Dopamine receptor D2 confers colonization resistance via microbial metabolites.

The gut microbiome has major roles in modulating host physiology. One such function is colonization resistance, or the ability of the microbial collective to protect the host against enteric pathogens1-3, including enterohaemorrhagic Escherichia coli (EHEC) serotype O157:H7, an attaching and effacing (AE) food-borne pathogen that causes severe gastroenteritis, enterocolitis, bloody diarrhea and acute renal failure4,5 (haemolytic uremic syndrome). Although gut microorganisms can provide colonization resistance by outcompeting some pathogens or modulating host defence provided by the gut barrier and intestinal immune cells6,7, this phenomenon remains poorly understood. Here, we show that activation of the neurotransmitter receptor dopamine receptor D2 (DRD2) in the intestinal epithelium by gut microbial metabolites produced upon dietary supplementation with the essential amino acid L-tryptophan protects the host against Citrobacter rodentium, a mouse AE pathogen that is widely used as a model for EHEC infection8,9. We further find that DRD2 activation by these tryptophan-derived metabolites decreases expression of a host actin regulatory protein involved in C. rodentium and EHEC attachment to the gut epithelium via formation of actin pedestals. Our results reveal a noncanonical colonization resistance pathway against AE pathogens that features an unconventional role for DRD2 outside the nervous system in controlling actin cytoskeletal organization in the gut epithelium. Our findings may inspire prophylactic and therapeutic approaches targeting DRD2 with dietary or pharmacological interventions to improve gut health and treat gastrointestinal infections, which afflict millions globally.

Cefepime versus carbapenems for treatment of AmpC beta-lactamase-producing Enterobacterales bloodstream infections.

PURPOSE: Cefepime is recommended for treating infections caused by AmpC beta-lactamase-producing Enterobacterales (AmpC-PE), though supporting evidence is limited. Therefore, this study compared outcomes associated with cefepime versus carbapenem therapy for bloodstream infections (BSIs) caused by AmpC-PE after phenotypic exclusion of ESBL-co-producing isolates. METHODS: This retrospective cohort study compared definite cefepime versus carbapenem treatment for AmpC-PE BSI in hospitalized patients of the University Hospital Basel, Switzerland, between 01/2015 and 07/2020. Primary outcomes included in-hospital death, renal impairment and neurologic adverse events; secondary outcomes included length of hospital stay and recurrent infection. RESULTS: Two hundred and seventy episodes of AmpC-PE BSI were included, 162, 77 and 31 were treated with a carbapenem, cefepime and other antibiotics, respectively. Patients treated with carbapenems were more likely to be transferred to the ICU on admission and more frequently had central venous catheter as a source of infection. In uni- and multivariable analyses, primary and secondary outcomes did not differ between the two treatment groups, except for more frequent occurrence of neurological adverse events among patients treated with carbapenems and shorter length of hospital stay among survivors treated with cefepime. CONCLUSION: After excluding isolates with phenotypic ESBL-co-production, cefepime was not associated with adverse outcomes compared to carbapenems when used to treat BSIs caused by AmpC-PE. Our study provides evidence to support the use of cefepime as a safe treatment strategy for AmpC-PE BSI, particularly in clinically stable patients without initial renal impairment or increased susceptibility to neurological adverse events.

Risk Factors for Carbapenem-Resistant Enterobacterales Clinical Treatment Failure.

