Impact of Bicarbonate on PBP2a Production, Maturation, and Functionality in Methicillin-Resistant Staphylococcus aureus (MRSA).

Certain methicillin-resistant Staphylococcus aureus (MRSA) strains exhibit ß-lactam-susceptibility in vitro, ex vivo and in vivo in the presence of NaHCO3 (NaHCO3-responsive MRSA). Herein, we investigate the impact of NaHCO3 on factors required for PBP2a functionality. Prototype NaHCO3-responsive and -nonresponsive MRSA strains (as defined in vitro) were assessed for the impact of NaHCO3 on: expression of genes involved in PBP2a production-maturation pathways (mecA, blaZ, pbp4, vraSR, prsA, sigB, and floA); membrane PBP2a and PrsA protein content; and membrane carotenoid content. Following NaHCO3 exposure in NaHCO3-responsive (vs - nonresponsive) MRSA, there was significantly reduced expression of: i) mecA and blaZ; ii) the vraSR-prsA gene axis; and iii) pbp4 Carotenoid production was reduced, while floA expression was increased by NaHCO3 exposure in all MRSA strains. This work underscores the distinct regulatory impact of NaHCO3 on a cadre of genes encoding factors required for maintenance of the MRSA phenotype through PBP2a functionality and maturation.

Combinations of Daptomycin plus Ceftriaxone, but Not Ascending Daptomycin Dose-Regimens, Are Effective in Experimental Endocarditis Caused by Streptococcus mitis-oralis Strains: Target Tissue Clearances and Prevention of Emergence of Daptomycin-Resistance.

The Streptococcus mitis-oralis subgroup of the viridans group streptococci (VGS) are the most common cause of infective endocarditis (IE) in many parts of the world. These organisms are frequently resistant in vitro to standard ß-lactams (e.g., penicillin; ceftriaxone [CRO]), and have the notable capacity for rapidly developing high-level and durable daptomycin resistance (DAP-R) during exposures in vitro, ex vivo, and in vivo. In this study, we used 2 prototypic DAP-susceptible (DAP-S) S. mitis-oralis strains (351; and SF100), which both evolved stable, high-level DAP-R in vitro within 1 to 3 days of DAP passage (5 to 20 µg/mL DAP). Of note, the combination of DAP + CRO prevented this rapid emergence of DAP-R in both strains during in vitro passage. The experimental rabbit IE model was then employed to quantify both the clearance of these strains from multiple target tissues, as well as the emergence of DAP-R in vivo under the following treatment conditions: (i) ascending DAP-alone dose-strategies encompassing human standard-dose and high-dose-regimens; and (ii) combinations of DAP + CRO on these same metrics. Ascending DAP-alone dose-regimens (4 to 18 mg/kg/d) were relatively ineffective at either reducing target organ bioburdens or preventing emergence of DAP-R in vivo. In contrast, the combination of DAP (4 or 8 mg/kg/d) + CRO was effective at clearing both strains from multiple target tissues (often with sterilization of bio-burdens in such organs), as well as preventing the emergence of DAP-R. In patients with serious S. mitis-oralis infections such as IE, especially caused by strains exhibiting intrinsic ß-lactam resistance, initial therapy with combinations of DAP + CRO may be warranted.

Outcomes of open vs laparoscopic vs robotic vs transanal total mesorectal excision (TME) for rectal cancer: a network meta-analysis.

