A New Method for Isolating Host-Independent Variants of Bdellovibrio bacteriovorus Using E. coli Auxotrophs

Bdellovibrios are Gram-negative bacteria that are characterized by predatory behavior. Although Bdellovibrios exhibit an obligatory parasitic life cycle, it is possible to isolate Bdellovibrio variants that no longer require host cells for their growth. In this study, a new method for isolating Bdellovibrio bacteriovorus host-independent (HI) variants was developed. Filtered B. bacteriovorus prey cells were cultured with E. coli diaminopimelic acid (DAP) auxotrophs as host cells. Thereafter, the lysate was plated on DAP minus media, allowing only HI colonies to develop. Using this method, we have isolated numerous HI variants and demonstrated that the emergence of HI variants may be occurring at a higher frequency than was previously suggested

The Use of Commercially Available Alpha-Amylase Compounds to Inhibit and Remove Staphylococcus aureus Biofilms

Staphylococcus aureus, a versatile human pathogen, is commonly associated with medical device infections. Its capacity to establish and maintain these infections is thought to be related to its ability to form adherent biofilms. In this study, commercially available α-amylase compounds from various biological sources were evaluated for their ability to reduce and prevent biofilm formation of several S. aureus isolates. Our data demonstrates that α-amylase compounds can rapidly detach biofilms of S. aureus, as well as inhibit biofilm formation. Our data also demonstrates that α-amylase compounds have an ability to reduce and disassociate S. aureus cell-aggregates grown in liquid suspension. These findings suggest that commercially available α-amylase compounds could be used in the future to control S. aureus biofilm-related infections

Relationships between parenting styles and risk behaviors in adolescent health: an integrative literature review

Pesquisas realizadas durante os últimos 20 anos sugerem que a qualidade da relação entre pais e adolescentes tem obtido impacto significante no desenvolvimento de comportamentos de risco a saúde dos adolescentes. A finalidade deste estudo é apresentar uma revisão bibliográfica de estudos publicados entre o ano de 1996 e 2007, que analisam relações especificas entre modelos de pais e seis principais comportamentos de risco em adolescentes. Os adolescentes crescidos sob disciplina autoritária demonstraram consistentemente mais comportamentos seguros e menos comportamentos de risco comparados a adolescentes vindos de famílias não autoritárias. O modelo dos pais e comportamentos relacionados a afetividade, comunicação familiar e práticas disciplinares, predizem importantes mediadores na formação do adolescente, incluindo o desenvolvimento acadêmico e o ajuste psico-social. Avaliações cuidadosas de modelos padrões de pais em diversas populações, será uma próxima etapa crítica no desenvolvimento de intervenções eficazes e culturalmente adaptadas, na promoção de saúde a adolescentes.Resultados de investigaciones realizadas durante los últimos 20 años muestran que la calidad en las relaciones entre padres e hijos ha provocado un impacto significativo en el desarrollo de comportamientos de riesgo para la salud del adolescente. El objetivo de este artículo es mostrar una revisión bibliográfica de estudios publicados entre 1996-2007, analizando relaciones específicas entre los tipos de padres y los seis principales comportamientos de riesgo en adolescentes. Adolescentes criados bajo una disciplina autoritaria muestran comportamientos más seguros y menores comportamientos de riesgo al ser comparados con adolescentes que provienen de familias poco autoritarias. El tipo paternal y comportamientos relacionados con la afectividad, comunicación familiar y disciplina predicen importantes mediadores para la formación del adolescente, incluyendo desarrollo académico y adaptación psico-social. Cuidadosas evaluaciones sobre los tipos de padres estándar en poblaciones diversas será una próxima etapa crítica para el desarrollo de intervenciones eficaces y adaptadas culturalmente para la promoción de la salud del adolescente.Research over the past 20 years suggests that the quality of the parent-adolescent relationship significantly affects the development of risk behaviors in adolescent health. The purpose of this paper is to present a review of studies published between 1996-2007 that address specific relationships between parenting styles and six priority adolescent risk behaviors. The review supports the substantial influence of parenting style on adolescent development. Adolescents raised in authoritative households consistently demonstrate higher protective and fewer risk behaviors than adolescents from non-authoritative families. There is also considerable evidence to show that parenting styles and behaviors related to warmth, communication and disciplinary practices predict important mediators, including academic achievement and psychosocial adjustment. Careful examination of parenting style patterns in diverse populations, particularly with respect to physical activity and unintentional injury, will be a critical next step in the development of efficacious, culturally tailored adolescent health promotion interventions

Predatory Bacteria: A Potential Ally against Multidrug-Resistant Gram-Negative Pathogens

Multidrug-resistant (MDR) Gram-negative bacteria have emerged as a serious threat to human and animal health. Bdellovibrio spp. and Micavibrio spp. are Gram-negative bacteria that prey on other Gram-negative bacteria. In this study, the ability of Bdellovibrio bacteriovorus and Micavibrio aeruginosavorus to prey on MDR Gram-negative clinical strains was examined. Although the potential use of predatory bacteria to attack MDR pathogens has been suggested, the data supporting these claims is lacking. By conducting predation experiments we have established that predatory bacteria have the capacity to attack clinical strains of a variety of ß-lactamase-producing, MDR Gram-negative bacteria. Our observations indicate that predatory bacteria maintained their ability to prey on MDR bacteria regardless of their antimicrobial resistance, hence, might be used as therapeutic agents where other antimicrobial drugs fail. © 2013 Kadouri et al

Minding the gap and moving forward in children's long-term conditions: A vital role for health psychology.

