RESUMO
Extending the network of strict forest reserves is one of the conservation measures promoted by the French National Strategy for Biodiversity. However, there is a lack of evidence concerning the efficiency of setting aside strict forest reserves to preserve biodiversity in the case of temperate forests. Moreover, there are potentially unexplored underlying ecological mechanisms that forest management could usefully mimic. In order to disentangle the respective roles of management abandonment, stand structural attributes and climatic and topographic variables in determining forest biodiversity, we conducted the first national-scale study in France comparing biodiversity in managed and in unmanaged forests. Here we focus on bryophytes (all species combined and forest specialists separately). We analyzed data from 127 plots in ten lowland forests in France. Our aim was to disentangle the relationships between bryophyte richness and (i) management abandonment per se, (ii) associated forest-structure variables like deadwood volume, and (iii) macroclimatic variables important for bryophytes (temperature, precipitation, relative humidity, solar radiation and vapor pressure deficit). For each studied combination of variables (univariate, additive or interactive models), we compared hierarchical models of several types: linear with a fixed slope, linear with a random slope, quadratic, sigmoid or threshold models. We found that deadwood variables were the main drivers of bryophyte richness in managed as well as in unmanaged stands. We observed a sigmoid relationship of total deadwood volume to overall richness, and a threshold effect of large and very large deadwood volume on forest specialist richness. The effect of management abandonment was globally non-significant, though impact varied strongly among the different forest sites. A combination of deadwood and macroclimatic variables best predicted bryophyte richness, through non-linear relationships: 1) higher solar radiation reinforced the positive effects of large deadwood on forest-specialist bryophyte richness; and 2) higher mean annual temperatures counteracted the positive effects of total deadwood amount on total bryophyte species richness. Maintaining high amounts of deadwood in both managed and unmanaged forests is likely to improve bryophyte richness and will be particularly important under ongoing climate change.
Assuntos
Biodiversidade , Briófitas , Florestas , Conservação dos Recursos Naturais , FrançaRESUMO
INTRODUCTION: In health care, measures against cross-transmission of microorganisms are codified by standard precautions, and if necessary, they are supplemented by additional precautions. STATE OF THE ART: Several factors impact transmission of microorganisms via the respiratory route: size and quantity of the emitted particles, environmental conditions, nature and pathogenicity of the microorganisms, and degree of host receptivity. While some microorganisms necessitate additional airborne or droplet precautions, others do not. PROSPECTS: For most microorganisms, transmission patterns are well-understood and transmission-based precautions are well-established. For others, measures to prevent cross-transmission in healthcare facilities remain under discussion. CONCLUSIONS: Standard precautions are essential to the prevention of microorganism transmission. Understanding of the modalities of microorganism transmission is essential to implementation of additional transmission-based precautions, particularly in view of opting for appropriate respiratory protection.
Assuntos
Infecção Hospitalar , Infecções Respiratórias , Humanos , Infecção Hospitalar/prevenção & controle , Controle de Infecções , Infecções Respiratórias/epidemiologia , Infecções Respiratórias/prevenção & controle , Atenção à SaúdeRESUMO
Candida auris is an emerging species responsible for life-threatening infections. Its ability to be resistant to most systemic antifungal classes and its capacity to persist in a hospital environment have led to health concerns. Currently, data about environmental reservoirs are limited but remain essential in control of C. auris spread. The aim of our study was to explore the interactions between C. auris and two free-living amoeba (FLA) species, Vermamoeba vermiformis and Acanthamoeba castellanii, potentially found in the same water environment. Candida auris was incubated with FLA trophozoites or their culture supernatants. The number of FLA and yeasts was determined at different times and transmission electron microscopy (TEM) was performed. Supernatants of FLAs promoted yeast survival and proliferation. Internalization of viable C. auris within both FLA species was also evidenced by TEM. A water environmental reservoir of C. auris can therefore be considered through FLAs and contamination of the hospital water networks would consequently be possible.
Assuntos
Amoeba/fisiologia , Candida/fisiologia , Microbiologia da Água , Candida/crescimento & desenvolvimento , Candida albicans/fisiologia , Proliferação de CélulasRESUMO
Acanthamoeba keratitis due to a genus of free-living amoebae is a severe corneal infection. Treatment of this disease is based on the combined use of antiseptics and other drugs, including azoles. We tested isavuconazole, the latest marketed azole, in vitro, against A. castellanii, A. lenticulata and A. hatchetti. Our results show that isavuconazole presents slight amoebistatic activity against A. castellanii trophozoites but no cysticidal activity. Isavuconazole could be used only in association for management of AK due to A. castellanii.
