Caractéristiques bactériologiques des infections de liquide de dialyse péritonéale

La péritonite infectieuse (PI) est la principale complication de la dialyse péritonéale (DP). L'objectif de notre travail était de déterminer l'écologie bactérienne des PI et d'adapter l'antibiothérapie selon les germes isolés et les résistances observées. Étude rétrospective effectuée chez tous les enfants traités par DP et ayant présenté une PI dans le service de pédiatrie de l'hôpital Charles Nicolle de Tunis  (2004-2013). Au total, 61 ont développé 97 PI. L'incidence des PI était de 0,75 épisode/patient-année. La culture du LDP était négative dans 40 cas. Les Gram Positif ont été notés dans 56% des cas avec prédominance du Staphylococcus aureus. Les Gram négatif étaient retrouvés en seconde position (40%) représentés principalement par le Klebsiella  pneumoniae et le Pseudomonas aeruginosa. Des souches de Staphylocoque méticilline résistant étaient isolées dans 21,4%. Les bactéries à Gram positif étaient résistantes aux céphalosporines de première génération dans 25% des cas et aucune résistance à la vancomycine n'avait été décelée. Les bactéries à Gram négatif avaient une résistance globale de 38% avec des souches C-lactamase à spectre élargi (BLSE). L'antibiothérapie empirique devra couvrir les germes à Gram positif par la vancomycine et les germes à Gram négatif par la ceftazidime.Key words: Péritonite, antibiotiques, dialyse péritonéale, bactéries, enfan

Follow-up of fluorine pollution effect on grapevine

Effects of atmospheric pollution on three local grapevines, Asli, Jerbi and Tounsi, growing in the vicinity of a phosphate fertiliser factory, consist of an exhibition of characteristic necrosis on leaves and fruits. Analysis of necrotic leaf areas allowed us to distribute local vines into sensitivity classes. The follow-up, in function of time and space, of stomatal conductance and leaf fluoride content during the different seasons allowed us to reveal some offensive strategies allowing these vines to escape from pollutants toxicity and maintaining its vitality. Therefore, giving that fluorine is strange to its metabolism, grapevine tends to accumulate it, thanks to an external concentration mechanism, in the tips and leaf margins. Necrotic areas are delimited by a narrow brown border line. Thus, allowing the plant not only to avoid F- toxicity, but also to keep a big assimilation surface. In addition, possibilities as F- excluding, F- vacuol partitioning, temporary closing of stoma, F- trapping as CaF2, SiF4 are also to be considered. By another way, our results seem to show that full mature grapevine leaves may constitute an efficient tool to assess fluorine pollution impact. Berries contamination seems to be affected directly by the factory smoke, there is no endogenous supply. Likewise, by its characteristic necrosis in the leaf boundaries, grapevine may be considered as a bioindicator variety of fluorine pollution which can be used in mapping polluted areas

Nutritional Composition and Phytochemical, Antioxidative, and Antifungal Activities of Pergularia tomentosa L.

Crude extracts from a medicinal Tunisian plant, Pergularia tomentosa L., were the investigated natural material. Butanolic extract of roots analyzed with IR spectra revealed the presence of hydroxyl, alcoholic, and carboxylic groups and sugars units. Analysis of some secondary metabolites, total phenolic, flavonoids, flavonols, and procyanidins, was performed using different solvents following the increased gradient of polarity. Fruits and leaves contained the highest amounts of all these compounds. Antioxidant properties were evaluated by the determination of free radical scavenging activity and the reducing power of methanolic extracts. Fruits and leaf extracts were the most powerful antioxidants for the two-assay in vitro system. Stems and fruits extracts exhibit an antifungal activity against Fusarium oxysporum f. sp. lycopersici which could become an alternative to synthetic fungicide to control Solanum species fungal diseases

Biochemical characterization of Tunisian grapevine varieties

61 tunisian autochton grapevine varieties have been collected for biochemical identification. Isozymes analysis with starch gel electrophoresis technique was used to confirn or to cancel random denominations awarded to the majority of these local varieties. In our conditions, concentrated plant extracts were obtained from vigorous donnant canes newly cut off from selected mother plants during automn. These allowed us to dispose of rigorously interpretable isozyme banding patterns of GPI and PGM systems and to overcome difficulties often related to the use of PGM system. The study of GPII and PGM enzyme systems allowed us to classify the autochton accessions into 16 different groups from which 5 groups containing only 2 or 3 varieties. On the other hand, the study of AAT and peroxydase enzyme systems has shown stable and legible isozyme banding patterns allowing to discriminate between equivalent accessions such as Sakasly and Kahli (two black local vines very similar), 3 varieties of Bidh Hamem (Bidh Hamem, Bidh Hamem Rafraf and Bidh Hamem Sfax), and 2 varieties of Bezzoul Kelba Bidha (Sfax and Gabes). In addition, certain varieties having for longtime the same denominations were characterized. A case of point the 4 varieties Khalt meaning mixture (Bouchemma, Abiedh, Mdaouer and Souche 1) and the 3 varieties of Arich (Ahmar, Dressée, and Jerba) were proved to be completely different from each other. In the same way, Bezzoul Khadem has been differed from Hemri variety. The complementary use of berry colour allowed to discriminate between Saouadi, Khdhiri and Jebbi varieties and to subdivise the remainig groups into sub-groups. The study of GPI, PGM, AAT and peroxydase isozyme banding patterns in combination with berry colour has led to establish a classification of the 61 autochton varieties into 37 groups including 26 varieties definitely differentiated through the results of this biochemical study

Exogenous proline enhances growth, mineral uptake, antioxidant defense, and reduces cadmium-induced oxidative damage in young date palm (Phoenix dactylifera L.)

