Metagenome-derived SusD-homologs affiliated with Bacteroidota bind to synthetic polymers.

Starch utilization system (Sus)D-homologs are well known for their carbohydrate-binding capabilities and are part of the sus operon in microorganisms affiliated with the phylum Bacteroidota. Until now, SusD-like proteins have been characterized regarding their affinity toward natural polymers. In this study, three metagenomic SusD homologs (designated SusD1, SusD38489, and SusD70111) were identified and tested with respect to binding to natural and non-natural polymers. SusD1 and SusD38489 are cellulose-binding modules, while SusD70111 preferentially binds chitin. Employing translational fusion proteins with superfolder GFP (sfGFP), pull-down assays, and surface plasmon resonance (SPR) has provided evidence for binding to polyethylene terephthalate (PET) and other synthetic polymers. Structural analysis suggested that a Trp triad might be involved in protein adsorption. Mutation of these residues to Ala resulted in an impaired adsorption to microcrystalline cellulose (MC), but not so to PET and other synthetic polymers. We believe that the characterized SusDs, alongside the methods and considerations presented in this work, will aid further research regarding bioremediation of plastics. IMPORTANCE: SusD1 and SusD38489 can be considered for further applications regarding their putative adsorption toward fossil-fuel based polymers. This is the first time that SusD homologs from the polysaccharide utilization loci (PUL), largely described for the phylum Bacteroidota, are characterized as synthetic polymer-binding proteins.

The clinical effectiveness of Fidaxomicin compared to Vancomycin in the treatment of Clostridioides difficile infection, a single center real-world experience.

BACKGROUND: The use of fidaxomicin is recommended as first line therapy for all patients with Clostridioides difficile infection (CDI). However, real-world studies have shown conflicting evidence of superiority. METHODS: We conducted a retrospective single center study of patients diagnosed with CDI between 2011-2021. A primary composite outcome of clinical failure, 30-day relapse or CDI-related death was used. A multivariable cause specific Cox proportional hazards model was used to evaluate fidaxomicin compared to vancomycin in preventing the composite outcome. A separate model was fit on a subset of patients with C. difficile ribotypes adjusting for ribotype. RESULTS: There were 598 patients included, of whom 84 received fidaxomicin. The primary outcome occurred in 8 (9.5%) in the fidaxomicin group compared to 111 (21.6%) in the vancomycin group. The adjusted multivariable model showed fidaxomicin was associated with 63% reduction in the risk of the composite outcome compared to vancomycin (HR = 0.37, 95% CI 0.17-0.80). In the 337 patients with ribotype data after adjusting for ribotype 027, the results showing superiority of fidaxomicin were maintained (HR = 0.19, 95% CI 0.05-0.77). CONCLUSION: In the treatment of CDI, we showed that real-world use of fidaxomicin is associated with lower risk of a composite endpoint of treatment failure.

Development of an Algorithm to Screen for Frailty Using the Clinical Frailty Scale with Postoperative Patients Entering Cardiac Rehabilitation.

Purpose: Frailty is not commonly assessed on intake to cardiac rehabilitation (CR), but screening could enable targeted interventions and potentially reduce secondary complications. This study aimed to develop and retrospectively examine the feasibility of utilizing a CR-specific algorithm based on the Clinical Frailty Scale (CFS). Our CFS-CR algorithm endeavoured to screen for frailty in older adults (> 65 y) entering CR following cardiac surgery/procedure. Method: The charts of 30 former patients (mean age: 74.0 ± 6.9 y) were examined by a clinician working in CR. Results: The clinician was unable to score any of the patients based on their medical charts using the CFS-CR due to insufficient data. Documentation was typically limited in the areas of instrumental and basic activities of daily living whereas exercise data were readily available. Conclusions: Current intake documentation in CR limited the ability to retrospectively screen for frailty. This finding suggests a need for a frailty-specific tool to support routine clinical screening. Prospective evaluation of the CFS-CR is warranted to further examine the clinical utility of the algorithm during CR intake assessments.