BACKGROUND: Total mesorectal excision (TME) for rectal cancer can be achieved using open (OpTME), laparoscopic (LapTME), robotic (RoTME), or transanal techniques (TaTME). However, the optimal approach for access remains controversial. The aim of this network meta-analysis was to assess operative and oncological outcomes of all four surgical techniques. METHODS: Ovid MEDLINE, EMBASE, and PubMed databases were searched systematically from inception to September 2020, for randomised controlled trials (RCTs) comparing any two TME surgical techniques. A network meta-analysis using a Bayesian random-effects framework and mixed treatment comparison was performed. Primary outcomes were the rate of clear circumferential resection margin (CRM), defined as > 1 mm from the closest tumour to the cut edge of the tissue, and completeness of mesorectal excision. Secondary outcomes included radial and distal resection margin distance, postoperative complications, locoregional recurrence, disease-free survival, and overall survival. Surface under cumulative ranking (SUCRA) was used to rank the relative effectiveness of each intervention for each outcome. The higher the SUCRA value, the higher the likelihood that the intervention is in the top rank or one of the top ranks. RESULTS: Thirty-two RCTs with a total of 6151 patients were included. Compared with OpTME, there was no difference in the rates of clear CRM: LapTME RR = 0.99 (95% (Credible interval) CrI 0.97-1.0); RoTME RR = 1.0 (95% CrI 0.96-1.1); TaTME RR = 1.0 (95% CrI 0.96-1.1). There was no difference in the rates of complete mesorectal excision: LapTME RR = 0.98 (95% CrI 0.98-1.1); RoTME RR = 1.1 (95% CrI 0.98-1.4); TaTME RR = 1.0 (95% CrI 0.91-1.2). RoTME was associated with improved distal resection margin distance compared to other techniques (SUCRA 99%). LapTME had a higher rate of conversion to open surgery when compared with RoTME: RoTME RR = 0.23 (95% CrI 0.034-0.70). Length of stay was shortest in RoTME compared to other surgical approaches: OpTME mean difference in days (MD) 3.3 (95% CrI 0.12-6.0); LapTME MD 1.7 (95% CrI - 1.1-4.4); TaTME MD 1.3 (95% CrI - 5.2-7.4). There were no differences in 5-year overall survival (LapTME HR 1.1, 95% CrI 0.74, 1.4; TaTME HR 1.7, 95% CrI 0.79, 3.4), disease-free survival rates (LapTME HR 1.1, 95% CrI 0.76, 1.4; TaTME HR 1.1, 95% CrI 0.52, 2.4), or anastomotic leakage (LapTME RR = 0.92 (95% CrI 0.63, 1.1); RoTME RR = 1.0 (95% CrI 0.48, 1.8); TaTME RR = 0.53 (95% CrI 0.19, 1.2). The overall quality of evidence as per Grading of Recommendations Assessment, Development and Evaluation (GRADE) assessments across all outcomes including primary and secondary outcomes was deemed low. CONCLUSIONS: In selected patients eligible for a RCT, RoTME achieved improved distal resection margin distance and a shorter length of hospital stay. No other differences were observed in oncological or recovery parameters between (OpTME), laparoscopic (LapTME), robotic (RoTME), or trans-anal TME (TaTME). However, the overall quality of evidence across all outcomes was deemed low.

Synergy Mechanisms of Daptomycin-Fosfomycin Combinations in Daptomycin-Susceptible and -Resistant Methicillin-Resistant Staphylococcus aureus: In Vitro, Ex Vivo, and In Vivo Metrics.

Increased usage of daptomycin (DAP) for methicillin-resistant Staphylococcus aureus (MRSA) infections has led to emergence of DAP-resistant (DAP-R) strains, resulting in treatment failures. DAP-fosfomycin (Fosfo) combinations are synergistically active against MRSA, although the mechanism(s) of this interaction is not fully understood. The current study explored four unique but likely interrelated activities of DAP-Fosfo combinations: (i) synergistic killing, (ii) prevention of evolution of DAP-R, (iii) resensitization of already DAP-R subpopulations to a DAP-susceptible (DAP-S) phenotype, and (iv) perturbations of specific cell envelope phenotypes known to correlate with DAP-R in MRSA. Using an isogenic DAP-S (CB1483)/DAP-R (CB185) clinical MRSA strain pair, we demonstrated that combinations of DAP plus Fosfo (DAP+Fosfo) (i) enhanced killing of both strains in vitro and ex vivo, (ii) increased target tissue clearances of the DAP-R strain in an in vivo model of experimental infective endocarditis (IE), (iii) prevented emergence of DAP-R in the DAP-S parental strain both in vitro and ex vivo, and (iv) resensitized the DAP-R strain to a DAP-S phenotype ex vivo. Phenotypically, following exposure to sub-MIC Fosfo, the DAP-S/DAP-R strain pair exhibited distinct modifications in (i) net positive surface charge (P < 0.05), (ii) quantity (P < 0.0001) and localization of cell membrane cardiolipin (CL), (iii) DAP surface binding, and (iv) membrane fluidity (P < 0.05). Furthermore, preconditioning this strain pair to DAP with or without Fosfo (DAP+/-Fosfo) sensitized these organisms to killing by the human host defense peptide LL37. These data underscore the notion that DAP-Fosfo combinations can impact MRSA clearances within multiple microenvironments, likely based on specific phenotypic adaptations.

Malignant Features in Pretreatment Metastatic Lateral Lymph Nodes in Locally Advanced Low Rectal Cancer Predict Distant Metastases.