The Centers for Disease Control and Prevention (CDC) categorized carbapenem-resistant Enterobacterales (CRE) infections as an "urgent" health care threat requiring public attention and research. Certain patients with CRE infections may be at higher risk for poor clinical outcomes than others. Evidence on risk or protective factors for CRE infections are warranted in order to determine the most at-risk populations, especially with newer beta-lactam/beta-lactamase inhibitor (BL/BLI) antibiotics available to treat CRE. We aimed to identify specific variables involved in CRE treatment that are associated with clinical failure (either 30-day mortality, 30-day microbiologic recurrence, or clinical worsening/failure to improve throughout antibiotic treatment). We conducted a retrospective, observational cohort study of hospitalized patients with CRE infection sampled from 2010 to 2020 at two medical systems in Detroit, Michigan. Patients were included if they were ≥18 years old and culture positive for an organism in the Enterobacterales order causing clinical infection with in vitro resistance by Clinical and Laboratory Standards Institute (CLSI) breakpoints to at least one carbapenem. Overall, there were 140 confirmed CRE infections of which 39% had clinical failure. The most common infection sources were respiratory (38%), urinary (20%), intra-abdominal (16%), and primary bacteremia (14%). A multivariable logistic regression model was developed to identify statistically significant associated predictors with clinical failure, and they included Sequential Organ Failure Assessment (SOFA) score (adjusted odds ratio [aOR], 1.18; 95% confidence interval [CI], 1.06 to 1.32), chronic dialysis (aOR, 5.86; 95% CI, 1.51-22.7), and Klebsiella pneumoniae in index culture (aOR, 3.09; 95% CI, 1.28 to 7.47). Further research on CRE infections is needed to identify best practices to promote treatment success. IMPORTANCE This work compares carbapenem-resistant Enterobacterales (CRE) infections using patient, clinical, and treatment variables to understand which characteristics are associated with the highest risk of clinical failure. Knowing which risk factors are associated with CRE infection failure can provide clinicians better prognostic and targeted interventions. Research can also further investigate why certain risk factors cause more clinical failure and can help develop treatment strategies to mitigate associated risk factors.

Comparative genomics of Enterobacter cloacae complex before and after acquired clinical resistance to Ceftazidime-Avibactam.

Resistance to Ceftazidime-Avibactam in Enterobacter cloacae is poorly understood. Whole genome sequencing identified 6 variants in isolates collected from a patient before and after acquiring Ceftazidime-Avibactam resistance. This included a Phe396Leu mutation in acrB, a component of the AcrAB-TolC efflux pump, possibly mediating enhanced efflux of Ceftazidime and/ or Avibactam.

Epidemiology, risk factors, and prediction score of carbapenem resistance among inpatients colonized or infected with 3rd generation cephalosporin resistant Enterobacterales.

In this study, we determined the incidence and risk factors of Carbapenem-resistant Enterobacterales (CRE) acquisition in inpatients with 3rd generation cephalosporin-resistant (3GCR) Enterobacterales at a tertiary-care hospital in Lebanon, and suggested a risk prediction score for it. This is a retrospective matched case-control study of inpatients with 3GCR Enterobacterales that are carbapenem resistant (cases) versus those with carbapenem-sensitive isolates (controls). Data analysis was performed on IBM SPSS program, version 23.0 (Armonk, NY, USA: IBM Corp.). Categorical variables were compared between cases and controls through bivariate analysis and those with statistical significance (P < 0.05) were included in the forward stepwise multiple logistic regression analysis. To develop the CRE acquisition risk score, variables that maintained statistical significance in the multivariate model were assigned a point value corresponding to the odds ratio (OR) divided by the smallest OR identified in the regression model, and the resulting quotient was multiplied by two and rounded to the nearest whole number. Summation of the points generated by the calculated risk factors resulted in a quantitative score that was assigned to each patient in the database. Predictive performance was determined by assessing discrimination and calibration. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated for different cutoffs of the score. The incidence of CRE acquisition significantly increased with time from 0.21 cases/1000 patient-days (PD) in 2015 to 1.89 cases/1000PD in 2019 (r2 = 0.789, P = 0.041). Multivariate analysis of matched data revealed that the history of cerebrovascular disease (OR 1.96; 95% CI 1.04-3.70; P = 0.039), hematopoietic cells transplantation (OR 7.75; 95% CI 1.52-39.36; P = 0.014), presence of a chronic wound (OR 3.38; 95% CI 1.73-6.50; P < 0.001), endoscopy done during the 3 months preceding the index hospitalization (OR 2.96; 95% CI 1.51-4.73; P = 0.01), nosocomial site of acquisition of the organism in question (OR 2.68; 95% CI 1.51-4.73; P = 0.001), and the prior use of meropenem within 3 months of CRE acquisition (OR 5.70; 95% CI 2.61-12.43; P < 0.001) were independent risk factors for CRE acquisition. A risk score ranging from 0 to 25 was developed based on these independent variables. At a cut-off of ≥ 5 points, the model exhibited a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 64.5%, 85.8%, 82%, 70.7% and 75%, respectively. We also showed that only meropenem consumption intensity and CRE acquisition incidence density showed a strong positive correlation(r = 0.798, P = 0.106), unlike imipenem (r = - 0.868, P = 0.056) and ertapenem (r = 0.385, P = 0.522). Patients with a score of ≥ 5 points in our model were likely to acquire CRE. Only meropenem was associated with CRE carriage. Our proposed risk prediction score would help target surveillance screening for CRE amongst inpatients at the time of hospital admission and properly guide clinicians on using anti-CRE therapy.

