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1.  Commensal microbes provide first line defense against Listeria monocytogenes infection 
The Journal of Experimental Medicine  2017;214(7):1973-1989.
Becattini et al. provide evidence that a diverse gut microbiota antagonizes the foodborne pathogen Listeria monocytogenes in the intestinal lumen, thereby reducing bloodstream invasion. Microbiota perturbation by antibiotic treatment increases susceptibility to listeriosis, with dramatic effects in immunocompromised hosts.
Listeria monocytogenes is a foodborne pathogen that causes septicemia, meningitis and chorioamnionitis and is associated with high mortality. Immunocompetent humans and animals, however, can tolerate high doses of L. monocytogenes without developing systemic disease. The intestinal microbiota provides colonization resistance against many orally acquired pathogens, and antibiotic-mediated depletion of the microbiota reduces host resistance to infection. Here we show that a diverse microbiota markedly reduces Listeria monocytogenes colonization of the gut lumen and prevents systemic dissemination. Antibiotic administration to mice before low dose oral inoculation increases L. monocytogenes growth in the intestine. In immunodeficient or chemotherapy-treated mice, the intestinal microbiota provides nonredundant defense against lethal, disseminated infection. We have assembled a consortium of commensal bacteria belonging to the Clostridiales order, which exerts in vitro antilisterial activity and confers in vivo resistance upon transfer into germ free mice. Thus, we demonstrate a defensive role of the gut microbiota against Listeria monocytogenes infection and identify intestinal commensal species that, by enhancing resistance against this pathogen, represent potential probiotics.
doi:10.1084/jem.20170495
PMCID: PMC5502438  PMID: 28588016
2.  A spoonful of sugar could be the medicine 
Nature  2017;546(7659):479-480.
Pili are filamentous bacterial structures that promote adhesion to host cells. It emerges that a small molecule that inhibits this adhesion can prevent colonization of the mouse gut by a pathogenic bacterium.
doi:10.1038/nature23084
PMCID: PMC5737771  PMID: 28614303
3.  Enterococci and their interactions with the intestinal microbiome 
Microbiology spectrum  2014;5(6):10.1128/microbiolspec.BAD-0014-2016.
doi:10.1128/microbiolspec.BAD-0014-2016
PMCID: PMC5691600  PMID: 29125098
4.  A Whole Genome Sequencing (WGS) Approach to Predict Daptomycin (DAP) Susceptibility of Enterococcus faecium 
Open Forum Infectious Diseases  2017;4(Suppl 1):S602.
Abstract
Background
We have previously shown that vancomycin-resistant E. faecium (VRE) with DAP MICs close to the breakpoint (4 µg/mL) harbor genetic changes associated with DAP resistance (DAP-R). Further, DAP MIC was a predictor of poor microbiological eradication in patients with VRE bacteremia treated with DAP. Furthermore, DAP-susceptible VRE isolates with DAP MIC of 3–4 µg/mL (Etest) were more likely to fail DAP therapy, independently of the DAP dose used. Here, we used WGS to determine whether mutations associated with DAP-R could predict DAP MICs.
Methods
We performed WGS to identify potential determinants of DAP-R in 80 E. faecium isolates (62 DAP-S and 18 DAP-R recovered from bloodstream and other infection sites) in diverse US geographical locations. Two modeling strategies were employed with the aim of increasing the robustness of our prediction strategy, (i) a logistic regression model approach to predict the probability of an isolate of exhibiting a DAP MIC of ≥ 3µg/dl based on the presence of relevant mutations, and (ii) a linear regression model to predict a single doubling dilution increase on DAP MIC in the presence or absence of mutations associated with DAP-R, after transforming MICs to a log2 scale. Statistical significance (P value) was set at <0.05.
Results
Out of 62 genetic determinants examined, the presence of substitutions in LiaFSR or YycFGHI systems were independent predictors of an isolate exhibiting DAP MIC ≥ 3 µg/mL (logistic model, LiaFSR OR 8.9, P < 0.0001 and YycFGHI OR 6.2; P < 0.0001) or of an increase in DAP MIC (lineal model; LiaFSR β 14.6; P < 0.04; YycFGHI β 1.7; P < 0.0001) and were consistent in both models. When we evaluated individual genetic changes within the proteins from both systems, substitutions in YycG were associated with the greatest increase on DAP MIC (8.0-fold; β = 3.0, 95% CI 2.8–4.1 P < 0.0001), followed by LiaF (3.0-fold; β 1.5, 95% CI 0.17–2.9 P = 0.028;), LiaS (2.0-fold; β = 0.9, 95% CI 0.2–1.6; P = 0.006) and LiaR (1.7-fold; β = 0.8, 95% CI 0.1–1.5, P = 0.021).
Conclusion
Our data indicate that WGS may identify organisms with elevated DAP MIC that, even if not above the clinical breakpoint, may lead to microbiological failure. WGS has the potential of providing a better guidance for DAP therapy.
Disclosures
M. Zervos, Merck: Investigator, Research grant Genentech: Investigator, Research grant Cempra: Investigator, Research grant Pfizer: Investigator, Research grant
doi:10.1093/ofid/ofx163.1580
PMCID: PMC5631548
5.  Bile acid sensitivity and in vivo virulence of clinical Clostridium difficile isolates 
Anaerobe  2016;41:32-36.