INTRODUCTION: Pretreatment enlarged lateral lymph nodes (LLN) in patients with locally advanced low rectal cancer are predictive for local recurrences after neoadjuvant (chemo)radiotherapy (n(C)RT) followed by total mesorectal excision (TME). Not much is known of the impact on oncological outcomes when in addition malignant features are present in enlarged LLN. PATIENTS AND METHODS: A multicenter retrospective cohort study was conducted at five tertiary referral centers in the Netherlands and Australia. All patients were diagnosed with locally advanced low rectal cancer with LLN on pretreatment magnetic resonance imaging (MRI) and underwent n(C)RT followed by TME. LLN were considered enlarged with a short axis of ≥ 5 mm. Malignant features were defined as nodes with internal heterogeneity and/or border irregularity. Outcomes of interest were local recurrence-free survival (LRFS), distant metastatic-free survival (DMFS), and overall survival (OS). RESULTS: Out of 115 patients, the majority was male (75%) and the median age was 64 years (range 26-85 years). Median pretreatment LLN short axis was 7 mm (range 5-28 mm), and 60 patients (52%) had malignant features. After a median follow-up of 47 months, patients with larger LLN (7 + mm) had a worse LRFS (p = 0.01) but no difference in DMFS (p = 0.37) and OS (p = 0.54) compared with patients with smaller LLN (5-6 mm). LLN patients with malignant features had no difference in LRFS (p = 0.20) but worse DMFS (p = 0.004) and OS (p = 0.006) compared with patients without malignant features in the LLN. Cox regression analysis identified LLN short axis as an independent factor for LR. Malignant features in LLN were an independent factor for DMFS. CONCLUSION: The current study suggests that pretreatment enlarged LLN that also harbor malignant features are predictive of a worse DMFS. More studies will be required to further explore the role of malignant features in LLN.

Interstitial cystitis/bladder pain syndrome (IC/BPS): Single-center 20 year experience and treatment results in India.

OBJECTIVES: Interstitial cystitis/bladder pain syndrome (IC/BPS) is an enigmatic disease that is difficult to treat. Even among physicians, the prevalent belief is that patients do not improve over time. In this study, we retrospectively reviewed our experience and treatment results for patients diagnosed with IC/BPS at our clinic in India over the past 20 years. MATERIALS AND METHODS: Three hundred and eighty IC/BPS patients diagnosed between January 2001 and December 2020 were included. Patients underwent cystoscopy and hydrodistension and were treated with oral drugs, intravesical instillations, and surgery as needed. From January 2021 to June 2021, all patients were contacted by telephone. RESULTS: The study had 380 participants, but only 231 could be contacted for analysis. Follow-up averaged 6.37 years and the median was 14 years. Eighteen percent showed no improvement, 2% showed a slight improvement on Global Response Assessment (GRA) questionnaire and were considered nonresponders (NR). Yet, 67% reported notable improvements, and 13% moderate improvements, all of which make up 80% responders (R). In 11 patients who were operated on for ileocystoplasty, 9 showed significant improvements. In addition, three patients developed Urothelial Malignancy. Pregnancy did not affect the disease in any way. CONCLUSIONS: Long-term results have been encouraging for IC/BPS patients. Unfortunately, Hunner's lesions patients need a more intensive treatment regimen. Re-evaluation with cystoscopy is recommended in NR. In spite of good results of surgery in our series, it is best to perform surgery only as a last resort.

ß-Lactam-Induced Cell Envelope Adaptations, Not Solely Enhanced Daptomycin Binding, Underlie Daptomycin-ß-Lactam Synergy in Methicillin-Resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious clinical threat due to innate virulence properties, high infection rates, and the ability to develop resistance to multiple antibiotics, including the lipopeptide daptomycin (DAP). The acquisition of DAP resistance (DAP-R) in MRSA has been linked with several characteristic alterations in the cell envelope. Clinical treatment of DAP-R MRSA infections has generally involved DAP-plus-ß-lactam combinations, although definable synergy of such combinations varies in a strain-dependent as well as a ß-lactam-dependent manner. We investigated distinct ß-lactam-induced cell envelope adaptations of nine clinically derived DAP-susceptible (DAP-S)/DAP-R strain pairs following in vitro exposure to a panel of six standard ß-lactams (nafcillin, meropenem, cloxacillin, ceftriaxone, cefaclor, or cefoxitin), which differ in their penicillin-binding protein (PBP)-targeting profiles. In general, in both DAP-S and DAP-R strains, exposure to these ß-lactams led to (i) a decreased positive surface charge; (ii) decreased cell membrane (CM) fluidity; (iii) increased content and delocalization of anionic phospholipids (i.e., cardiolipin), with delocalization being more pronounced in DAP-R strains; and (iv) increased DAP binding in DAP-S (but not DAP-R) strains. Collectively, these results suggest that ß-lactam-induced alterations in at least three major cell envelope phenotypes (surface charge, membrane fluidity, and cardiolipin content) could underlie improved DAP activity, not mediated solely by an increase in DAP binding. (Note that for ease of presentation, we utilize the terminology "DAP-R" instead of "DAP nonsusceptibility.").

Artificial intelligence for pre-operative lymph node staging in colorectal cancer: a systematic review and meta-analysis.

