Management of Recurrent Sigmoid Volvulus in the Pediatric Population.

Sigmoid volvulus is a rare etiology of bowel obstruction in the pediatric population that can be easily misdiagnosed, leading to delayed treatment and potential complications. Given that sigmoid volvulus is a common cause of bowel obstruction in the adult population and the significant lack of literature on its management in children, treatment strategies for pediatric patients often follow standardized protocols for adults. We report the case of a 15-year-old boy who presented with recurrent episodes of sigmoid volvulus over a 1-month period. Computed tomography demonstrated a sigmoid volvulus without evidence of ischemia or bowel infarction. Colonoscopy demonstrated a descending megacolon, and bowel transit studies demonstrated normal transit time. Acute episodes were managed conservatively with colonoscopic decompression. After a complete study, laparoscopic sigmoidectomy was performed. This work demonstrates the importance of early recognition and treatment of sigmoid volvulus in the pediatric population to limit recurrent episodes.

Necrotizing cellulitis due to Rhizopus arrhizus in an extremely premature infant.

We report an extremely premature infant with necrotizing cellulitis. After minor trauma to the left arm when removing an adhesive sensor, patient developed rapidly progressive cellulitis, which evolved into a necrotic ulcer. Microbiological studies (mass spectroscopy and molecular assay) identified Rhizopus arrhizus as the responsible fungus.

Estrategias para la implementación y reporte de los puntos de corte CLSI vigentes y pruebas fenotípicas confirmatorias para BLEE y carbapenemasas en bacilos Gram negativos en laboratorios clínicos de Colombia / Strategies for implementation and reporting of current CLSI Breakpoints and phenotypic confirmatory tests for ESBLs and carbapenemases in Gram-negative bacilli in Colombian clinical laboratories

En 2010, el Instituto Americano de Estándares Clínicos y de Laboratorio (CLSI) inició un proceso de revisión y actualización de los puntos de corte para microdilución y disco difusión para cefalosporinas (cefazolina, cefotaxima, ceftriaxona, ceftizoxima, ceftazidima), monobactámicos (aztreonam) y carbapenémicos (imipenem, meropenem, ertapenem, doripenem). Los cambios se basaron en modelos PK/PD que buscan predecir la respuesta clínica con el uso exclusivo de la concentración inhibitoria mínima (CIM) y esquemas específicos de dosificación de forma independiente al mecanismo de resistencia expresado. Este nuevo paradigma eliminaría la necesidad de realizar pruebas fenotípicas para beta-lactamasas de espectro extendido (BLEE) y carbapenemasas para tomar decisiones terapéuticas y permitiría utilizarlas únicamente para fines epidemiológicos. Sin embargo, ante las limitaciones de las metodologías actuales para pruebas de susceptibilidad en Colombia, el desconocimiento de estos cambios y la alarma epidemiológica por la aparición de nuevas ß-lactamasas en el país, se hace necesario generar recomendaciones para los laboratorios clínicos, con el fi n de unifi car los criterios para la realización e informe de los antibiogramas en bacilos Gram negativos, incluyendo la implementación de los puntos de corte actuales y la aplicación de las pruebas fenotípicas para la detección de BLEE y carbapenemasas.

In 2010, the Clinical and Laboratory Standards Institute (CLSI) began a process to revise and update the breakpoints for broth microdilution and disk diffusion for cephalosporins (Cefazolin, Cefotaxime, Ceftriaxone, Ceftazidime), monobactams (Aztreonam) and carbapenems (Imipenem, Meropenem, Ertapenem and Doripenem). The changes made were based on PK/PD models that attempt to predict clinical outcomes using minimum inhibitory concentration (MIC) and specific dosage regimens, regardless of the resistance mechanism expressed by the organism. The new breakpoints would eliminate the need to perform screening and confirmatory testing for ESBLs and carbapenemases for treatment decisions, and thus they would be used only for infection control purposes. Nevertheless, there are limitations to current methods in Colombia, a lack of knowledge regarding the recent changes and epidemiologic alarm over new B-lactamases spreading in our country. Therefore it was necessary to formulate and issue recommendations for clinical laboratories, with the aim of standardizing the criteria for reports on antibiograms in Gram-negative bacilli, including the current CLSI breakpoints and applying phenotypic confirmatory testing to detect ESBLs and Carbapenemases.