Carbapenem-resistant Enterobacter cloacae complex in a tertiary Hospital in Northeast China, 2010-2019.

BACKGROUND: Carbapenem-resistant Enterobacter cloacae complex (CREC) is a new emerging threat to global public health. The objective of the study was to investigate the clinical characteristics and molecular epidemiology of CREC infections in the medical center of northeast China. METHODS: Twenty-nine patients were infected/colonized with CREC during a ten-year period (2010-2019) by WHONET analysis. Antibiotic susceptibilities were tested with VITEK 2 and micro broth dilution method (for polymyxin B and tigecycline). Carbapenemase encoding genes, ß-lactamase genes, and seven housekeeping genes for MLST were amplified and sequenced for 18 cryopreserved CREC isolates. Maximum likelihood phylogenetic tree was built with the concentrated sequences to show the relatedness between the 18 isolates. RESULTS: There was a rapid increase in CREC detection rate during the ten-year period, reaching 8.11% in 2018 and 6.48% in 2019. The resistance rate of CREC isolates to imipenem and meropenem were 100.0 and 77.8%, however, they showed high sensitivity to tigecycline, polymyxin B and amikacin. The 30-day crude mortality of CREC infection was 17.4%, indicating that it may be a low-virulence bacterium. Furthermore, molecular epidemiology revealed that ST93 was the predominant sequence type followed by ST171 and ST145, with NDM-1 and NDM-5 as the main carbapenemase-encoding genes. Moreover, E. hormaechei subsp. steigerwaltii and E. hormaechei subsp. oharae were the main species, which showed different resistance patterns. CONCLUSION: Rising detection rate of CREC was observed in a tertiary hospital, which showed heterogeneity in drug resistance patterns, resistance genes, and MLST types. Effective infection prevention and control measures should be taken to reduce the spread of CREC.

Temocillin versus carbapenems for urinary tract infection due to ESBL-producing Enterobacteriaceae: a multicenter matched case-control study.

OBJECTIVES: To compare the efficacy of temocillin with carbapenems for extended spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae urinary tract infections (ESBL-E UTI). METHODS: A multicenter retrospective case-control study of adults with ESBL-E UTI was conducted between January 2015 and October 2019. Cases received temocillin ≥ 50% of the effective antibiotic therapy duration and controls exclusively received carbapenem; they were statistically matched (1:1 ratio) on 6-month period, sex and age. The clinical cure at the end of antibiotic therapy was analysed using conditional logistic regression. RESULTS: Seventy-two temocillin cases were matched to 72 carbapenem controls. Most (67%) were male, median age was 69.4 years, 81 (56%) were immunocompromised, including 44 (31%) solid organ transplant recipients. There was no difference between cases and controls for baseline characteristics and microorganisms involved: Klebsiella pneumoniae in 59 (41%), Escherichia coli in 57 (40%), and Enterobacter spp. in 24 (17%). The median time from admission to effective antibiotic therapy was 0 days [range, 0-2]. Among cases, first-line antibiotic therapy (≤ 72 hours) was temocillin in six (8%) and carbapenems in 39 (54%). Temocillin was given at the median daily dose of 4 g [range, 2-4] after 3 days [range, 2-5] of carbapenems. Patients received temocillin for 81% [range, 70-93] of the effective antibiotic course duration over 11 days [range, 8-14]. The effective antibiotic duration was similar in cases and controls (P = 0.067). Clinical cure at the end of antibiotic therapy was 94% (68/72) in cases vs. 99% (71/72) in controls (P = 0.206), with no difference among immunocompromised and solid organ transplant patients (P > 0.050). CONCLUSIONS: Temocillin effectively relayed ß-lactams, including carbapenems, to treat (complicated) ESBL-E UTI. Its efficacy was consistent among kidney transplant recipients.