BACKGROUND: Artificial intelligence (AI) is increasingly being used in medical imaging analysis. We aimed to evaluate the diagnostic accuracy of AI models used for detection of lymph node metastasis on pre-operative staging imaging for colorectal cancer. METHODS: A systematic review was conducted according to PRISMA guidelines using a literature search of PubMed (MEDLINE), EMBASE, IEEE Xplore and the Cochrane Library for studies published from January 2010 to October 2020. Studies reporting on the accuracy of radiomics models and/or deep learning for the detection of lymph node metastasis in colorectal cancer by CT/MRI were included. Conference abstracts and studies reporting accuracy of image segmentation rather than nodal classification were excluded. The quality of the studies was assessed using a modified questionnaire of the QUADAS-2 criteria. Characteristics and diagnostic measures from each study were extracted. Pooling of area under the receiver operating characteristic curve (AUROC) was calculated in a meta-analysis. RESULTS: Seventeen eligible studies were identified for inclusion in the systematic review, of which 12 used radiomics models and five used deep learning models. High risk of bias was found in two studies and there was significant heterogeneity among radiomics papers (73.0%). In rectal cancer, there was a per-patient AUROC of 0.808 (0.739-0.876) and 0.917 (0.882-0.952) for radiomics and deep learning models, respectively. Both models performed better than the radiologists who had an AUROC of 0.688 (0.603 to 0.772). Similarly in colorectal cancer, radiomics models with a per-patient AUROC of 0.727 (0.633-0.821) outperformed the radiologist who had an AUROC of 0.676 (0.627-0.725). CONCLUSION: AI models have the potential to predict lymph node metastasis more accurately in rectal and colorectal cancer, however, radiomics studies are heterogeneous and deep learning studies are scarce. TRIAL REGISTRATION: PROSPERO CRD42020218004 .

First complete genome characterization of swinepox virus directly from a clinical sample indicates divergence of a Eurasian-lineage virus.

In this study, we report the complete genome sequence of swinepox virus from a clinical sample from a naturally occurring infection in India. The sequencing was done on a Nanopore MinION sequencer from Oxford Nanopore Technologies. Two new annotations were added to the genome. Three of the genes were found to have frameshifts, which might be of importance in relation to infection. When compared to the only other reported whole genome sequence of swinepox virus, which was obtained from an isolate from America in 1999, our sequence is only 98.19% identical at the nucleotide level. The average amino acid sequence identity of the viral proteins, based on the common 149 annotations, is also 98.19%, demonstrating that these viruses are distinctly divergent. Owing to the fact that swinepox virus infects only swine, it could not have entered America until the introduction of swine in the 16th century from Europe. The swinepox viruses in both continents have continued to evolve independently. The sequence divergence identified here indicates a Eurasian-lineage virus that is geographically distinct from the American-lineage swinepox virus.

Current practice in Australia and New Zealand for defunctioning ileostomy after rectal cancer surgery with anastomosis: Analysis of the Binational Colorectal Cancer Audit.

AIM: This study aimed to investigate the use of defunctioning stomas after rectal cancer surgery in Australia and New Zealand, as current practice is unknown. METHODS: From the Binational Colorectal Cancer Audit database, data on rectal cancer patients who underwent a resection between 2007 and 2019 with the formation of an anastomosis were extracted and analysed. The primary outcome was the rate of defunctioning stoma formation. Secondary outcomes were anastomotic leakage (AL) rates and other postoperative complications, length of hospital stay (LOS), readmissions and 30-day mortality rates between stoma and no-stoma groups. Propensity score matching was performed to correct for differences in baseline characteristics between stoma and no-stoma groups. RESULTS: In total, 2581 (89%) received a defunctioning stoma and 319 (11%) did not. There were more male patients in the stoma group (65.5% vs. 57.7% for the no-stoma group; P = 0.006). The median age was 64 years in both groups. The stoma group underwent more ultra-low anterior resections (79.9% vs. 30.1%; P < 0.0001), included more American Joint Committee on Cancer Stage III patients (53.7% vs. 29.2%; P < 0.0001) and received more neoadjuvant therapy (66.9% vs. 16.3%; P < 0.0001). The AL rate was similar in both groups (5.1% vs. 6.0%; P = 0.52). LOS was longer in the stoma group (8 vs. 6 days; P < 0.0001) with higher 30-day readmission rates (14.9% vs. 8.3%; P = 0.003). After propensity score matching (n = 208 in both groups), AL rates remained similar (2.9% for stoma vs. 5.8% for no-stoma group; P = 0.15), but stoma patients required less reoperations (0% vs. 8%; P = 0.016). The stoma group had higher postoperative ileus rates and an increased LOS. CONCLUSION: In Australia and New Zealand, most patients who underwent rectal cancer resections with the formation of an anastomosis received a defunctioning stoma. A defunctioning stoma does not prevent AL from occurring but is mostly associated with a lower reoperation rate. Patients with a defunctioning stoma experienced a higher postoperative ileus rate and had an increased LOS.

