Langmuir and Langmuir-Blodgett films of lipids and penicillinase: Studies on adsorption and enzymatic activity.

Bioelectronic devices, such as biosensors, can be constructed with enzymes immobilized in ultrathin solid films, for which preserving the enzymatic catalytic activity is fundamental for optimal performance. In this sense, nanostructured films in which molecular architectures can be controlled are of interest. In this present work, the adsorption of the enzyme penicillinase onto Langmuir monolayers of the phospholipid dimyristoylphosphatidic acid was investigated and characterized with surface pressure-area isotherms and polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS). The incorporation of the enzyme in the lipid monolayer not only caused the film to expand, but also could be identified through amide bands in the PM-IRRAS spectra, with the CN and CO dipole moments being identified, lying parallel to monolayer plane. Structuring of the enzyme into α-helices was identified in the mixed enzyme-phospholipid monolayer and preserved when transferred to solid as a Langmuir-Blodgett (LB) film. The enzyme-lipid LB films were then characterized with PM-IRRAS, atomic force microscopy and fluorescence spectroscopy. Measurements of the catalytic activity showed that the enzyme accommodated in the LB films preserved 76% of the enzyme activity in relation to the homogeneous medium. The method presented here not only allows for enhanced catalytic activity toward penicillin, but also can be useful to explain why certain film architectures exhibit better enzyme activity.

Metalo-ß-lactamasas en aislamientos clínicos de pseudomonas aeruginosa en Lima, Perú / Metalo-ß-lactamases in clinical isolates of pseudomonas aeruginosa in Lima, Peru

Con el objetivo de detectar y caracterizar molecularmente las metalo-ß-lactamasas (MßL) en aislamientos clínicos de Pseudomonas aeruginosa, se realizó un estudio trasversal en seis hospitales de referencia de Lima (Perú) en agosto de 2011. Se evaluó 51 aislamientos de P. aeruginosa, resistentes a ceftazidima y con sensibilidad reducida a carbapenémicos. El ensayo fenotípico se realizó con el método de aproximación de discos con sustratos (ceftazidima, imipenem y meropenem) y con ácido etilendiaminotetraacético (EDTA). La detección de genes MßL se realizó mediante la técnica de reacción en cadena de polimerasa multiplex. A través del método fenotípico se detectaron MßL en el 15,7% de los aislamientos, en todos ellos la detección de genes mostró la presencia del gen blaIMP. La descripción del primer reporte de MßL en aislamientos de P. aeruginosa en el Perú debería alertar a los equipos de vigilancia epidemiológica intrahospitalaria para promover su control y prevenir su diseminación.

The aim of this study was to detect and characterize molecularly metallo-ß-lactamase (MßL) in clinical isolates of Pseudomonas aeruginosa. We carry out a cross sectional study in six publics hospital in Lima on August 2011. 51 isolates of P. aeruginosa resistant to ceftazidime and reduced susceptibility to carbapenemes were evaluated.The phenotypic assay was performed using the approximation method with substrate disks (ceftazidime, imipenem and meropenem) and ethylenediaminetetraacetic acid (EDTA). MßL gene detection was performed using the technique of polymerase chain reaction (PCR) multiplex. Through MßL detected phenotypic method in 15.7% of isolates. Detection of genes revealed the presence of the gene in the 8 isolates blaIMP. The first report of MßL in P. aeruginosa in Peru was described, this should alert the monitoring equipment in the institutions to promote control their spread.