Facile accelerated specific therapeutic (FAST) platform develops antisense therapies to counter multidrug-resistant bacteria.

Multidrug-resistant (MDR) bacteria pose a grave concern to global health, which is perpetuated by a lack of new treatments and countermeasure platforms to combat outbreaks or antibiotic resistance. To address this, we have developed a Facile Accelerated Specific Therapeutic (FAST) platform that can develop effective peptide nucleic acid (PNA) therapies against MDR bacteria within a week. Our FAST platform uses a bioinformatics toolbox to design sequence-specific PNAs targeting non-traditional pathways/genes of bacteria, then performs in-situ synthesis, validation, and efficacy testing of selected PNAs. As a proof of concept, these PNAs were tested against five MDR clinical isolates: carbapenem-resistant Escherichia coli, extended-spectrum beta-lactamase Klebsiella pneumoniae, New Delhi Metallo-beta-lactamase-1 carrying Klebsiella pneumoniae, and MDR Salmonella enterica. PNAs showed significant growth inhibition for 82% of treatments, with nearly 18% of treatments leading to greater than 97% decrease. Further, these PNAs are capable of potentiating antibiotic activity in the clinical isolates despite presence of cognate resistance genes. Finally, the FAST platform offers a novel delivery approach to overcome limited transport of PNAs into mammalian cells by repurposing the bacterial Type III secretion system in conjunction with a kill switch that is effective at eliminating 99.6% of an intracellular Salmonella infection in human epithelial cells.

Evidence from comparative genomic analyses indicating that Lactobacillus-mediated irritable bowel syndrome alleviation is mediated by conjugated linoleic acid synthesis.

Irritable bowel syndrome (IBS) is a chronic intestinal disorder accompanied by low-grade inflammation, visceral hypersensitivity, and gut microbiota dysbiosis. Several studies have indicated that Lactobacillus supplementation can help to alleviate IBS symptoms and that these effects are strain-specific. Therefore, this study aimed to investigate the key physiological characteristics and functional genes contributing to the IBS-alleviating effects of Lactobacillus. An IBS model was established by subjecting C57BL/6 mice to Citrobacter rodentium ingestion and water avoidance stress. Lactobacillus strains with different physiological characteristics were administered to mice intragastrically for 4 weeks (5 × 109 CFU/0.2 mL per mouse per day). Indicators of colonic inflammation, visceral hypersensitivity, and gut microbiota were also evaluated. Finally, differences in functional genes between Lactobacillus strains were analyzed by a comparative genomic analysis, and the relationships between the physiological characteristics, functional genes, and IBS-alleviating effects of the strains were quantified using correlation analysis. Among the eight tested Lactobacillus strains, only Lactobacillus plantarum CCFM8610 significantly inhibited the expression of IL-1ß, IL-6, PAR-2, and mast cell tryptase. L. plantarum CCFM8610 also significantly increased the intestinal barrier function, inhibited visceral hypersensitivity symptoms, and modulated the gut microbiota diversity and composition. The correlation analysis of factors associated with the IBS-alleviating effects of Lactobacillus revealed the ability to synthesize conjugated linoleic acid as the most strongly associated physiological characteristic and COG1028-related genes as the most strongly associated functional genes. In conclusion, these findings can facilitate the rapid screening of Lactobacillus strains with IBS-alleviating effects and lay a foundation for studies of the related mechanisms.

Dietary Interventions Ameliorate Infectious Colitis by Restoring the Microbiome and Promoting Stem Cell Proliferation in Mice.

