Phylogenetic position of parabasalid symbionts from the termite Calotermes flavicollis based on small subunit rRNA sequences

Small subunit rDNA genes were amplified by polymerase chain reaction using specific primers from mixed-population DNA obtained from the whole hindgut of the termite Calotermes flavicollis. Comparative sequence analysis of the clones revealed two kinds of sequences that were both from parabasalid symbionts. In a molecular tree inferred by distance, parsimony and likelihood methods, and including 27 parabasalid sequences retrieved from the data bases, the sequences of the group II (clones Cf5 and Cf6) were closely related to the Devescovinidae/Calonymphidae species and thus were assigned to the Devescovinidae Foaina. The sequence of the group I (clone Cf1) emerged within the Trichomonadinae and strongly clustered with Tetratrichomonas gallinarum. On the basis of morphological data, the Monocercomonadidae Hexamastix termitis might be the most likely origin of this sequence

Taxonomic and functional dynamics during chytrid epidemics in an aquatic ecosystem

International audienc

Phylogenetic analysis of Blastocystis isolates from different hosts based on the comparison of small-subunit rRNA gene sequences

In conclusion, the present study confirms that genetic diversity exists among Blastocystis organisms isolated from different hosts and suggests that more than one species of Blastocystis infect humans. The possibility of cross-contamination between animals and humans exists, and the data suggest a low host specificity of these microorganisms. Thus, if Blastocystis isolated from animals are capable of infecting humans, the number of animals found to be infected with Blastocystis could represent a large potential reservoir for infection of humans

Fiabilisation de l’analyse de

La quantification de Legionella pneumophila dans les échantillons d’eaux résiduaires selon les méthodes normalisées existantes (normes NF T90-431 et XP T90-471, respectivement basées sur la mise en culture et la PCR quantitative) sont rendues difficiles, du fait notamment de l’hétérogénéité et la richesse en inhibiteurs (microorganismes susceptibles de générer une flore interférente et composés organominéraux inhibant l’amplification PCR). Or, la recherche des sources de contamination lors d’épisodes épidémiques de légionellose nécessite de disposer de méthodes fiables pour l’analyse de ce type de matrices. Sur la base de la méthode normalisée NF T90-431 (2003), les temps de contact et l ’ intensité des paramètres physico - chimiques (température, pH acide) instaurant une pression sélective favorable à la croissance des légionelles sur milieu de culture ont été optimisés. De même, l’application de la PCR quantitative sur ces matrices a nécessité l’évaluation et la comparaison de différents procédés d’extraction - purification d’ADN. Applicable en amont de la PCR, la séparation immunomagnétique (IMS), basée sur la reconnaissance spécifique antigène-anticorps, offre une solution alternative pour la concentration de L. pneumophila en permettant l’élimination d’une grande partie de la matière organique en suspension potentiellement inhibitrice de la PCR. Les développements analytiques ainsi obtenus permettront d’accéder à des matrices naturelles dont la complexité limitait le nombre d’analyses réalisées et empêchait jusqu’à présent de disposer de résultats fiables

Molecular Identification of Tritrichomonas foetus-Like Organisms as Coinfecting Agents of Human Pneumocystis Pneumonia

Trichomonads closely related to the bovid parasite Tritrichomonas foetus were identified in the bronchoalveolar lavage sample from a patient with AIDS in association with Pneumocystis pneumonia. This human case of T. foetus-like infection emphasizes the zoonotic potential of trichomonads, although the existence of a human-host-adapted T. foetus strain cannot be excluded

Molecular Phylogenies of Blastocystis Isolates from Different Hosts: Implications for Genetic Diversity, Identification of Species, and Zoonosis

Small-subunit (SSU) rRNA gene sequences were obtained by PCR from 12 Blastocystis isolates from humans, rats, and reptiles for which elongation factor 1α (EF-1α) gene sequences are already available. These new sequences were analyzed by the Bayesian method in a broad phylogeny including, for the first time, all Blastocystis sequences available in the databases. Phylogenetic trees identified seven well-resolved groups plus several discrete lineages that could represent newly defined clades. Comparative analysis of SSU rRNA- and EF-1α-based trees obtained by maximum-likelihood methods from a restricted sampling (13 isolates) revealed overall agreement between the two phylogenies. In spite of their morphological similarity, sequence divergence among Blastocystis isolates reflected considerable genetic diversity that could be correlated with the existence of potentially ≥12 different species within the genus. Based on this analysis and previous PCR-based genotype classification data, six of these major groups might consist of Blastocystis isolates from both humans and other animal hosts, confirming the low host specificity of Blastocystis. Our results also strongly suggest the existence of numerous zoonotic isolates with frequent animal-to-human and human-to-animal transmissions and of a large potential reservoir in animals for infections in humans

Rapid Method for Enumeration of Viable Legionella pneumophila and Other Legionella spp. in Water

A sensitive and specific method has been developed to enumerate viable L. pneumophila and other Legionella spp. in water by epifluorescence microscopy in a short period of time (a few hours). This method allows the quantification of L. pneumophila or other Legionella spp. as well as the discrimination between viable and nonviable Legionella. It simultaneously combines the specific detection of Legionella cells using antibodies and a bacterial viability marker (ChemChrome V6), the enumeration being achieved by epifluorescence microscopy. The performance of this immunological double-staining (IDS) method was investigated in 38 natural filterable water samples from different aquatic sources, and the viable Legionella counts were compared with those obtained by the standard culture method. The recovery rate of the IDS method is similar to, or higher than, that of the conventional culture method. Under our experimental conditions, the limit of detection of the IDS method was <176 Legionella cells per liter. The examination of several samples in duplicates for the presence of L. pneumophila and other Legionella spp. indicated that the IDS method exhibits an excellent intralaboratory reproducibility, better than that of the standard culture method. This immunological approach allows rapid measurements in emergency situations, such as monitoring the efficacy of disinfection shock treatments. Although its field of application is as yet limited to filterable waters, the double-staining method may be an interesting alternative (not equivalent) to the conventional standard culture methods for enumerating viable Legionella when rapid detection is required