Clostridium difficile is an anaerobic bacterium that causes diarrheal illnesses. Disease onset is linked with exposure to oral antibiotics and consequent depletion of secondary bile acids. Here we investigate the relationship between in vitro secondary bile acid tolerance and in vivo disease scores of diverse C. difficile strains in mice.
doi:10.1016/j.anaerobe.2016.05.010
PMCID: PMC5050091  PMID: 27241781
Clostridium difficile; secondary bile acid
6.  Celecoxib alters the intestinal microbiota and metabolome in association with reducing polyp burden 
Treatment with celecoxib, a selective COX-2 inhibitor, reduces formation of premalignant adenomatous polyps in the gastrointestinal tracts of humans and mice. In addition to its chemopreventive activity, celecoxib can exhibit anti-microbial activity. Differing bacterial profiles have been found in feces from colon cancer patients compared with that of normal subjects. Moreover, preclinical studies suggest that bacteria can modulate intestinal tumorigenesis by secreting specific metabolites. In the current study, we determined whether celecoxib treatment altered the luminal microbiota and metabolome in association with reducing intestinal polyp burden in mice. Administration of celecoxib for 10 weeks markedly reduced intestinal polyp burden in APCMin/+ mice. Treatment with celecoxib also altered select luminal bacterial populations in both APCMin/+ and wild-type mice including decreased Lactobacillaceae and Bifidobacteriaceae as well as increased Coriobacteriaceae. Metabolomic analysis demonstrated that celecoxib caused a strong reduction in many fecal metabolites linked to carcinogenesis including glucose, amino acids, nucleotides and lipids. Ingenuity Pathway Analysis suggested that these changes in metabolites may contribute to reduced cell proliferation. To this end, we showed that celecoxib reduced cell proliferation in the base of normal appearing ileal and colonic crypts of APCMin/+ mice. Consistent with this finding, lineage tracing indicated that celecoxib treatment reduced the rate at which Lgr5-positive stem cells gave rise to differentiated cell types in the crypts. Taken together, these results demonstrate that celecoxib alters the luminal microbiota and metabolome along with reducing epithelial cell proliferation in mice. We hypothesize that these actions contribute to its chemopreventive activity.
doi:10.1158/1940-6207.CAPR-16-0095
PMCID: PMC5010963  PMID: 27432344
celecoxib; microbiota; metabolome; prevention; stem cells
7.  Gut Microbiota Predict Pulmonary Infiltrates after Allogeneic Hematopoietic Cell Transplantation 
Rationale: Pulmonary complications (PCs) cause significant morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HCT). Shifts in gut microbiota have been linked to HCT outcomes; however, their effect on PCs is unknown.
Objectives: To investigate whether changes in gut microbiota are associated with PCs after HCT.
Methods: A single-center observational study was performed on 94 patients who underwent HCT from 2009 to 2011 and who were previously enrolled in a protocol for 16S ribosomal RNA sequencing of fecal microbiota. The primary endpoint, PC, was defined by new abnormal parenchymal findings on chest imaging in the setting of respiratory signs and/or symptoms. Outcomes were collected up to 40 months after transplant. Clinical and microbiota risk factors for PCs and mortality were evaluated using survival analysis.
Measurements and Main Results: One hundred twelve PCs occurred in 66 (70.2%) subjects. A high comorbidity index (hazard ratio [HR], 2.30; 95% confidence interval [CI], 1.30–4.00; P = 0.004), fluoroquinolones (HR, 2.29, 95% CI, 1.32–3.98; P = 0.003), low baseline diversity (HR, 2.63; 95% CI, 1.22–5.32; P = 0.015), and γ-proteobacteria domination of fecal microbiota (HR, 2.64; 95% CI, 1.10–5.65; P = 0.031), which included common respiratory pathogens, predicted PCs. In separate analyses, low baseline diversity was associated with PCs that occurred preengraftment (HR, 6.30; 95% CI, 1.42–31.80; P = 0.016), whereas γ-proteobacteria domination predicted PCs postengraftment (HR, 3.68; 95% CI, 1.49–8.21; P = 0.006) and overall mortality (HR, 3.52; 95% CI, 1.28–9.21; P = 0.016). Postengraftment PCs were also independent predictors of death (HR, 2.50; 95% CI, 1.25–5.22; P = 0.009).
Conclusions: This is the first study to demonstrate prospective changes in gut microbiota associated with PCs after HCT. Postengraftment PCs and γ-proteobacteria domination were predictive of mortality. This suggests an adverse relationship between the graft and lung, which is perhaps mediated by bacterial composition in the gut. Further study is warranted.
doi:10.1164/rccm.201507-1491OC
PMCID: PMC5003327  PMID: 26886180
stem cell transplantation; microbiota; pulmonary disease
8.  Pathogenicity Locus, Core Genome, and Accessory Gene Contributions to Clostridium difficile Virulence 
mBio  2017;8(4):e00885-17.
ABSTRACT
Clostridium difficile is a spore-forming anaerobic bacterium that causes colitis in patients with disrupted colonic microbiota. While some individuals are asymptomatic C. difficile carriers, symptomatic disease ranges from mild diarrhea to potentially lethal toxic megacolon. The wide disease spectrum has been attributed to the infected host’s age, underlying diseases, immune status, and microbiome composition. However, strain-specific differences in C. difficile virulence have also been implicated in determining colitis severity. Because patients infected with C. difficile are unique in terms of medical history, microbiome composition, and immune competence, determining the relative contribution of C. difficile virulence to disease severity has been challenging, and conclusions regarding the virulence of specific strains have been inconsistent. To address this, we used a mouse model to test 33 clinical C. difficile strains isolated from patients with disease severities ranging from asymptomatic carriage to severe colitis, and we determined their relative in vivo virulence in genetically identical, antibiotic-pretreated mice. We found that murine infections with C. difficile clade 2 strains (including multilocus sequence type 1/ribotype 027) were associated with higher lethality and that C. difficile strains associated with greater human disease severity caused more severe disease in mice. While toxin production was not strongly correlated with in vivo colonic pathology, the ability of C. difficile strains to grow in the presence of secondary bile acids was associated with greater disease severity. Whole-genome sequencing and identification of core and accessory genes identified a subset of accessory genes that distinguish high-virulence from lower-virulence C. difficile strains.
