Luminescent Ln(III)-Metallopeptide Sensors for Monitoring Elastase B Activity in Complex Biological Media.

The detection and monitoring of and its virulence factors, such as the LasB protease, are crucial for managing bacterial infections. Traditional fluorescent sensors for this protease face limitations in bacterial cultures due to interference from pigments like pyoverdine secreted by this opportunistic pathogen. We report here a Ln(III)-metallopeptide that combines a DO3A-Ln(III) complex and a sensitizing unit via a short peptide sequence as a simple, tunable, and selective probe for detecting 's LasB.

The Inactivation of the Putative Two-Component System Sensor PA14_27940 Increases the Susceptibility to Several Antibiotics and Reduces the Motility of .

The identification of targets whose inactivation increases the activity of antibiotics helps to fight antibiotic resistance. Previous work showed that a transposon-insertion mutant in the gene increases susceptibility to aminoglycosides. Since polar effects may affect the phenotype, in the present work, we generated an in-frame deletion mutant.

Virulence and Metabolism Crosstalk: Impaired Activity of the Type Three Secretion System (T3SS) in a Crc-Defective Mutant.

is a ubiquitous nosocomial opportunistic pathogen that harbors many virulence determinants. Part of success colonizing a variety of habitats resides in its metabolic robustness and plasticity, which are the basis of its capability of adaptation to different nutrient sources and ecological conditions, including the infected host. Given this situation, it is conceivable that virulence might be, at least in part, under metabolic control, in such a way that virulence determinants are produced just when needed.

Collateral Sensitivity to Fosfomycin of Tobramycin-Resistant Mutants of Is Contingent on Bacterial Genomic Background.

Understanding the consequences in bacterial physiology of the acquisition of drug resistance is needed to identify and exploit the weaknesses derived from it. One of them is collateral sensitivity, a potentially exploitable phenotype that, unfortunately, is not always conserved among different isolates. The identification of robust, conserved collateral sensitivity patterns is then relevant for the translation of this knowledge into clinical practice.

The Acquisition of Colistin Resistance Is Associated to the Amplification of a Large Chromosomal Region in kp52145.

The appearance of carbapenem-resistant has increased the use of colistin as a last-resort antibiotic for treating infections by this pathogen. A consequence of its use has been the spread of colistin-resistant strains, in several cases carrying colistin resistance genes. In addition, when susceptible strains are confronted with colistin during treatment, mutation is a major cause of the acquisition of resistance.

Prediction of the intestinal resistome by a three-dimensional structure-based method.

The intestinal microbiota is considered to be a major reservoir of antibiotic resistance determinants (ARDs) that could potentially be transferred to bacterial pathogens via mobile genetic elements. Yet, this assumption is poorly supported by empirical evidence due to the distant homologies between known ARDs (mostly from culturable bacteria) and ARDs from the intestinal microbiota. Consequently, an accurate census of intestinal ARDs (that is, the intestinal resistome) has not yet been fully determined.

The intrinsic resistome of Klebsiella pneumoniae.

Molecular epidemiology studies aiming at understanding the acquisition of antimicrobial resistance by clinical isolates of Klebsiella pneumoniae are regularly published; however, information on the genes that contribute to its characteristic phenotype of resistance to antibiotics (intrinsic resistome) is scarce. To fill this gap, a K. pneumoniae transposon mutant library was screened and 171 mutants presenting changes in their susceptibility to antibiotics were selected, in which the transposon insertion site was determined in 75.

Isolation and characterization of pcsB, the gene for a polyene carboxamide synthase that tailors pimaricin into AB-400.

From cell-free extracts of Streptomyces RGU5.3, a tailoring activity of pimaricin, leading to the biosynthesis of its natural carboxamide derivative AB-400, was recently identified. The two polyene macrolides, pimaricin and AB-400, were produced in almost equal quantities and can be detected in the fermentation broth of the producer strain.

Two polyene amides produced by genetically modified Streptomyces diastaticus var. 108.

Streptomyces diastaticus var. 108, a newly isolated strain, was recently characterized as a producer of two polyene macrolide antibiotics (rimocidin and CE-108), and the biosynthetic gene cluster was partially characterized. When the producer strain was genetically modified by transformation with some engineered SCP2*-derived vectors carrying the ermE gene, two previously uncharacterized macrolides were detected in the fermentation broth of the recombinant strain and chemically characterized as the amides of the parental polyene carboxylic acids.