PyRICo-Pilot: pyridostigmine to reduce the duration of postoperative ileus after colorectal surgery - a phase II study.

AIM: Postoperative ileus (POI) is a major problem after colorectal surgery. Acetylcholinesterase inhibitors such as pyridostigmine increase gastrointestinal (GI) motility through a cholinergic anti-inflammatory pathway. The purpose of this phase II pilot study is to determine the safety of oral pyridostigmine after elective colorectal surgery. METHOD: This is a Stage 2b safety study (IDEAL framework). All adult patients undergoing elective colorectal resection or formation or reversal of stoma at the Royal Adelaide Hospital between September 2020 and January 2021 were eligible. The primary outcomes were 30-day postoperative complications, reported adverse events and GI-2 - a validated composite outcome measure of recovery of GI function after surgery, defined as the interval from surgery until first passage of stool and tolerance of a solid intake for 24 h (in whole days) in the absence of vomiting. RESULTS: Fifteen patients were included in the study. The median age was 58 (range 50-82) years and seven (47%) were men. Most participants had an American Society of Anesthesiologists grade ≥2 (53%) and the median body mass index was 27 (24-35) kg/m2 . There were 13 postoperative complications [seven were Clavien-Dindo (CD) 1, five CD 2 and one CD 3]. None appeared directly related to pyridostigmine administration, and none of the patients had any overt symptoms of excessive parasympathetic activity. Median GI-2 was 2 (1-4) days. CONCLUSION: Oral pyridostigmine appears to be safe to use after elective colorectal surgery in a select group of patients. However, considering this is a pilot study with a small sample size, larger controlled studies are needed to confirm this finding and establish efficacy for prevention of POI.

Patient-Reported Outcome Measures in Colorectal Surgery: Construction of Core Measures Using Open-Source Research Method.

Purpose. The primary aim of the study was to review the existing literature about patient-reported outcome measures (PROMs) in colorectal cancer and IBD. The secondary aim was to present a road map to develop a core outcome set via opinion gathering using social media. Method. This study is the first step of a three-step project aimed at constructing simple, applicable PROMs in colorectal surgery. This article was written in a collaborative manner with authors invited both through Twitter via the #OpenSourceResearch hashtag. The 5 most used PROMs were presented and discussed as slides/images on Twitter. Inputs from a wide spectrum of participants including researchers, surgeons, physicians, nurses, patients, and patients' organizations were collected and analyzed. The final draft was emailed to all contributors and 6 patients' representatives for proofreading and approval. Results. Five PROM sets were identified and discussed: EORTC QLQ-CR29, IBDQ short health questionnaire, EORTC QLQ-C30, ED-Q5-5L, and Short Form-36. There were 315 tweets posted by 50 tweeters with 1458 retweets. Awareness about PROMs was generally limited. The general psycho-physical well-being score (GPP) was suggested and discussed, and then a survey was conducted in which more than 2/3 of voters agreed that GPP covers the most important aspects in PROMs. Conclusion. Despite the limitations of this exploratory study, it offered a new method to conduct clinical research with opportunity to engage patients. The general psycho-physical well-being score suggested as simple, applicable PROMs to be eventually combined procedure-specific, disease-specific, or symptom-specific PROMs if needed.

Membrane trafficking of the bacterial adhesin GspB and the accessory Sec transport machinery.

The serine-rich repeat (SRR) glycoproteins of Gram-positive bacteria are large, cell wall-anchored adhesins that mediate binding to many host cells and proteins and are associated with bacterial virulence. SRR glycoproteins are exported to the cell surface by the accessory Sec (aSec) system comprising SecA2, SecY2, and 3-5 additional proteins (Asp1 to Asp5) that are required for substrate export. These adhesins typically have a 90-amino acid-long signal peptide containing an elongated N-region and a hydrophobic core. Previous studies of GspB (the SRR adhesin of Streptococcus gordonii) have shown that a glycine-rich motif in its hydrophobic core is essential for selective, aSec-mediated transport. However, the role of this extended N-region in transport is poorly understood. Here, using protein-lipid co-flotation assays and site-directed mutagenesis, we report that the N-region of the GspB signal peptide interacts with anionic lipids through electrostatic forces and that this interaction is necessary for GspB preprotein trafficking to lipid membranes. Moreover, we observed that protein-lipid binding is required for engagement of GspB with SecA2 and for aSec-mediated transport. We further found that SecA2 and Asp1 to Asp3 also localize selectively to liposomes that contain anionic lipids. These findings suggest that the GspB signal peptide electrostatically binds anionic lipids at the cell membrane, where it encounters SecA2. After SecA2 engagement with the signal peptide, Asp1 to Asp3 promote SecA2 engagement with the mature domain, which activates GspB translocation.

