High-resolution analyses of associations between medications, microbiome, and mortality in cancer patients.

Discerning the effect of pharmacological exposures on intestinal bacterial communities in cancer patients is challenging. Here, we deconvoluted the relationship between drug exposures and changes in microbial composition by developing and applying a new computational method, PARADIGM (parameters associated with dynamics of gut microbiota), to a large set of longitudinal fecal microbiome profiles with detailed medication-administration records from patients undergoing allogeneic hematopoietic cell transplantation. We observed that several non-antibiotic drugs, including laxatives, antiemetics, and opioids, are associated with increased Enterococcus relative abundance and decreased alpha diversity. Shotgun metagenomic sequencing further demonstrated subspecies competition, leading to increased dominant-strain genetic convergence during allo-HCT that is significantly associated with antibiotic exposures. We integrated drug-microbiome associations to predict clinical outcomes in two validation cohorts on the basis of drug exposures alone, suggesting that this approach can generate biologically and clinically relevant insights into how pharmacological exposures can perturb or preserve microbiota composition. The application of a computational method called PARADIGM to a large dataset of cancer patients' longitudinal fecal specimens and detailed daily medication records reveals associations between drug exposures and the intestinal microbiota that recapitulate in vitro findings and are also predictive of clinical outcomes.

The gut microbiota is associated with immune cell dynamics in humans.

The gut microbiota influences development1-3 and homeostasis4-7 of the mammalian immune system, and is associated with human inflammatory8 and immune diseases9,10 as well as responses to immunotherapy11-14. Nevertheless, our understanding of how gut bacteria modulate the immune system remains limited, particularly in humans, where the difficulty of direct experimentation makes inference challenging. Here we study hundreds of hospitalized-and closely monitored-patients with cancer receiving haematopoietic cell transplantation as they recover from chemotherapy and stem-cell engraftment. This aggressive treatment causes large shifts in both circulatory immune cell and microbiota populations, enabling the relationships between the two to be studied simultaneously. Analysis of observed daily changes in circulating neutrophil, lymphocyte and monocyte counts and more than 10,000 longitudinal microbiota samples revealed consistent associations between gut bacteria and immune cell dynamics. High-resolution clinical metadata and Bayesian inference allowed us to compare the effects of bacterial genera in relation to those of immunomodulatory medications, revealing a considerable influence of the gut microbiota-together and over time-on systemic immune cell dynamics. Our analysis establishes and quantifies the link between the gut microbiota and the human immune system, with implications for microbiota-driven modulation of immunity.

Microbiota-derived lantibiotic restores resistance against vancomycin-resistant Enterococcus.

Intestinal commensal bacteria can inhibit dense colonization of the gut by vancomycin-resistant Enterococcus faecium (VRE), a leading cause of hospital-acquired infections1,2. A four-strained consortium of commensal bacteria that contains Blautia producta BPSCSK can reverse antibiotic-induced susceptibility to VRE infection3. Here we show that BPSCSK reduces growth of VRE by secreting a lantibiotic that is similar to the nisin-A produced by Lactococcus lactis. Although the growth of VRE is inhibited by BPSCSK and L. lactis in vitro, only BPSCSK colonizes the colon and reduces VRE density in vivo. In comparison to nisin-A, the BPSCSK lantibiotic has reduced activity against intestinal commensal bacteria. In patients at high risk of VRE infection, high abundance of the lantibiotic gene is associated with reduced density of E. faecium. In germ-free mice transplanted with patient-derived faeces, resistance to VRE colonization correlates with abundance of the lantibiotic gene. Lantibiotic-producing commensal strains of the gastrointestinal tract reduce colonization by VRE and represent potential probiotic agents to re-establish resistance to VRE.

Preservation of the fecal microbiome is associated with reduced severity of graft-versus-host disease.