Decreases in short-chain-fatty-acids (SCFAs) are linked to inflammatory bowel disease (IBD). Yet, the mechanisms through which SCFAs promote wound healing, orchestrated by intestinal stem cells, are poorly understood. We discovered that, in mice with Citrobacter rodentium (CR)-induced infectious colitis, treatment with Pectin and Tributyrin diets reduced the severity of colitis by restoring Firmicutes and Bacteroidetes and by increasing mucus production. RNA-seq in young adult mouse colon (YAMC) cells identified higher expression of Lgr4, Lgr6, DCLK1, Muc2, and SIGGIR after Butyrate treatment. Lineage tracing in CR-infected Lgr5-EGFP-IRES-CreERT2/ROSA26-LacZ (Lgr5-R) mice also revealed an expansion of LacZ-labeled Lgr5(+) stem cells in the colons of both Pectin and Tributyrin-treated mice compared to control. Interestingly, gut microbiota was required for Pectin but not Tributyrin-induced Lgr5(+) stem cell expansion. YAMC cells treated with sodium butyrate exhibited increased Lgr5 promoter reporter activity due to direct Butyrate binding with Lgr5 at -4.0 Kcal/mol, leading to thermal stabilization. Upon ChIP-seq, H3K4me3 increased near Lgr5 transcription start site that contained the consensus binding motif for a transcriptional activator of Lgr5 (SPIB). Thus, a multitude of effects on gut microbiome, differential gene expression, and/or expansion of Lgr5(+) stem cells seem to underlie amelioration of colitis following dietary intervention.

Detection of Carbapenemase and CTX-M Encoding Genes Directly from Bronchoalveolar Lavage Using the CRE and ESBL ELITe MGB Assays: Toward Early and Optimal Antibiotic Therapy Management of Critically Ill Patients with Pneumonia.

The detection of carbapenemase extended-spectrum ß-lactamase (ESBL)-producing Enterobacterales (EB) has become a major issue among critically ill patients, especially due to their impact on appropriate antimicrobial therapy. This study aimed at evaluating the potential contribution of molecular assays to early optimization of empirical antibiotic therapy among critically ill patients with carbapenemase- and/or CTX-M-producing EB pneumonia. The CRE and ESBL ELITe MGB® assays were evaluated directly on 197 bronchoalveolar lavage (BAL) samples obtained from 120 patients. Molecular results were then compared to routine culture-based diagnostic results, and a retrospective analysis of the therapeutic antimicrobial management was performed. Among the 197 clinical specimens, blaKPC-like and blaCTX-M-like were detected in 20 (10.2%) and 12 (6.1%) specimens belonging to 15 and 11 patients, respectively. Positive predictive value (PPV) and negative predictive value (NPV) of the CRE ELITe MGB Kit were 85% [95% confidence interval [CI]: 64.9-94.6] and 100%, respectively. PPV and NPV of the ESBL ELITe MGB Kit were 75% [95% CI: 49.4-90.2] and 100%, respectively. Retrospective analysis of the therapeutic antimicrobial management at the time of BAL collection showed that in ∼50% of patients with carbapenemase- and CTX-M-producing EB pneumonia empirical antibiotic therapy could have been optimized at least 48-72 hr earlier if positive molecular data had been used. The CRE and ESBL ELITe MGB assays might be an interesting tool for expediting optimization of empirical antibiotic therapy in critically ill patients with pneumonia, depending on local epidemiology of antibiotic resistance, patient risk stratification for EB infection, and availability of an antimicrobial stewardship team.

Intestinal microbiota-derived short-chain fatty acids regulation of immune cell IL-22 production and gut immunity.

Innate lymphoid cells (ILCs) and CD4+ T cells produce IL-22, which is critical for intestinal immunity. The microbiota is central to IL-22 production in the intestines; however, the factors that regulate IL-22 production by CD4+ T cells and ILCs are not clear. Here, we show that microbiota-derived short-chain fatty acids (SCFAs) promote IL-22 production by CD4+ T cells and ILCs through G-protein receptor 41 (GPR41) and inhibiting histone deacetylase (HDAC). SCFAs upregulate IL-22 production by promoting aryl hydrocarbon receptor (AhR) and hypoxia-inducible factor 1α (HIF1α) expression, which are differentially regulated by mTOR and Stat3. HIF1α binds directly to the Il22 promoter, and SCFAs increase HIF1α binding to the Il22 promoter through histone modification. SCFA supplementation enhances IL-22 production, which protects intestines from inflammation. SCFAs promote human CD4+ T cell IL-22 production. These findings establish the roles of SCFAs in inducing IL-22 production in CD4+ T cells and ILCs to maintain intestinal homeostasis.

