Triclosan, a very widely used biocide, specifically inhibits fatty acid synthesis by inhibition of enoyl-acyl carrier protein (ACP) reductase. Escherichia coli FabI is the prototypical triclosan-sensitive enoyl-ACP reductase, and E. coli is extremely sensitive to the biocide. However, other bacteria are resistant to triclosan, because they encode triclosan-resistant enoyl-ACP reductase isozymes. In contrast, the triclosan resistance of Pseudomonas aeruginosa PAO1 has been attributed to active efflux of the compound (R. Chuanchuen, R. R. KarkhoffSchweizer, and H. P. Schweizer, Am. J. Infect. Control 31:124-127, 2003). We report that P. aeruginosa contains two enoyl-ACP reductase isozymes, the previously characterized FabI homologue plus a homologue of FabV, a triclosan-resistant enoyl-ACP reductase recently demonstrated in Vibrio cholerae. By deletion of the genes encoding P. aeruginosa FabI and FabV, we demonstrated that FabV confers triclosan resistance on P. aeruginosa. Upon deletion of the fabV gene, the mutant strain became extremely sensitive to triclosan (>2,000-fold more sensitive than the wild-type strain), whereas the mutant strain lacking FabI remained completely resistant to the biocide.

BackgroundThis meta-analysis aimed to evaluate the postoperative clinical outcomes and safety of the direct anterior approach (DAA) versus posterior approach (PA) in total hip arthroplasty (THA).MethodsWe searched PubMed, Embase, Web of Science, the Cochrane Library, and Google databases from inception to June 2018 to select studies that compared the DAA and PA for THA. Only randomized controlled trials (RCTs) were included. Outcomes included Harris hip score at 2 weeks, 6 weeks, 12 weeks, and 1 year; VAS at 24 h, 48 h, and 72 h; incision length, operation time, postoperative blood loss, length of hospital stay, and complications (intraoperative fracture, postoperative dislocation, heterotopic ossification (HO), and groin pain).ResultsNine RCTs totaling 754 THAs (DAA group = 377, PA group = 377) met the criteria to be included in this meta-analysis. The present meta-analysis indicated that, compared with PA group, DAA group was associated with an increase of the Harris hip score at the 2-week and 4-week time points. No significant difference was found between DAA and PA groups of the Harris hip scores at 12 weeks, 1 year length of hospital stay (p > 0.05). DAA group was associated with a reduction of the VAS at 24 h, 48 h, and 72 h with statistical significance (p < 0.05). What is more, DAA was associated with a reduction of the incision length and postoperative blood loss (p < 0.05). There was no significant difference between the operation time and complications (intraoperative fracture, postoperative dislocation, HO, and groin pain).ConclusionIn THA patients, compared with PA, DAA was associated with an early functional recovery and less pain scores. What is more, DAA was associated with shorter incision length and blood loss.

Summary Signal molecules of the Diffusible Signal Factor (DSF) family have been shown recently to be involved in regulation of pathogenesis and biofilm formation in diverse Gram-negative bacteria. DSF signals are reported to be active not only on their cognate bacteria, but also on unrelated bacteria and the pathogenic yeast, Candida albicans. DSFs are monounsaturated fatty acids of medium chain length containing an unusual cis-2 double bond. Although genetic analyses had identified genes involved in DSF synthesis, the pathway of DSF synthesis was unknown. The DSF of the important human pathogen Burkholderia cenocepacia (called BDSF) is cis-2-dodecenoic acid. We report that BDSF is synthesized from a fatty acid synthetic intermediate, the acyl carrier protein (ACP) thioester of 3-hydroxydodecanoic acid. This intermediate is intercepted by protein Bcam0581 and converted to cis-2-dodecenoyl-ACP. Bcam0581 is annotated as a homologue of crotonase, the first enzyme of the fatty acid degradation pathway. We demonstrated Bcam0581to be a bifunctional protein that not only catalyzed dehydration of 3-hydroxydodecanoyl-ACP to cis-2-dodecenoyl-ACP, but also cleaved the thioester bond to give the free acid. Both activities required the same set of active site residues. Although dehydratase and thioesterase activities are known activities of the crotonase superfamily, Bcam0581 is the first protein shown to have both activities.

The anaerobic unsaturated fatty acid synthetic pathway of Escherichia coli requires two specialized proteins, FabA and FabB. However, the fabA and fabB genes are found only in the Gram-negative ␣-and ␥-proteobacteria, and thus other anaerobic bacteria must synthesize these acids using different enzymes. We report that the Gram-positive bacterium Enterococcus faecalis encodes a protein, annotated as FabZ1, that functionally replaces the E. coli FabA protein, although the sequence of this protein aligns much more closely with E. coli FabZ, a protein that plays no specific role in unsaturated fatty acid synthesis. Therefore E. faecalis FabZ1 is a bifunctional dehydratase/isomerase, an enzyme activity heretofore confined to a group of Gram-negative bacteria. The FabZ2 protein is unable to replace the function of E. coli FabZ, although FabZ2, a second E. faecalis FabZ homologue, has this ability. Moreover, an E. faecalis FabF homologue (FabF1) was found to replace the function of E. coli FabB, whereas a second FabF homologue was inactive. From these data it is clear that bacterial fatty acid biosynthetic pathways cannot be deduced solely by sequence comparisons.