Following allogeneic hematopoietic cell transplantation (allo-HCT), the gastrointestinal (GI) tract is frequently affected by acute graft-versus-host disease (aGVHD), the pathophysiology of which is associated with a dysbiotic microbiome. Since microbial composition varies along the length of the GI tract, the authors hypothesized that microbiome features correlate with the pattern of organ involvement after allo-HCT. We evaluated 266 allo-HCT recipients from whom 1303 stool samples were profiled by 16S ribosomal gene sequencing. Patients were classified according to which organs were affected by aGVHD. In the 20 days prior to disease onset, GVHD patients had lower abundances of members of the class Clostridia, lower counts of butyrate producers, and lower ratios of strict-to-facultative (S/F) anaerobic bacteria compared with allograft recipients who were free of GVHD. GI GVHD patients showed significant reduction in microbial diversity preonset. Patients with lower GI aGVHD had lower S/F anaerobe ratios compared with those with isolated upper GI aGVHD. In the 20 days after disease onset, dysbiosis was observed only in GVHD patients with GI involvement, particularly those with lower-tract disease. Importantly, Clostridial and butyrate-producer abundance as well as S/F anaerobe ratio were predictors of longer overall survival; higher abundance of butyrate producers and higher S/F anaerobe ratio were associated with decreased risk of GVHD-related death. These findings suggest that the intestinal microbiome can serve as a biomarker for outcomes of allo-HCT patients with GVHD.

Early intestinal microbial features are associated with CD4 T-cell recovery after allogeneic hematopoietic transplant.

Low intestinal microbial diversity is associated with poor outcomes after allogeneic hematopoietic cell transplantation (HCT). Using 16S rRNA sequencing of 2067 stool samples and flow cytometry data from 2370 peripheral blood samples drawn from 894 patients who underwent allogeneic HCT, we have linked features of the early post-HCT microbiome with subsequent immune cell recovery. We examined lymphocyte recovery and microbiota features in recipients of both unmodified and CD34-selected allografts. We observed that fecal microbial diversity was an independent predictor of CD4 T-cell count 3 months after HCT in recipients of a CD34-selected allograft, who are dependent on de novo lymphopoiesis for their immune recovery. In multivariate models using clinical factors and microbiota features, we consistently observed that increased fecal relative abundance of genus Staphylococcus during the early posttransplant period was associated with worse CD4 T-cell recovery. Our observations suggest that the intestinal bacteria, or the factors they produce, can affect early lymphopoiesis and the homeostasis of allograft-derived T cells after transplantation.

Microbiota as Predictor of Mortality in Allogeneic Hematopoietic-Cell Transplantation.

BACKGROUND: Relationships between microbiota composition and clinical outcomes after allogeneic hematopoietic-cell transplantation have been described in single-center studies. Geographic variations in the composition of human microbial communities and differences in clinical practices across institutions raise the question of whether these associations are generalizable. METHODS: The microbiota composition of fecal samples obtained from patients who were undergoing allogeneic hematopoietic-cell transplantation at four centers was profiled by means of 16S ribosomal RNA gene sequencing. In an observational study, we examined associations between microbiota diversity and mortality using Cox proportional-hazards analysis. For stratification of the cohorts into higher- and lower-diversity groups, the median diversity value that was observed at the study center in New York was used. In the analysis of independent cohorts, the New York center was cohort 1, and three centers in Germany, Japan, and North Carolina composed cohort 2. Cohort 1 and subgroups within it were analyzed for additional outcomes, including transplantation-related death. RESULTS: We profiled 8767 fecal samples obtained from 1362 patients undergoing allogeneic hematopoietic-cell transplantation at the four centers. We observed patterns of microbiota disruption characterized by loss of diversity and domination by single taxa. Higher diversity of intestinal microbiota was associated with a lower risk of death in independent cohorts (cohort 1: 104 deaths among 354 patients in the higher-diversity group vs. 136 deaths among 350 patients in the lower-diversity group; adjusted hazard ratio, 0.71; 95% confidence interval [CI], 0.55 to 0.92; cohort 2: 18 deaths among 87 patients in the higher-diversity group vs. 35 deaths among 92 patients in the lower-diversity group; adjusted hazard ratio, 0.49; 95% CI, 0.27 to 0.90). Subgroup analyses identified an association between lower intestinal diversity and higher risks of transplantation-related death and death attributable to graft-versus-host disease. Baseline samples obtained before transplantation already showed evidence of microbiome disruption, and lower diversity before transplantation was associated with poor survival. CONCLUSIONS: Patterns of microbiota disruption during allogeneic hematopoietic-cell transplantation were similar across transplantation centers and geographic locations; patterns were characterized by loss of diversity and domination by single taxa. Higher diversity of intestinal microbiota at the time of neutrophil engraftment was associated with lower mortality. (Funded by the National Cancer Institute and others.).

