Hypericibacter terrae gen. nov., sp. nov. and Hypericibacter adhaerens sp. nov., two new members of the family Rhodospirillaceae isolated from the rhizosphere of Hypericum perforatum.

Two strains of the family Rhodospirillaceae were isolated from the rhizosphere of the medicinal plant Hypericum perforatum. Cells of both strains were Gram-stain-negative, motile by means of a single polar flagellum, non-spore-forming, non-capsulated, short rods that divided by binary fission. Colonies were small and white. Strains R5913T and R5959T were oxidase-positive, mesophilic, neutrophilic and grew optimally without NaCl. Both grew under aerobic and microaerophilic conditions and on a limited range of substrates with best results on yeast extract. Major fatty acids were C19 : 0 cyclo ω8c and C16 : 0; in addition, C18 : 1ω7c was also found as a predominant fatty acid in strain R5913T. The major respiratory quinone was ubiquinone 10 (Q-10). The DNA G+C contents of strains R5913T and R5959T were 66.0 and 67.4 mol%, respectively. 16S rRNA gene sequence comparison revealed that the closest relatives (<92 % similarity) of the strains are Oceanibaculum pacificum MCCC 1A02656T, Dongia mobilis CGMCC 1.7660T, Dongia soli D78T and Dongia rigui 04SU4-PT. The two novel strains shared 98.6 % sequence similarity and represent different species on the basis of low average nucleotide identity of their genomes (83.8 %). Based on the combined phenotypic, genomic and phylogenetic investigations, the two strains represent two novel species of a new genus in the family Rhodospirillaceae, for which the name Hypericibacter gen. nov. is proposed, comprising the type species Hypericibacter terrae sp. nov. (type strain R5913T=DSM 109816T=CECT 9472T) and Hypericibacter adhaerens sp. nov. (type strain R5959T=DSM 109817T=CECT 9620T).

Repurposing human kinase inhibitors to create an antibiotic active against drug-resistant Staphylococcus aureus, persisters and biofilms.

New drugs are desperately needed to combat methicillin-resistant Staphylococcus aureus (MRSA) infections. Here, we report screening commercial kinase inhibitors for antibacterial activity and found the anticancer drug sorafenib as major hit that effectively kills MRSA strains. Varying the key structural features led to the identification of a potent analogue, PK150, that showed antibacterial activity against several pathogenic strains at submicromolar concentrations. Furthermore, this antibiotic eliminated challenging persisters as well as established biofilms. PK150 holds promising therapeutic potential as it did not induce in vitro resistance, and shows oral bioavailability and in vivo efficacy. Analysis of the mode of action using chemical proteomics revealed several targets, which included interference with menaquinone biosynthesis by inhibiting demethylmenaquinone methyltransferase and the stimulation of protein secretion by altering the activity of signal peptidase IB. Reduced endogenous menaquinone levels along with enhanced levels of extracellular proteins of PK150-treated bacteria support this target hypothesis. The associated antibiotic effects, especially the lack of resistance development, probably stem from the compound's polypharmacology.

Liposomal mupirocin holds promise for systemic treatment of invasive Staphylococcus aureus infections.

Staphylococcus aureus is a major cause of severe invasive infections. The increasing incidence of infections caused by antibiotic-resistant strains such as methicillin-resistant S. aureus (MRSA), calls for exploration of new approaches to treat these infections. Mupirocin is an antibiotic with a unique mode of action that is active against MRSA, but its clinical use is restricted to topical administration because of its limited plasma stability and rapid degradation to inactive metabolites. Mupirocin was identified by a machine learning approach to be suitable for nano-liposome encapsulation. The computational predictions were verified experimentally and PEGylated nano-liposomal formulation of mupirocin (Nano-mupirocin) was developed. The aim of this study was to investigate the efficacy of this formulation when administered parenterally for the treatment of S. aureus invasive infections. Nano-mupirocin exhibited prolonged half-life of active antibiotic and displayed superior antimicrobial activity against S. aureus than free mupirocin in the presence of plasma. Parenteral application of Nano-mupirocin in a murine model of S. aureus bloodstream infection resulted in improved antibiotic distribution to infected organs and in a superior therapeutic efficacy than the free drug. Parenterally administered Nano-mupirocin was also more active against MRSA than free mupirocin in a neutropenic murine lung infection model. In addition, Nano-mupirocin was very efficiently taken up by S. aureus-infected macrophages via phagocytosis leading to enhanced delivery of mupirocin in the intracellular niche and to a more efficient elimination of intracellular staphylococci. The outcome of this study highlights the potential of Nano-mupirocin for the treatment of invasive MRSA infections and support the further clinical development of this effective therapeutic approach.

Macrophage entrapped silica coated superparamagnetic iron oxide particles for controlled drug release in a 3D cancer model.

