Klebsiella pneumoniae sequence type 11 from companion animals bearing ArmA methyltransferase, DHA-1 β-lactamase, and QnrB4

Seven Klebsiella pneumoniae isolates from dogs and cats in Spain were found to be highly resistant to aminoglycosides, and ArmA methyltransferase was responsible for this phenotype. All isolates were typed by multilocus sequence typing (MLST) as ST11, a human epidemic clone reported worldwide and associated with, among others, OXA-48 and NDM carbapenemases. In the seven strains, armA was borne by an IncR plasmid, pB1025, of 50 kb. The isolates were found to coproduce DHA-1 and SHV-11 β-lactamases, as well as the QnrB4 resistance determinant. This first report of the ArmA methyltransferase in pets illustrates their importance as a reservoir for human multidrug-resistant K. pneumoniae.

Association of extended-spectrum β-lactamase VEB-5 and 16S rRNA methyltransferase armA in Salmonella enterica from the United Kingdom

Aminoglycosides and beta-lactams are used for the treatment of a wide range of infections due to both Gram-negative and Gram-positive. An emerging aminoglycoside resistance mechanism, methylation of the aminoacyl site of the 16S rRNA, confers high-level resistance to clinically important aminoglycosides such as amikacin, tobramycin and gentamicin. Eight 16S rRNA methyltransferase genes, armA, rmtA, rmtB, rmtC, rmtD, rmtE, rmtF and npmA, have been identified in several species of enterobacteria worldwide (2, 6, 7, 9, 11, 13, 14). Resistance to extended spectrum β-lactams remains additionally an important clinical problem. Apart from the large TEM, SHV, and CTX-M families, several other extended-spectrum β-lactamases (ESBLs) have been identified, including VEB enzymes, which confer high-level resistance to cephalosporins and monobactams. Although 16S rRNA methyltransferases have been frequently identified associated with different ESBLs, there has been no report of association of a 16S rRNA methyltransferase with a VEB enzyme, except for the identification of rmtC with blaVEB-6 (14)

ArmA methyltransferase in a monophasic Salmonella enterica isolate from food

The 16S rRNA methyltransferase ArmA is a worldwide emerging determinant that confers high-level resistance to most clinically relevant aminoglycosides. We report here the identification and characterization of a multidrug-resistant Salmonella enterica subspecies I.4,12:i:- isolate recovered from chicken meat sampled in a supermarket on February 2009 in La Reunion, a French island in the Indian Ocean. Susceptibility testing showed an unusually high-level resistance to gentamicin, as well as to ampicillin, expanded-spectrum cephalosporins and amoxicillin-clavulanate. Molecular analysis of the 16S rRNA methyltransferases revealed presence of the armA gene, together with bla(TEM-1), bla(CMY-2), and bla(CTX-M-3). All of these genes could be transferred en bloc through conjugation into Escherichia coli at a frequency of 10(-5) CFU/donor. Replicon typing and S1 pulsed-field gel electrophoresis revealed that the armA gene was borne on an ~150-kb broad-host-range IncP plasmid, pB1010. To elucidate how armA had integrated in pB1010, a PCR mapping strategy was developed for Tn1548, the genetic platform for armA. The gene was embedded in a Tn1548-like structure, albeit with a deletion of the macrolide resistance genes, and an IS26 was inserted within the mel gene. To our knowledge, this is the first report of ArmA methyltransferase in food, showing a novel route of transmission for this resistance determinant. Further surveillance in food-borne bacteria will be crucial to determine the role of food in the spread of 16S rRNA methyltransferase genes worldwide.