Fecal microbiota diversity disruption and clinical outcomes after auto-HCT: a multicenter observational study.

We previously described clinically relevant reductions in fecal microbiota diversity in patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT). Recipients of high-dose chemotherapy and autologous HCT (auto-HCT) incur similar antibiotic exposures and nutritional alterations. To characterize the fecal microbiota in the auto-HCT population, we analyzed 1161 fecal samples collected from 534 adult recipients of auto-HCT for lymphoma, myeloma, and amyloidosis in an observational study conducted at 2 transplantation centers in the United States. By using 16S ribosomal gene sequencing, we assessed fecal microbiota composition and diversity, as measured by the inverse Simpson index. At both centers, the diversity of early pretransplant fecal microbiota was lower in patients than in healthy controls and decreased further during the course of transplantation. Loss of diversity and domination by specific bacterial taxa occurred during auto-HCT in patterns similar to those with allo-HCT. Above-median fecal intestinal diversity in the periengraftment period was associated with decreased risk of death or progression (progression-free survival hazard ratio, 0.46; 95% confidence interval, 0.26-0.82; P = .008), adjusting for disease and disease status. This suggests that further investigation into the health of the intestinal microbiota in auto-HCT patients and posttransplant outcomes should be undertaken.

The Effect of Neutropenia and Filgrastim (G-CSF) on Cancer Patients With Coronavirus Disease 2019 (COVID-19) Infection.

BACKGROUND: Neutropenia is commonly encountered in cancer patients. Recombinant human granulocyte colony-stimulating factor (G-CSF, filgrastim), a cytokine that initiates proliferation and differentiation of mature granulocytes, is widely given to oncology patients to counteract neutropenia, reducing susceptibility to infection. However, the clinical impact of neutropenia and G-CSF use in cancer patients with coronavirus disease 2019 (COVID-19) remains unknown. METHODS: An observational cohort of 379 actively treated cancer patients with COVID-19 was assembled to investigate links between concurrent neutropenia and G-CSF administration on COVID-19-associated respiratory failure and death. These factors were encoded as time-dependent predictors in an extended Cox model, controlling for age and underlying cancer diagnosis. To determine whether the degree of granulocyte response to G-CSF affected outcomes, the degree of response to G-CSF, based on rise in absolute neutrophil count (ANC) 24 hours after growth factor administration, was also incorporated into a similar Cox model. RESULTS: In the setting of active COVID-19 infection, outpatient receipt of G-CSF led to an increased number of hospitalizations (hazard ratio [HR]: 3.54, 95% confidence interval [CI]: 1.25-10.0, P value: .017). Furthermore, among inpatients, G-CSF administration was associated with increased need for high levels of oxygen supplementation and death (HR: 3.56, 95% CI: 1.19-10.2, P value: .024). This effect was predominantly seen in patients that exhibited a high response to G-CSF based on their ANC increase post-G-CSF administration (HR: 7.78, 95% CI: 2.05-27.9, P value: .004). CONCLUSIONS: The potential risks versus benefits of G-CSF administration should be considered in neutropenic cancer patients with COVID-19, because G-CSF administration may lead to worsening clinical and respiratory status.

The microbe-derived short-chain fatty acids butyrate and propionate are associated with protection from chronic GVHD.

Studies of the relationship between the gastrointestinal microbiota and outcomes in allogeneic hematopoietic stem cell transplantation (allo-HCT) have thus far largely focused on early complications, predominantly infection and acute graft-versus-host disease (GVHD). We examined the potential relationship of the microbiome with chronic GVHD (cGVHD) by analyzing stool and plasma samples collected late after allo-HCT using a case-control study design. We found lower circulating concentrations of the microbe-derived short-chain fatty acids (SCFAs) propionate and butyrate in day 100 plasma samples from patients who developed cGVHD, compared with those who remained free of this complication, in the initial case-control cohort of transplant patients and in a further cross-sectional cohort from an independent transplant center. An additional cross-sectional patient cohort from a third transplant center was analyzed; however, serum (rather than plasma) was available, and the differences in SCFAs observed in the plasma samples were not recapitulated. In sum, our findings from the primary case-control cohort and 1 of 2 cross-sectional cohorts explored suggest that the gastrointestinal microbiome may exert immunomodulatory effects in allo-HCT patients at least in part due to control of systemic concentrations of microbe-derived SCFAs.