Objectif: la fragilité est peu évaluée à l'admission en réadaptation cardiaque (RC), mais le dépistage pourrait permettre de cibler des interventions et peutêtre de réduire les complications secondaires. La présente étude visait à créer un algorithme de RC d'après l'échelle de fragilité clinique (ÉFC) et à procéder à une analyse rétrospective pour déterminer la faisabilité de l'utiliser. L'algorithme ÉFC-RC était conçu pour dépister la fragilité chez les personnes âgées (de 65 ans ou plus) qui arrivaient en RC après une opération ou une intervention cardiaque. Méthodologie: une clinicienne qui travaillait en RC a examiné les dossiers de 30 anciens patients (âge moyen de 74,0 ± 6,9 ans). Résultats: la clinicienne n'a pu mesurer les résultats d'aucun patient d'après leur dossier médical au moyen de l'ÉFC-RC en raison de données insuffisantes. Les éléments du dossier se limitaient généralement aux activités déterminantes et courantes de la vie quotidienne, tandis que les données sur les exercices étaient facilement accessibles. Conclusions: l'information contenue dans les dossiers d'admission actuels en RC limitait la possibilité de procéder à l'analyse rétrospective de la fragilité. Cette observation laisse croire à la nécessité de concevoir un outil axé sur la fragilité pour contribuer au dépistage clinique systématique. Une évaluation prospective de l'ÉFC-RC s'impose pour mieux analyser l'utilité clinique de l'algorithme lors des évaluations à l'admission en RC.

Comparative Effectiveness of Fidaxomicin vs Vancomycin in Populations With Immunocompromising Conditions for the Treatment of Clostridioides difficile Infection: A Single-Center Study.

Background: Clostridioides difficile infection (CDI) is a leading cause of morbidity in immunocompromised hosts with increased risk of complications and recurrences. In this study, we examined the clinical effectiveness of fidaxomicin vs vancomycin in treating CDI in this patient population. Methods: This single-center retrospective study evaluated patients with CDI between 2011 and 2021. The primary outcome was a composite of clinical failure, relapse at 30 days, or CDI-related death. A multivariable cause-specific Cox proportional hazards model was used to test the relationship between treatment and the composite outcome, adjusting for confounders and treating death from other causes as a competing risk. Results: This study analyzed 238 patients who were immunocompromised and treated for CDI with oral fidaxomicin (n = 38) or vancomycin (n = 200). There were 42 composite outcomes: 4 (10.5%) in the fidaxomicin arm and 38 (19.0%) in the vancomycin arm. After adjustment for sex, number of antecedent antibiotics, CDI severity and type of immunosuppression, fidaxomicin use significantly decreased the risk of the composite outcome as compared with vancomycin (10.5% vs 19.0%; hazard ratio, 0.28; 95% CI, .08-.93). Furthermore, fidaxomicin was associated with 70% reduction in the combined risk of 30- and 90-day relapse following adjustment (hazard ratio, 0.27; 95% CI, .08-.91). Conclusions: The findings of this study suggest that the use of fidaxomicin for treatment of CDI reduces poor outcomes in patients who are immunocompromised.

The metagenome-derived esterase PET40 is highly promiscuous and hydrolyses polyethylene terephthalate (PET).

Polyethylene terephthalate (PET) is a widely used synthetic polymer and known to contaminate marine and terrestrial ecosystems. Only few PET-active microorganisms and enzymes (PETases) are currently known, and it is debated whether degradation activity for PET originates from promiscuous enzymes with broad substrate spectra that primarily act on natural polymers or other bulky substrates, or whether microorganisms evolved their genetic makeup to accepting PET as a carbon source. Here, we present a predicted diene lactone hydrolase designated PET40, which acts on a broad spectrum of substrates, including PET. It is the first esterase with activity on PET from a GC-rich Gram-positive Amycolatopsis species belonging to the Pseudonocardiaceae (Actinobacteria). It is highly conserved within the genera Amycolatopsis and Streptomyces. PET40 was identified by sequence-based metagenome search using a PETase-specific hidden Markov model. Besides acting on PET, PET40 has a versatile substrate spectrum, hydrolyzing δ-lactones, ß-lactam antibiotics, the polyester-polyurethane Impranil® DLN, and various para-nitrophenyl ester substrates. Molecular docking suggests that the PET degradative activity is likely a result of the promiscuity of PET40, as potential binding modes were found for substrates encompassing mono(2-hydroxyethyl) terephthalate, bis(2-hydroxyethyl) terephthalate, and a PET trimer. We also solved the crystal structure of the inactive PET40 variant S178A to 1.60 Å resolution. PET40 is active throughout a wide pH (pH 4-10) and temperature range (4-65 °C) and remarkably stable in the presence of 5% SDS, making it a promising enzyme as a starting point for further investigations and optimization approaches.