Prolonged Exposure to ß-Lactam Antibiotics Reestablishes Susceptibility of Daptomycin-Nonsusceptible Staphylococcus aureus to Daptomycin.

Daptomycin-nonsusceptible (DAP-NS) Staphylococcus aureus often exhibits gain-in-function mutations in the mprF gene (involved in positive surface charge maintenance). Standard ß-lactams, although relatively inactive against methicillin-resistant S. aureus (MRSA), may prevent the emergence of mprF mutations and DAP-NS. We determined if ß-lactams might also impact DAP-NS isolates already possessing an mprF mutation to revert them to DAP-susceptible (DAP-S) phenotypes and, if so, whether this is associated with specific penicillin-binding protein (PBP) targeting. This study included 25 DAP-S/DAP-NS isogenic, clinically derived MRSA bloodstream isolates. MICs were performed for DAP, nafcillin (NAF; PBP-promiscuous), cloxacillin (LOX; PBP-1), ceftriaxone (CRO; PBP-2), and cefoxitin (FOX; PBP-4). Three DAP-NS isolates were selected for a 28-day serial passage in subinhibitory ß-lactams. DAP MICs and time-kill assays, host defense peptide (LL-37) susceptibilities, and whole-genome sequencing were performed to associate genetic changes with key phenotypic profiles. Pronounced decreases in baseline MICs were observed for NAF and LOX (but not for CRO or FOX) among DAP-NS versus DAP-S isolates ("seesaw" effect). Prolonged (28-d) ß-lactam passage of three DAP-NS isolates significantly reduced DAP MICs. LOX was most impactful (∼16-fold decrease in DAP MIC; 2 to 0.125 mg/liter). In these DAP-NS isolates with preexisting mprF polymorphisms, accumulation of additional mprF mutations occurred with prolonged LOX exposures. This was associated with enhanced LL-37 killing activity and reduced surface charge (both mprF-dependent phenotypes). ß-lactams that either promiscuously or specifically target PBP-1 have significant DAP "resensitizing" effects against DAP-NS S. aureus strains. This may relate to the acquisition of multiple mprF single nucleotide polymorphism (SNPs), which, in turn, affect cell envelope function and metabolism.

Metabolic changes associated with adaptive resistance to daptomycin in Streptococcus mitis-oralis.

BACKGROUND: Viridans group streptococci of the Streptococcus mitis-oralis subgroup are important endovascular pathogens. They can rapidly develop high-level and durable non-susceptibility to daptomycin both in vitro and in vivo upon exposure to daptomycin. Two consistent genetic adaptations associated with this phenotype (i.e., mutations in cdsA and pgsA) lead to the depletion of the phospholipids, phosphatidylglycerol and cardiolipin, from the bacterial membrane. Such alterations in phospholipid biosynthesis will modify carbon flow and change the bacterial metabolic status. To determine the metabolic differences between daptomycin-susceptible and non-susceptible bacteria, the physiology and metabolomes of S. mitis-oralis strains 351 (daptomycin-susceptible) and 351-D10 (daptomycin non-susceptible) were analyzed. S. mitis-oralis strain 351-D10 was made daptomycin non-susceptible through serial passage in the presence of daptomycin. RESULTS: Daptomycin non-susceptible S. mitis-oralis had significant alterations in glucose catabolism and a re-balancing of the redox status through amino acid biosynthesis relative to daptomycin susceptible S. mitis-oralis. These changes were accompanied by a reduced capacity to generate biomass, creating a fitness cost in exchange for daptomycin non-susceptibility. CONCLUSIONS: S. mitis-oralis metabolism is altered in daptomycin non-susceptible bacteria relative to the daptomycin susceptible parent strain. As demonstrated in Staphylococcus aureus, inhibiting the metabolic changes that facilitate the transition from a daptomycin susceptible state to a non-susceptible one, inhibits daptomycin non-susceptibility. By preventing these metabolic adaptations in S. mitis-oralis, it should be possible to deter the formation of daptomycin non-susceptibility.

Outcomes of Minimally Invasive Versus Open Proctectomy for Rectal Cancer: A Propensity-Matched Analysis of Bi-National Colorectal Cancer Audit Data.

