Insights into the behavior of six rationally designed peptides based on Escherichia coli's OmpA at the water-dodecane interface.

The Escherichia coli's membrane protein OmpA has been identified as a potential biosurfactant due to their amphiphilic nature, and their capacity to stabilize emulsions of dodecane in water. In this study, the influence of surfactant type, concentration, preservation time and droplet size on the crystallization of n-dodecane and water, in oil-in-water emulsions stabilized with six rationally designed Escherichia coli's OmpA-based peptides was investigated. A differential scanning calorimetry (DSC) protocol was established using emulsions stabilized with Tween 20® and Tween 80®. A relationship between the surfactant concentration and the crystallization temperatures of n-dodecane and water was observed, where the crystallization temperatures seem to be dependent on the preservation time. A deconvolution analysis shows that the peak morphology possibly depends on the interactions at the interface because the enthalpic contributions of each Gaussian peak remained similar in emulsions stabilized with the same peptide. Adsorption results show that the main driver for adsorption and thus stabilization of emulsions is polar interactions (e.g. H-bonding) through the hydrophilic parts of the peptides. Those peptides with a preponderance of polar interaction groups distribution (i.e. NH2, COOH, imidazole) showed the highest interfacial activity under favorable pH conditions. This suggests that custom-made peptides whose hydrophilic/hydrophobic regions can be fine-tuned depending on the application can be easily produced with the additional advantage of their biodegradable nature.

Traumatismo Cráneo Encefálico penetrante no asociado a proyectil. Presentación de un caso / Non-bullet related penetrating head trauma: case presentation

Introducción: Los traumatismos craneoencefálicos penetrantes son cada vez más frecuentes en la sociedad actual, por lo que el neurocirujano debe estar preparado para atenderlas, siguiendo las guías y recomendaciones para su manejo. Caso: Paciente masculino joven, quien recibió puñalada en el rostro, llegó a la sala de emergencia desorientado y hemiparético. Se comprobó la presencia de arma blanca intracraneal y luego de los exámenes de imagen se procedió en sala de operaciones a retirar el arma retenida, luego de hemostasia y cierre de fístula. Luego de la intervención quirúrgica, fue atendido en la Unidad de Cuidados Intensivos. El control tomográfico posoperatorio no evidenció sangrado. Hubo reversióncompleta de la hemiparesia, sin signos de fistula ni infección. El paciente tuvo una buena evolución hasta su egreso, 12 días más tarde. Discusión: Las imágenes tomográficas y de angiotomografía son de gran ayuda para el neurocirujano, quien precisa de esa información para prevenir potenciales complicaciones intraoperatorias y secuelas neurológicas en el tratamiento quirúrgico de pacientes que han sufrido un trauma craneoencefálico penetrante.

Introduction: Penetrating head injuries are becoming more and more frequent in nowadays socity, therefore, the neurosurgeon should be prepared to deal with. We must stick at rigid surgical protocols. Case: A young male patient stabbed on his face was admitted in the emergency unit of our hospital. He was disoriented and hemiparetic with a knife inside the skull shown by image examns. Patient was sent to the operating room where the neurosurgeon proceeded to remove the knife, under controlled conditions and hemostasis. A brain fistula was closed and the patient was sent to the Intensive Care Unit in the postoperative period. Tomographic control showed no bleeding. Eventually, he was discharged in good condition after 12 days with complete reversal of hemiparesis, without infection or fistula. Discusion: Tomographic imaging and angiography are useful tools for the neurosurgeon, who needs key information to prevent surgical complications and neurologic sequelae when dealing with patients who suffered penetrating head trauma.

Clinical, microbiological, and genetic characteristics of heteroresistant vancomycin-intermediate Staphylococcus aureus bacteremia in a teaching hospital.

The emergence of vancomycin intermediate Staphylococcus aureus (VISA) and heterogeneous VISA (hVISA) is of major concern worldwide. Our objective was to investigate the prevalence, phenotypic and molecular features of hVISA strains isolated from bacteremic patients and to determine the clinical significance of the hVISA phenotype in patients with bacteremia. A total of 104 S. aureus blood isolates were collected from a teaching hospital of Argentina between August 2009 and November 2010. No VISA isolate was recovered, and 3 out of 92 patients (3.3%) were infected with hVISA, 2 of them methicillin-resistant S. aureus (MRSA) (4.5% of MRSA). Macro Etest and prediffusion method detected 3/3 and 2/3 hVISA respectively. Considering the type of bacteremia, the three cases were distributed as follows: two patients had suffered multiple episodes of bacteremia (both hVISA strains recovered in the second episode), while only one patient had suffered a single episode of bacteremia with hVISA infection. MRSA bloodstream isolates exhibiting the hVISA phenotype were related to HA-MRSA Cordobes clone (ST5-SCCmec I-spa t149) and MRSA Argentinean pediatric clone (ST100-SCCmec IVNV-spa t002), but not to CA-MRSA-ST30-SCCmec IV-spa t019 clone that was one of the most frequent in our country. Although still relatively infrequent in our hospital, hVISA strains were significantly associated with multiple episodes of bacteremia (p=0.037) and genetically unrelated.

Isolation of Kerstersia gyiorum from a patient with cholesteatomatous chronic otitis media.

We describe the first case of a Kerstersia gyiorum strain isolated from a patient with cholesteatomatous chronic otitis media. We emphasize the isolation of members of the family Alcaligenaceae in serious infections and unusual sites and the importance of polyphasic identification addressing the definitive identification.