A Clinical Model to Predict the Occurrence of Select High-risk Infections in the First Year Following Heart Transplantation.

Background: Invasive infection remains a dangerous complication of heart transplantation (HT). No objectively defined set of clinical risk factors has been established to reliably predict infection in HT. The aim of this study was to develop a clinical prediction model for use at 1 mo post-HT to predict serious infection by 1 y. Methods: A retrospective cohort study of HT recipients (2000-2018) was performed. The composite endpoint included cytomegalovirus (CMV), herpes simplex or varicella zoster virus infection, blood stream infection, invasive fungal, or nocardial infection occurring 1 mo to 1 y post-HT. A least absolute shrinkage and selection operator regression model was constructed using 10 candidate variables. A concordance statistic, calibration curve, and mean calibration error were calculated. A scoring system was derived for ease of clinical application. Results: Three hundred seventy-five patients were analyzed; 93 patients experienced an outcome event. All variables remained in the final model: aged 55 y or above, history of diabetes, need for renal replacement therapy in first month, CMV risk derived from donor and recipient serology, use of induction and/or early lymphodepleting therapy in the first month, use of trimethoprim-sulfamethoxazole prophylaxis at 1 mo, lymphocyte count under 0.75 × 103cells/µL at 1 mo, and inpatient status at 1 mo. Good discrimination (C-index 0.80) and calibration (mean absolute calibration error 3.6%) were demonstrated. Conclusion: This model synthesizes multiple highly relevant clinical parameters, available at 1 mo post-HT, into a unified, objective, and clinically useful prediction tool for occurrence of serious infection by 1 y post-HT.

An archaeal lid-containing feruloyl esterase degrades polyethylene terephthalate.

Polyethylene terephthalate (PET) is a commodity polymer known to globally contaminate marine and terrestrial environments. Today, around 80 bacterial and fungal PET-active enzymes (PETases) are known, originating from four bacterial and two fungal phyla. In contrast, no archaeal enzyme had been identified to degrade PET. Here we report on the structural and biochemical characterization of PET46 (RLI42440.1), an archaeal promiscuous feruloyl esterase exhibiting degradation activity on semi-crystalline PET powder comparable to IsPETase and LCC (wildtypes), and higher activity on bis-, and mono-(2-hydroxyethyl) terephthalate (BHET and MHET). The enzyme, found by a sequence-based metagenome search, is derived from a non-cultivated, deep-sea Candidatus Bathyarchaeota archaeon. Biochemical characterization demonstrated that PET46 is a promiscuous, heat-adapted hydrolase. Its crystal structure was solved at a resolution of 1.71 Å. It shares the core alpha/beta-hydrolase fold with bacterial PETases, but contains a unique lid common in feruloyl esterases, which is involved in substrate binding. Thus, our study widens the currently known diversity of PET-hydrolyzing enzymes, by demonstrating PET depolymerization by a plant cell wall-degrading esterase.

Towards Sustainable Recycling of Epoxy-Based Polymers: Approaches and Challenges of Epoxy Biodegradation.

Epoxy resins are highly valued for their remarkable mechanical and chemical properties and are extensively used in various applications such as coatings, adhesives, and fiber-reinforced composites in lightweight construction. Composites are especially important for the development and implementation of sustainable technologies such as wind power, energy-efficient aircrafts, and electric cars. Despite their advantages, their non-biodegradability raises challenges for the recycling of polymer and composites in particular. Conventional methods employed for epoxy recycling are characterized by their high energy consumption and the utilization of toxic chemicals, rendering them rather unsustainable. Recent progress has been made in the field of plastic biodegradation, which is considered more sustainable than energy-intensive mechanical or thermal recycling methods. However, the current successful approaches in plastic biodegradation are predominantly focused on polyester-based polymers, leaving more recalcitrant plastics underrepresented in this area of research. Epoxy polymers, characterized by their strong cross-linking and predominantly ether-based backbone, exhibit a highly rigid and durable structure, placing them within this category. Therefore, the objective of this review paper is to examine the various approaches that have been employed for the biodegradation of epoxy so far. Additionally, the paper sheds light on the analytical techniques utilized in the development of these recycling methods. Moreover, the review addresses the challenges and opportunities entailed in epoxy recycling through bio-based approaches.