BACKGROUND: Minimally invasive surgery is commonly used in the treatment of rectal cancer, despite the lack of evidence to support oncological equivalence or improved recovery compared with open surgery. OBJECTIVE: This study aims to analyze prospectively collected data from a large Australasian colorectal cancer database. DESIGN: This is a retrospective cohort study using propensity score matching. SETTING: This study was conducted using data supplied by the Bi-National Colorectal Cancer Audit. PATIENTS: A total of 3451 patients who underwent open (n = 1980), laparoscopic (n = 1269), robotic (n = 117), and transanal total mesorectal excision (n = 85) for rectal cancer were included in this study. MAIN OUTCOME MEASURE: The primary outcome was positive margin rates (circumferential resection margin and/or distal resection margin) in patients treated with curative intent. RESULTS: Propensity score matching yielded 1132 patients in each of the open and minimally invasive surgery groups. Margin positivity rates and lymph node yields did not differ between groups. The open group had a significantly lower total complication rate (27.6% vs 35.8%, p < 0.0001), including a lower rate of postoperative small-bowel obstruction (1.2% vs 2.5%, p = 0.03). The minimally invasive surgery group had significantly lower wound infection rate (2.9% vs 5.0%, p = 0.02) and a shorter length of hospital stay (8 vs 9 days, p < 0.0001). There was no difference in 30-day mortality. LIMITATIONS: Results are limited by the quality of registry data entries. CONCLUSION: In this patient population, minimally invasive proctectomy demonstrated similar margin rates in comparison with open proctectomy, with a reduced length of stay but a higher overall complication rate. See Video Abstract at http://links.lww.com/DCR/B190. RESULTADOS DE LA PROCTECTOMÍA MÍNIMA INVASIVA VERSUS ABIERTA PARA EL CÁNCER DE RECTO: UN ANÁLISIS DE PROPENSIÓN DE LOS DATOS BINACIONALES DE AUDITORÍA DEL CÁNCER COLORRECTAL: La cirugía mínima invasiva, frecuentemente se utiliza en el tratamiento del cáncer rectal, a pesar de la falta de evidencia que respalde la equivalencia oncológica o la mejor recuperación, en comparación con la cirugía abierta.El estudio tiene como objetivo analizar datos prospectivamente obtenidos, de una gran base de datos de cáncer colorrectal de Australia.Estudio de cohorte retrospectivo utilizando el emparejamiento de puntaje de propensión.Este estudio se realizó utilizando datos proporcionados por la Auditoría Binacional del Cáncer Colorrectal.Se incluyeron en este estudio un total de 3451 pacientes que se trataron de manera abierta (n = 1980), laparoscópica (n = 1269), robótica (n = 117) y taTME (n = 85) para cáncer rectal.Los resultados primarios fueron de tasas de margen positivas (margen de resección circunferencial y/o margen de resección distal) en pacientes con intención curativa.La coincidencia de puntaje de propensión arrojó 1132 pacientes en cada uno de los grupos de cirugía abierta y mínima invasiva. Las tasas de positividad del margen y los rendimientos de los ganglios linfáticos no difirieron entre los dos grupos. El grupo abierto tuvo una tasa de complicaciones totales significativamente menor (27.6% vs 35.8%, p <0.0001), incluida una tasa menor de obstrucción postoperatoria del intestino delgado (1.2% vs 2.5%, p = 0.03). El grupo de cirugía mínimamente invasiva tuvo una tasa de infección de la herida significativamente menor (2.9% frente a 5.0%, p = 0,02) y una estancia hospitalaria más corta (8 frente a 9 días, p <0.0001). No hubo diferencias en la mortalidad a los 30 días.Los resultados están limitados por la calidad de la entrada de datos de registro.En esta población de pacientes, la proctectomía mínima invasiva demostró tasas de margen similares en comparación con la proctectomía abierta, con una estadía reducida pero una tasa más alta de complicaciones en general. Consulte Video Resumen en http://links.lww.com/DCR/B190. (Traducción-Dr. Fidel Ruiz Healy).

A global survey of surgeons' preferences and practice with regard to laxative use after elective colorectal surgery.

PURPOSE: The role of laxatives after elective colorectal surgery is unclear, resulting in heterogenous guidelines and variability in clinical practice. This study aimed to gauge surgeons' preferences and practice with regard to laxative use following elective colorectal surgery. METHODS: A short one-minute anonymous web-based questionnaire designed in English and Chinese (Mandarin) using the Research Electronic Data Capture application (REDCap) was distributed to member surgeons of every identifiable international colorectal specialist society via email communication, physical newsletters and social media channels. Frequency of laxative use after elective colorectal surgery, type of laxative used, and, if not used, the reasons for not using laxatives were collected. RESULTS: A total of 852 surgeons, representing 28 surgical societies completed the survey: 80% were colorectal surgeons and 20% were general surgeons with colorectal interest. Twenty-seven percent of the respondents routinely prescribed laxatives after colorectal surgery. There was wide variation in the type of laxatives used, with magnesium-based laxatives (42%), macrogol (Movicol, 36%) and lactulose (Duphalac, 22%) being the most common. Geographical location was correlated with choice of laxative. Those not routinely using laxatives stated the reasons as being no evidence for benefit (48%), potential of adverse events (24%), more than one reason (21%) and other (7%). The majority (93%) non-users would consider using laxatives if better evidence was available. CONCLUSION: Most surgeons do not routinely prescribe laxatives after elective colorectal surgery due to lack of evidence. Amongst those surgeons who do use them, there is wide variability in the type of laxatives used.