IMPORTANCE
Clostridium difficile is an important cause of hospital-associated intestinal infections, and recent years have seen an increase in the number and severity of cases in the United States. A patient’s antibiotic history, immune status, and medical comorbidities determine, in part, the severity of C. difficile infection. The relative virulence of different clinical C. difficile strains, although postulated to determine disease severity in patients, has been more difficult to consistently associate with mild versus severe colitis. We tested 33 distinct clinical C. difficile isolates for their ability to cause disease in genetically identical mice and found that C. difficile strains belonging to clade 2 were associated with higher mortality. Differences in survival were not attributed to differences in toxin production but likely resulted from the distinct gene content in the various clinical isolates.
doi:10.1128/mBio.00885-17
PMCID: PMC5550754  PMID: 28790208
Clostridium difficile; accessory genome; bile salt; genome analysis; pathogenicity locus; toxin
9.  Influence of Minimum Inhibitory Concentration in Clinical Outcomes of Enterococcus faecium Bacteremia Treated With Daptomycin: Is it Time to Change the Breakpoint? 
Daptomycin-susceptible Enterococcus faecium with minimum inhibitory concentrations (MICs) of 3–4 µg/mL often harbor mutations associated with daptomycin resistance. In a multicenter retrospective study, daptomycin MICs of 3–4 µg/mL in E. faecium predicted prolonged time to clearance in bacteremia.
Background. Daptomycin has become a front-line antibiotic for multidrug-resistant Enterococcus faecium bloodstream infections (BSIs). We previously showed that E. faecium strains with daptomycin minimum inhibitory concentrations (MICs) in the higher end of susceptibility frequently harbor mutations associated with daptomycin resistance. We postulate that patients with E. faecium BSIs exhibiting daptomycin MICs of 3–4 µg/mL treated with daptomycin are more likely to have worse clinical outcomes than those exhibiting daptomycin MICs ≤2 µg/mL.
Methods. We conducted a multicenter retrospective cohort study that included adult patients with E. faecium BSI for whom initial isolates, follow-up blood culture data, and daptomycin administration data were available. A central laboratory performed standardized daptomycin MIC testing for all isolates. The primary outcome was microbiologic failure, defined as clearance of bacteremia ≥4 days after the index blood culture. The secondary outcome was all-cause in-hospital mortality.
Results. A total of 62 patients were included. Thirty-one patients were infected with isolates that exhibited daptomycin MICs of 3–4 µg/mL. Overall, 34 patients had microbiologic failure and 25 died during hospitalization. In a multivariate logistic regression model, daptomycin MICs of 3–4 µg/mL (odds ratio [OR], 4.7 [1.37–16.12]; P = .014) and immunosuppression (OR, 5.32 [1.20–23.54]; P = .028) were significantly associated with microbiologic failure. Initial daptomycin dose of ≥8 mg/kg was not significantly associated with evaluated outcomes.
Conclusions. Daptomycin MICs of 3–4 µg/mL in the initial E. faecium blood isolate predicted microbiological failure of daptomycin therapy, suggesting that modification in the daptomycin breakpoint for enterococci should be considered.
doi:10.1093/cid/ciw173
PMCID: PMC4885651  PMID: 27045126
E. faecium; daptomycin; MIC; bloodstream infection; resistance
10.  Antibiotic-Induced Changes in the Intestinal Microbiota and Disease 
Trends in molecular medicine  2016;22(6):458-478.
The gut microbiota is a key player in many physiological and pathological processes occurring in humans. Recent investigations suggest that the efficacy of some clinical approaches depends on the action of commensal bacteria. Antibiotics are invaluable weapons to fight infectious diseases. However, by altering the composition and functions of the microbiota, they can also produce long-lasting deleterious effects for the host. The emergence of multidrug-resistant pathogens raises concerns about the common, and at times inappropriate, use of antimicrobial agents. Here we review the most recently discovered connections between host pathophysiology, microbiota, and antibiotics highlighting technological platforms, mechanistic insights, and clinical strategies to enhance resistance to diseases by preserving the beneficial functions of the microbiota.
doi:10.1016/j.molmed.2016.04.003
PMCID: PMC4885777  PMID: 27178527
Antibiotics; Gut Microbiota; Immunity; Disease; Antibiotic Resistance
11.  Innate lymphocyte/Ly6Chi monocyte crosstalk promotes Klebsiella pneumoniae clearance 
Cell  2016;165(3):679-689.
SUMMARY
Increasing antibiotic resistance among bacterial pathogens has rendered some infections untreatable with available antibiotics. Klebsiella pneumoniae, a bacterial pathogen that has acquired high-level antibiotic resistance, is a common cause of pulmonary infections. Optimal clearance of K. pneumoniae from the host lung requires TNF and IL-17A. Herein we demonstrate that inflammatory monocytes are rapidly recruited to the lungs of K. pneumoniae infected mice, and produce TNF, which markedly increases the frequency of IL-17-producing innate lymphoid cells. While pulmonary clearance of K. pneumoniae is preserved in neutrophil-depleted mice, monocyte depletion or TNF deficiency impairs IL-17A–dependent resolution of pneumonia. Monocyte-mediated bacterial uptake and killing is enhanced by ILC production of IL-17A, indicating that innate lymphocytes engage in a positive feedback loop with monocytes that promotes clearance of pneumonia. Innate immune defense against a highly antibiotic-resistant bacterial pathogen depends on crosstalk between inflammatory monocytes and innate lymphocytes that is mediated by TNF and IL-17A.
doi:10.1016/j.cell.2016.03.017
PMCID: PMC4842125  PMID: 27040495
12.  Role of Clinicogenomics in Infectious Disease Diagnostics and Public Health Microbiology 
Journal of Clinical Microbiology  2016;54(7):1686-1693.
Clinicogenomics is the exploitation of genome sequence data for diagnostic, therapeutic, and public health purposes. Central to this field is the high-throughput DNA sequencing of genomes and metagenomes. The role of clinicogenomics in infectious disease diagnostics and public health microbiology was the topic of discussion during a recent symposium (session 161) presented at the 115th general meeting of the American Society for Microbiology that was held in New Orleans, LA. What follows is a collection of the most salient and promising aspects from each presentation at the symposium.
doi:10.1128/JCM.02664-15
PMCID: PMC4922100  PMID: 26912755
13.  From hype to hope: the gut microbiota in enteric infectious disease 
Cell  2015;163(6):1326-1332.