Outcomes of Patients with COVID-19 from a Specialized Cancer Care Emergency Room.

PURPOSE: Our goal was to identify discrete clinical characteristics associated with safe discharge from an emergency department/urgent care for patients with a history of cancer and concurrent COVID-19 infection during the SARS-CoV-2 pandemic and prior to widespread vaccination. PATIENTS AND METHODS: We retrospectively analyzed 255 adult patients with a history of cancer who presented to Memorial Sloan Kettering Cancer Center (MSKCC) urgent care center (UCC) from March 1, 2020 to May 31, 2020 with concurrent COVID-19 infection. We evaluated associations between patient characteristics and 30-day mortality from initial emergency department (ED) or urgent care center (UCC) visit and the absence of a severe event within 30 days. External validation was performed on a retrospective data from 29 patients followed at Fred Hutchinson Cancer Research Center that presented to the local emergency department. A late cohort of 108 additional patients at MSKCC from June 1, 2020 to January 31, 2021 was utilized for further validation. RESULTS: In the MSKCC cohort, 30-day mortality and severe event rate was 15% and 32% respectively. Using stepwise regression analysis, elevated BUN and glucose, anemia, and tachypnea were selected as the main predictors of 30-day mortality. Conversely, normal albumin, BUN, calcium, and glucose, neutrophil-lymphocyte ratio <3, lack of (severe) hypoxia, lack of bradycardia or tachypnea, and negative imaging were selected as the main predictors of an uneventful course as defined as a Lack Of a Severe Event within Thirty Days (LOSETD). Utilizing this information, we devised a tool to predict 30-day mortality and LOSETD which achieved an area under the operating curve (AUC) of 79% and 74% respectively. Similar estimates of AUC were obtained in an external validation cohort. A late cohort at MSKCC was consistent with the prior, albeit with a lower AUC. CONCLUSION: We identified easily obtainable variables that predict 30-day mortality and the absence of a severe event for patients with a history of cancer and concurrent COVID-19. This has been translated into a bedside tool that the clinician may utilize to assist disposition of this group of patients from the emergency department or urgent care setting.

COVID-19 in patients with cancer: can baseline radiologic severity and early evolution predict clinical outcomes?

OBJECTIVE: To determine whether the degree of parenchymal involvement on chest radiograph (CXR) at the time of COVID-19 diagnosis and its early radiologic evolution can predict adverse events including hospitalization, intubation, and death in patients with cancer. METHODS: Retrospective study of 627 COVID-19-positive patients between March and April 2020, of which 248 had baseline CXR within 72 h of diagnosis and 64 patients had follow-up wihtin72 h. CXRs were classified as abnormal (i.e., radiologic findings suggestive of COVID-19 infection were noted), normal, or indeterminate. Baseline and follow-up severity scores were calculated based on lung regions in abnormal CXRs. Statistical analysis was performed to determine associations between abnormal CXR or severity score with adverse events. RESULTS: Of 248 patients (median age = 65) with a baseline CXR, 172/248 (69%) had an abnormal baseline study, which was associated with hospitalization (p < 0.001), intubation (p = 0.001), and death (p = 0.005). For patients with solid neoplasms, when adjusted for stage, it was associated with hospitalization (p = 0.0002), intubation (p = 0.019), and death (p = 0.03). The median baseline severity score was 3 (range = 1-10); the greater the score, the higher the likelihood of adverse outcome (p < 0.003 for all). A baseline severity score > 9 predicted > 50% probability of intubation and a score of ≥ 10 predicted > 50% of probability of death. The baseline severity score was not correlated with cancer-related treatment. Early radiologic progression was not correlated with hospitalization, intubation, or death. CONCLUSION: The degree of parenchymal involvement on CXR within 72 h of COVID-19 diagnosis is associated with adverse outcomes in patients with cancer. KEY POINTS: • In patients with cancer, the presence and severity of radiologic manifestation of COVID-19 on chest radiographs within 72 h of COVID-19 diagnosis are associated with hospitalization, intubation, and death. • Early radiologic progression on chest radiographs is not correlated with adverse outcomes.

Compositional Flux Within the Intestinal Microbiota and Risk for Bloodstream Infection With Gram-negative Bacteria.

