D contain membrane vesicles corresponding to 120 μg of protein in a final volume of 20 μl.

HisHF overproduction does not cause reduced activity of PBP3.

As an indicator of the functionality of PBP3 in membrane extracts from HisO⁺ and HisO^c strains, we analyzed their capacities to bind covalently ³H-labelled benzylpenicillin (2). Cultures were prepared as described above. Protein separation was performed on an SDS-polyacrylamide gel (2). Radioactivity was detected by fluorography (28, 30). Protein quantitation was performed by the method of Bradford (4). No differences in penicillin binding were found (Fig. ​(Fig.33 and densitometric data not shown). A side observation is that the remaining high-molecular-weight PBPs were also unaffected (Fig. ​(Fig.3).3). Open in a separate windowFIG. 3Binding of ³H-labelled benzylpenicillin to cell envelopes from exponentially growing cells of the His⁺ strain LT2 (lane I) and the His^c strain TR6753 (lane II). PBPs are numbered on the right by standard nomenclature (27).

Peptidoglycan composition of His^c strains.

To investigate the possibility that His^c strains might synthesize an abnormal cell wall, we prepared peptidoglycan extracts from strains LT2 and TR6753 grown in E medium containing 2% glucose. Concentrated exponential cultures containing approximately 10¹¹ bacterial cells were cooled to 4°C, centrifuged at 12,000 × g for 15 min, and resuspended in 3 ml of phosphate-buffered saline, pH 7.4. The suspension was mixed 1:1 (vol/vol) with a boiling solution of 8% SDS (24). The SDS-insoluble material was washed in distilled water (13). Peptidoglycan was digested with Cellosyl muramidase (20 μg/ml) (Hoechst, Sommerville, N.J.); this treatment yields muropeptides of low molecular weight (23). The reaction was stopped in a boiling bath for 5 min. Insoluble material was removed by centrifugation (1,000 × g, 10 min). Peptidoglycan composition was determined by high-performance liquid chromatography analysis (13, 14). The main conclusions are that (i) abnormal peptidoglycan muropeptides were not found and (ii) gross differences in peptidoglycan composition or organization were not found between HisO⁺ and HisO^c strains (Table ​(Table1).1). These experiments do not rule out the formation of an abnormal PBP3 substrate but certainly exclude the possibility that any unusual substrate is incorporated into growing peptidoglycan chains. This absence of differences does not eliminate the possibility that His^c strains may have a defect in the reaction catalyzed by PBP3; peptidoglycan from strain LT2 treated with the PBP3 inhibitor aztreonam showed also standard composition (Table ​(Table1).1). In fact, a well-known and surprising feature of cell wall synthesis is that the global peptidoglycan composition remains unaltered under conditions that cause major changes in cell shape (20).

TABLE 1

Muropeptide composition of peptidoglycan from His⁺ and His^c strains and from a His⁺ strain treated with aztreonam

Capsular polysaccharides secreted by building façade colonisers: characterisation and adsorption to surfaces

Exopolymers secreted by algal and cyanobacterial strains isolated from building fa?ades were imaged by microscopy techniques. They were extracted and characterised to investigate their possible contribution to interactions with solid surfaces. The polymers were polysaccharides, with anionic and hydrophobic properties varying between the various strains. Capsular polysaccharides extracted from a strain of Klebsormidium flaccidum adsorbed in higher amounts on hydrophobic than on hydrophilic surfaces. These results tend to confirm the hypothesis that exopolymers are important in the colonisation process of microorganisms to surfaces.     

Parasitism of Iron-siderophore Receptors of Escherichia Coli by the Siderophore-peptide Microcin E492m and its Unmodified Counterpart

Microcin E492 (MccE492) is an antibacterial peptide naturally secreted by Klebsiella pneumoniae RYC492. Initially described as an 84-residue unmodified peptide, it was also recently isolated in a posttranslationally modified form, MccE492m. The production of MccE492m is dependent on the synthesis of enterobactin and the mceABCDEFGHIJ gene cluster. The posttranslational modification was characterized as a trimer of N-(2,3-dihydroxybenzoyl)-l-serine (DHBS) linked to the Ser84-carboxylate via a β-d-glucose moiety. MccE492m was shown to bind ferric ions through the trimer of DHBS. This is the first example of a novel type of antibacterial peptide termed siderophore-peptide. Recognition of MccE492m, but also of the unmodified MccE492, was shown to be mediated by the catecholate siderophore receptors FepA, Cir and Fiu at the outer membrane of E. coli. The siderophore-type modification was shown to be responsible for a significant enhancement of the microcin antibacterial activity. Therefore, we propose that MccE492 and MccE492m use iron-siderophore receptors for uptake into the target bacteria and that improvement of MccE492 antimicrobial activity upon modification results from an increase in the microcin/receptor affinity.