A worldwide survey on perioperative antimicrobial prophylaxis for heart transplantation: From theory to clinical practice.

BACKGROUND: The aim of our survey was to analyze the current attitudes toward antimicrobial prophylaxis in heart transplanting centers worldwide. METHODS: The survey was composed of a total of 50 questions, it consisted of four different sections as follows. The first section collected physicians' personal data and centers' general characteristics, second assessed the approach to patients colonized with multidrug-resistant organisms (MDROs), while the third consisted of the infection risk related to cardiovascular devices, and antimicrobial treatment data, the last focused on donor's colonization. RESULTS: A total of 56 answers from 26 different countries were collected, mostly from Europe (n = 30) and the USA (n = 16). A first-generation cephalosporin (58.9%) or a combination therapy with vancomycin (10.7%) were the most frequently prescribed antimicrobial prophylaxis. Roughly 30% of the centers used different antimicrobial prophylaxis,mostly including Gram negative bacteria coverage. The frequency of screening for multidrug resistant Gram-negative bacteria was higher in Europe, where the percentage of centers providing screening for extended spectrum beta-lactamase (46.7%) and carbapenem-resistant Enterobacteriaceae (CRE) (53.3%) was higher than in other geographic area (p = .019; p = .013, respectively). CONCLUSION: This survey highlights a heterogeneity of clinical practice concerning antimicrobial prophylaxis at transplant. The concern for potential Gram-negative bacteria infection was responsible for broader antimicrobial coverage in 30% of centers.

Sex- and age-based comparison of serum immunoglobulins following liver transplantation.

BACKGROUND: Over a quarter of organ transplant recipients have low immunoglobulin levels in their early post-transplant course, which is associated with increased risk of infection and mortality. Although immunoglobulin level varies by sex among healthy individuals, it is unknown how such differences are affected by transplant-related immunosuppression. This study compared post-liver transplant immunoglobulin G (IgG) between sexes at varying ages. METHODS: Serum specimens from a prospective cohort of 130 liver transplant recipients were analyzed. IgG was measured at time of transplant and from one-month post-transplant samples. Post-transplant IgG was compared between sexes using multivariable linear regression. Four age and sex categories were created (women<50, women≥50, men<50, men≥50) and the model repeated with this as the explanatory variable. The relationship between sex hormone concentrations and post-transplant IgG was also explored. Infection type and incidence were examined within groups. RESULTS: The cohort included 99 men, 31 women (mean age 53). In adjusted linear regression, post-transplant IgG was not significantly different by sex (p = 0.92). However, when broken into four categories by age and sex, the contrast in IgG levels between younger versus older patients was strikingly greater among women than among men. An interaction term including age and sex was statistically significant (p = 0.03). The combined age-sex categorical variable was also significantly associated with post-transplant IgG (p = 0.01). Finally, an association was identified between baseline estradiol level and post-transplant change in IgG (p = 0.04). CONCLUSIONS: Sex and age have an important relationship with post-transplant IgG with older women demonstrating lowest concentrations. Immunoglobulin levels have previously demonstrated association with post-transplant outcomes.

An Ultra-Sensitive Comamonas thiooxidans Biosensor for the Rapid Detection of Enzymatic Polyethylene Terephthalate (PET) Degradation.