BACKGROUND: Gram-negative bloodstream infections (BSIs) represent a significant complication facing allogeneic hematopoietic cell transplant (allo-HCT) recipients, as a result of intestinal translocation during neutropenia. In this study we sought to better understand how the composition of the intestinal microbiota is connected to risk of gram-negative BSIs, expanding on our prior work in these patients. METHODS: Fecal specimens were collected from recipients of allo-HCT and analyzed using 16S ribosomal RNA gene sequencing. Samples and clinical data extending from the pretransplant conditioning period through stem cell engraftment were used in the analysis. Intestinal domination (relative abundance ≥ 30%) by gram-negative bacteria was used as predictor of gram-negative BSI using Cox proportional hazards modeling. Further analysis of microbiota composition was performed at the genus level. RESULTS: Seven hundred eight allo-HCT subjects were studied (7.5% developed gram-negative infection), with 4768 fecal samples for analysis. Gram-negative intestinal domination was associated with subsequent BSI, which was observed overall and individually at the genus level: Escherichia, Klebsiella, Enterobacter, Pseudomonas, and Stenotrophomonas. Fluoroquinolone prophylaxis was associated with decreased BSI and intestinal colonization by gram-negative microbes. In fluoroquinolone-prophylaxed patients, Escherichia coli was more frequently observed as breakthrough, both in terms of intestinal colonization and BSIs, compared with nonprophylaxed patients. Initial colonization by members of Ruminococcaceae and Bacteroidetes were associated with protection against gram-negative BSI. CONCLUSIONS: Gram-negative intestinal colonization is highly predictive of BSI in the setting of allo-HCT. Fluoroquinolones appear to reduce these infections by influencing gut colonization.

Projecting COVID-19 disease severity in cancer patients using purposefully-designed machine learning.

BACKGROUND: Accurately predicting outcomes for cancer patients with COVID-19 has been clinically challenging. Numerous clinical variables have been retrospectively associated with disease severity, but the predictive value of these variables, and how multiple variables interact to increase risk, remains unclear. METHODS: We used machine learning algorithms to predict COVID-19 severity in 348 cancer patients at Memorial Sloan Kettering Cancer Center in New York City. Using only clinical variables collected on or before a patient's COVID-19 positive date (time zero), we sought to classify patients into one of three possible future outcomes: Severe-early (the patient required high levels of oxygen support within 3 days of being tested positive for COVID-19), Severe-late (the patient required high levels of oxygen after 3 days), and Non-severe (the patient never required oxygen support). RESULTS: Our algorithm classified patients into these classes with an area under the receiver operating characteristic curve (AUROC) ranging from 70 to 85%, significantly outperforming prior methods and univariate analyses. Critically, classification accuracy is highest when using a potpourri of clinical variables - including basic patient information, pre-existing diagnoses, laboratory and radiological work, and underlying cancer type - suggesting that COVID-19 in cancer patients comes with numerous, combinatorial risk factors. CONCLUSIONS: Overall, we provide a computational tool that can identify high-risk patients early in their disease progression, which could aid in clinical decision-making and selecting treatment options.

Precision microbiome reconstitution restores bile acid mediated resistance to Clostridium difficile.

The gastrointestinal tracts of mammals are colonized by hundreds of microbial species that contribute to health, including colonization resistance against intestinal pathogens. Many antibiotics destroy intestinal microbial communities and increase susceptibility to intestinal pathogens. Among these, Clostridium difficile, a major cause of antibiotic-induced diarrhoea, greatly increases morbidity and mortality in hospitalized patients. Which intestinal bacteria provide resistance to C. difficile infection and their in vivo inhibitory mechanisms remain unclear. Here we correlate loss of specific bacterial taxa with development of infection, by treating mice with different antibiotics that result in distinct microbiota changes and lead to varied susceptibility to C. difficile. Mathematical modelling augmented by analyses of the microbiota of hospitalized patients identifies resistance-associated bacteria common to mice and humans. Using these platforms, we determine that Clostridium scindens, a bile acid 7α-dehydroxylating intestinal bacterium, is associated with resistance to C. difficile infection and, upon administration, enhances resistance to infection in a secondary bile acid dependent fashion. Using a workflow involving mouse models, clinical studies, metagenomic analyses, and mathematical modelling, we identify a probiotic candidate that corrects a clinically relevant microbiome deficiency. These findings have implications for the rational design of targeted antimicrobials as well as microbiome-based diagnostics and therapeutics for individuals at risk of C. difficile infection.