Mutations in cdsA and pgsA Correlate with Daptomycin Resistance in Streptococcus mitis and S. oralis.

We investigated the ability of several recent clinical viridans group streptococci (VGS) bloodstream isolates (Streptococcus mitis/S. oralis subgroup) from daptomycin (DAP)-naive patients to develop DAP resistance in vitro All strains rapidly developed high-level and stable DAP resistance. Substitutions in two enzymes involved in the cardiolipin biosynthesis pathway were identified, i.e., CdsA (phosphatidate cytidylyltransferase) and PgsA (CDP-diacylglycerol-glycerol-3-phosphate-3-phosphatidyltransferase). These mutations were associated with complete disappearance of phosphatidylglycerol and cardiolipin from cell membranes. DAP interactions with the cell membrane differed in isolates with PgsA versus CdsA substitutions.

Daptomycin Dose-Ranging Evaluation with Single-Dose versus Multidose Ceftriaxone Combinations against Streptococcus mitis/oralis in an Ex Vivo Simulated Endocarditis Vegetation Model.

The viridans group streptococci (VGS) are a heterogeneous group of organisms which are important components of the normal human oral flora. Among the VGS, the Streptococcus mitis/oralis subgroup is one of the most common causes of infective endocarditis (IE). Daptomycin (DAP) is a potential alternative therapeutic option for invasive S. mitis infections, given high rates of ß-lactam resistance and vancomycin tolerance in such strains. However, the ability of these strains to rapidly evolve high-level and durable DAP resistance (DAP-R) is problematic. Recent data suggest that combination DAP-ß-lactam therapy circumvents this issue. Human-simulated dose-escalating DAP-alone dose regimens (6, 8, 10, or 12 mg/kg/day times 4 days) versus DAP (6 mg/kg/day) plus ceftriaxone (CRO) (2 g once daily times 4 days or 0.5 g, single dose) were assessed against two prototypical DAP-susceptible (DAP-S) S. mitis/oralis strains (SF100 and 351), as measured by a pharmacokinetic/pharmacodynamic (PK/PD) model of simulated endocardial vegetations (SEVs). No DAP-alone regimen was effective, with regrowth of high-level DAP-R isolates observed for both strains over 96-h exposures. Combinations of DAP-CRO with either single- or multidose regimens yielded significant reductions in log10 CFU/g amounts within SEVs for both strains (∼6 log10 CFU/g) within 24 h. In addition, no DAP-R strains were detected in either DAP-CRO combination regimens over the 96-h exposure. In contrast to prior in vitro studies, no perturbations in two key cardiolipin biosynthetic genes (cdsA and pgsA) were identified in DAP-R SEV isolates emerging from strain 351, despite defective phospholipid production. The combination of DAP-CRO warrants further investigation for treatment of IE due to S. mitis/oralis.

Metabolic interventions for the prevention and treatment of daptomycin non-susceptibility in Staphylococcus aureus.

BACKGROUND: A major developing problem in the treatment of Staphylococcus aureus infections is the emergence of resistance during treatment with daptomycin. Previous metabolomic analyses of isogenic S. aureus strains prior to and after evolution into a daptomycin non-susceptible (DapNS) state provided important metabolic information about this transition (e.g. perturbations of the tricarboxylic acid cycle). OBJECTIVES: To assess the significance of these metabolic changes, in vitro susceptibility to daptomycin was determined in daptomycin-susceptible (DapS) and DapNSS. aureus strains cultivated with metabolic inhibitors targeting these changes. METHODS: Only inhibitors that are approved for use in humans were chosen (i.e. fosfomycin, valproate, trimetazidine and 6-mercaptopurine) to assess the importance of metabolic pathways for daptomycin non-susceptibility. The ability of these inhibitors to forestall the emergence of DapNS strains was also assessed. RESULTS: The combination of daptomycin and fosfomycin synergistically killed both DapS and DapNS strains in vitro and enhanced the in vivo outcome against a DapNS strain in experimental endocarditis. Interestingly, fosfomycin acts on the peptidoglycan biosynthetic enzyme UDP-N-acetylglucosamine enolpyruvyl transferase (MurA); however, it also had a significant effect on the enzymatic activity of enolase, an essential enzyme in S. aureus. While fosfomycin acted synergistically with daptomycin, it failed to prevent the in vitro evolution of daptomycin non-susceptibility. In contrast, trimetazidine, an anti-angina drug that stimulates glucose oxidation, abolished the ability of DapSS. aureus strains to transition to a DapNS state. CONCLUSIONS: These data reveal that metabolic adaptations associated with DapNS strains can be targeted to prevent the emergence of and/or reverse pre-existing resistance to daptomycin.