α-Catenin and vinculin cooperate to promote high E-cadherin-based adhesion strength.

Maintaining cell cohesiveness within tissues requires that intercellular adhesions develop sufficient strength to support traction forces applied by myosin motors and by neighboring cells. Cadherins are transmembrane receptors that mediate intercellular adhesion. The cadherin cytoplasmic domain recruits several partners, including catenins and vinculin, at sites of cell-cell adhesion. Our study used force measurements to address the role of αE-catenin and vinculin in the regulation of the strength of E-cadherin-based adhesion. αE-catenin-deficient cells display only weak aggregation and fail to strengthen intercellular adhesion over time, a process rescued by the expression of αE-catenin or chimeric E-cadherin·αE-catenins, including a chimera lacking the αE-catenin dimerization domain. Interestingly, an αE-catenin mutant lacking the modulation and actin-binding domains restores cadherin-dependent cell-cell contacts but cannot strengthen intercellular adhesion. The expression of αE-catenin mutated in its vinculin-binding site is defective in its ability to rescue cadherin-based adhesion strength in cells lacking αE-catenin. Vinculin depletion or the overexpression of the αE-catenin modulation domain strongly decreases E-cadherin-mediated adhesion strength. This supports the notion that both molecules are required for intercellular contact maturation. Furthermore, stretching of cell doublets increases vinculin recruitment and α18 anti-αE-catenin conformational epitope immunostaining at cell-cell contacts. Taken together, our results indicate that αE-catenin and vinculin cooperatively support intercellular adhesion strengthening, probably via a mechanoresponsive link between the E-cadherin·ß-catenin complexes and the underlying actin cytoskeleton.

Integrins stimulate E-cadherin-mediated intercellular adhesion by regulating Src-kinase activation and actomyosin contractility.

Cadherins and integrins are major adhesion molecules regulating cell-cell and cell-matrix interactions. In vitro and in vivo studies have demonstrated the existence of crosstalk between integrins and cadherins in cell adhesion and motility. We used a dual pipette assay to measure the force required to separate E-cadherin-producing cell doublets and to investigate the role of integrin in regulating the strength of intercellular adhesion. A greater force was required to separate cell doublets bound to fibronectin or vitronectin-coated beads than for doublets bound to polylysine-coated beads. This effect depended on cell spreading and the duration of stimulation. Cells expressing type II cadherin-7 also responded to fibronectin stimulation to produce a higher intercellular adhesion. Establishment of cadherin-mediated adhesion needed ROCK, MLCK and myosin ATPase II activity. The regulation of intercellular adhesion strength by integrin stimulation required activation of Src family kinases, ROCK and actomyosin contractility. These findings highlight the importance and mechanisms of molecular crosstalk between cadherins and integrins in the control of cell plasticity during histogenesis and morphogenesis.

Perfil microbiológico y resistenciaantibiótica en las bacteremias postbiopsia transrectal de próstata en el Hospital Universitario Fundación Santa Fé de Bogotá / Microbiologic profile and antibiotic resistance in post biopsy bacteremias at the Hospital Universitario Fundación Santa Fé de Bogotá

Objetivo: Describir el perfil microbiológico y la resistencia antibiótica identificada en urocultivos y hemocultivos de pacientes con diagnostico de bacteremia postbiopsia de próstata, atendidos en el Hospital Universitario Fundación Santa Fe de Bogotá. Materiales y métodos: Se realizo un análisis retrospectivo de las historias clínicas de pacientes con diagnostico de bacteremia post biopsia de próstata desde enero de 2006 hasta abril de 2008, realizadas en diversas instituciones de la ciudad, encontrando 30 casos con esta patología. Análisis de los resultados: La bacteria más frecuente obtenida en los cultivos fue E.coli en un 73.3 por cien, seguido por Klebsiella pneumonie 6.7 por cien, Enterococo sp 6.7 por cien y 3 por cien otros gérmenes. El 6.7 por cien de los pacientes ingresaron a UCI por choque séptico. En la profilaxis antibiótica obtuvimos que el 78 por cien recibieron ciprofloxacina asociado a otro antibiótico, y el 13 por cien aminoglucosido. De estos aislamientos el 66. 7 por cien resistente a ciprofloxacina, 36.7 por cien resistente a ampicilina sulbactam, 40 por cien resistente a trimetoprim sulfametoxazol, 13.3 por cien resistente a aminoglicocidos, el 6.7 por cien resistente a ceftriaxona y el 3.3 por cien a Nitrofurantoina. Solo 2 pacientes tuvieron cultivos negativos. El tratamiento más común fue ceftriaxona en el 97 por cien obteniendo adecuada evolución clínica. Ninguno de estos pacientes se cultivo para anaerobios. Conclusiones: El germen mas comúnmente involucradoen las bacteremia postbiopsia transrectal de próstata continua siendo la E. coli. Según los cultivos y antibiogramas, el perfil de resistencia es alarmante para quinolonas, ampicilina sulbactam, algunos aminoglucocidos y trimetoprin sulfametoxazol, siendo las quinolonas los antibióticos mas frecuentemente utilizados en esquemas de profilaxis pre biopsia. Recomendamos que nuevos esquemas de profilaxis antibiótica sean establecidos y utilizados para disminuir la frecuencia de es...