Impact of gut colonization with butyrate-producing microbiota on respiratory viral infection following allo-HCT.

Respiratory viral infections are frequent in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HCT) and can potentially progress to lower respiratory tract infection (LRTI). The intestinal microbiota contributes to resistance against viral and bacterial pathogens in the lung. However, whether intestinal microbiota composition and associated changes in microbe-derived metabolites contribute to the risk of LRTI following upper respiratory tract viral infection remains unexplored in the setting of allo-HCT. Fecal samples from 360 allo-HCT patients were collected at the time of stem cell engraftment and subjected to deep, 16S ribosomal RNA gene sequencing to determine microbiota composition, and short-chain fatty acid levels were determined in a nested subset of fecal samples. The development of respiratory viral infections and LRTI was determined for 180 days following allo-HCT. Clinical and microbiota risk factors for LRTI were subsequently evaluated using survival analysis. Respiratory viral infection occurred in 149 (41.4%) patients. Of those, 47 (31.5%) developed LRTI. Patients with higher abundances of butyrate-producing bacteria were fivefold less likely to develop viral LRTI, independent of other factors (adjusted hazard ratio = 0.22, 95% confidence interval 0.04-0.69). Higher representation of butyrate-producing bacteria in the fecal microbiota is associated with increased resistance against respiratory viral infection with LRTI in allo-HCT patients.

Diversification and Evolution of Vancomycin-Resistant Enterococcus faecium during Intestinal Domination.

Vancomycin-resistant Enterococcus faecium (VRE) is a leading cause of hospital-acquired infections. This is particularly true in immunocompromised patients, where the damage to the microbiota caused by antibiotics can lead to VRE domination of the intestine, increasing a patient's risk for bloodstream infection. In previous studies we observed that the intestinal domination by VRE of patients hospitalized to receive allogeneic bone marrow transplantation can persist for weeks, but little is known about subspecies diversification and evolution during prolonged domination. Here we combined a longitudinal analysis of patient data and in vivo experiments to reveal previously unappreciated subspecies dynamics during VRE domination that appeared to be stable from 16S rRNA microbiota analyses. Whole-genome sequencing of isolates obtained from sequential stool samples provided by VRE-dominated patients revealed an unanticipated level of VRE population complexity that evolved over time. In experiments with ampicillin-treated mice colonized with a single CFU, VRE rapidly diversified and expanded into distinct lineages that competed for dominance. Mathematical modeling shows that in vivo evolution follows mostly a parabolic fitness landscape, where each new mutation provides diminishing returns and, in the setting of continuous ampicillin treatment, reveals a fitness advantage for mutations in penicillin-binding protein 5 (pbp5) that increase resistance to ampicillin. Our results reveal the rapid diversification of host-colonizing VRE populations, with implications for epidemiologic tracking of in-hospital VRE transmission and susceptibility to antibiotic treatment.

Antibiotic-Induced Shifts in Fecal Microbiota Density and Composition during Hematopoietic Stem Cell Transplantation.

Dramatic microbiota changes and loss of commensal anaerobic bacteria are associated with adverse outcomes in hematopoietic cell transplantation (HCT) recipients. In this study, we demonstrate these dynamic changes at high resolution through daily stool sampling and assess the impact of individual antibiotics on those changes. We collected 272 longitudinal stool samples (with mostly daily frequency) from 18 patients undergoing HCT and determined their composition by multiparallel 16S rRNA gene sequencing as well as the density of bacteria in stool by quantitative PCR (qPCR). We calculated microbiota volatility to quantify rapid shifts and developed a new dynamic systems inference method to assess the specific impact of antibiotics. The greatest shifts in microbiota composition occurred between stem cell infusion and reconstitution of healthy immune cells. Piperacillin-tazobactam caused the most severe declines among obligate anaerobes. Our approach of daily sampling, bacterial density determination, and dynamic systems modeling allowed us to infer the independent effects of specific antibiotics on the microbiota of HCT patients.

Gut microbiota dysbiosis and diarrhea in kidney transplant recipients.

