Bacterial respiratory inhibition triggers dispersal of Pseudomonas aeruginosa biofilms.

Pseudomonas aeruginosa grows as a biofilm under many environmental conditions, and the bacterium can disperse from biofilms via highly regulated, dynamic processes. However, physiologic triggers of biofilm dispersal remain poorly understood. Based on prior literature describing dispersal triggered by forms of starvation, we tested bacterial respiratory inhibitors for biofilm dispersal in two models resembling chronic airway infections. Our underlying hypothesis was that respiratory inhibitors could serve as a model for the downstream effects of starvation. We used two experimental conditions. In the first condition, biofilms were grown and dispersed from the surface of airway epithelial cells, and the second condition was a model where biofilms were grown on glass in cell culture media supplemented with host-relevant iron sources. In both biofilm models, the respiratory inhibitors potassium cyanide and sodium azide each triggered biofilm dispersal. We hypothesized that cyanide-induced dispersal was due to respiratory inhibition rather than signaling via an alternative mechanism, and, indeed, if respiration was supported by overexpression of cyanide-insensitive oxidase, dispersal was prevented. Dispersal required the activity of the cyclic-di-GMP regulated protease LapG, reinforcing the role of matrix degradation in dispersal. Finally, we examined the roles of individual phosphodiesterases, previously implicated in dispersal to specific triggers, and found signaling to be highly redundant. Combined deletion of the phosphodiesterases dipA, bifA, and rbdA was required to attenuate the dispersal phenotype. In summary, this work adds insight into the physiology of biofilm dispersal under environmental conditions in which bacterial respiration is abruptly limited. IMPORTANCE The bacterium Pseudomonas aeruginosa grows in biofilm communities that are very difficult to treat in human infections. Growing as a biofilm can protect bacteria from antibiotics and the immune system. Bacteria can leave a biofilm through a process called "dispersal." Dispersed bacteria seed new growth areas and are more susceptible to killing by antibiotics. The triggers for biofilm dispersal are not well understood, and if we understood dispersal better it might lead to the development of new treatments for infection. In this paper, we find that inhibiting P. aeurginosa's ability to respire (generate energy) can trigger dispersal from a biofilm grown in association with human respiratory epithelial cells in culture. The dispersal process requires a protease which is previously known to degrade the biofilm matrix. These findings give us a better understanding of how the biofilm dispersal process works so that future research can discover better ways of clearing bacteria growing in biofilms.

Stepping Together in Stepped Care Trauma-Focused Cognitive Behavioral Therapy: Case Report of Core Components.

New service delivery systems are needed to expand the reach of evidence-based practices for childhood trauma. Cognitive behavioral therapy is an effective approach for treating -childhood trauma, yet treatment barriers remain. Stepped care models that incorporate parent-led -treatment with therapist assistance may be one approach to improve access. This case study highlights the core components of a parent-led therapist-assisted treatment called Stepping Together that serves as a Step 1 treatment within a stepped care model. The components and structure of Stepping Together are described, along with excerpts from therapy sessions to illustrate the therapist's implementation of the model. Results of the case, in which improvements occurred, are presented. Stepping Together, a parent-led therapist-assisted first-line treatment within stepped care trauma-focused cognitive behavioral therapy, may be an effective treatment for some children after trauma and their caregivers, although more research is needed.

Dispersal of Epithelium-Associated Pseudomonas aeruginosa Biofilms.

Pseudomonas aeruginosa grows in highly antibiotic-tolerant biofilms during chronic airway infections. Dispersal of bacteria from biofilms may restore antibiotic susceptibility or improve host clearance. We describe models to study biofilm dispersal in the nutritionally complex environment of the human airway. P. aeruginosa was cocultured in the apical surface of airway epithelial cells (AECs) in a perfusion chamber. Dispersal, triggered by sodium nitrite, a nitric oxide (NO) donor, was tracked by live cell microscopy. Next, a static model was developed in which biofilms were grown on polarized AECs without flow. We observed that NO-triggered biofilm dispersal was an energy-dependent process. From the existing literature, NO-mediated biofilm dispersal is regulated by DipA, NbdA, RbdA, and MucR. Interestingly, altered signaling pathways appear to be used in this model, as deletion of these genes failed to block NO-induced biofilm dispersal. Similar results were observed using biofilms grown in an abiotic model on glass with iron-supplemented cell culture medium. In cystic fibrosis, airway mucus contributes to the growth environment, and a wide range of bacterial phenotypes are observed; therefore, we tested biofilm dispersal in a panel of late cystic fibrosis clinical isolates cocultured in the mucus overlying primary human AECs. Finally, we examined dispersal in combination with the clinically used antibiotics ciprofloxacin, aztreonam and tobramycin. In summary, we have validated models to study biofilm dispersal in environments that recapitulate key features of the airway and identified combinations of currently used antibiotics that may enhance the therapeutic effect of biofilm dispersal.IMPORTANCE During chronic lung infections, Pseudomonas aeruginosa grows in highly antibiotic-tolerant communities called biofilms that are difficult for the host to clear. We have developed models for studying P. aeruginosa biofilm dispersal in environments that replicate key features of the airway. We found that mechanisms of biofilm dispersal in these models may employ alternative or additional signaling mechanisms, highlighting the importance of the growth environment in dispersal events. We have adapted the models to accommodate apical fluid flow, bacterial clinical isolates, antibiotics, and primary human airway epithelial cells, all of which are relevant to understanding bacterial behaviors in the context of human disease. We also examined dispersal agents in combination with commonly used antipseudomonal antibiotics and saw improved clearance when nitrite was combined with the antibiotic aztreonam.

