Biochemical characterization of a novel extended-spectrum beta-lactamase from Pseudomonas aeruginosa 802

Pseudomonas aeruginosa 802 was isolated at Rabta hospital in Tunis and was resistant to extended-spectrum cephalosporins and aztreonam. It produced a pI 7.6 extended-spectrum beta-lactamase (ESBL). The ESBL, named LBT 802, was purified to homogeneity by filtration on Sephadex G-75 followed by CM-Sepharose chromatography and high-performance liquid chromatography (HPLC) on a TSK-gel SP-5PW column. The LBT 802 enzyme had a molecular mass of 30 kDa. It showed a broad-substrate profile by hydrolyzing benzylpenicillin, ampicillin, cephalothin, cephaloridine, cefotaxime, ceftriaxone, and cefpirome but not ceftazidime, cefoxitin, imipenem, or aztreonam. The highest hydrolytic efficiency (Vmax/Km) was obtained for ampicillin, cephalothin, cephaloridine, and benzylpenicillin. Among extended-spectrum cephalosporins the best substrate was ceftriaxone followed by cefotaxime and cefpirome. LBT 802 activity was inhibited by clavulanic acid, sulbactam, imipenem, cefoxitin, and aztreonam. It showed its lowest Ki values for clavulanic acid, imipenem and sulbactam.     

Endothelial-like nitric oxide synthase immunolocalization by using gold nanoparticles and dyes

Immunofluorescence is a biological technique that allows displaying the localization of the target molecule through a fluorescent microscope. We used a combination of gold nanoparticles and the fluorescein isothiocianate, FITC, as optical contrast agents for laser scanning confocal microscopy imaging to localize the endothelial-like nitric oxide synthase in skeletal muscle cells in a three-dimensional tissue phantom at the depth of 4µm. The FITC detected fluorescence intensity from gold-nanoparticles-labelled cells was brighter than the emission intensity from unlabelled cells.OCIS codes: (170.1790) Confocal microscopy, (280.1415) Biological sensing and sensors     

Demographic, clinical and therapeutic features of adult visceral leishmaniasis at the Rabta hospital in Tunis (tunisia) from 1983 to 2002

The purpose of this study was to evaluate in a retrospective analysis, cases of Mediterranean visceral leishmaniasis (VL) diagnosed in adults during a 20-year period in a department of infectious diseases. Demographic data, clinical and laboratory features and therapeutic findings were considered. During the study period, 22 cases of VL were diagnosed, and 6 (27%) were associated with HIV infection. Fever and splenomegaly were observed in all cases. Anaemia was constant. The anti-leishmanial IF titer was positive among 21 patients (95%). Smears from bone marrow aspiration were positive at microscopy in 95% of cases. Zymodeme analysis was carried out in nine isolates. L. infantum zymodeme MON-1 was characterized in all cases. Seventeen patients (77%) received meglumine antimoniate (MA) (20 mg SbV/kg per day) and 5 (23%) patients amphotericin B (AB) (0.5-1 mg/kg per day) for an average period of 25 days (10-49 days). Adverse events occurred in 7 patients (32%), among them 4 received AB. Clinical cure was achieved with success in 21 patients (95%). After a successful MA treatment of the initial episode, VL relapse was observed in one HIV-positive patient. Only one HIV-positive patient died from neurological disorders. VL is rare in adults. However, its incidence is increasing everywhere in the world, because of HIV-related cases. Its prognosis depends on the precocity of diagnosis and treatment.     

Plasmodium falciparum causing hemophagocytic syndrome after allogeneic blood stem cell transplantation

We describe a case of Plasmodium falciparum infection in a 25-year-old male patient with a myelodysplastic syndrome, who underwent allogeneic peripheral blood stem cell transplantation (PBSCT) in September 2003. Conditioning regimen consisted of total body irradiation (10 Gy) and cyclophosphamide 60 mg/kg for 2 days. A dose of 4 x 10(6) CD34+ cells/kg was transfused. Engraftment was well documented on day 17 post-transplantation. Spiking fevers occurred on days 19 and 21, associated with a pancytopenia, hepatosplenomegaly and neurological signs. P. falciparum parasites were found on the peripheral blood smear (parasitemia = 23%). Marrow aspiration showed P. falciparum parasites and proliferation of mature histiocytes with hemophagocytosis. Quinine 10 mg/kg i.v. three times a day for 10 consecutive days was given. The fever subsided within 3 days, and pancytopenia vanished in 14 days. Parasitemia cleared in 6 days. The patient left the unit on day 46 with no further complications. The screening of donors showed that infection was acquired from two blood units (from a single donor) given 5 days before transplantation. We report the first case of profound hemophagocytosis in immunosuppressed patient with malaria of high parasitemia after a bone marrow transplant.     

Tricuspid endocarditis with right-left shunt in the atrium

A case of tricuspid regurgitation due to endocarditis causing a right-to-left shunt through a patent foramen ovale is reported. Tricuspid valve endocarditis occurred after septic abortion and caused valvular regurgitation with dyspnea and cyanosis. The diagnosis was made by echocardiography and the finding of peripheral arterial desaturation, and it was confirmed at surgery. The physiopathology of these right-to-left shunts is the same as that already described during traumatic tricuspid regurgitation: reopening of the foramen ovale by the right atrial dilatation and ventricularisation of right atrial pressures. The presence of a shunt is an indication for surgery.     

Asthme du petit enfant : facteurs prédictifs de sévérité et de persistance Analyse de 180 observations

Background : Asthma is the most common chronic disease in infants. In young children, asthma still raises many questions and many points are still being debated. Aim : The aim of this study is to identifies, in asthmatic children, factors predictors of severity and persistence of symptoms. Methods: A retrospective study of asthmatic infants<3 years enrolled in the pediatric department of Sfax over a period of 5 years (2007-2011). We were interested to social and environmental factors, the allergic background, clinical severity of the disease, results of allergic skin tests, treatment and respiratory outcome.Results: We collected 180 children with a sex ratio of 2.2. Family history of atopy and exposition to passive tobacco were noted in 45 % and 52% of cases respectively. The mean age of onset of wheezing was 6.6 months. Skin tests were positives in 32% of cases. At the time of diagnosis, asthma was classified intermittent (21%), mild to moderate (55.6%) and severe (22.2%). Inhaled corticosteroids was initiated in 142 infants (78.8%). Skin tests performed in 84 patients, were positive in 32%. Factors associated with severe asthma were passive smoking, early age of onset, number of hospitalizations for exacerbation and existence of an aggravating factor.Factors predictors of persistence were an early age of onset, caesarean delivery, passive smoking and positive skin tests. Conclusion : Factors associated with persistence of asthma at the individual level remains uncertain. However, atopy and passive smoking are major indicators.