Targeted delivery of drugs is a major challenge in treatment of diverse diseases. Systemically administered drugs demand high doses and are accompanied by poor selectivity and side effects on non-target cells. Here, we introduce a new principle for targeted drug delivery. It is based on macrophages as transporters for nanoparticle-coupled drugs as well as controlled release of drugs by hyperthermia mediated disruption of the cargo cells and simultaneous deliberation of nanoparticle-linked drugs. Hyperthermia is induced by an alternating electromagnetic field (AMF) that induces heat from silica-coated superparamagnetic iron oxide nanoparticles (SPIONs). We show proof-of-principle of controlled release by the simultaneous disruption of the cargo cells and the controlled, AMF induced release of a toxin, which was covalently linked to silica-coated SPIONs via a thermo-sensitive linker. Cells that had not been loaded with SPIONs remain unaffected. Moreover, in a 3D co-culture model we demonstrate specific killing of associated tumour cells when employing a ratio as low as 1:40 (SPION-loaded macrophage: tumour cells). Overall, our results demonstrate that AMF induced drug release from macrophage-entrapped nanoparticles is tightly controlled and may be an attractive novel strategy for targeted drug release.

Azithromycin Synergizes with Cationic Antimicrobial Peptides to Exert Bactericidal and Therapeutic Activity Against Highly Multidrug-Resistant Gram-Negative Bacterial Pathogens.

Antibiotic resistance poses an increasingly grave threat to the public health. Of pressing concern, rapid spread of carbapenem-resistance among multidrug-resistant (MDR) Gram-negative rods (GNR) is associated with few treatment options and high mortality rates. Current antibiotic susceptibility testing guiding patient management is performed in a standardized manner, identifying minimum inhibitory concentrations (MIC) in bacteriologic media, but ignoring host immune factors. Lacking activity in standard MIC testing, azithromycin (AZM), the most commonly prescribed antibiotic in the U.S., is never recommended for MDR GNR infection. Here we report a potent bactericidal action of AZM against MDR carbapenem-resistant isolates of Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii. This pharmaceutical activity is associated with enhanced AZM cell penetration in eukaryotic tissue culture media and striking multi-log-fold synergies with host cathelicidin antimicrobial peptide LL-37 or the last line antibiotic colistin. Finally, AZM monotherapy exerts clear therapeutic effects in murine models of MDR GNR infection. Our results suggest that AZM, currently ignored as a treatment option, could benefit patients with MDR GNR infections, especially in combination with colistin.

Efficiency of conditionally attenuated Salmonella enterica serovar Typhimurium in bacterium-mediated tumor therapy.

UNLABELLED: Increasing numbers of cancer cases generate a great urge for new treatment options. Applying bacteria like Salmonella enterica serovar Typhimurium for cancer therapy represents an intensively explored option. These bacteria have been shown not only to colonize solid tumors but also to exhibit an intrinsic antitumor effect. In addition, they could serve as tumor-targeting vectors for therapeutic molecules. However, the pathogenic S. Typhimurium strains used for tumor therapy need to be attenuated for safe application. Here, lipopolysaccharide (LPS) deletion mutants (ΔrfaL, ΔrfaG, ΔrfaH, ΔrfaD, ΔrfaP, and ΔmsbB mutants) of Salmonella were investigated for efficiency in tumor therapy. Of such variants, the ΔrfaD and ΔrfaG deep rough mutants exhibited the best tumor specificity and lowest pathogenicity. However, the intrinsic antitumor effect was found to be weak. To overcome this limitation, conditional attenuation was tested by complementing the mutants with an inducible arabinose promoter. The chromosomal integration of the respective LPS biosynthesis genes into the araBAD locus exhibited the best balance of attenuation and therapeutic benefit. Thus, the present study establishes a basis for the development of an applicably cancer therapeutic bacterium. IMPORTANCE: Cancer has become the second most frequent cause of death in industrialized countries. This and the drawbacks of routine therapies generate an urgent need for novel treatment options. Applying appropriately modified S. Typhimurium for therapy represents the major challenge of bacterium-mediated tumor therapy. In the present study, we demonstrated that Salmonella bacteria conditionally modified in their LPS phenotype exhibit a safe tumor-targeting phenotype. Moreover, they could represent a suitable vehicle to shuttle therapeutic compounds directly into cancerous tissue without harming the host.

Characterization of JG024, a pseudomonas aeruginosa PB1-like broad host range phage under simulated infection conditions.

BACKGROUND: Pseudomonas aeruginosa causes lung infections in patients suffering from the genetic disorder Cystic Fibrosis (CF). Once a chronic lung infection is established, P. aeruginosa cannot be eradicated by antibiotic treatment. Phage therapy is an alternative to treat these chronic P. aeruginosa infections. However, little is known about the factors which influence phage infection of P. aeruginosa under infection conditions and suitable broad host range phages. RESULTS: We isolated and characterized a phage, named JG024, which infects a broad range of clinical and environmental P. aeruginosa strains. Sequencing of the phage genome revealed that the phage JG024 is highly related to the ubiquitous and conserved PB1-like phages. The receptor of phage JG024 was determined as lipopolysaccharide. We used an artificial sputum medium to study phage infection under conditions similar to a chronic lung infection. Alginate production was identified as a factor reducing phage infectivity. CONCLUSIONS: Phage JG024 is a suitable broad host range phage which could be used in phage therapy. Phage infection experiments under simulated chronic lung infection conditions showed that alginate production reduces phage infection efficiency.

