Mining Virulence Genes Using Metagenomics

When a bacterial genome is compared to the metagenome of an environment it inhabits, most genes recruit at high sequence identity. In free-living bacteria (for instance marine bacteria compared against the ocean metagenome) certain genomic regions are totally absent in recruitment plots, representing therefore genes unique to individual bacterial isolates. We show that these Metagenomic Islands (MIs) are also visible in bacteria living in human hosts when their genomes are compared to sequences from the human microbiome, despite the compartmentalized structure of human-related environments such as the gut. From an applied point of view, MIs of human pathogens (e.g. those identified in enterohaemorragic Escherichia coli against the gut metagenome or in pathogenic Neisseria meningitidis against the oral metagenome) include virulence genes that appear to be absent in related strains or species present in the microbiome of healthy individuals. We propose that this strategy (i.e. recruitment analysis of pathogenic bacteria against the metagenome of healthy subjects) can be used to detect pathogenicity regions in species where the genes involved in virulence are poorly characterized. Using this approach, we detect well-known pathogenicity islands and identify new potential virulence genes in several human pathogens

Pregnancy and Mental Health of Young Homeless Women

Pregnancy rates among women in the U.S. who are homeless are much higher than rates among women who are housed (Greene & Ringwalt, 1998). Yet little research has addressed mental health, risk and resilience among young mothers who are homeless. This study utilizes a sample of women from the Midwest Longitudinal Study of Homeless Adolescents (MLSHA) to investigate pregnancy and motherhood over three years among unaccompanied homeless young mothers. Our data are supplemented by in-depth interviews with a subset of these women. Results show that almost half of sexually active young women (n = 222, μ age = 17.2) had been pregnant at baseline (46.4%), and among the longitudinal subsample of 171 women (μ age = 17.2), almost 70.0% had been pregnant by the end of the study. Among young mothers who are homeless, only half reported that they helped to care for their children consistently over time, and one-fifth of the women reported never seeing their children. Of the young women with children in their care at the last interview of the study (Wave 13), almost one-third met criteria for lifetime major depressive episode (MDE), lifetime posttraumatic stress disorder (PTSD), and lifetime drug abuse, and onehalf met criteria for lifetime antisocial personality disorder (APD). Twelve-month diagnoses are also reported. The impacts of homelessness on maternal and child outcomes are discussed, including the implications for practice, policy, and research