Assuntos
Ceratite por Acanthamoeba/parasitologia , Acanthamoeba/efeitos dos fármacos , Nitrilas/farmacologia , Piridinas/farmacologia , Triazóis/farmacologia , Acanthamoeba/classificação , Acanthamoeba/crescimento & desenvolvimento , Acanthamoeba/fisiologia , Ceratite por Acanthamoeba/tratamento farmacológico , Acanthamoeba castellanii/efeitos dos fármacos , Acanthamoeba castellanii/crescimento & desenvolvimento , Acanthamoeba castellanii/fisiologia , Animais , Relação Dose-Resposta a Droga , Humanos , Nitrilas/uso terapêutico , Encistamento de Parasitas/efeitos dos fármacos , Testes de Sensibilidade Parasitária , Piridinas/uso terapêutico , Triazóis/uso terapêutico , Trofozoítos/efeitos dos fármacosRESUMO
OBJECTIVES: Besides the potential to identify a wide variety of gastrointestinal parasites, microscopy remains the reference standard in clinical microbiology for amoeba species identification and, especially when coupled with adhesin detection, to discriminate the pathogenic Entamoeba histolytica from its sister but non-pathogenic species Entamoeba dispar/Entamoeba moshkovskii. However, this approach is time-consuming, requires a high-level of expertise that can be jeopardized considering the low prevalence of gastrointestinal parasites in non-endemic countries. Here, we evaluated the CE-IVD-marked multiplex PCR (ParaGENIE G-Amoeba, Ademtech) targeting E. histolytica and E. dispar/E. moshkovskii and Giardia intestinalis. METHODS: This evaluation was performed blindly on a reference panel of 172 clinical stool samples collected prospectively from 12 laboratories and analysed using a standardized protocol relying on microscopy (and adhesin detection by ELISA for the detection of E. histolytica) including G. intestinalis (n = 37), various amoeba species (n = 55) including E. dispar (n = 15), E. histolytica (n = 5), as well as 17 other gastrointestinal parasites (n = 80), and negative samples (n = 37). RESULTS: This new multiplex PCR assay offers fast and reliable results with appropriate sensitivity and specificity for the detection of G. intestinalis and E. dispar/E. moshkovskii from stools (89.7%/96.9% and 95%/100%, respectively). Detection rate and specificity were greatly improved by the PCR assay, highlighting several samples misidentified by microscopy, including false-negative and false-positive results for both E. dispar/E. moshkovskii and E. histolytica. CONCLUSION: Given the clinical relevance of amoeba species identification, microbiologists should be aware of the limitations of using an algorithm relying on microscopy coupled with adhesin detection by ELISA.
Assuntos
Entamoeba/isolamento & purificação , Entamebíase/diagnóstico , Fezes/parasitologia , Giardia lamblia/isolamento & purificação , Giardíase/diagnóstico , Reação em Cadeia da Polimerase Multiplex/métodos , Reação em Cadeia da Polimerase em Tempo Real/métodos , Entamebíase/parasitologia , Giardíase/parasitologia , Humanos , Microscopia , Especificidade da EspécieRESUMO
Microscopy is the reference standard for routine laboratory diagnosis in faecal parasitology but there is growing interest in alternative methods to overcome the limitations of microscopic examination, which is time-consuming and highly dependent on an operator's skills and expertise. Compared with microscopy, DNA detection by PCR is simple and can offer a better turnaround time. However, PCR performances remain difficult to assess as most studies have been conducted on a limited number of positive clinical samples and used in-house PCR methods. Our aim was to evaluate a new multiplex PCR assay (G-DiaParaTrio; Diagenode Diagnostics), targeting Giardia intestinalis, Cryptosporidium parvum/Cryptosporidium hominis and Entamoeba histolytica. To minimize the turnaround time, PCR was coupled with automated DNA extraction (QiaSymphony; Qiagen). The PCR assay was evaluated using a reference panel of 185 samples established by routine microscopic examination using a standardized protocol including Ziehl-Neelsen staining and adhesin detection by ELISA (E. histolytica II; TechLab). This panel, collected from 12 French parasitology laboratories, included 135 positive samples for G. intestinalis (n = 38), C. parvum/C. hominis (n = 26), E. histolytica (n = 5), 21 other gastrointestinal parasites, together with 50 negative samples. In all, the G-DiaParaTrio multiplex PCR assay identified 38 G. intestinalis, 25 C. parvum/C. hominis and five E. histolytica leading to sensitivity/specificity of 92%/100%, 96%/100% and 100%/100% for G. intestinalis, C. parvum/C. hominis and E. histolytica, respectively. This new multiplex PCR assay offers fast and reliable results, similar to microscopy-driven diagnosis for the detection of these gastrointestinal protozoa, allowing its implementation in routine clinical practice.