Summary
One of the clearest functions of the gut microbiota in humans is resistance to colonization by enteric bacterial pathogens. Reconstitution of the microbiota offers an exciting therapeutic approach, but great challenges must be overcome.
doi:10.1016/j.cell.2015.11.032
PMCID: PMC4672394  PMID: 26638069
14.  Clostridium difficile colitis: pathogenesis and host defence 
Nature reviews. Microbiology  2016;14(10):609-620.
Clostridium difficile is a major cause of intestinal infection and diarrhoea in individuals following antibiotic treatment. Recent studies have begun to elucidate the mechanisms that induce spore formation and germination and have determined the roles of C. difficile toxins in disease pathogenesis. Exciting progress has also been made in defining the role of the microbiome, specific commensal bacterial species and host immunity in defence against infection with C. difficile. This Review will summarize the recent discoveries and developments in our understanding of C. difficile infection and pathogenesis.
ToC blurb
Treating infection with Clostridium difficile and post-antibiotic disease can be difficult. In this Review, Abt, McKenney and Pamer show how insights into spore germination, virulence and interactions with the host and microbiota can help to combat this pathogen.
doi:10.1038/nrmicro.2016.108
PMCID: PMC5109054  PMID: 27573580
15.  31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016): part one 
Lundqvist, Andreas | van Hoef, Vincent | Zhang, Xiaonan | Wennerberg, Erik | Lorent, Julie | Witt, Kristina | Sanz, Laia Masvidal | Liang, Shuo | Murray, Shannon | Larsson, Ola | Kiessling, Rolf | Mao, Yumeng | Sidhom, John-William | Bessell, Catherine A. | Havel, Jonathan | Schneck, Jonathan | Chan, Timothy A. | Sachsenmeier, Eliot | Woods, David | Berglund, Anders | Ramakrishnan, Rupal | Sodre, Andressa | Weber, Jeffrey | Zappasodi, Roberta | Li, Yanyun | Qi, Jingjing | Wong, Philip | Sirard, Cynthia | Postow, Michael | Newman, Walter | Koon, Henry | Velcheti, Vamsidhar | Callahan, Margaret K. | Wolchok, Jedd D. | Merghoub, Taha | Lum, Lawrence G. | Choi, Minsig | Thakur, Archana | Deol, Abhinav | Dyson, Gregory | Shields, Anthony | Haymaker, Cara | Uemura, Marc | Murthy, Ravi | James, Marihella | Wang, Daqing | Brevard, Julie | Monaghan, Catherine | Swann, Suzanne | Geib, James | Cornfeld, Mark | Chunduru, Srinivas | Agrawal, Sudhir | Yee, Cassian | Wargo, Jennifer | Patel, Sapna P. | Amaria, Rodabe | Tawbi, Hussein | Glitza, Isabella | Woodman, Scott | Hwu, Wen-Jen | Davies, Michael A. | Hwu, Patrick | Overwijk, Willem W. | Bernatchez, Chantale | Diab, Adi | Massarelli, Erminia | Segal, Neil H. | Ribrag, Vincent | Melero, Ignacio | Gangadhar, Tara C. | Urba, Walter | Schadendorf, Dirk | Ferris, Robert L. | Houot, Roch | Morschhauser, Franck | Logan, Theodore | Luke, Jason J. | Sharfman, William | Barlesi, Fabrice | Ott, Patrick A. | Mansi, Laura | Kummar, Shivaani | Salles, Gilles | Carpio, Cecilia | Meier, Roland | Krishnan, Suba | McDonald, Dan | Maurer, Matthew | Gu, Xuemin | Neely, Jaclyn | Suryawanshi, Satyendra | Levy, Ronald | Khushalani, Nikhil | Wu, Jennifer | Zhang, Jinyu | Basher, Fahmin | Rubinstein, Mark | Bucsek, Mark | Qiao, Guanxi | MacDonald, Cameron | Hylander, Bonnie | Repasky, Elizabeth | Chatterjee, Shilpak | Daenthanasanmak, Anusara | Chakraborty, Paramita | Toth, Kyle | Meek, Megan | Garrett-Mayer, Elizabeth | Nishimura, Michael | Paulos, Chrystal | Beeson, Craig | Yu, Xuezhong | Mehrotra, Shikhar | Zhao, Fei | Evans, Kathy | Xiao, Christine | Holtzhausen, Alisha | Hanks, Brent A. | Scharping, Nicole | Menk, Ashley V. | Moreci, Rebecca | Whetstone, Ryan | Dadey, Rebekah | Watkins, Simon | Ferris, Robert | Delgoffe, Greg M. | Peled, Jonathan | Devlin, Sean | Staffas, Anna | Lumish, Melissa | Rodriguez, Kori Porosnicu | Ahr, Katya | Perales, Miguel | Giralt, Sergio | Taur, Ying | Pamer, Eric | van den Brink, Marcel R. M. | Jenq, Robert | Annels, Nicola | Pandha, Hardev | Simpson, Guy | Mostafid, Hugh | Harrington, Kevin | Melcher, Alan | Grose, Mark | Davies, Bronwyn | Au, Gough | Karpathy, Roberta | Shafren, Darren | Ricca, Jacob | Merghoub, Taha | Wolchok, Jedd D. | Zamarin, Dmitriy | Batista, Luciana | Marliot, Florence | Vasaturo, Angela | Carpentier, Sabrina | Poggionovo, Cécile | Frayssinet, Véronique | Fieschi, Jacques | Van den Eynde, Marc | Pagès, Franck | Galon, Jérôme | Hermitte, Fabienne | Smith, Sean G. | Nguyen, Khue | Ravindranathan, Sruthi | Koppolu, Bhanu | Zaharoff, David | Schvartsman, Gustavo | Bassett, Roland | McQuade, Jennifer L. | Haydu, Lauren E. | Davies, Michael A. | Tawbi, Hussein | Glitza, Isabella | Kline, Douglas | Chen, Xiufen | Fosco, Dominick | Kline, Justin | Overacre, Abigail | Chikina, Maria | Brunazzi, Erin | Shayan, Gulidanna | Horne, William | Kolls, Jay | Ferris, Robert L. | Delgoffe, Greg M. | Bruno, Tullia C. | Workman, Creg | Vignali, Dario | Adusumilli, Prasad S. | Ansa-Addo, Ephraim A | Li, Zihai | Gerry, Andrew | Sanderson, Joseph P. | Howe, Karen | Docta, Roslin | Gao, Qian | Bagg, Eleanor A. L. | Tribble, Nicholas | Maroto, Miguel | Betts, Gareth | Bath, Natalie | Melchiori, Luca | Lowther, Daniel E. | Ramachandran, Indu | Kari, Gabor | Basu, Samik | Binder-Scholl, Gwendolyn | Chagin, Karen | Pandite, Lini | Holdich, Tom | Amado, Rafael | Zhang, Hua | Glod, John | Bernstein, Donna | Jakobsen, Bent | Mackall, Crystal | Wong, Ryan | Silk, Jonathan D. | Adams, Katherine | Hamilton, Garth | Bennett, Alan D. | Brett, Sara | Jing, Junping | Quattrini, Adriano | Saini, Manoj | Wiedermann, Guy | Gerry, Andrew | Jakobsen, Bent | Binder-Scholl, Gwendolyn | Brewer, Joanna | Duong, MyLinh | Lu, An | Chang, Peter | Mahendravada, Aruna | Shinners, Nicholas | Slawin, Kevin | Spencer, David M. | Foster, Aaron E. | Bayle, J. 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Peter | Shankaran, Veena | Piha-Paul, Sarina A. | Yearley, Jennifer | Seiwert, Tanguy | Ribas, Antoni | McClanahan, Terrill K. | Cristescu, Razvan | Mogg, Robin | Ayers, Mark | Albright, Andrew | Murphy, Erin | Yearley, Jennifer | Sher, Xinwei | Liu, Xiao Qiao | Nebozhyn, Michael | Lunceford, Jared | Joe, Andrew | Cheng, Jonathan | Plimack, Elizabeth | Ott, Patrick A. | McClanahan, Terrill K. | Loboda, Andrey | Kaufman, David R. | Forrest-Hay, Alex | Guyre, Cheryl A. | Narumiya, Kohei | Delcommenne, Marc | Hirsch, Heather A. | Deshpande, Amit | Reeves, Jason | Shu, Jenny | Zi, Tong | Michaelson, Jennifer | Law, Debbie | Trehu, Elizabeth | Sathyanaryanan, Sriram | Hodkinson, Brendan P. | Hutnick, Natalie A. | Schaffer, Michael E. | Gormley, Michael | Hulett, Tyler | Jensen, Shawn | Ballesteros-Merino, Carmen | Dubay, Christopher | Afentoulis, Michael | Reddy, Ashok | David, Larry | Fox, Bernard | Jayant, Kumar | Agrawal, Swati | Agrawal, Rajendra | Jeyakumar, Ghayathri | Kim, Seongho | Kim, Heejin | Silski, Cynthia | Suisham, Stacey | Heath, Elisabeth | Vaishampayan, Ulka | Vandeven, Natalie | Viller, Natasja Nielsen | O’Connor, Alison | Chen, Hui | Bossen, Bolette | Sievers, Eric | Uger, Robert | Nghiem, Paul | Johnson, Lisa | Kao, Hsiang-Fong | Hsiao, Chin-Fu | Lai, Shu-Chuan | Wang, Chun-Wei | Ko, Jenq-Yuh | Lou, Pei-Jen | Lee, Tsai-Jan | Liu, Tsang-Wu | Hong, Ruey-Long | Kearney, Staci J. | Black, Joshua C. | Landis, Benjamin J. | Koegler, Sally | Hirsch, Brooke | Gianani, Roberto | Kim, Jeffrey | He, Ming-Xiao | Zhang, Bingqing | Su, Nan | Luo, Yuling | Ma, Xiao-Jun | Park, Emily | Kim, Dae Won | Copploa, Domenico | Kothari, Nishi | doo Chang, Young | Kim, Richard | Kim, Namyong | Lye, Melvin | Wan, Ee | Kim, Namyong | Lye, Melvin | Wan, Ee | Kim, Namyong | Lye, Melvin | Wan, Ee | Knaus, Hanna A. | Berglund, Sofia | Hackl, Hubert | Karp, Judith E. | Gojo, Ivana | Luznik, Leo | Hong, Henoch S. | Koch, Sven D. | Scheel, Birgit | Gnad-Vogt, Ulrike | Kallen, Karl-Josef | Wiegand, Volker | Backert, Linus | Kohlbacher, Oliver | Hoerr, Ingmar | Fotin-Mleczek, Mariola | Billingsley, James M. | Koguchi, Yoshinobu | Conrad, Valerie | Miller, William | Gonzalez, Iliana | Poplonski, Tomasz | Meeuwsen, Tanisha | Howells-Ferreira, Ana | Rattray, Rogan | Campbell, Mary | Bifulco, Carlo | Dubay, Christopher | Bahjat, Keith | Curti, Brendan | Urba, Walter | Vetsika, E-K | Kallergi, G. | Aggouraki, Despoina | Lyristi, Z. | Katsarlinos, P. | Koinis, Filippos | Georgoulias, V. | Kotsakis, Athanasios | Martin, Nathan T. | Aeffner, Famke | Kearney, Staci J. | Black, Joshua C. | Cerkovnik, Logan | Pratte, Luke | Kim, Rebecca | Hirsch, Brooke | Krueger, Joseph | Gianani, Roberto | Martínez-Usatorre, Amaia | Jandus, Camilla | Donda, Alena | Carretero-Iglesia, Laura | Speiser, Daniel E. | Zehn, Dietmar | Rufer, Nathalie | Romero, Pedro | Panda, Anshuman | Mehnert, Janice | Hirshfield, Kim M. | Riedlinger, Greg | Damare, Sherri | Saunders, Tracie | Sokol, Levi | Stein, Mark | Poplin, Elizabeth | Rodriguez-Rodriguez, Lorna | Silk, Ann | Chan, Nancy | Frankel, Melissa | Kane, Michael | Malhotra, Jyoti | Aisner, Joseph | Kaufman, Howard L. | Ali, Siraj | Ross, Jeffrey | White, Eileen | Bhanot, Gyan | Ganesan, Shridar | Monette, Anne | Bergeron, Derek | Amor, Amira Ben | Meunier, Liliane | Caron, Christine | Morou, Antigoni | Kaufmann, Daniel | Liberman, Moishe | Jurisica, Igor | Mes-Masson, Anne-Marie | Hamzaoui, Kamel | Lapointe, Rejean | Mongan, Ann | Ku, Yuan-Chieh | Tom, Warren | Sun, Yongming | Pankov, Alex | Looney, Tim | Au-Young, Janice | Hyland, Fiona | Conroy, Jeff | Morrison, Carl | Glenn, Sean | Burgher, Blake | Ji, He | Gardner, Mark | Mongan, Ann | Omilian, Angela R. | Conroy, Jeff | Bshara, Wiam | Angela, Omilian | Burgher, Blake | Ji, He | Glenn, Sean | Morrison, Carl | Mongan, Ann | Obeid, Joseph M. | Erdag, Gulsun | Smolkin, Mark E. | Deacon, Donna H. | Patterson, James W. | Chen, Lieping | Bullock, Timothy N. | Slingluff, Craig L. | Obeid, Joseph M. | Erdag, Gulsun | Deacon, Donna H. | Slingluff, Craig L. | Bullock, Timothy N. | Loffredo, John T. | Vuyyuru, Raja | Beyer, Sophie | Spires, Vanessa M. | Fox, Maxine | Ehrmann, Jon M. | Taylor, Katrina A. | Korman, Alan J. | Graziano, Robert F. | Page, David | Sanchez, Katherine | Ballesteros-Merino, Carmen | Martel, Maritza | Bifulco, Carlo | Urba, Walter | Fox, Bernard | Patel, Sapna P. | De Macedo, Mariana Petaccia | Qin, Yong | Reuben, Alex | Spencer, Christine | Guindani, Michele | Bassett, Roland | Wargo, Jennifer | Racolta, Adriana | Kelly, Brian | Jones, Tobin | Polaske, Nathan | Theiss, Noah | Robida, Mark | Meridew, Jeffrey | Habensus, Iva | Zhang, Liping | Pestic-Dragovich, Lidija | Tang, Lei | Sullivan, Ryan J. | Logan, Theodore | Khushalani, Nikhil | Margolin, Kim | Koon, Henry | Olencki, Thomas | Hutson, Thomas | Curti, Brendan | Roder, Joanna | Blackmon, Shauna | Roder, Heinrich | Stewart, John | Amin, Asim | Ernstoff, Marc S. | Clark, Joseph I. | Atkins, Michael B. | Kaufman, Howard L. | Sosman, Jeffrey | Weber, Jeffrey | McDermott, David F. | Weber, Jeffrey | Kluger, Harriet | Halaban, Ruth | Snzol, Mario | Roder, Heinrich | Roder, Joanna | Asmellash, Senait | Steingrimsson, Arni | Blackmon, Shauna | Sullivan, Ryan J. | Wang, Chichung | Roman, Kristin | Clement, Amanda | Downing, Sean | Hoyt, Clifford | Harder, Nathalie | Schmidt, Guenter | Schoenmeyer, Ralf | Brieu, Nicolas | Yigitsoy, Mehmet | Madonna, Gabriele | Botti, Gerardo | Grimaldi, Antonio | Ascierto, Paolo A. | Huss, Ralf | Athelogou, Maria | Hessel, Harald | Harder, Nathalie | Buchner, Alexander | Schmidt, Guenter | Stief, Christian | Huss, Ralf | Binnig, Gerd | Kirchner, Thomas | Sellappan, Shankar | Thyparambil, Sheeno | Schwartz, Sarit | Cecchi, Fabiola | Nguyen, Andrew | Vaske, Charles | Hembrough, Todd
Journal for Immunotherapy of Cancer  2016;4(Suppl 1):1-106.
doi:10.1186/s40425-016-0172-7
PMCID: PMC5123387
16.  Loss of Microbiota-Mediated Colonization Resistance to Clostridium difficile Infection With Oral Vancomycin Compared With Metronidazole 
The Journal of Infectious Diseases  2015;212(10):1656-1665.
Antibiotic administration disrupts the intestinal microbiota, increasing susceptibility to pathogens such as Clostridium difficile. Metronidazole or oral vancomycin can cure C. difficile infection, and administration of these agents to prevent C. difficile infection in high-risk patients, although not sanctioned by Infectious Disease Society of America guidelines, has been considered. The relative impacts of metronidazole and vancomycin on the intestinal microbiota and colonization resistance are unknown. We investigated the effect of brief treatment with metronidazole and/or oral vancomycin on susceptibility to C. difficile, vancomycin-resistant Enterococcus, carbapenem-resistant Klebsiella pneumoniae, and Escherichia coli infection in mice. Although metronidazole resulted in transient loss of colonization resistance, oral vancomycin markedly disrupted the microbiota, leading to prolonged loss of colonization resistance to C. difficile infection and dense colonization by vancomycin-resistant Enterococcus, K. pneumoniae, and E. coli. Our results demonstrate that vancomycin, and to a lesser extent metronidazole, are associated with marked intestinal microbiota destruction and greater risk of colonization by nosocomial pathogens.