Posttransplant diarrhea is associated with kidney allograft failure and death, but its etiology remains unknown in the majority of cases. Because altered gut microbial ecology is a potential basis for diarrhea, we investigated whether posttransplant diarrhea is associated with gut dysbiosis. We enrolled 71 kidney allograft recipients for serial fecal specimen collections in the first 3 months of transplantation and profiled the gut microbiota using 16S ribosomal RNA (rRNA) gene V4-V5 deep sequencing. The Shannon diversity index was significantly lower in 28 diarrheal fecal specimens from 25 recipients with posttransplant diarrhea than in 112 fecal specimens from 46 recipients without posttransplant diarrhea. We found a lower relative abundance of 13 commensal genera (Benjamini-Hochberg adjusted P ≤ .15) in the diarrheal fecal specimens including the same 4 genera identified in our prior study. The 28 diarrheal fecal specimens were also evaluated by a multiplexed polymerase chain reaction (PCR) assay for 22 bacterial, viral, and protozoan gastrointestinal pathogens, and 26 specimens were negative for infectious etiologies. Using PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) to predict metagenomic functions, we found that diarrheal fecal specimens had a lower abundance of metabolic genes. Our findings suggest that posttransplant diarrhea is not associated with common infectious diarrheal pathogens but with a gut dysbiosis.

Butyrate-producing gut bacteria and viral infections in kidney transplant recipients: A pilot study.

BACKGROUND: The gut microbiome is being associated increasingly with development of infections besides Clostridium difficile infection. A recent study found an association between butyrate-producing gut (BPG) bacteria and less frequent development of lower respiratory viral infections in allogeneic hematopoietic stem cell transplant recipients (Haak et al, Blood 131(26): 2978, 2018). In this investigation, we examine the relationship between the abundance of BPG bacteria and the development of viral infections in a cohort of kidney transplant recipients. METHODS: We recruited 168 kidney transplant recipients who provided 510 fecal specimens in the first 3 months after transplantation and profiled the gut microbiota using 16S rRNA gene sequencing of the V4-V5 hypervariable region. We classified the kidney transplant recipients into higher BPG Bacteria Group and lower BPG Bacteria Group using the same criteria of 1% relative gut abundance of BPG bacteria as the Haak et al study. RESULTS: Administration of antibiotics against anaerobes was associated with a significant decrease in the relative gut abundance of BPG bacteria. The higher BPG Bacteria Group was associated with less development of respiratory viral infections (Hazard Ratio [HR]: 0.28, P = .01) but not with less development of CMV viremia (HR: 0.38, P = .13) or BK viremia (HR: 1.02, P = .98) at 2 years post transplantation. CONCLUSION: Our pilot investigation supports future validation of the relationship between high relative gut abundance of BPG bacteria and decreased risk for development of respiratory viral infections.

Cytokine Release Syndrome Grade as a Predictive Marker for Infections in Patients With Relapsed or Refractory B-Cell Acute Lymphoblastic Leukemia Treated With Chimeric Antigen Receptor T Cells.

Background: Chimeric antigen receptor (CAR)-modified T cells that target the CD19 antigen present a novel promising therapy for the treatment of relapsed B-cell acute lymphoblastic leukemia (B-ALL). Although cytokine release syndrome (CRS) and neurotoxicity have emerged as predominant noninfectious complications of CD19 CAR T-cell therapy, infections associated with this treatment modality have not been well documented. Methods: We analyzed infectious complications that followed CD19 CAR T-cell therapy in 53 adult patients with relapsed B-ALL enrolled in a phase I clinical trial at Memorial Sloan Kettering Cancer Center (NCT01044069). Results: Overall, 22 patients (42%) experienced 26 infections (17 bacterial, 4 fungal, and 5 viral) within the first 30 days of CAR T-cell infusion. In 10 of 32 (31%) patients in whom complete remission was achieved, 15 infections developed between days 31 and 180; the majority of these late infections were due to respiratory viruses. In general, bacterial, fungal, and viral infections were detected at a median of 18, 23, and 48 days, respectively, after CAR T-cell infusion. CRS grade 3 or higher was independently associated with increased risk of subsequent infection (adjusted hazard ratio [HR], 2.67; P = .05) and in particular with bloodstream infection (adjusted HR, 19.97; P < .001). Three of 53 patients (6%) died of an infection-related cause. Conclusions: Infections in adult patients with relapsed B-ALL are common after CD19 CAR T-cell therapy. Understanding the infectious complications that are temporally coincident with CD19 CAR T-cell therapy is critical for developing effective prophylactic and other supportive care measures to improve clinical outcomes. Clinical Trials Registration: NCT01044069.