Activity of ceftolozane-tazobactam and comparators when tested against bacterial surveillance isolates collected from patients at risk of infections caused by resistant gram-negative pathogens.

Ceftolozane-tazobactam is an antipseudomonal cephalosporin combined with a ß-lactamase inhibitor. Ceftolozane-tazobactam has been approved for treatment of complicated urinary tract infections and acute pyelonephritis, for complicated intra-abdominal infections (with metronidazole) in adults, and for hospital-acquired bacterial pneumonia including ventilator-associated bacterial pneumonia. This study analyzed gram-negative pathogen susceptibility in US and European patients who are considered at risk for infections caused by pathogens resistant to commonly used antimicrobials: patients in the intensive care unit (ICU), patients on the hematology/oncology or transplant service who may be immunocompromised, and patients >65 years old (yo). ICU patients had the lowest susceptibility for Enterobacterales and PSA. The susceptibility for isolates from the immunocompromised and >65 yo groups was similar. Ceftolozane-tazobactam was the most active agent against PSA, with ≥90%S for >65 yo and immunocompromised, and >80%S for ICU. Meropenem and ceftolozane-tazobactam were the most active agents against Enterobacterales.

Host immunity and the colon microbiota of mice infected with Citrobacter rodentium are beneficially modulated by lipid-soluble extract from late-cutting alfalfa in the early stages of infection.

Alfalfa is a forage legume commonly associated with ruminant livestock production that may be a potential source of health-promoting phytochemicals. Anecdotal evidence from producers suggests that later cuttings of alfalfa may be more beneficial to non-ruminants; however, published literature varies greatly in measured outcomes, supplement form, and cutting. The objective of this study was to measure body weight, average daily feed intake, host immunity, and the colon microbiota composition in mice fed hay, aqueous, and chloroform extracts of early (1st) and late (5th) cutting alfalfa before and after challenge with Citrobacter rodentium. Prior to inoculation, alfalfa supplementation did not have a significant impact on body weight or feed intake, but 5th cutting alfalfa was shown to improve body weight at 5- and 6-days post-infection compared to 1st cutting alfalfa (P = 0.02 and 0.01). Combined with the observation that both chloroform extracts improved mouse body weight compared to control diets in later stages of C. rodentium infection led to detailed analyses of the immune system and colon microbiota in mice fed 1st and 5th cutting chloroform extracts. Immediately following inoculation, 5th cutting chloroform extracts significantly reduced the relative abundance of C. rodentium (P = 0.02) and did not display the early lymphocyte recruitment observed in 1st cutting extract. In later timepoints, both chloroform extracts maintained lower splenic B-cell and macrophage populations while increasing the relative abundance of potentially beneficially genera such as Turicibacter (P = 0.02). At 21dpi, only 5th cutting chloroform extracts increased the relative abundance of beneficial Akkermansia compared to the control diet (P = 0.02). These results suggest that lipid soluble compounds enriched in late-cutting alfalfa modulate pathogen colonization and early immune responses to Citrobacter rodentium, contributing to protective effects on body weight.

Single or Combined Dietary Supply of Psidium guajava and Phyllanthus amarus Extracts Differentially Modulate Immune Responses and Liver Proteome in Striped Catfish (Pangasianodon hyphophthalmus).