doi:10.1093/infdis/jiv256
PMCID: PMC4621244  PMID: 25920320
Clostridium difficile; metronidazole; vancomycin; microbiota; colonization resistance
17.  Role of intestinal microbiota in transplantation outcomes 
While allogeneic hematopoietic stem cell transplantations have a curative potential, infections and graft-versus-host disease remain significant problems. The intestinal microbiota can influence responses to cancer chemotherapy and the role of the microbiota in affecting allogeneic hematopoietic stem cell transplantation outcomes is increasingly appreciated. The following paper discusses the most recent developments in this area.
doi:10.1016/j.beha.2015.10.013
PMCID: PMC4656136  PMID: 26590773
Allo-HSCT; bacteremia; diversity; intestinal microbiota; microbial dominance; metronidazole; mortality; survival
18.  Short- and long-term effects of oral vancomycin on the human intestinal microbiota 
Background
Oral vancomycin remains the mainstay of therapy for severe infections produced by Clostridium difficile, the most prevalent cause of healthcare-associated infectious diarrhoea in developed countries. However, its short- and long-term effects on the human intestinal microbiota remain largely unknown.
Methods
We utilized high-throughput sequencing to analyse the effects of vancomycin on the faecal human microbiota up to 22 weeks post-antibiotic cessation. The clinical relevance of the observed microbiota perturbations was studied in mice.
Results
During vancomycin therapy, most intestinal microbiota genera and operational taxonomic units (OTUs) were depleted in all analysed subjects, including all baseline OTUs from the phylum Bacteroidetes. This was accompanied by a vast expansion of genera associated with infections, including Klebsiella and Escherichia/Shigella. Following antibiotic cessation, marked differences in microbiota resilience were observed among subjects. While some individuals recovered a microbiota close to baseline composition, in others, up to 89% of abundant OTUs could no longer be detected. The clinical relevance of the observed microbiota changes was further demonstrated in mice, which developed analogous microbiota alterations. During vancomycin treatment, mice were highly susceptible to intestinal colonization by an antibiotic-resistant pathogen and, upon antibiotic cessation, a less-resilient microbiota allowed higher levels of pathogen colonization.
Conclusions
Oral vancomycin induces drastic and consistent changes in the human intestinal microbiota. Upon vancomycin cessation, the microbiota recovery rate varied considerably among subjects, which could influence, as validated in mice, the level of susceptibility to pathogen intestinal colonization. Our results demonstrate the negative long-term effects of vancomycin, which should be considered as a fundamental aspect of the cost–benefit equation for antibiotic prescription.
doi:10.1093/jac/dkw383
PMCID: PMC5161046  PMID: 27707993
19.  Absence of MHC class II on cDCs results in microbial-dependent intestinal inflammation 
Nussenzweig et al. use a novel mutant mouse lacking MHC class II expression on conventional dendritic cells (cDCs) to demonstrate the importance of cDCs in the maintenance of intestinal homeostasis.
Conventional dendritic cells (cDCs) play an essential role in host immunity by initiating adaptive T cell responses and by serving as innate immune sensors. Although both innate and adaptive functions of cDCs are well documented, their relative importance in maintaining immune homeostasis is poorly understood. To examine the significance of cDC-initiated adaptive immunity in maintaining homeostasis, independent of their innate activities, we generated a cDC-specific Cre mouse and crossed it to a floxed MHC class II (MHCII) mouse. Absence of MHCII on cDCs resulted in chronic intestinal inflammation that was alleviated by antibiotic treatment and entirely averted under germ-free conditions. Uncoupling innate and adaptive functions of cDCs revealed that innate immune functions of cDCs are insufficient to maintain homeostasis and antigen presentation by cDCs is essential for a mutualistic relationship between the host and intestinal bacteria.
doi:10.1084/jem.20160062
PMCID: PMC4821651  PMID: 27001748
20.  Commensal microbiota affects ischemic stroke outcome by regulating intestinal γδT cells 
Nature medicine  2016;22(5):516-523.
Commensal gut bacteria impact the host immune system and can influence disease processes in several organs, including the brain. However, it remains unclear whether the microbiota has an impact on the outcome of acute brain injury. Here we show that antibiotic-induced alterations in the intestinal flora reduces ischemic brain injury in mice, an effect transmissible by fecal transplants. Intestinal dysbiosis alters immune homeostasis in the small intestine leading to an increase in regulatory T cells and a reduction in IL-17+ γδ T cells, through altered dendritic cell activity. Dysbiosis suppresses trafficking of effector T cells from the gut to the leptomeninges after stroke. Interleukin-10 (IL-10) and IL-17 are required for the neuroprotection afforded by intestinal dysbiosis. The findings reveal a previously unrecognized gut-brain axis and the impact of the intestinal flora and meningeal IL-17+ γδ T cells on ischemic injury.
doi:10.1038/nm.4068
PMCID: PMC4860105  PMID: 27019327
21.  TLR-7 activation enhances IL-22–mediated colonization resistance against vancomycin-resistant enterococcus 
Science translational medicine  2016;8(327):327ra25.
Antibiotic administration can disrupt the intestinal microbiota and down-regulate innate immune defenses, compromising colonization resistance against orally acquired bacterial pathogens. Vancomycin-resistant Enterococcus faecium (VRE), a major cause of antibiotic-resistant infections in hospitalized patients, thrives in the intestine when colonization resistance is compromised, achieving extremely high densities that can lead to bloodstream invasion and sepsis. Viral infections, by mechanisms that remain incompletely defined, can stimulate resistance against invading bacterial pathogens. We report that murine norovirus infection reduces the density of VRE in the intestinal tract of mice with antibiotic-induced loss of colonization resistance. Resiquimod (R848), a synthetic ligand for Toll-like receptor 7 (TLR-7) that stimulates antiviral innate immune defenses, restores expression of the antimicrobial peptide Reg3γ and reestablishes colonization resistance against VRE in antibiotic-treated mice. Orally administered R848 triggers TLR-7 on CD11c+ dendritic cells, inducing interleukin-23 (IL-23) expression followed by a burst of IL-22 secretion by innate lymphoid cells, leading to Reg3γ expression and restoration of colonization resistance against VRE. Our findings reveal that an orally bioavailable TLR-7 ligand that stimulates innate antiviral immune defenses in the intestine restores colonization resistance against a highly antibiotic-resistant bacterial pathogen.
doi:10.1126/scitranslmed.aad6663
PMCID: PMC4991618  PMID: 26912904
22.  Control of T cell antigen reactivity via programmed TCR downregulation 
Nature immunology  2016;17(4):379-386.
