Preparation, crystallization and preliminary X-ray crystallographic analysis of OXA-23, a carbapenemase conferring widespread antibiotic resistance.

OXA-23, a class D carbapenemase that confers widespread antibiotic resistance hydrolyzes the β-lactam rings of β-lactam antibiotics, presenting an enormous challenge to infection control, particularly in the eradication of pathogenic bacteria such as Acinetobacter baumannii, one of six top-priority dangerous pathogens. Thus, the enzyme is a potential target for developing antimicrobial agents against pathogens producing carbapenemases. In this study, OXA-23 was purified and crystallized at 298 K and X-ray diffraction data from OXA-23 crystal were collected at 2.03 Å resolution using synchrotron radiation. The crystal of OXA-23 belonged to space group P41 with unit cell parameters a = 82.47, b = 82.47 and c = 172.01 Å. Analysis of the packing density showed that the asymmetric unit probably contained two molecules with a solvent content of 73.64%.

Resistance to tetracycline and β-lactams and distribution of resistance markers in enteric microorganisms and pseudomonads isolated from the oral cavity

This study evaluated the occurrence of enteric bacteria and pseudomonads resistant to tetracycline and β-lactams in the oral cavity of patients exhibiting gingivitis (n=89), periodontitis (n=79), periodontally healthy (n=50) and wearing complete dentures (n=41). Microbial identification and presence of resistance markers associated with the production of β-lactamases and tetracycline resistance were performed by using biochemical tests and PCR. Susceptibility tests were carried out in 201 isolates of enteric cocci and rods. Resistance to ampicillin, amoxicillin/clavulanic acid, imipenem, meropenem and tetracycline was detected in 57.4 percent, 34.6 percent, 2.4 percent, 1.9 percent and 36.5 percent of the isolates, respectively. β-lactamase production was observed in 41.2 percent of tested microorganisms, while the most commonly found β-lactamase genetic determinant was gene blaTEM. Tetracycline resistance was disseminated and a wide scope of tet genes were detected in all studied microbial genus.

Synthesis of a novel beta-lactamase hydrolysis resistant penicillin analog

It has been suggested that Lys234 residue participates in beta-lactamase catalysis by acting as an electrostatic anchor for the C-3 carboxylate of penicillin. The aim of the present work is to test the role of the carboxylate group at C-3 in binding with the enzyme. A novel penicillin derivative, 3- aminomethyl-6-phenylacetamidopenicillanate, was prepared in which the carboxylic acid group at C-3 was replaced by an amino group. This was achieved by the reduction of a mixed anhydride of penicillin G to obtain 6-phenylacetamidopenicillanyl alcohol. The behavior of the alcoholic function in reacting with acidic components, following Mitsunobu reaction, was investigated, and 3-di-tert-butoxycarbonylaminomethyl-6-phenylacetamidopenicillanate was prepared as a crude product. After purification using column chromatography, the crude product undergoes deprotection of the amino group to produce the desired compound 3-aminomethyl-6- phenylacetamidopenicillanate. The hydrolysis of this compound by beta-lactamase and the altered beta- lactamase was determined and studied. The alteration in beta-lactamase was done by changing the lys234 residue to glutamic acid residue using site specific mutagenesis

Terapia de bacterias productoras de b-lactamasas de espectro extendido / Treatment of extended spectrum betalactamases producing bacteria

Se analizan aspectos epidemiológicos de Enterobacteriaceas productoras de ß-lactamasas de espectro expandido y alternativas terapéuticas; dentro de éstas se discute el rol de cefepime, aminoglucósidos, quinolonas, ß lactámicos combinados con inhibidores de ß -lactamasas y carbapenems. Estos últimos constituyen la elección en la terapia de infecciones graves causadas por estas bacterias multiresistentes.

Moraxela, subespecie branhamella catarrhalis: primera cepa aislada en un sintomatico respiratorio como causa etiologica, en la ciudad de La Paz-Bolivia / Moraxela, subspecies branhamella catarralis: first isolated chains in the sintomatic respiratory as isolated chains etiology, in the La Paz city-Bolivia

Paciente adulto de sexo masculino atendido en el hospital "San gabriel" que ingresa con signo-sintomatologia de sindrome de condensacion pulmonar y al que en fecha 30-05-1994 se le practico examen bacteriologico de esputo (muestra No 131/94) para determinar el agente etiologico. El estudio reaslizado demuestra a moraxella, subespecie branhamella catarrhalis como el agente causal, y en la prueba para deteccion de beta-lactamasa resulto ser positiva. Es necesario reconocer en los procedimientos bacteriologicos de rutina la psibilidad de diagnosticar a este microorganismo, observando con especial cuidado la resistencia a las penicilinas.