Synthesis and study of new siderophore analog-ciprofloxacin conjugates with antibiotic activities against Pseudomonas aeruginosa and Burkholderia spp.

Antibacterial resistance is a healthcare burden. Among Gram-negative bacteria, Pseudomonas aeruginosa belongs to the first list of antibiotic-resistant "priority pathogens" described by the World Health Organization. Formerly Pseudomonas pseudomallei, Burkholderia pseudomallei, responsible for melioidosis, is considered as a potential bioterrorist weapon by the Centers of Diseases Control and Prevention. We are interested in the development of new ways to combat these bacteria, targeted due to their high level of resistance to antibiotics via a lack of membrane permeability or efflux. Using iron transport systems is a promising strategy to bypass the bacteria cell membrane and restore the activity of conventional antibiotics such as ciprofloxacin. Specific outer membrane receptors are necessary to most microbes as they allow iron uptake, essential for their survival through siderophore-dependent mechanisms. These systems may allow the introduction of antibacterial agents, chemically coupled to a natural or synthetic siderophore molecule to form siderophore-antibiotic conjugates. In this work, we describe the synthesis of six new siderophore analog-ciprofloxacin conjugates including cleavable linker or not. The siderophore analogs correspond to a mono-catechol or a hydroxypyridinone moiety recognized by both Pseudomonas and Burkholderia species. Physico-chemical studies showed that (i) conjugates were unable to interact or cross the membrane by passive diffusion and (ii) conjugates with cleavable linker are stable in physiologic environment. Biological evaluations have highlighted a promising compound 2d, bearing an hydroxypyridinone moiety with a cleavable linker, active on a large panel of strains of Pseudomonas aeruginosa, Burkholderia pseudomallei and Burkholderia thailandensis without toxicity observed in vitro.

[Usefulness of a rapid intrapartum real-time PCR assay in comparison with the group B Streptococcus culture screening at the end of pregnancy in pregnant women]. / Intérêt d'un test de PCR en temps réel en intrapartum en comparaison à la culture de fin de grossesse pour le dépistage du streptocoque du groupe B chez la femme enceinte.

OBJECTIVES: The objectives were to evaluate and compare the diagnostic accuracy of a rapid real-time PCR assay at the onset of labor with those of the current antenatal culture-based test at 34-38 weeks gestation for group B Streptococcus (GBS) screening. MATERIALS AND METHODS: A prospective study including all pregnant women admitted for delivery after a 34-week gestation period was conducted in October 2012 at the Grenoble University Hospital Centre. A first culture-based GBS screening test was performed between 34 and 38 weeks of gestation followed by a second screening test at the onset of labor, using a real-time PCR Assay and a culture-based method (gold standard) in order to calculate the diagnostic accuracy. RESULTS: One hundred an fifty-seven patients were enrolled. The sensitivity was 94.4% (95% CI, 72.7-99.9%) with intrapartum PCR assay and 50% (95% CI, 26-74%) with antepartum culture. Prevalence of GBS colonization was 7.6% with the antepartum culture method, 11.5% with intrapartum culture and 16.6% by using PCR-test. CONCLUSION: Intrapartum PCR shows a much higher sensitivity compared to the antepartum culture-based screening mainly due to variations in GBS colonization and could allow us to target patients requiring intrapartum antibiotic prophylaxis more effectively.

[Melioidosis: an emerging tropical disease]. / La mélioïdose: une maladie tropicale en quête de reconnaissance.

Melioidosis is an infection affecting both human and animal health. The causative agent is Burkholderia pseudomallei, a Gram-negative soil bacterium. Melioidosis is endemic in tropical areas of Southeast Asia and Northern Australia, and sporadic in many other countries. Clinical presentation is variable ranging from acute septicemia, isolated pulmonary infection, or chronic granulomatous lesions to asymptomatic forms with positive serology. There is no vaccine and treatment is difficult because B. pseudomallei is resistant to a wide range of antibiotics. Relapses are common. B. pseudomallei is listed as a biological risk class 3 and considered as a potential bioterrorism agent due to its high virulence by inhalation, to the difficulty of treatment, and to the lack of vaccine.

Two novel fibrinogen variants found in patients with pulmonary embolism and their families.

BACKGROUND: The occurrence of dysfibrinogen is quite rare in comparison with other hemostatic defects, specially in cases of venous thrombosis. OBJECTIVES: Fibrinogen is known to have multiple functions, which are not evaluated by simple coagulation testing. We have used gel electrophoresis to search for new mutations. PATIENTS AND METHODS: Specimens of purified fibrinogen from 217 consecutive patients with familial or recurrent or early thrombosis and from 490 control subjects were evaluated by electrophoresis. Plasma fibrinogen levels and coagulation-dependent tests (electromechanical and optical coagulometric determinations, immunological measurement, thrombin and Reptilase(R) times) were normal. RESULTS: Two novel familial variants were detected. For a 42-year-old patient, an in-frame 117 base pair insertion in the Aalpha-chain gene caused a 5-kDa mobility shift of the Aalpha chain. This corresponds to a 39 amino acid duplication in the connector domain (fibrinogen Champagne au Mont d'Or). This pattern was also found in the patient's mother and child. A second 31-year-old patient presented an extra band under non-reducing conditions, 30 kDa larger than HMW fibrinogen and reacting with antifibrinogen antibodies (fibrinogen Lozanne). A heterozygous 5909A-->G mutation was found on the Bbeta-chain gene leading to heterozygous Bbeta Tyr236--> stop codon. The predicted truncated Bbeta chain could participate in chain assembly. Two family members were also affected, one of whom had suffered early venous thrombosis. CONCLUSIONS: Electrophoretic testing of apparently normal fibrinogens can reveal new variants which may be clinically relevant.

A database for human fibrinogen variants.

Identifying and studying abnormal human fibrinogens is a source of much information, and helps in taking care of the affected patients. To permit exhaustive numbering and easy updates, an extensive register has been compiled and made available on the internet. Known molecular abnormalities are mentioned with the essential clinical features.