Caldanaerovirga acetigignens gen. nov., sp. nov., an anaerobic xylanolytic, alkalithermophilic bacterium isolated from Trego Hot Spring, Nevada, USA.

An anaerobic thermophilic bacterium, designated strain JW/SA-NV4(T), was isolated from a xylan-supplemented enrichment culture from Trego hot spring located within the Black Rock Desert (NV, USA). Cells were generally straight or slightly bent rod-shaped, 0.4-0.8 microm in width and 3-6 microm in length during exponential growth. Cells from stationary phase were variable in size and shape, showing curved or bent morphology. Motility was not seen and flagella were not observed in electron micrographs. Sporulation was not observed. Strain JW/SA-NV4(T) stained Gram-negative but is phylogenetically Gram-type positive. Growth occurred at pH(25 degrees C) 6.8-8.8, with optimum growth at pH 8.4; no growth occurred at pH 9.0 or above or at 6.5 or below. With glucose or xylose as the carbon source, strain JW/SA-NV4(T) grew at 44-74 degrees C; no growth occurred at 76 degrees C or above or at 42 degrees C or below. However, the optimum temperature was 62 and 66 degrees C when grown on glucose and xylose, respectively. The shortest doubling time observed with glucose was approximately 4 h, and with xylose approximately 3.4 h. Strain JW/SA-NV4(T) tolerated an atmosphere containing up to 0.1 % O(2); no growth occurred at a gas atmosphere of 0.2 % O(2). Chemo-organotrophic growth occurred with xylose, glucose, mannose, xylan, pyruvate, fructose, ribose, Casamino acids, mannitol, tryptone, peptone, cellobiose and yeast extract. When grown in mineral media containing 1 g yeast extract l(-1) as an electron donor, thiosulfate and sulfur were reduced to sulfide. The G+C content of the DNA was 38.6 mol% (HPLC). 16S rRNA gene sequence analysis placed strain JW/SA-NV4(T) within the order Thermoanaerobacterales and within the Thermoanaerobacterales Incertae Sedis Family III, specifically between taxa classified within the genera Thermosediminibacter and Thermovenabulum. The closest phylogenetic neighbours were Thermosediminibacter oceani JW/IW-1228P(T) (94.2 % 16S rRNA gene sequence similarity) and Thermosediminibacter litoriperuensis JW/YJL-1230-7/2(T) (94.0 %) [Lee, Y.-J., Wagner, I. D., Brice, M. E., Kevbrin, V. V., Mills, G. L., Romanek, C. S. & Wiegel, J. (2005). Extremophiles 9, 375-383]. Based on physiological and genotypic characteristics, strain JW/SA-NV4(T) (=DSM 18802(T)=ATCC BAA-1454(T)) is proposed to represent the type strain of a novel species in a novel genus, Caldanaerovirga acetigignens gen. nov., sp. nov.

The host response to the probiotic Escherichia coli strain Nissle 1917: specific up-regulation of the proinflammatory chemokine MCP-1.

BACKGROUND: The use of live microorganisms to influence positively the course of intestinal disorders such as infectious diarrhea or chronic inflammatory conditions has recently gained increasing interest as a therapeutic alternative. In vitro and in vivo investigations have demonstrated that probiotic-host eukaryotic cell interactions evoke a large number of responses potentially responsible for the effects of probiotics. The aim of this study was to improve our understanding of the E. coli Nissle 1917-host interaction by analyzing the gene expression pattern initiated by this probiotic in human intestinal epithelial cells. METHODS: Gene expression profiles of Caco-2 cells treated with E. coli Nissle 1917 were analyzed with microarrays. A second human intestinal cell line and also pieces of small intestine from BALB/c mice were used to confirm regulatory data of selected genes by real-time RT-PCR and cytometric bead array (CBA) to detect secretion of corresponding proteins. RESULTS: Whole genome expression analysis revealed 126 genes specifically regulated after treatment of confluent Caco-2 cells with E. coli Nissle 1917. Among others, expression of genes encoding the proinflammatory molecules monocyte chemoattractant protein-1 ligand 2 (MCP-1), macrophage inflammatory protein-2 alpha (MIP-2alpha) and macrophage inflammatory protein-2 beta (MIP-2beta) was increased up to 10 fold. Caco-2 cells cocultured with E. coli Nissle 1917 also secreted high amounts of MCP-1 protein. Elevated levels of MCP-1 and MIP-2alpha mRNA could be confirmed with Lovo cells. MCP-1 gene expression was also up-regulated in mouse intestinal tissue. CONCLUSION: Thus, probiotic E. coli Nissle 1917 specifically upregulates expression of proinflammatory genes and proteins in human and mouse intestinal epithelial cells.