Polyethylene terephthalate (PET) is a prevalent synthetic polymer that is known to contaminate marine and terrestrial environments. Currently, only a limited number of PET-active microorganisms and enzymes (PETases) are known. This is in part linked to the lack of highly sensitive function-based screening assays for PET-active enzymes. Here, we report on the construction of a fluorescent biosensor based on Comamonas thiooxidans strain S23. C. thiooxidans S23 transports and metabolizes TPA, one of the main breakdown products of PET, using a specific tripartite tricarboxylate transporter (TTT) and various mono- and dioxygenases encoded in its genome in a conserved operon ranging from tphC-tphA1. TphR, an IclR-type transcriptional regulator is found upstream of the tphC-tphA1 cluster where TPA induces transcription of tphC-tphA1 up to 88-fold in exponentially growing cells. In the present study, we show that the C. thiooxidans S23 wild-type strain, carrying the sfGFP gene fused to the tphC promoter, senses TPA at concentrations as low as 10 µM. Moreover, a deletion mutant lacking the catabolic genes involved in TPA degradation thphA2-A1 (ΔtphA2A3BA1) is up to 10,000-fold more sensitive and detects TPA concentrations in the nanomolar range. This is, to our knowledge, the most sensitive reporter strain for TPA and we demonstrate that it can be used for the detection of enzymatic PET breakdown products. IMPORTANCE Plastics and microplastics accumulate in all ecological niches. The construction of more sensitive biosensors allows to monitor and screen potential PET degradation in natural environments and industrial samples. These strains will also be a valuable tool for functional screenings of novel PETase candidates and variants or monitoring of PET recycling processes using biocatalysts. Thereby they help us to enrich the known biodiversity and efficiency of PET degrading organisms and enzymes and understand their contribution to environmental plastic degradation.

The PET-Degrading Potential of Global Metagenomes: From In Silico Mining to Active Enzymes.

Against the background of the steadily increasing amount of plastic waste in the sea and on land, it is more important than ever to find ways out of this situation. In recent years, microorganisms have been discovered that are capable of degrading artificial polymers such as polyethylene terephthalate (PET). Even if the turnover rates of the enzymes responsible for this reaction may be too low to solve the global plastic pollution problem, it is still of great societal interest to find microorganisms that are able to degrade the polymer. The corresponding enzymes, PET esterases (PETases) can be used in biotechnological processes and could contribute to a resource-saving circular economy. In this chapter, we present a sequence-based in silico screening method to find new PETases in metagenomic datasets. This method can easily be adapted to find other enzyme classes. We also list a number of assays that can be used to test the enzymes for activity on PET as well as other substrates.

Microbial enzymes will offer limited solutions to the global plastic pollution crisis.

Global economies depend on the use of fossil-fuel-based polymers with 360-400 million metric tons of synthetic polymers being produced per year. Unfortunately, an estimated 60% of the global production is disposed into the environment. Within this framework, microbiologists have tried to identify plastic-active enzymes over the past decade. Until now, this research has largely failed to deliver functional biocatalysts acting on the commodity polymers such as polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), ether-based polyurethane (PUR), polyamide (PA), polystyrene (PS) and synthetic rubber (SR). However, few enzymes are known to act on low-density and low-crystalline (amorphous) polyethylene terephthalate (PET) and ester-based PUR. These above-mentioned polymers represent >95% of all synthetic plastics produced. Therefore, the main challenge microbiologists are currently facing is in finding polymer-active enzymes targeting the majority of fossil-fuel-based plastics. However, identifying plastic-active enzymes either to implement them in biotechnological processes or to understand their potential role in nature is an emerging research field. The application of these enzymes is still in its infancy. Here, we summarize the current knowledge on microbial plastic-active enzymes, their global distribution and potential impact on plastic degradation in industrial processes and nature. We further outline major challenges in finding novel plastic-active enzymes, optimizing known ones by synthetic approaches and problems arising through falsely annotated and unfiltered use of database entries. Finally, we highlight potential biotechnological applications and possible re- and upcycling concepts using microorganisms.

Investigation of the halophilic PET hydrolase PET6 from Vibrio gazogenes.