The T cell receptor (TCR) is unique in that its affinity for ligand is unknown prior to encounter and can vary by orders of magnitude. How the immune system regulates individual T cells that display highly different reactivity to antigen remains unclear. Here we identified that activated CD4+ T cells, at the peak of clonal expansion, persistently downregulate TCR expression in proportion to the strength of initial antigen recognition. This programmed response increases the threshold for cytokine production and recall proliferation in a clone-specific manner, ultimately excluding clones with the highest antigen reactivities. Thus, programmed TCR downregulation represents a negative feedback mechanism to constrain T cell effector function with a suitable time delay, thereby allowing pathogen control while avoiding excess inflammatory damage.
doi:10.1038/ni.3386
PMCID: PMC4803589  PMID: 26901151
23.  Increased GVHD-related mortality with broad-spectrum antibiotic use after allogeneic hematopoietic stem cell transplantation in human patients and mice 
Science translational medicine  2016;8(339):339ra71.
After allogeneic hematopoietic stem cell transplantation (allo-HSCT), intestinal bacteria modulate risks of infection and graft-versus-host disease (GVHD). Neutropenic fever is common and treated with a choice of clinically equivalent antibiotics that target obligately anaerobic bacteria (anaerobes) to varying degrees. We retrospectively examined 857 allo-HSCT recipients and found that treatment of neutropenic fever with imipenem-cilastatin and piperacillin-tazobactam was associated with increased GVHD-related mortality at 5 years (21.5% in imipenem-cilastatin-treated patients vs. 13.1% in untreated patients, p=0.025, and 19.8% in piperacillin-tazobactam-treated patients vs. 11.9% in untreated patients, p=0.007). However, two other antibiotics also used to treat neutropenic fever, aztreonam and cefepime, were not associated with GVHD-related mortality (p=0.78 and p=0.98, respectively). Analysis of stool microbiota composition showed that piperacillin-tazobactam administration was associated with increased compositional perturbation. Studies in mouse models demonstrated similar effects of these antibiotics, as well as aggravated GVHD mortality with imipenem-cilastatin or piperacillin-tazobactm compared to aztreonam (p<0.01 and p<0.05, respectively). We found pathological evidence for increased GVHD in the colon of imipenem-cilastatin-treated mice (p<0.05), but no differences in short-chain fatty acid concentrations or regulatory T cells numbers. Notably, imipenem-cilastatin treatment of mice with GVHD led to loss of the protective lining of mucus in the colon (p<0.01) and intestinal barrier function was compromised (p<0.05). Sequencing of mouse stool specimens showed expansion of Akkermansia muciniphila (p<0.001), a commensal bacterium with mucus-degrading capabilities, raising the possibility that mucus degradation can contribute to murine GVHD. We demonstrate an underappreciated risk for antibiotics with activity against anaerobes to exacerbate colonic GVHD after transplant.
doi:10.1126/scitranslmed.aaf2311
PMCID: PMC4991773  PMID: 27194729
24.  Resurrecting the intestinal microbiota to combat antibiotic-resistant pathogens 
Science (New York, N.Y.)  2016;352(6285):535-538.
The intestinal microbiota, which is composed of diverse populations of commensal bacterial species, provides resistance against colonization and invasion by pathogens. Antibiotic treatment can damage the intestinal microbiota and, paradoxically, increase susceptibility to infections. Reestablishing microbiota-mediated colonization resistance after antibiotic treatment could markedly reduce infections, particularly those caused by antibiotic-resistant bacteria. Ongoing studies are identifying commensal bacterial species that can be developed into next-generation probiotics to reestablish or enhance colonization resistance. These live medicines are at various stages of discovery, testing, and production and are being subjected to existing regulatory gauntlets for eventual introduction into clinical practice. The development of next-generation probiotics to reestablish colonization resistance and eliminate potential pathogens from the gut is warranted and will reduce health care–associated infections caused by highly antibiotic-resistant bacteria.
doi:10.1126/science.aad9382
PMCID: PMC4984266  PMID: 27126035
25.  Intestinal Blautia is associated with reduced death from graft-versus-host disease 
The relationship between intestinal microbiota composition and acute graft-versus-host disease (GVHD) after allogeneic blood/marrow transplantation (allo BMT) is not well understood. Intestinal bacteria have long been thought to contribute to GVHD pathophysiology, but recent animal studies in non-transplant settings have found that anti-inflammatory effects are mediated by certain subpopulations of intestinal commensals. Hypothesizing that a more nuanced relationship may exist between the intestinal bacteria and GVHD, we evaluated the fecal bacterial composition of 64 patients 12 days after BMT. We found that increased bacterial diversity was associated with reduced GVHD-related mortality. Furthermore, harboring increased amounts of bacteria belonging to the genus Blautia was associated with reduced GVHD lethality in this cohort and was confirmed in another independent cohort of 51 patients from the same institution. Blautia abundance was also associated with improved overall survival. We evaluated the abundance of Blautia with respect to clinical factors and found that loss of Blautia was associated with: 1) treatment with antibiotics that inhibit anaerobic bacteria and 2) receiving total parenteral nutrition (TPN) for longer durations. We conclude that increased abundance of commensal bacteria belonging to the Blautia genus is associated with reduced lethal GVHD and improved overall survival.
doi:10.1016/j.bbmt.2015.04.016
PMCID: PMC4516127  PMID: 25977230

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