Codiversification of gut microbiota with humans.

The gut microbiomes of human populations worldwide have many core microbial species in common. However, within a species, some strains can show remarkable population specificity. The question is whether such specificity arises from a shared evolutionary history (codiversification) between humans and their microbes. To test for codiversification of host and microbiota, we analyzed paired gut metagenomes and human genomes for 1225 individuals in Europe, Asia, and Africa, including mothers and their children. Between and within countries, a parallel evolutionary history was evident for humans and their gut microbes. Moreover, species displaying the strongest codiversification independently evolved traits characteristic of host dependency, including reduced genomes and oxygen and temperature sensitivity. These findings all point to the importance of understanding the potential role of population-specific microbial strains in microbiome-mediated disease phenotypes.

Ivermectin for causal malaria prophylaxis: a randomised controlled human infection trial.

OBJECTIVE: Ivermectin is safe and widely used for treating helminth infections. It also kills arthropods feeding on treated subjects, including malaria vectors. Thus, ivermectin mass drug administration as an additional tool for malaria control is being evaluated by WHO. As in vitro data, animal experiments and epidemiological observations suggest that ivermectin has a direct effect on the liver stages of the malaria parasite, this study was designed to assess the prophylactic effect of ivermectin on Plasmodium falciparum controlled human malaria infection. METHODS: A total of 4 volunteers were randomised to placebo, and 8 volunteers were randomised to receive ivermectin 0.4 mg/kg, orally, once 2 h before being experimentally infected intravenously with 3200 P. falciparum sporozoites. The primary endpoint was time to parasitaemia detected by positive thick blood smear; RT-qPCR was performed in parallel. RESULTS: All but one volunteer became thick blood smear positive between day 11 and day 12 after infection, and there was no significant effect of ivermectin on parasitaemia. CONCLUSION: Ivermectin - at the dose used - has no clinically relevant activity against the pre-erythrocytic stages of P. falciparum.

OBJECTIF: L'ivermectine est sûr et largement utilisé pour traiter les helminthiases. Il tue également les arthropodes se nourrissant sur les sujets traités, y compris les vecteurs du paludisme. Ainsi, l'administration en masse d'ivermectine en tant qu'outil supplémentaire de lutte contre le paludisme est actuellement évaluée par l'OMS. Comme les données in vitro, les expériences sur animaux et les observations épidémiologiques suggèrent que l'ivermectine a un effet direct sur les stades hépatiques du parasite du paludisme, cette étude a été conçue pour évaluer l'effet prophylactique de l'ivermectine sur l'infection paludéenne humaine par Plasmodium falciparum contrôlée. MÉTHODES: Quatre volontaires ont été randomisés pour un placebo et 8 volontaires ont été randomisés pour recevoir de l'ivermectine à 0,4 mg/kg en une fois par voie orale, 2 heures avant d'être expérimentalement infectés par voie intraveineuse avec 3.200 sporozoïtes de P. falciparum. Le critère d'évaluation principal était le temps à la parasitémie détectée par un frottis sanguin épais positif. Une RT-qPCR a été réalisée en parallèle. RÉSULTATS: Tous les volontaires sauf un sont devenus positifs pour les frottis sanguins épais entre le jour 11 et le jour 12 après l'infection et il n'y avait aucun effet significatif de l'ivermectine sur la parasitémie. CONCLUSION: L'ivermectine - à la dose utilisée - n'a aucune activité cliniquement pertinente contre les stades pré-érythrocytaires de P. falciparum.

Non-contiguous finished genome sequence and description of Clostridium ihumii sp. nov.

Clostridium ihumii strain AP5(T) sp. nov. is a new species within the genus Clostridium. This strain, whose genome is described here, was isolated from the stool sample of a 21-year-old French Caucasian female with anorexia nervosa. C. ihumii is a Gram-positive, anaerobic bacillus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 4,433,668 bp long genome contains 4,076 protein-coding and 85 RNA genes, including 9 rRNA genes.