The handling of plastic waste and the associated ubiquitous occurrence of microplastic poses one of the biggest challenges of our time. Recent investigations of plastic degrading enzymes have opened new prospects for biological microplastic decomposition as well as recycling applications. For polyethylene terephthalate, in particular, several natural and engineered enzymes are known to have such promising properties. From a previous study that identified new PETase candidates by homology search, we chose the candidate PET6 from the globally distributed, halophilic organism Vibrio gazogenes for further investigation. By mapping the occurrence of Vibrios containing PET6 homologs we demonstrated their ubiquitous prevalence in the pangenome of several Vibrio strains. The biochemical characterization of PET6 showed that PET6 has a comparatively lower activity than other enzymes but also revealed a superior turnover at very high salt concentrations. The crystal structure of PET6 provides structural insights into this adaptation to saline environments. By grafting only a few beneficial mutations from other PET degrading enzymes onto PET6, we increased the activity up to three-fold, demonstrating the evolutionary potential of the enzyme. MD simulations of the variant helped rationalize the mutational effects of those mutants and elucidate the interaction of the enzyme with a PET substrate. With tremendous amounts of plastic waste in the Ocean and the prevalence of Vibrio gazogenes in marine biofilms and estuarine marshes, our findings suggest that Vibrio and the PET6 enzyme are worthy subjects to study the PET degradation in marine environments.

Female sex and advanced age are associated with invasive cytomegalovirus disease in solid organ transplant recipients.

BACKGROUND: Limited data exist to describe sex-based differences in the severity of cytomegalovirus (CMV) infection after solid organ transplant (SOT). We sought to identify if a difference exists in likelihood of tissue-invasive disease between male and female SOT recipients and to understand how age affects this relationship. METHODS: A retrospective cohort of 180 heart, liver, and kidney recipients treated for CMV was examined. A logistic regression model was developed to assess the relationship between female sex and CMV type (noninvasive vs. invasive). A secondary regression analysis looked at the relationship of invasive CMV with a variable combining sex with age above or below 50. RESULTS: There were 37 cases of proven or probable invasive CMV, occurring in 30% of females versus 16% of males. After adjustment for potential confounders, females with CMV infection were significantly more likely to have invasive disease (odds ratio (OR) 2.69, 95% confidence interval (CI) 1.25-5.90, p = .01). Females 50 years or older were at particular risk compared with males under 50 years (adjusted OR 4.54, 95% CI 1.33-18.83, p = .02). CONCLUSION: Female SOT recipients with CMV in our cohort were more likely than males to have tissue-invasive disease, with the highest risk among older females. Further prospective studies are warranted to explore underlying immunologic mechanisms.

A novel metagenome-derived viral RNA polymerase and its application in a cell-free expression system for metagenome screening.

The mining of genomes from non-cultivated microorganisms using metagenomics is a powerful tool to discover novel proteins and other valuable biomolecules. However, function-based metagenome searches are often limited by the time-consuming expression of the active proteins in various heterologous host systems. We here report the initial characterization of novel single-subunit bacteriophage RNA polymerase, EM1 RNAP, identified from a metagenome data set obtained from an elephant dung microbiome. EM1 RNAP and its promoter sequence are distantly related to T7 RNA polymerase. Using EM1 RNAP and a translation-competent Escherichia coli extract, we have developed an efficient medium-throughput pipeline and protocol allowing the expression of metagenome-derived genes and the production of proteins in cell-free system is sufficient for the initial testing of the predicted activities. Here, we have successfully identified and verified 12 enzymes acting on bis(2-hydroxyethyl) terephthalate (BHET) in a completely clone-free approach and proposed an in vitro high-throughput metagenomic screening method.

Plastics degradation by hydrolytic enzymes: The plastics-active enzymes database-PAZy.

Petroleum-based plastics are durable and accumulate in all ecological niches. Knowledge on enzymatic degradation is sparse. Today, less than 50 verified plastics-active enzymes are known. First examples of enzymes acting on the polymers polyethylene terephthalate (PET) and polyurethane (PUR) have been reported together with a detailed biochemical and structural description. Furthermore, very few polyamide (PA) oligomer active enzymes are known. In this article, the current known enzymes acting on the synthetic polymers PET and PUR are briefly summarized, their published activity data were collected and integrated into a comprehensive open access database. The Plastics-Active Enzymes Database (PAZy) represents an inventory of known and experimentally verified enzymes that act on synthetic fossil fuel-based polymers. Almost 3000 homologs of PET-active enzymes were identified by profile hidden Markov models. Over 2000 homologs of PUR-active enzymes were identified by BLAST. Based on multiple sequence alignments, conservation analysis identified the most conserved amino acids, and sequence motifs for PET- and PUR-active enzymes were derived.