Guava Psidium guajava L (Pg) and bhumi amla Phyllanthus amarus Schum. et Thonn (Pa) are well-known plants in traditional medicine. However, the capacity of these plants for improving the immune system of aquatic species has received less attention so far. This study aimed to investigate the effects of single supply or mixture of Pg and Pa extracts on immune responses, disease resistance and liver proteome profiles in striped catfish Pangasianodon hypophthalmus. Fish were fed diets including basal diet 0% or one of three doses of each plant extract, either alone or in mixture, 0.08, 0.2, or 0.5% Pg, Pa or mixture (Pg:Pa, v/v) for 6 weeks. The immune parameters (respiratory burst activity (RBA); nitric oxide synthase (NOS), total immunoglobulin, lysozyme, and complement activities) were examined at W3, W6 post-feeding, and after challenge test. The growth parameters and the challenge test with Edwardsiella ictaluri were done at W6. The liver proteome profiles were analyzed in W6 at 0.08 and 0.5% of each extract. The results showed that extract-based diets significantly improved growth parameters in the Pg0.2 group compared to control. The cellular immune responses in spleen and the humoral immune responses in plasma were significantly improved in a dose and time-dependent manner. Diets supplemented with single Pg and Pa extracts, and to lesser extent to combined extracts, could significantly decrease the mortality of striped catfish following bacterial infection compared to control. The proteomic results indicated that some pathways related to immune responses, antioxidant and lipid metabolism were enriched in liver at W6. Several proteins (i.e., CD8B, HSP90AA1, HSP90AB1, PDIA3, CASP8, TUBA1C, CCKAR, GNAS, GRIN2D, PLCG1, PRKCA, SLC25A5, VDAC2, ACTN4, GNAI2, LCK, CARD9, NLRP12, and NLRP3) were synergistically upregulated in mixture of Pg and Pa-based diets compared to control and single dietary treatments. Taken together, the results revealed that single Pg and Pa extracts at 0.2 and 0.5% and their mixture at 0.08 and 0.5% have the potential to modulate the immune mechanisms and disease resistance of striped catfish. Moreover, the combination of Pg and Pa in diets suggested positive synergistic effects liver proteome profile related to immune system processes.

Rheum officinale extract promotes the innate immunity of orange-spotted grouper (Epinephelus coioides) and exerts strong bactericidal activity against six aquatic pathogens.

We investigated the antimicrobial properties and the effects of Rheum officinale extract (ROE) on nonspecific immune parameters of orange-spotted grouper (Epinephelus coioides) in vitro and in vivo. The in vitro analysis was conducted by treating grouper primary head kidney leukocytes with various concentrations of ROE. The phagocytic rate of the leukocytes was elevated in a dose-dependent manner from 0.01 to 0.1 mg/ml, but decreased with higher concentrations of ROE (0.5 and 1.0 mg/ml). The production of reactive oxygen species (ROS) was strongly enhanced in a dose-dependent manner by treatment with ROE doses of 0.1-10.0 mg/ml. However, morphological changes (e.g., rounding and shrinkage of cells, chromatin condensation, fragmentation, and appearance of apoptotic bodies) were observed in the leukocytes after incubation with higher concentrations of ROE (1.0 and 10.0 mg/ml). A 28-day feeding trial was performed to assess the impact of dietary administration of ROE on grouper innate immunity parameters. Fish were fed with feed supplemented with 0, 0.1, 1.0, or 5.0 g ROE per kg of feed. The phagocytic activity of the animals' leukocytes was significantly elevated in all ROE-fed groups on day 1 and in groups fed with ROE at 0.1 or 1.0 g/kg on day 14. Production of ROS was substantially increased on day 1 in fish fed with ROE at 1.0 and 5.0 g/kg, but decreased steadily later on. The ability to generate ROS increased steadily until day 7 in fish fed the lowest concentration of ROE (0.1 mg/ml), but decreased thereafter. ROE showed excellent antibacterial activity against six pathogens of aquatic animals: Vibrio parahaemolyticus, V. vulnificus, V. alginolyticus, V. carchariae, Aeromonas hydrophila, and Edwardsiella tarda. The minimum inhibitory and bactericidal concentrations of measured ROE-derived anthraquinones were 10.57-84.53 µg/ml and 10.57-169.05 µg/ml, respectively.

Use of Monte Carlo simulation to optimize antibiotic selection for bloodstream infections caused by Enterobacteriaceae in Shandong Province, China.