Assuntos
Cryptosporidium parvum/isolamento & purificação , Entamoeba histolytica/isolamento & purificação , Fezes/parasitologia , Giardia lamblia/isolamento & purificação , Reação em Cadeia da Polimerase Multiplex/métodos , Cryptosporidium parvum/genética , Entamoeba histolytica/genética , Giardia lamblia/genética , Humanos , Enteropatias Parasitárias/diagnóstico , Enteropatias Parasitárias/parasitologia , Técnicas de Diagnóstico Molecular , Sensibilidade e EspecificidadeRESUMO
Free-living amoebae (FLA) are ubiquitous protozoa that do not require a host organism for survival. They are found in natural environments such as water or soil, and man-made environments including tap water or swimming pools, where they may interact with other micro-organisms, including bacteria, fungi and viruses. FLA can harbour micro-organisms including those found in hospital water systems, offering them protection against hostile conditions, providing a vehicle of dissemination, and enabling them to prepare for subsequent survival in macrophages. The interaction between Legionella pneumophila and FLA has been studied extensively; subsequent investigations have shown that FLA may serve as a reservoir for other bacteria including mycobacteria, Pseudomonas aeruginosa, Acinetobacter baumannii, or even fungi and viruses. Amoebae found in hospital water systems can serve as a reservoir of potential pathogens and thus be indirectly related to healthcare-associated infections.
Assuntos
Amoeba/isolamento & purificação , Amoeba/microbiologia , Infecções Bacterianas/epidemiologia , Infecções Bacterianas/microbiologia , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Acinetobacter baumannii/isolamento & purificação , Humanos , Legionella pneumophila/isolamento & purificação , Mycobacterium/isolamento & purificação , Pseudomonas aeruginosa/isolamento & purificação , Microbiologia da ÁguaRESUMO
AIMS: The amoebae of the genus Hartmanella are frequently recovered from hospital water taps, whereas Pseudomonas aeruginosa is often implicated in nosocomial infections. Previous works suggested that free living amoebae can act as vehicles of bacterial transmission. The present work investigates the relationships between a strain of Hartmanella vermiformis and three strains of P. aeruginosa: a reference strain, a strain from a patient and an environmental strain. METHODS AND RESULTS: In a saline medium, H. vermiformis is not able to favour for the development of P. aeruginosa. In a rich co-cultivation medium, only the environmental strain has shown a growth. CONCLUSIONS: We showed that P. aeruginosa is not a good nutrient source for H. vermiformis. SIGNIFICANCE AND IMPACT OF THE STUDY: Nevertheless, in particular conditions and with particular strains, the presence of H. vermiformis could represent a possibility of growth for P. aeruginosa.
Assuntos
Hartmannella/microbiologia , Pseudomonas aeruginosa/crescimento & desenvolvimento , Animais , Microbiologia Ambiental , Humanos , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/isolamento & purificaçãoRESUMO
Aminocandin is a new representative of the echinocandins that could potentially affect the cellular morphology and metabolic status of Candida albicans cells within biofilms. This study investigated the influence of a sub-inhibitory concentration (MIC/2) of aminocandin on in-vitro growth of C. albicans and subsequent fungal adherence to plastic surfaces coated with fibronectin or extracellular matrix (ECM) proteins. Eleven strains of C. albicans were studied, of which six were susceptible and five were resistant to fluconazole. All 11 strains were susceptible to aminocandin in vitro, regardless of the culture medium used for the microdilution method. Aminocandin induced a significant (p <0.005) decrease in adherence when polystyrene was coated with ECM gel (ten strains) or fibronectin (seven strains). Growth in medium containing aminocandin (MIC/2) decreased the adherence of five (ECM gel) or three (fibronectin) of the six strains susceptible to fluconazole, and inhibition was observed for all five (ECM gel) or four (fibronectin) of the five fluconazole-resistant strains. Overall, the study demonstrated the anti-adherent properties of aminocandin with fluconazole-susceptible strains, and suggested that this activity was at least equivalent with fluconazole-resistant strains. Thus, the ability of aminocandin to inhibit the first step in the development of C. albicans biofilms appeared to be independent of the in-vitro resistance of C. albicans to fluconazole.