Difference in absolute lymphocyte count among male and female heart transplant recipients.

The impact of sex on immune composition in the setting of solid organ transplantation is unknown. Immunocompetent men and women have quantitative differences in multiple markers of immunity, including lymphocyte subsets. Lymphocytes are of particular interest given the routine use of medications targeted at cell-mediated immunity. The objective of this retrospective cohort study was to compare absolute lymphocyte count (ALC) measurements of male and female heart recipients immediately before, and 1 month after, transplantation. Data was collected on 375 adult recipients (104 female and 271 male) from 2000 to 2018 at a single center. Mean ALC was compared using Student's t-test. Women had higher mean ALC both at baseline (female 1.6 × 103 cells/µl vs. male 1.3 × 103 cells/µl; P < .001) and at 1 month post-transplantation (mean 1.2 × 103 cells/µl vs. .8 × 103 cells/µl; P < .001). This finding could have important implications for sex-based differences in predisposition to rejection or response to infection or vaccination.

The Komagataeibacter europaeus GqqA is the prototype of a novel bifunctional N-Acyl-homoserine lactone acylase with prephenate dehydratase activity.

Previously, we reported the isolation of a quorum quenching protein (QQ), designated GqqA, from Komagataeibacter europaeus CECT 8546 that is highly homologous to prephenate dehydratases (PDT) (Valera et al. in Microb Cell Fact 15, 88. https://doi.org/10.1186/s12934-016-0482-y , 2016). GqqA strongly interfered with N-acyl-homoserine lactone (AHL) quorum sensing signals from Gram-negative bacteria and affected biofilm formation in its native host strain Komagataeibacter europaeus. Here we present and discuss data identifying GqqA as a novel acylase. ESI-MS-MS data showed unambiguously that GqqA hydrolyzes the amide bond of the acyl side-chain of AHL molecules, but not the lactone ring. Consistent with this observation the protein sequence does not carry a conserved Zn2+ binding motif, known to be essential for metal-dependent lactonases, but in fact harboring the typical periplasmatic binding protein domain (PBP domain), acting as catalytic domain. We report structural details for the native structure at 2.5 Å resolution and for a truncated GqqA structure at 1.7 Å. The structures obtained highlight that GqqA acts as a dimer and complementary docking studies indicate that the lactone ring of the substrate binds within a cleft of the PBP domain and interacts with polar residues Y16, S17 and T174. The biochemical and phylogenetic analyses imply that GqqA represents the first member of a novel type of QQ family enzymes.

Factors associated with neutropenia post heart transplantation.

BACKGROUND: Neutropenia is a serious complication following heart transplantation (OHT); however, risk factors for its development and its association with outcomes is not well described. We sought to study the prevalence of neutropenia, risk factors associated with its development, and its impact on infection, rejection, and survival. METHODS: A retrospective single-center analysis of adult OHT recipients from July 2004 to December 2017 was performed. Demographic, laboratory, medication, infection, rejection, and survival data were collected for 1 year post-OHT. Baseline laboratory measurements were collected within the 24 hours before OHT. Neutropenia was defined as absolute neutrophil count ≤1000 cells/mm3. Cox proportional hazards models explored associations with time to first neutropenia. Associations between neutropenia, analyzed as a time-dependent covariate, with secondary outcomes of time to infection, rejection, or death were also examined. RESULTS: Of 278 OHT recipients, 84 (30%) developed neutropenia at a median of 142 days (range 81-228) after transplant. Factors independently associated with increased risk of neutropenia included lower baseline WBC (HR 1.12; 95% CI 1.11-1.24), pre-OHT ventricular assist device (1.63; 1.00-2.66), high-risk CMV serostatus [donor positive, recipient negative] (1.86; 1.19-2.88), and having a previous CMV infection (4.07; 3.92-13.7). CONCLUSIONS: Neutropenia is a fairly common occurrence after adult OHT. CMV infection was associated with subsequent neutropenia, however, no statistically significant differences in outcomes were found between neutropenic and non-neutropenic patients in this small study. It remains to be determined in future studies if medication changes in response to neutropenia would impact patient outcomes.