El VII Marqués del Carpio y las letras

Esta tesis pretende, por un lado, estudiar las distintas bibliotecas de Gaspar de Haro y Guzmán, VII marqués del Carpio. Durante sus 58 años de vida reunió alrededor de 6.000 libros que repartió en sus residencias de Madrid, Lisboa, Roma y Nápoles, y que conocemos gracias a distintos inventarios que permiten un estudio completo y cronológico. Se ha atendido para el estudio al conjunto del inventario de bienes, y no sólo a la parte dedicada a los libros, permitiendo reconstruir no sólo el contenido de la biblioteca sino también su decoración y sus usos prácticos. En segundo lugar, se atiende al intencionado uso político de las letras (dedicatorias, usos de la imprenta, patronazgo) como arma para la lucha política y cortesana. La tesis aspira a ser un trabajo relacionado con el amplio campo de la Cultura escrita, entendida como aquella línea de investigación histórica que reflexiona sobre los procesos que generan documentación (impresa y manuscrita), sus usos y fines, así como los espacios y dispositivos que han permitido su conservación, no siempre de forma conjunta. Pero es sobre todo un estudio que podríamos englobar en el vasto campo de la Historia cultural de la política, tomando como case study a Gaspar de Haro y Guzmán...

Fitness cost and interference of Arm/Rmt aminoglycoside resistance with the RsmF housekeeping methyltransferases

Arm/Rmt methyltransferases have emerged recently in pathogenic bacteria as enzymes that confer high-level resistance to 4,6-disubstituted aminoglycosides through methylation of the G1405 residue in the 16S rRNA (like ArmA and RmtA to -E). In prokaryotes, nucleotide methylations are the most common type of rRNA modification, and they are introduced posttranscriptionally by a variety of site-specific housekeeping enzymes to optimize ribosomal function. Here we show that while the aminoglycoside resistance methyltransferase RmtC methylates G1405, it impedes methylation of the housekeeping methyltransferase RsmF at position C1407, a nucleotide that, like G1405, forms part of the aminoglycoside binding pocket of the 16S rRNA. To understand the origin and consequences of this phenomenon, we constructed a series of in-frame knockout and knock-in mutants of Escherichia coli, corresponding to the genotypes rsmF(+), ΔrsmF, rsmF(+) rmtC(+), and ΔrsmF rmtC(+). When analyzed for the antimicrobial resistance pattern, the ΔrsmF bacteria had a decreased susceptibility to aminoglycosides, including 4,6- and 4,5-deoxystreptamine aminoglycosides, showing that the housekeeping methylation at C1407 is involved in intrinsic aminoglycoside susceptibility in E. coli. Competition experiments between the isogenic E. coli strains showed that, contrary to expectation, acquisition of rmtC does not entail a fitness cost for the bacterium. Finally, matrix-assisted laser desorption ionization (MALDI) mass spectrometry allowed us to determine that RmtC methylates the G1405 residue not only in presence but also in the absence of aminoglycoside antibiotics. Thus, the coupling between housekeeping and acquired methyltransferases subverts the methylation architecture of the 16S rRNA but elicits Arm/Rmt methyltransferases to be selected and retained, posing an important threat to the usefulness of aminoglycosides worldwide.

Ira, odio, rutina, dolor. La Primera Guerra mundial en los testimonios directos

Se trata de abordar una sociología de la guerra desde la perspectiva del soldado, cuestionando algunos de los tópicos sobre los motivos de los actos bélicos (combate ideológico, lucha por la civilización, defensa de la patria) los cuales se ven desplazados por otros impulsos que aparecen de manera reiterada en los relatos o memorias de aquellos (solidaridad, hermandad de lucha, antagonismos con los oficiales) y que a su vez convocan aspectos inusitados del combate (el aburrimiento masivo, la culpabilidad de matar, la compleja relación con la retaguardia). La intención estriba en proponer una historia de las emociones en la guerra a través del análisis de los testimonios del frente para lo que se cuenta con una ingente cantidad de cartas, memorias y otros relatos de primera mano que fueron especialmente abundantes y se vieron estimulados por los dirigentes políticos y militares para cuidar la moral de la tropa en el conflicto de la Gran Guerra. La imagen resultante sugiere que la guerra no es (solo) el infierno y el soldado que empuña un arma no es una bestia enloquecida. En la guerra los actos de matar los cometen sujetos históricos provistos de lenguaje, emoción y deseo; dicho de otro modo, matar en tiempos bélicos es inseparable de cuestiones sociales y culturales más amplias, por lo que el combate no acaba con las relaciones sociales, sino que más bien las reestructura.