Genome sequence and description of Bacteroides timonensis sp. nov.

Bacteroides timonensis strain AP1(T) (= CSUR P194 = DSM 26083) is the type strain of B. timonensis sp. nov. This strain, whose genome is described here, was isolated from the fecal flora of a 21-year-old French Caucasoid female who suffered from severe anorexia nervosa. Bacteroides timonensis is a Gram-negative, obligate anaerobic bacillus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 7,130,768 bp long genome (1 chromosome, no plasmid) exhibits a G+C content of 43.3% and contains 5,786 protein-coding and 59 RNA genes, including 2 rRNA genes.

Non-contiguous finished genome sequence and description of Alistipes ihumii sp. nov.

Alistipes ihumii strain AP11(T) sp. nov. is the type strain of A. ihumii sp. nov., a new species within the genus Alistipes. This strain, whose genome is described here, was isolated from the fecal flora of a 21-year-old French Caucasian female, suffering from a severe restrictive form of anorexia nervosa since the age of 12 years. A. ihumii is a Gram-negative anaerobic bacillus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 2,753,264 bp long genome (one chromosome but no plasmid) contains 2,254 protein-coding and 47 RNA genes, including 3 rRNA genes.

Culturomics and pyrosequencing evidence of the reduction in gut microbiota diversity in patients with broad-spectrum antibiotics.

The human gut flora is currently widely characterised using molecular techniques. Microbial culturomics (large-scale culture conditions with identification of colonies using MALDI-TOF or 16S rRNA) is part of the rebirth of bacterial culture that was initiated by environmental microbiologists for the design of axenic culture for intracellular bacteria in clinical microbiology. Culturomics was performed on four stool samples from patients treated with large-scale antibiotics to assess the diversity of their gut flora in comparison with other culture-dependent studies. Pyrosequencing of the V6 region was also performed and was compared with a control group. Gut richness was also estimated by bacterial counting after microscopic observation. In total, 77 culture conditions were tested and 32,000 different colonies were generated; 190 bacterial species were identified, with 9 species that had not been isolated from the human gut before this study, 7 newly described in humans and 8 completely new species. A dramatic reduction in diversity was observed for two of the four stool samples for which antibiotic treatment was prolonged and uninterrupted. The total number of bacteria was generally preserved, suggesting that the original population was replaced but was sustained in size. Discordances between culture and pyrosequencing biodiversity biomarkers highlight the depth of bias of molecular studies. Stool samples studied showed a dramatic reduction in bacterial diversity. Considering the variable antibiotic concentration in the gut, this reduction in the number of species is possibly linked to the production of bacteriocin in the upper digestive tract by specific bacteria, such as Lactobacillus spp.

Non-contiguous finished genome sequence and description of Bacillus massilioanorexius sp. nov.

Bacillus massilioanorexius strain AP8(T) sp. nov. is the type strain of B. massilioanorexius sp. nov., a new species within the genus Bacillus. This strain, whose genome is described here, was isolated from the fecal flora of a 21-year-old Caucasian French female suffering from a severe form of anorexia nervosa since the age of 12 years. B. massilioanorexius is a Gram-positive aerobic bacillus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 4,616,135 bp long genome (one chromosome but no plasmid) contains 4,432 protein-coding and 87 RNA genes, including 8 rRNA genes.

Non-contiguous finished genome sequence and description of Holdemania massiliensis sp. nov.

Holdemania massiliensis strain AP2(T) sp. nov. is the type strain of H. massiliensis sp. nov., a new species within the genus Holdemania. This strain, whose genome is described here, was isolated from the fecal flora of a 21-year-old French Caucasian female suffering from severe restrictive anorexia nervosa. H. massiliensis is a Gram-positive, anaerobic bacillus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 3,795,625 bp-long genome (one chromosome but no plasmid) contains 3,461 protein-coding and 49 RNA genes, including 3 rRNA genes.