Clonal Parabacteroides from Gut Microfistulous Tracts as Transmissible Cytotoxic Succinate-Commensal Model of Crohn's Disease Complications.

Crohn's disease (CD) has been traditionally viewed as a chronic inflammatory disease that cause gut wall thickening and complications, including fistulas, by mechanisms not understood. By focusing on Parabacteroides distasonis (presumed modern succinate-producing commensal probiotic), recovered from intestinal microfistulous tracts (cavernous fistulous micropathologies CavFT proposed as intermediate between 'mucosal fissures' and 'fistulas') in two patients that required surgery to remove CD-damaged ilea, we demonstrate that such isolates exert pathogenic/pathobiont roles in mouse models of CD. Our isolates are clonally-related; potentially emerging as transmissible in the community and mice; proinflammatory and adapted to the ileum of germ-free mice prone to CD-like ileitis (SAMP1/YitFc) but not healthy mice (C57BL/6J), and cytotoxic/ATP-depleting to HoxB8-immortalized bone marrow derived myeloid cells from SAMP1/YitFc mice when concurrently exposed to succinate and extracts from CavFT-derived E. coli , but not to cells from healthy mice. With unique genomic features supporting recent genetic exchange with Bacteroides fragilis -BGF539, evidence of international presence in primarily human metagenome databases, these CavFT Pdis isolates could represent to a new opportunistic Parabacteroides species, or subspecies (' cavitamuralis' ) adapted to microfistulous niches in CD.

Targeting Multidrug-Resistant Acinetobacter spp.: Sulbactam and the Diazabicyclooctenone ß-Lactamase Inhibitor ETX2514 as a Novel Therapeutic Agent.

Multidrug-resistant (MDR) Acinetobacter spp. poses a significant therapeutic challenge in part due to the presence of chromosomally encoded ß-lactamases, including class C Acinetobacter-derived cephalosporinases (ADC) and class D oxacillinases (OXA), as well as plasmid-mediated class A ß-lactamases. Importantly, OXA-like ß-lactamases represent a gap in the spectrum of inhibition by recently approved ß-lactamase inhibitors such as avibactam and vaborbactam. ETX2514 is a novel, rationally designed, diazabicyclooctenone inhibitor that effectively targets class A, C, and D ß-lactamases. We show that addition of ETX2514 significantly increased the susceptibility of clinical Acinetobacterbaumannii isolates to sulbactam. AdeB and AdeJ were identified to be key efflux constituents for ETX2514 in A. baumannii The combination of sulbactam and ETX2514 was efficacious against A. baumannii carrying blaTEM-1, blaADC-82, blaOXA-23, and blaOXA-66 in a neutropenic murine thigh infection model. We also show that, in vitro, ETX2514 inhibited ADC-7 (k2/Ki 1.0 ± 0.1 × 106 M-1 s-1) and OXA-58 (k2/Ki 2.5 ± 0.3 × 105 M-1 s-1). Cocrystallization of ETX2514 with OXA-24/40 revealed hydrogen bonding interactions between ETX2514 and residues R261, S219, and S128 of OXA-24/40 in addition to a chloride ion occupied in the active site. Further, the C3 methyl group of ETX2514 shifts the position of M223. In conclusion, the sulbactam-ETX2514 combination possesses a broadened inhibitory range to include class D ß-lactamases as well as class A and C ß-lactamases and is a promising therapeutic candidate for infections caused by MDR Acinetobacter spp.IMPORTANCE The number and diversity of ß-lactamases are steadily increasing. The emergence of ß-lactamases that hydrolyze carbapenems poses a significant threat to our antibiotic armamentarium. The explosion of OXA enzymes that are carbapenem hydrolyzers is a major challenge (carbapenem-hydrolyzing class D [CHD]). An urgent need exists to discover ß-lactamase inhibitors with class D activity. The sulbactam-ETX2514 combination demonstrates the potential to become a treatment regimen of choice for Acinetobacter spp. producing class D ß-lactamases.

Microbial contamination of hematopoietic progenitor and other regenerative cells used in transplantation and regenerative medicine.

BACKGROUND: Microbial contamination of hematopoietic progenitor cells (HPCs) and other regenerative cells used in transplantation and regenerative medicine can occur during collection and after in vitro manipulation, including purging, cryopreservation, thawing, and infusion. STUDY DESIGN AND METHODS: Microbiologic culture findings on consecutive HPCs and other cell preparations at a single institution derived from peripheral blood, marrow, cord blood, and mesenchymal stromal cells during all phases of manipulation were retrospectively examined from 2005 through 2011. Results were classified as confirmed positive, false positive, and indeterminate. RESULTS: During the 6-year surveillance period, 365 patients underwent 912 procedures involving HPC or other cell-based transfusion. True positive microbial contamination was found in five of 663 (0.8%) peripheral blood and two of 34 (5.9%) marrow preparations (p = 0.04), while no contamination was found in 118 preparations from other sources. True-positive microbial contaminants included coagulase-negative staphylococci in autologous HPC products derived from peripheral blood from two patients with asymptomatic central venous catheter infections at time of apheresis and Propionibacterium acnes in one apheresis and two marrow products. Organism loads were low in all cases (≤500 colony-forming units/mL), and no adverse sequelae occurred in four patients that received contaminated products. CONCLUSION: The incidence of microbial contamination of progenitor cell products in our institution over a 6-year period was low (0.8% overall), with contaminants originating from infected central venous catheters or from skin flora. All contaminants were bacterial species of low virulence, present in low titers and, if transfused, did not result in adverse reactions.