Separation force measurements reveal different types of modulation of E-cadherin-based adhesion by nectin-1 and -3.

Nectins are Ca2+-independent cell adhesion molecules found at cadherin-based adherens junctions. We used a dual pipette assay that measures the forces required to separate cell doublets to determine how nectins affect the formation and strength of cell-cell adhesion. Less force was required to separate doublets of L cells expressing nectin-1 or nectin-3 than to separate doublets of E-cadherin-expressing cells. Heterodimers formed between cells expressing nectin-1 or nectin-3 adhered more strongly than homodimers. Nectin-3 that does not trans-interact with nectin-1 inhibited E-cadherin-mediated adhesion. However, the extracellular fragment of nectin-1 did not have an agonistic effect on E-cadherin-dependent cell adhesion when it trans-interacted with nectin-3, expressed at high levels in cells. In contrast, the extracellular fragment of nectin-3 had a significant agonistic effect on cadherin-based adhesion when it interacted with endogenous nectin-1, expressed at low levels in cells. Our results indicate that E-cadherin is the key molecule involved in cell adhesion and that the regulation of E-cadherin-based adhesion involving cellular nectin-1 trans-interacting with nectin-3 is qualitatively different from that involving cellular nectin-3 trans-interacting with nectin-1 and depends on the nectin levels expressed by cells.

Two Bacillus sphaericus binary toxins share the midgut receptor binding site: implications for resistance of Culex pipiens complex (Diptera: Culicidae) larvae.

This work demonstrates that Bin1 and Bin2 toxins, produced by Bacillus sphaericus strains IAB59 and 2362, respectively, share a binding site in midgut brush border membranes (BBMF) from Culex pipiens complex larvae. However, a colony selected with strain IAB59, displaying a resistance ratio of only 42-fold to IAB59, but a 162,000-fold resistance to strain 2362, was found to miss receptors for Bin2 in the BBMF. This correlates with results showing that Bin1, produced in strain IAB59, failed to bind specifically to BBMF from other colony highly resistant to strain 2362. Data indicate the loss of the BBMF bound receptor as a general mechanism of resistance to binary toxins in mosquito.

Surveillance of surgical site infections: decade of experience at a Colombian tertiary care center.

A protocol for surveillance of surgical site infections (SSIs) was established in a tertiary care center in 1991 in Bogota, Colombia and followed for 10 years. Wounds were classified according to the Centers for Disease Control guidelines. The National Nosocomial Infection Surveillance and Study of the Efficacy of Nosocomial Infection Control scores for risk factors were included from June 1999. A total of 33027 surgical procedures were followed by the surveillance team. The overall infection rate was 2.6%. Most surgical procedures (70.6%) were classified as clean; 25.3%, 3.8%, and 0.26% were classified as clean/contaminated, contaminated, and dirty, respectively. Infection rates according to wound classification were 1.28%, 3.9%, 15.4%, and 38.4% for clean, clean/contaminated, contaminated, and dirty procedures, respectively. Escherichia coli and coagulase-negative staphylococci were the most frequently isolated microorganisms from SSI: 23.9% and 22.8% of isolates, respectively. A program of surveillance of SSIs has been successfully implemented in a country with limited resources and has maintained the infection rate within international standards.