Assessment the efficacy of some various treatment methods, in vitro and in vivo, against Aeromonas hydrophila infection in fish with regard to side effects and residues.

Aeromonas hydrophila is an opportunistic bacteria with an overwhelming impact on fish farming industry especially with upraising of drug resistant mutants. This study aimed to evaluate and compare the therapeutic and side effects of levofloxacin (LEV), chitosan-nanoparticles (CNPs), and fructooligosaccharides (FOS) in control of this infection in tilapia. A total of 160 Nile-tilapia divided into 8-groups; G1: negative-control, G2: infected-control, G3: non-infected-(levofloxacin (LEV) 10 mg/kg bwt), G4: non-infected-(chitosan-nanoparticles (CNPs) 1 g/kg ration), G5: non-infected-(fructooligosaccharides (FOS) 20 g/kg ration), G6: infected-LEV, G7: infected-CNPs and G8: infected-FOS for 7 days. MICs were (0.125 µg/ml and 1.25 mg/ml) for LEV and CNPs respectively. No mortalities or significant adverse effects were recorded in non-infected treated-groups while infected were (20%) LEV, (30%) CNPs, (40%) FOS and (70%) G2. Aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) decreased by LEV and CNPs than FOS while all increased total protein (TP) and albumin than G2. Malondialdehyde (MDA) significantly decreased and superoxide dismutase (SOD) and reduced glutathione (GSH) increased in all infected-treated groups than G2 in various degrees. Urea and creatinine descending order were FOS, LEV then CNPs decreased significantly than G2. LEV musculature residues, using HPLC, decreased gradually till the 5th day; 621.00 ± 0.66, 270.00 ± 0.48 then 64.00 ± 0.40, and 471.00 ± 0.79, 175.00 ± 0.52 ppb then not detected at 1st, 3rd, and 5th days of withdrawal in non-infected and infected groups respectively. Finally, LEV and CNPs were superior as bactericidal, decreasing mortalities and enzyme activities while CNPs and FOS increased performance, non-specific immunity, and antioxidant biomarkers.

Nano spirulina dietary supplementation augments growth, antioxidative and immunological reactions, digestion, and protection of Nile tilapia, Oreochromis niloticus, against Aeromonas veronii and some physical stressors.

The current study evaluated the effects of nano delivery of Spirulina platensis on growth performance, digestive enzymes, and biochemical, immunological, and antioxidative status, as well as resistance to Aeromonas veronii and some physical stressor challenges in Nile tilapia, Oreochromis niloticus. Three experimental fish groups (n = 270) with mean weights of 26 ± 0.30 g and mean lengths of 10 ± 0.5 cm were used; the first additive-free basal diet served as the control group, whereas the following two groups were supplemented with spirulina nanoparticles (SPNP) at 0 (control), 0.25, and 0.5%/kg diet for 4 weeks. Following the feeding trial, fish were challenged with hypoxia, cold stresses, and pathogenic bacteria (A. veronii) infection (9 × 108 CFU/ml). SPNP supplementation, especially 0.5%, (p < 0.05) significantly increased growth performance (specific growth rate % day-1, feed conversion ratio, and length gain rate %), immunological (plasma lysozyme and liver nitrous oxide) antioxidants (superoxide dismutase, catalase, and glutathione peroxidase in liver), biochemical (aspartate aminotransferase, alanine transaminase, glucose, and cortisol concentrations in plasma) assays, and digestive enzymes (lipase and amylase in plasma). The expression of liver's heat shock protein 70 (HSP70) and interleukin 1, beta (IL-1ß) genes showed a significant upregulation outline of 0.5% SPNP > 0.25% SPNP > 0% SPNP compared with the control. Protection in the incorporated fish groups exposed to A. veronii was 100% compared with the control group, which showed 50% cumulative mortalities. In conclusion, dietary SPNP supplementation improved growth performance, antioxidant activity, immune response, digestive enzymes, related gene expression, and resistance of Nile Tilapia to hypoxia, cold, and A. veronii infection. Thus, SPNP could be used as a natural therapy for controlling those stressors.