Children with a long‐term condition and their families are confronted with multiple biopsychosocial challenges. In this editorial, we outline the scope of the problem and then look at some examples of interventions for children with a long‐term condition and how health psychology can inform and influence these. Health psychology theories are often not very well applied or reported, and there is considerable scope for more health psychology input in this area. We discuss relevant issues and suggest directions for future research in which health psychologists might apply subject‐specific theory and knowledge to further research and practice in the paediatric domain.Peer reviewe

Serum albumin and osmolality inhibit Bdellovibrio bacteriovorus predation in human serum

We evaluated the bactericidal activity of Bdellovibrio bacteriovorus, strain HD100, within blood sera against bacterial strains commonly associated with bacteremic infections, including E. coli, Klebsiella pneumoniae and Salmonella enterica. Tests show that B. bacteriovorus HD100 is not susceptible to serum complement or its bactericidal activity. After a two hour exposure to human sera, the prey populations decreased 15- to 7,300-fold due to the serum complement activity while, in contrast, the B. bacteriovorus HD100 population showed a loss of only 33%. Dot blot analyses showed that this is not due to the absence of antibodies against this predator. Predation in human serum was inhibited, though, by both the osmolality and serum albumin. The activity of B. bacteriovorus HD100 showed a sharp transition between 200 and 250 mOsm/kg, and was progressively reduced as the osmolality increased. Serum albumin also acted to inhibit predation by binding to and coating the predatory cells. This was confirmed via dot blot analyses and confocal microscopy. The results from both the osmolality and serum albumin tests were incorporated into a numerical model describing bacterial predation of pathogens. In conclusion, both of these factors inhibit predation and, as such, they limit its effectiveness against pathogenic prey located within sera

Bdellovibrio bacteriovorus Inhibits Staphylococcus aureus Biofilm Formation and Invasion into Human Epithelial Cells

Bdellovibrio bacteriovorus HD100 is a predatory bacterium that attacks many Gram-negative human pathogens. A serious drawback of this strain, however, is its ineffectiveness against Gram-positive strains, such as the human pathogen Staphylococcus aureus. Here we demonstrate that the extracellular proteases produced by a host-independent B. bacteriovorus (HIB) effectively degrade/inhibit the formation of S. aureus biofilms and reduce its virulence. A 10% addition of HIB supernatant caused a 75% or greater reduction in S. aureus biofilm formation as well as 75% dispersal of pre-formed biofilms. LC-MS-MS analyses identified various B. bacteriovorus proteases within the supernatant, including the serine proteases Bd2269 and Bd2321. Tests with AEBSF confirmed that serine proteases were active in the supernatant and that they impacted S. aureus biofilm formation. The supernatant also possessed a slight DNAse activity. Furthermore, treatment of planktonic S. aureus with the supernatant diminished its ability to invade MCF-10a epithelial cells by 5-fold but did not affect the MCF-10a viability. In conclusion, this study illustrates the hitherto unknown ability of B. bacteriovorus to disperse Gram-positive pathogenic biofilms and mitigate their virulence.open6

An Eye to a Kill: Using Predatory Bacteria to Control Gram-Negative Pathogens Associated with Ocular Infections

Ocular infections are a leading cause of vision loss. It has been previously suggested that predatory prokaryotes might be used as live antibiotics to control infections. In this study, Pseudomonas aeruginosa and Serratia marcescens ocular isolates were exposed to the predatory bacteria Micavibrio aeruginosavorus and Bdellovibrio bacteriovorus. All tested S. marcescens isolates were susceptible to predation by B. bacteriovorus strains 109J and HD100. Seven of the 10 P. aeruginosa isolates were susceptible to predation by B. bacteriovorus 109J with 80% being attacked by M. aeruginosavorus. All of the 19 tested isolates were found to be sensitive to at least one predator. To further investigate the effect of the predators on eukaryotic cells, human corneal-limbal epithelial (HCLE) cells were exposed to high concentrations of the predators. Cytotoxicity assays demonstrated that predatory bacteria do not damage ocular surface cells in vitro whereas the P. aeruginosa used as a positive control was highly toxic. Furthermore, no increase in the production of the proinflammatory cytokines IL-8 and TNF-alpha was measured in HCLE cells after exposure to the predators. Finally, injection of high concentration of predatory bacteria into the hemocoel of Galleria mellonella, an established model system used to study microbial pathogenesis, did not result in any measurable negative effect to the host. Our results suggest that predatory bacteria could be considered in the near future as a safe topical bio-control agent to treat ocular infections. © 2013 Shanks et al

Mutation Detection with Next-Generation Resequencing through a Mediator Genome

The affordability of next generation sequencing (NGS) is transforming the field of mutation analysis in bacteria. The genetic basis for phenotype alteration can be identified directly by sequencing the entire genome of the mutant and comparing it to the wild-type (WT) genome, thus identifying acquired mutations. A major limitation for this approach is the need for an a-priori sequenced reference genome for the WT organism, as the short reads of most current NGS approaches usually prohibit de-novo genome assembly. To overcome this limitation we propose a general framework that utilizes the genome of relative organisms as mediators for comparing WT and mutant bacteria. Under this framework, both mutant and WT genomes are sequenced with NGS, and the short sequencing reads are mapped to the mediator genome. Variations between the mutant and the mediator that recur in the WT are ignored, thus pinpointing the differences between the mutant and the WT. To validate this approach we sequenced the genome of Bdellovibrio bacteriovorus 109J, an obligatory bacterial predator, and its prey-independent mutant, and compared both to the mediator species Bdellovibrio bacteriovorus HD100. Although the mutant and the mediator sequences differed in more than 28,000 nucleotide positions, our approach enabled pinpointing the single causative mutation. Experimental validation in 53 additional mutants further established the implicated gene. Our approach extends the applicability of NGS-based mutant analyses beyond the domain of available reference genomes