Rectal Carriage of Extended-Spectrum Beta-Lactamase-Producing Gram-Negative Bacilli in Community Settings in Madagascar

BACKGROUND: Extended-spectrum ß-lactamase-producing Enterobacteria (ESBL-PE) emerged at the end of the 1980s, causing nosocomial outbreaks and/or hyperendemic situations in hospitals and long-term care facilities. In recent years, community-acquired infections due to ESBL-PE have spread worldwide, especially across developing countries including Madagascar. OBJECTIVES: This study aimed to determine the prevalence and risk factors of intestinal carriage of ESBL-PE in the community of Antananarivo. METHODS: Non-hospitalized patients were recruited in three health centers in different socio economic settings. Fresh stool collected were immediately plated on Drigalski agar containing 3 mg/liter of ceftriaxone. Gram-negative bacilli species were identified and ESBL production was tested by a double disk diffusion (cefotaxime and ceftazidime +/- clavulanate) assay. Characterization of ESBLs were perfomed by PCR and direct sequencing . Molecular epidemiology was analysed by Rep-PCR and ERIC-PCR. RESULTS: 484 patients were screened (sex ratio  = 1.03, median age 28 years). 53 ESBL-PE were isolated from 49 patients (carrier rate 10.1%). The isolates included Escherichia coli (31), Klebsiella pneumoniae (14), Enterobacter cloacae (3), Citrobacter freundii (3), Kluyvera spp. (1) and Pantoae sp.(1). In multivariate analysis, only the socioeconomic status of the head of household was independently associated with ESBL-PE carriage, poverty being the predominant risk factor. CONCLUSIONS: The prevalence of carriage of ESBL in the community of Antananarivo is one of the highest reported worldwide. This alarming spread of resistance genes should be stopped urgently by improving hygiene and streamlining the distribution and consumption of antibiotics

Résilience d’une forêt de transition, Madagascar : rôle des banques et pluies de graines

International audienceLe Parc National d’Andohahela, Madagascar est composé de 3 sites distincts. Entre ces sites, l’agriculture est pratiquée et la forêt exploitée et donc fragmentée. La zone de transition entre les 2 sites majeurs est située le long d’un gradient altitudinal et de précipitation entre une forêt tropicale humide en altitude et une forêt tropicale sèche en plaine. Cette zone est essentielle à la migration des espèces, particulièrement dans un contexte de changements climatiques. Cependant, la forêt de transition est fragmentée et la dynamique végétale au niveau des friches ne mène pas à une forêt secondaire mais à des fourrés épineux dominés par Mimosa delicatula, dense et inaccessible. Ce travail a consisté à identifier les raisons de cette faible résilience en étudiant la banque de graines et la pluie de graines. Celles-ci ont été récoltées en fin de saison sèche et de saison des pluies dans 3 forêts et friches adjacentes. La banque de graines des forêts contient peu de graines n’appartenant qu’à quelques espèces (Gyrocarpus americanus, Commiphora humbertii, et plusieurs Croton et Euphorbia sp.). Celle des friches contient plus de graines et est dominée par Achyrantes aspera and Heteropogon contortus qui ne sont pas des espèces forestières. La pluie de graines contient beaucoup plus de graines et est dominée par les Euphorbiaceae et Burseraceae. Ce travail teste ensuite différentes façons d’accélérer la résilience. Le sol et la pluie de graines ont été transférés selon plusieurs traitements. Aucun de ces transferts n’a bien fonctionné et les raisons de cet échec seront discutées

Secondary succession in a forest corridor between two protected areas in Southeastern Madagascar leads to thorny thickets.

International audienc

Vegetation dynamics in a corridor between protected areas after slash-and-burn cultivation in south-eastern Madagascar

Slash-and-burn cultivation is a major cause of deforestation in Madagascar, and abandonment leads to the secondary vegetation dynamics, i.e. colonization by herbaceous vegetation, shrubs and trees. The study was conducted in south-eastern Madagascar in a steep transition zone along an altitudinal and a sharp precipitation gradient between a high altitude rainforest and a lowland dry tropical forest. The restoration of gaps created by abandoned fields in this narrow, winding corridor could be essential to maintain connectivity between two areas (areas 1 and 2) of Andohahela National Park. Prior to implementing restoration, baseline ecological information is needed on the reference ecosystem and vegetation resilience must be studied to identify restoration needs. This study aims to (1) assess whether cultivation practices (irrigated rice vs. cassava, maize and sweet potato) influence vegetation dynamics after abandonment; (2) study vegetation dynamics and soils over time since abandonment, and (3) compare secondary forest vegetation and soils with those of mature forest patches. Surveys of vegetation and soil were conducted in 26 secondary forest patches abandoned from 3 to >25 years (synchronic approach) and in 19 adjacent mature forest patches (controls). No relationship between age of abandonment and vegetation species richness, composition or structure was found, but clear differences were detected between secondary and mature forest patches. Secondary forests are not colonized by species from mature forests, but instead their vegetation dynamics appear to lead to the establishment of thorny thickets dominated by Mimosa delicatula, which is absent from the mature forest

Antimalarial 5,6-Dihydro-α-pyrones from Cryptocarya rigidifolia: Related Bicyclic Tetrahydro-α-Pyrones Are Artifacts

Antimalarial bioassay-guided fractionation of an EtOH extract of the root wood of Cryptocarya rigidifolia (Lauraceae) led to the isolation of the five new 5,6-dihydro-α-pyrones cryptorigidifoliols A–E (<b>1</b>–<b>5</b>) and the six bicyclic tetrahydro-α-pyrone derivatives cryptorigidifoliols F–K (<b>6</b>–<b>11</b>). The structure elucidations of all compounds were made on the basis of the interpretation of spectroscopic data and chemical derivatization, and the relative and absolute configurations were determined by NOESY, electronic circular dichroism (ECD), and ¹H NMR analysis of α-methoxyphenylacetyl (MPA) derivatives. The bicyclic tetrahydro-α-pyrone derivatives were identified as products of acid-catalyzed intramolecular Michael addition of the 5,6-dihydro-α-pyrones in the presence of silica gel. A structure–activity relationship study suggested that the presence of an α,β-unsaturated carbonyl moiety is not essential for potent antimalarial activity