Effect of C-Reactive Protein-Guided Antibiotic Treatment Duration, 7-Day Treatment, or 14-Day Treatment on 30-Day Clinical Failure Rate in Patients With Uncomplicated Gram-Negative Bacteremia: A Randomized Clinical Trial.

Importance: Antibiotic overuse drives antibiotic resistance. Gram-negative bacteremia is a common infection that results in substantial antibiotic use. Objective: To compare the clinical effectiveness of C-reactive protein (CRP)-guided, 7-day, and 14-day antibiotic durations 30, 60, and 90 days after treatment initiation. Design, Setting, and Participants: Multicenter, noninferiority, point-of-care randomized clinical trial including adults hospitalized with gram-negative bacteremia conducted in 3 Swiss tertiary care hospitals between April 2017 and May 2019, with follow-up until August 2019. Patients and physicians were blinded between randomization and antibiotic discontinuation. Adults (aged ≥18 years) were eligible for randomization on day 5 (±1 d) of microbiologically efficacious therapy for fermenting, gram-negative bacteria in blood culture(s) if they were afebrile for 24 hours without evidence for complicated infection (eg, abscess) or severe immunosuppression. Intervention: Randomization in a 1:1:1 ratio to an individualized CRP-guided antibiotic treatment duration (discontinuation once CRP declined by 75% from peak; n = 170), fixed 7-day treatment duration (n = 169), or fixed 14-day treatment duration (n = 165). Main Outcomes and Measures: The primary outcome was the clinical failure rate at day 30, defined as the presence of at least 1 of the following, with a non-inferiority margin of 10%: recurrent bacteremia, local suppurative complication, distant complication (growth of the same organism causing the initial bacteremia), restarting gram-negative-directed antibiotic therapy due to clinical worsening suspected to be due to the initial organism, or death due to any cause. Secondary outcomes included the clinical failure rate on day 90 of follow-up. Results: Among 504 patients randomized (median [interquartile range] age, 79 [68-86] years; 306 of 503 [61%] were women), 493 (98%) completed 30-day follow-up and 448 (89%) completed 90-day follow-up. Median antibiotic duration in the CRP group was 7 (interquartile range, 6-10; range, 5-28) days; 34 of the 164 patients (21%) who completed the 30-day follow-up had protocol violations related to treatment assignment. The primary outcome occurred in 4 of 164 (2.4%) patients in the CRP group, 11 of 166 (6.6%) in the 7-day group, and 9 of 163 (5.5%) in the 14-day group (difference in CRP vs 14-day group, -3.1% [1-sided 97.5% CI, -∞ to 1.1]; P < .001; difference in 7-day vs 14-day group, 1.1% [1-sided 97.5% CI, -∞ to 6.3]; P < .001). By day 90, clinical failure occurred in 10 of 143 patients (7.0%) in the CRP group, 16 of 151 (10.6%) in the 7-day group, and 16 of 153 (10.5%) in the 14-day group. Conclusions and Relevance: Among adults with uncomplicated gram-negative bacteremia, 30-day rates of clinical failure for CRP-guided antibiotic treatment duration and fixed 7-day treatment were noninferior to fixed 14-day treatment. However, interpretation is limited by the large noninferiority margin compared with the low observed event rate, as well as low adherence and wide range of treatment durations in the CRP-guided group. Trial Registration: ClinicalTrials.gov Identifier: NCT03101072.

Comparison of Treatment Outcomes between Analysis Populations in the RESTORE-IMI 1 Phase 3 Trial of Imipenem-Cilastatin-Relebactam versus Colistin plus Imipenem-Cilastatin in Patients with Imipenem-Nonsusceptible Bacterial Infections.

