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

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

International audienceSlash-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 imple- menting 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 cultiva- tion 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 vege- tation 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

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

a b s t r a c t 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

Regional forcing explains local species diversity and turnover on tropical islands

Aim: To determine the role of regional forcing on plot-level species diversity and composition, and to quantify the relative importance of biogeographical and climatic factors in explaining woody plant diversity and composition at the local-, island- and archipelago-scale. Location: Forty-one tropical islands of the Indo-Pacific region from Madagascar to Hawai'i Island. Methods: We analysed the diversity and composition of tropical woody plant communities located across 113 plots, 41 islands and 19 archipelagos. We used generalized linear mixed-effects models and generalized dissimilarity models to determine the role of regional forcing at the island and archipelago scale and to assess the relative importance of biogeographical (area and isolation of islands or archipelagos, geographical distance between plots) and climatic factors in explaining differences in local diversity and composition (species turnover). Analyses were conducted at different geographical scales (local, island and archipelago) and taxonomic levels (species, genus and family). Results: Variation in local (plot-level) diversity (as species density, the number of species per 100 woody plants) was primarily explained by island and archipelago identity. Maximum species density was positively correlated with the area of an island (or archipelago) and negatively correlated with the isolation of an archipelago. Local climatic variability was also a significant predictor of species density, but less important than regional forcing. Climate variables explained < 20% of the variation in species turnover across all plots. The importance of geographical distance between plots relative to climate in driving species turnover decreased from the species to family level, and from the regional to island level. Main conclusions: Regional forcing was the key driver of local diversity and composition on islands. Island area and archipelago isolation are likely driving local diversity through their effects on the pool of island species. Geographical distance between plots is the main factor explaining species turnover, while at higher taxonomic levels, climatic factors and niche conservatism are the main drivers