The influence of extrachromosomal elements in the anthrax "cross-over" strain Bacillus cereus G9241.

Bacillus cereus G9241 was isolated from a welder who survived a pulmonary anthrax-like disease. Strain G9241 carries two virulence plasmids, pBCX01 and pBC210, as well as an extrachromosomal prophage, pBFH_1. pBCX01 has 99.6% sequence identity to pXO1 carried by Bacillus anthracis and encodes the tripartite anthrax toxin genes and atxA, a mammalian virulence transcriptional regulator. This work looks at how the presence of pBCX01 and temperature may affect the lifestyle of B. cereus G9241 using a transcriptomic analysis and by studying spore formation, an important part of the B. anthracis lifecycle. Here we report that pBCX01 has a stronger effect on gene transcription at the mammalian infection relevant temperature of 37°C in comparison to 25°C. At 37°C, the presence of pBCX01 appears to have a negative effect on genes involved in cell metabolism, including biosynthesis of amino acids, whilst positively affecting the transcription of many transmembrane proteins. The study of spore formation showed B. cereus G9241 sporulated rapidly in comparison to the B. cereus sensu stricto type strain ATCC 14579, particularly at 37°C. The carriage of pBCX01 did not affect this phenotype suggesting that other genetic elements were driving rapid sporulation. An unexpected finding of this study was that pBFH_1 is highly expressed at 37°C in comparison to 25°C and pBFH_1 expression leads to the production of Siphoviridae-like phage particles in the supernatant of B. cereus G9241. This study provides an insight on how the extrachromosomal genetic elements in B. cereus G9241 has an influence in bacterial phenotypes.

From cereus to anthrax and back again: Assessment of the temperature-dependent phenotypic switching in the "cross-over" strain Bacillus cereus G9241.

Bacillus cereus G9241 was isolated from a Louisiana welder suffering from an anthrax-like infection. The organism carries two transcriptional regulators that have previously been proposed to be incompatible with each other in Bacillus anthracis: the pleiotropic transcriptional regulator PlcR found in most members of the Bacillus cereus group but truncated in all B. anthracis isolates, and the anthrax toxin regulator AtxA found in all B. anthracis strains and a few B. cereus sensu stricto strains. Here we report cytotoxic and hemolytic activity of cell free B. cereus G9241 culture supernatants cultured at 25°C to various eukaryotic cells. However, this is not observed at the mammalian infection relevant temperature 37°C, behaving much like the supernatants generated by B. anthracis. Using a combination of genetic and proteomic approaches to understand this unique phenotype, we identified several PlcR-regulated toxins to be secreted highly at 25°C compared to 37°C. Furthermore, results suggest that differential expression of the protease involved in processing the PlcR quorum sensing activator molecule PapR appears to be the limiting step for the production of PlcR-regulated toxins at 37°C, giving rise to the temperature-dependent hemolytic and cytotoxic activity of the culture supernatants. This study provides an insight on how B. cereus G9241 is able to "switch" between B. cereus and B. anthracis-like phenotypes in a temperature-dependent manner, potentially accommodating the activities of both PlcR and AtxA.

African American perspectives on racial disparities in child removals.

BACKGROUND: African American children are overrepresented in foster care at twice to three times the rate of white children. Scholars argue that racism and oppression underlie disproportionality (Kriz & Skivenes, 2011). OBJECTIVE: This study explored disproportionality as seen through the eyes of African American parents in the child welfare system. The aim was to understand why African American families are over-represented in child custody statistics and to improve family and parenting support for African American communities. PARTICIPANTS & SETTING: Participants included twenty-one African Americans--12 women and 9 men, two of whom were foster parents and 19 of whom were parents involved with child welfare services. All participants reside in two impoverished areas in southern United States. Focus groups were used to collect data and were conducted at a community center. METHODS: The method of analysis was constant comparison analysis (Strauss) and thematic analysis of the focus group discussions in the context of institutional policy. FINDINGS: Six themes (profound lack of trust; overwhelming trauma; severe and persistent poverty; health and mental health; socio-economic conditions; and sense of social isolation were identified, along with three participant suggestions to improve child welfare services (family support services, economic revival, and better communication). CONCLUSIONS: In the current study we note the strong link between poverty, child maltreatment, and child removal and conclude with an exploration of practice and policy implications with recommendations for a way forward. The need for culturally competent and trauma informed child welfare services is also discussed.

Unravelling the Links between Phage Adsorption and Successful Infection in Clostridium difficile.

Bacteriophage (phage) therapy is a promising alternative to antibiotics for the treatment of bacterial pathogens, including Clostridiumdifficile. However, as for many species, in C. difficile the physical interactions between phages and bacterial cells have not been studied in detail. The initial interaction, known as phage adsorption, is initiated by the reversible attachment of phage tail fibers to bacterial cell surface receptors followed by an irreversible binding step. Therefore binding can dictate which strains are infected by the phage. In this study, we investigated the adsorption rates and irreversible binding of three C. difficile myoviruses: CDHM1, CDHM3 and CDHM6 to ten strains that represent ten prevalent C. difficile ribotypes, regardless of their ability to infect. CDHM1 and CDHM3 phage particles adsorbed by ~75% to some strains that they infected. The infection dynamics for CDHM6 are less clear and ~30% of the phage particles bound to all strains, irrespective of whether a successful infection was established. The data highlighted adsorption is phage-host specific. However, it was consistently observed that irreversible binding had to be above 80% for successful infection, which was also noted for another two C. difficile myoviruses. Furthermore, to understand if there is a relationship between infection, adsorption and phage tail fibers, the putative tail fiber protein sequences of CDHM1, CDHM3 and CDHM6 were compared. The putative tail fiber protein sequence of CDHM1 shares 45% homology at the amino acid level to CDHM3 and CDHM6, which are identical to each other. However, CDHM3 and CDHM6 display differences in adsorption, which highlights that there is no obvious relationship between putative tail fiber sequence and adsorption. The importance of adsorption and binding to successful infection is often overlooked, and this study provides useful insights into host-pathogen interactions within this phage-pathogen system.