The RESTORE-IMI 1 phase 3 trial demonstrated the efficacy and safety of imipenem-cilastatin (IMI) combined with relebactam (REL) for treating imipenem-nonsusceptible infections. The objective of this analysis was to compare the outcomes among patients meeting eligibility requirements based on central laboratory susceptibility versus local laboratory susceptibility. Patients with serious infections caused by imipenem-nonsusceptible, colistin-susceptible, and imipenem-REL-susceptible pathogens were randomized 2:1 to IMI-REL plus placebo or colistin plus IMI for 5 to 21 days. The primary endpoint was a favorable overall response. Key endpoints included the clinical response and all-cause mortality. We compared outcomes between the primary microbiological modified intent-to-treat (mMITT) population, where eligibility was based on central laboratory susceptibility testing, and the supplemental mMITT (SmMITT) population, where eligibility was based on local, site-level testing. The SmMITT (n = 41) and MITT (n = 31) populations had similar baseline characteristics, including sex, age, illness severity, and renal function. In both analysis populations, favorable overall response rates in the IMI-REL treatment group were >70%. Favorable clinical response rates at day 28 were 71.4% for IMI-REL and 40.0% for colistin plus IMI in the mMITT population, whereas they were 75.0% for IMI-REL and 53.8% for colistin plus IMI in the SmMITT population. Day 28 all-cause mortality rates were 9.5% for IMI-REL and 30.0% for colistin plus IMI in the mMITT population, whereas they were 10.7% for IMI-REL and 23.1% for colistin plus IMI in the SmMITT population. The outcomes in the SmMITT population were generally consistent with those in the mMITT population, suggesting that outcomes may be applicable to the real-world use of IMI-REL for treating infections caused by imipenem-nonsusceptible Gram-negative pathogens. (This study has been registered at ClinicalTrials.gov under identifier NCT02452047.).

The effect of cefoperazone sulbactam and piperacillin tazobactam on mortality in Gram-negative nosocomial infections.

Cefoperazone-sulbactam (CS) and piperacillin-tazobactam (TZP) are used in the treatment of Gram-negative nosocomial infections (NIs). We aimed to compare the effects of these two antibiotics on mortality and treatment success. Patients treated with CS or TZP empirically for at least three days with suspicion of NI were included in this retrospective study. In total, 308 (154 patients in both treatment arms) patients were analyzed. Treatment success rate in CS and TZP group respectively (50% vs 51.2%, p = 0.18), 28-day mortality rate (46.1% vs 42.8%, p = 0.56) and antibiotic-related side effects (50.6% vs 46.1%, p = 0.42) were similar except prolonged prothrombin time (19.4% vs 6.4%; p = 0.001). According to this study results, CS and TZP have equal effectivity and safety for the empirical treatment of Gram-negative NIs. CS may be an appropriate alternative to TZP for antibiotic cycling or mixing strategy to reduce antibiotic resistance.

Treatment pattern, prognostic factors, and outcome in patients with infection due to pan-drug-resistant gram-negative bacteria.

The present study investigated the clinical course, treatment pattern, prognostic factors, and outcome of patients with pun-drug resistant (PDR) infections. This was a retrospective single-center cohort study including consecutive eligible patients with a PDR infection hospitalized at the University Hospital of Heraklion, Crete, Greece, between January 2010 and June 2018. In total, 65 patients with infections due to PDR gram-negative pathogens were identified. The median age was 64 years (interquartile range, IQR: 45.5-74.5) and the median Charlson comorbidity index 3.0 (IQR: 1.0-5.75). Of the 65 PDR isolates, 31 (48%) were Klebsiella pneumoniae, 28 (43%) Acinetobacter baumannii, and 6 (9%) Pseudomonas aeruginosa. The most common empirical therapy was colistin-based combination (n = 32; 49%), followed by non-colistin, non-tigecycline combination (n = 25; 39%), and carbapenemes + tigecycline (n = 8; 12%). The empirical therapy was effective in 50%, 37.5%, and 8% of patients receiving colistin combination, carbapenemes - tigecycline, and non-colistin, non-tigecycline combination, respectively (p value = 0.003). The infection-related in-hospital mortality was 32% (95% confidence interval, CI: 21-45%). Three factors were significantly associated with infection-related in-hospital mortality in multivariate analysis: Charlson comorbidity index (odds ratio, OR: 1.5, 95% CI: 1.0-2.3, p value = 0.030), prior steroid use (OR: 4.1, 95% CI: 1.0-17.0, p value = 0.049), and empirical treatment with non-colistin, non-tigecycline combination (OR: 7.5; 95% CI: 1.7-32.8, p value = 0.008). Infections due to PDR pathogens are associated with considerable mortality. Our results support the use of colistin and/or tigecycline-based combinations as empirical therapy when infection due to PDR pathogens is suspected.