International audienceThe aim of this study was to investigate the effects of cadmium stress on growth and physiological traits in young date palms and to evaluate the role of exogenous proline in cadmium stress alleviation. Two-year-old date palm plants were subjected for five months to different cadmium stress levels (10 and 30 mg CdCl2 kg−1 soil) supplied or not with exogenous proline (20 mM) through irrigation water. Cadmium stress caused a decline in growth, macronutrient contents (Ca2+, Mg2+, and K+), membrane stability index (MSI), starch content and guaiacol peroxidase (POD) activity. In contrast, an increase of H2O2, soluble sugar, ascorbate peroxidase (APX) activity as well as total polyphenols was observed. Interestingly, exogenous proline effectively mitigated the adverse effects of cadmium on young date palms. Indeed, Cd accumulation was decreased and antioxidant defense systems were significantly (p ≤ 0.05) activated in date palm leaves and roots. Consequently, growth and mineral nutrition were enhanced when proline was added to Cd stressed plant

Soil fluoride spiking effects on olive trees (Olea europaea L. cv. Chemlali)

International audienceA pot experiment under open air conditions was carried out to investigate the uptake, accumulation and toxicity effects of fluoride in olive trees (Olea europaea L.) grown in a soil spiked with inorganic sodium fluoride (NaF). Six different levels (0, 20, 40, 60, 80 and 100 mM NaF) of soil spiking were applied through NaF to irrigation water. At the end of the experiment, total fluoride content in soil was 20 and 1770 mg F kg−1 soil in control and 100 mM NaF treatments, respectively. The comparative distribution of fluoride partitioning among the different olive tree parts showed that the roots accumulated the most fluoride and olive fruits were minimally affected by soil NaF spiking as they had the lowest fluoride content. In fact, total fluoride concentration varied between 12 and 1070 µg F g−1 in roots, between 9 and 570 µg F g−1 in shoots, between 12 and 290 µg F g−1 in leaves, and between 10 and 29 µg F g−1 in fruits, respectively for control and 100 mM NaF treatments. Indeed, the fluoride accumulation pattern showed the following distribution: roots>shoots>leaves>fruits. On the other hand, fluoride toxicity symptoms such as leaf necrosis and leaf drop appeared only in highly spiked soils (60, 80 and 100 mM NaF)

Industrial fluoride pollution of Jerbi grape leaves and the distribution of F,Ca, Mg, and P in them

Fluoride damaged leaves of the Jerbi grape vine tree (Vitis vinifera L) growing in the vicinity of a phosphate fertilizer manufacturing plant near Sfax, Tunisia, were used to study the distribution of the chemical elements F, Ca, Mg, and P in the leaves and stalks. Photosynthesis and the chlorophyll content of healthy leaf parts were also investigated to determine tolerance mechanisms of this species to fluoride. The subdivision of the necrotic zone into concentric necrotic halos evidently reflects a series of plant reactions to preserve a large portion of the leaf assimilatory surface. Photosynthesis still occurred with 30 to 40% necrosis of the leaves. Preferential accumulation of F was found in the leaf margins along with a parallel accumulation of Ca. Necrosis becomes evident when a fall in Ca occurs with an excess of F. After this happens, the plant tends to maintain high Mg and P concentrations in its healthy leaf parts. At 60% leaf necrosis, F seems to be effective in reducing photosynthesis and chlorophyll content

Biochemical responses of Olea europaea L. cv. Chemlali exposed to air and soil pollution near the industrial complex in Sfax, Tunisia

International audienceThis study aims to evaluate the impact of complex air and soil pollutions on Olea europaea L. cv. chemlali, one of the most important commercially valuable crops in Tunisia. These field experiments were performed in the vicinity of the industrial complex in the South of Sfax, Tunisia for the polluted olive trees and in unpolluted areas for control ones. Several biomarkers were studied belonging mainly to the antioxidant system like enzymes or antioxidant compounds. Main results indicate that air and sol pollutions induced an oxidative stress as demonstrated by an increase in the rate of hydrogen-peroxide (H2O2) production, electrolyte leakage, and lipid peroxidation in all plant parts.This stress affects chlorophyll and carotenoid contents of leaves. Additionally, the activities of enzymes involved in reactive-oxygenspecies (ROS) detoxification were affected. Air and soil pollutions induce an increase in the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD) and catalase (CAT). Moreover, in polluted olive trees, the content of antioxidant molecules like polyphenols, flavonoids and anthocyanins increases strongly. This is consistent with the role of these potent antioxidants in scavenging ROS such as H2O2. This study evidences the deleterious effects of industrial activity on antioxidative defense system of Olea europaea L. cv. Chemlali