Fibrosis endomiocárdica / Endomyocardial fibrosis

Resumen Las miocardiopatías son trastornos intrínsecos del músculo cardíaco. Presentan fenotipos diferenciales que determinan su clasificación; estos son: dilatada, hipertrófica, restrictiva, displasia arritmogénica del ventrículo derecho y no clasificadas. Las miocardiopatías restrictivas se caracterizan por ventrículos de tamaño normal, con grosores de pared normales o ligeramente aumentados, paredes rígidas, disfunción diastólica severa y llenado restrictivo con presiones elevadas. Una de las formas más comunes de miocardiopatía restrictiva es la fibrosis endomiocárdica la cual es endémica en algunas zonas tropicales especialmente en África (países de bajos ingresos), pero en nuestro medio hay pocos reportes de aparición. Su etiología es desconocida, aunque existen diversos mecanismos que han sido involucrados en su fisiopatología. Su diagnóstico se basa en estudios imagenológicos (ecocardiograma transtorácico y resonancia magnética nuclear cardíaca). El pronóstico es muy pobre, y usualmente se diagnostica en etapas muy avanzadas de la enfermedad. Se describe el caso de una paciente femenina, adulta media, que debutó con cardiopatía restrictiva, cuyo diagnóstico final fue fibrosis endomiocárdica.

Abstract Cardiomyopathies are intrinsic conditions of the cardiac muscle. They present differential phenotypes that determine their classification. These are: dilated, hypertrophic, restrictive, arrhythmogenic right ventricular and unclassified. Restrictive cardiomyopathies are characterised by larger than normal ventricles with normal or slightly enlarged thickness of the walls, rigid walls, severe diastolic dysfunction and restrictive filling with high pressures. One of the most common restrictive cardiomyopathies is endomyocardial fibrosis, which is endemic to some tropical areas, especially Africa (low income countries), but there are few reports of its occurrence in our environment. Its aetiology is unknown, but there are several mechanisms that have been involved in its pathophysiology. Its diagnosis is based in imaging studies (transthoracic echocardiogram, cardiac nuclear magnetic resonance). Prognosis is very poor, and it is usually diagnoses in the latest stages of the disease. The case of a female, average adult patient that debuted with restrictive cardiomyopathy with a final diagnosis of endomyocardial fibrosis is described.

Reactions with Antisera and Pathological Effects of Staphylococcus aureus Gamma-Toxin in the Cornea.

PURPOSE: This study analyzed the toxicity of purified gamma-toxin from Staphylococcus aureus and the protectiveness of antisera to gamma-toxin in the rabbit cornea. MATERIALS AND METHODS: Gamma-toxin was purified from cultures of alpha-toxin deficient S. aureus strain Newman Δhla. Antisera to native gamma-toxin (Hlg) were produced in rabbits. These antisera and a commercial polyclonal antibody to recombinant HlgB (rHlgB) were analyzed for specificity and toxin neutralization. Heat-inactivated gamma-toxin, active gamma-toxin either alone or with antisera or with commercial antibody to rHlgB, was injected into the rabbit cornea to observe the pathological effects using slit lamp examination scoring (SLE) and histological analyses. RESULTS: Eyes with intrastromal injection of gamma-toxin developed SLE scores that were significantly higher than eyes injected with heat-inactivated gamma-toxin (p ≤ 0.003). Slit lamp and histological examination of eyes revealed that gamma-toxin injected into the cornea mediated conjunctival injection and chemosis, iritis, fibrin accumulation in the anterior chamber, and polymorphonuclear neutrophil infiltration of the cornea and iris. Also, eyes injected with gamma-toxin plus antisera to native whole gamma-toxin or HlgB, but not with commercial antibody to rHlgB, yielded significantly lower SLE scores than eyes injected with gamma-toxin alone (p ≤ 0.003). CONCLUSIONS: This study illustrates that S. aureus gamma-toxin is capable of causing significant corneal pathology. Furthermore, the use of polyclonal antisera specific for native gamma-toxin was found to inhibit the damaging effects of the toxin in the rabbit cornea.