The increasing rates of resistance to ß-lactams have made it more challenging for clinicians to select appropriate antibiotic treatment for bloodstream infections (BSIs) caused by suspected Enterobacteriaceae. The objective of this analysis was to determine the optimal dosage regimens of ß-lactams for treatment of BSIs based on analysis of 19,334 Enterobacteriaceae collected from blood specimens. Monte Carlo simulation using pharmacokinetic parameters of infected patients was performed to determine the probability of overall pharmacokinetic/pharmacodynamic (PK/PD) target attainment (OPTA). E. coli, K. pneumoniae, and E. cloacae were the 3 most common species. Nine of the 16 tested regimens had optimal OPTAs (>90%) for Enterobacteriaceae overall (meropenem 2g q8h, 3 h infusion; meropenem 2g q8h, 0.5h; meropenem 1g q8h, 0.5h; piperacillin/tazobactam 4.5g q8h, 3h; ceftazidime 2g q8h, 3h; imipenem 0.5g q6h, 0.5h; imipenem 1g q8h, 0.5h; piperacillin/tazobactam 3.375g q6h, 0.5h; ceftazidime 2g q8h, 0.5h). Four other regimens had sub-optimal OPTAs of 80 to 90% (piperacillin/tazobactam 4.5g q8h, 0.5h; ceftazidime 1g q8h, 0.5h; cefepime 2g q12h, 3h; and cefepime 2g q12h, 0.5h). Although there are high antibiotic MICs among Enterobacteriaceae in Shandong Province, carbapenem- , ceftazidime- and piperacillin/tazobactam- based regimens provide the optimal treatment.

Epidemiology of colistin-resistant, carbapenemase-producing Enterobacteriaceae and Acinetobacter baumannii in Croatia.

Colistin is a last-resort antibiotic for the treatment of infections caused by multidrug and carbapenem-resistant Gram-negative bacteria. Colistin resistance has been emerging and multiple outbreaks have been reported in Europe and elsewhere. It has been most frequently reported in carbapenem-resistant K. pneumoniae. In this study, 24 multidrug and colistin-resistant clinical isolates (14 K. pneumoniae, one E. aerogenes, one E. cloacae, and eight A. baumannii) were collected from four hospitals in Croatia from 2013 to 2018, in order to analyse the molecular epidemiology and mechanisms of antibiotic resistance. ß-lactamase and carbapenemase genes were detected by PCR. Genotyping was done on selected isolates by rep-PCR. Whole genome sequencing (WGS) was performed to discover possible molecular mechanisms for the observed colistin resistance. All isolates, except two K. pneumoniae isolates, were extensively drug resistant. Ten out of 16 (63%) K. pneumoniae isolates possessed blaOXA-48, which is the most common carbapenem resistance gene in Croatia and in other parts of Europe. All A. baumannii isolates possessed the OXA-23-like carbapenem hydrolysing oxacillinase and five turned out to be pandrug-resistant. Colistin resistance was most likely chromosomally mediated. After sequence analysis, none of the isolates were found to possess any of the mcr gene variants. Several previously reported mutations were found in PmrB, PhoP, PhoQ, and MgrB, which are associated with colistin resistance. In the global phylogenetic analysis, DNA mutations causing mutations in the MgrB protein were present mostly in lineages comprising colistin resistant isolates, and the second most prevalent mutation (K3X) was also encountered in our isolates. In addition, based on genotyping by rep-PCR, the spread of colistin resistance is most likely to be clonal. Most importantly, the presence of colistin resistance together with carbapenemase genes in extensively drug resistant isolates poses real threats in the use of carbapenems and colistin to fight infections.

Activity of Plazomicin Tested against Enterobacterales Isolates Collected from U.S. Hospitals in 2016-2017: Effect of Different Breakpoint Criteria on Susceptibility Rates among Aminoglycosides.

Plazomicin was active against 97.0% of 8,783 Enterobacterales isolates collected in the United States (2016 and 2017), and only 6 isolates carried 16S rRNA methyltransferases conferring resistance to virtually all aminoglycosides. Plazomicin (89.2% to 95.9% susceptible) displayed greater activity than amikacin (72.5% to 78.6%), gentamicin (30.4% to 45.9%), and tobramycin (7.8% to 22.4%) against carbapenem-resistant and extensively drug-resistant isolates. The discrepancies among the susceptibility rates for these agents was greater when applying breakpoints generated using the same stringent contemporary methods applied to determine plazomicin breakpoints.