Effects of thymol supplementation on performance, mortality and branchial energetic metabolism in grass carp experimentally infected by Aeromonas hydrophila.

We determined whether thymol supplementation of would minimize the negative effects of Aeromonas hydrophila infection on branchial energy metabolism, weight loss and mortality in grass carp (Ctenopharyngodon idella). We found that the infected fish all died, while 62.5% of those supplemented with 100 mg/kg thymol survived. Cytosolic and mitochondrial creatine kinase (CK) activities, as well as adenylate kinase (AK) and pyruvate kinase (PK) activities were significant lower in gills of A. hydrophila-infected fish than those of the control group, and adenosine triphosphate (ATP) levels were significant lower in the infected group. Finally, branchial reactive oxygen species (ROS) were significant higher in A. hydrophila-infected fish than in the control group. Supplementation with 100 and 300 mg thymol/kg diet prevented inhibition of branchial cytosolic and mitochondrial CK activities caused by infection, and also inhibited the reduction of branchial ATP levels. Supplementation with 100, 200 and 300 mg thymol/kg prevented the inhibition of branchial AK and PK activities induced by aeromonosis. Supplementation of 100 mg thymol/kg prevented weight loss after A. hydrophila infection. These data suggest that supplementation with 100 mg thymol/kg exerts potent bactericidal properties and augments longevity. Supplementation at all concentrations of thymol prevented A. hydrophila-induced branchial bioenergetics; nevertheless, higher concentrations were associated with side-effects.

Choice of therapeutic interventions and outcomes for the treatment of infections caused by multidrug-resistant gram-negative pathogens: a systematic review.

Background: Antimicrobial resistance is an increasingly serious threat to public health, and the increased occurrence of multidrug-resistant (MDR) bacteria is a concern in both high-income and low- and middle-income countries. The purpose of this systematic review was to identify and critically appraise current antimicrobial treatment options for infections with MDR Gram-negative bacteria. Methods: A literature search for treatment of MDR extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, A. baumannii, and P. aeruginosa was conducted in MEDLINE in January 2019. Relevant studies published in English, German, and French that evaluated clinical success, microbiological success, and 30-day mortality outcomes were included. The population of interest was adult patients. Results: Of 672 studies, 43 met the inclusion criteria. Carbapenems are the most common antibiotics used for the treatment of ESBL-producing Enterobacteriaceae. The clinical and microbiological success was similar for group 1 carbapenems (imipenem, meropenem, or doripenem), group 2 carbapenems (ertapenem), and non-carbapenem antibiotics. Mortality data were contradictory for group 1 carbapenems compared to group 2 carbapenems. The most common treatment option for A. baumannii and P. aeruginosa infections was intravenous colistin, regardless of infection site. Clinical success and mortality were similar in A. baumannii infections treated with colistin combination therapy vs. colistin monotherapy, whereas heterogeneous results were found with respect to microbiological success. Monotherapy and colistin combination therapy were used against P. aeruginosa with clinical and microbiological success (70-100%) depending on the infection site and severity, and the antibiotic used. Ceftazidime-avibactam therapy for ESBL-producing Enterobacteriaceae and P. aeruginosa showed good clinical success in one study. Conclusion: We did not find robust evidence for antibiotic treatment of any infection with MDR Gram-negative bacteria, including ESBL-producing Enterobacteriaceae, A. baumannii, and P. aeruginosa, that would lead to a firm recommendation for one specific antibiotic over another or for monotherapy over combination therapy. The choice of antibiotic treatment should be based on susceptibility testing balancing the expected clinical success rate against the risk of development of antibiotic resistance and the risk of severe side effects.

The intervention by an antimicrobial stewardship team can improve clinical and microbiological outcomes of resistant gram-negative bacteria.

Antibiotic stewardship (AS) improves patient outcomes and rates of antibiotic susceptibilities. However, the long-term effect of AS programs (ASPs) on mortality is unclear. This study aimed to assess the impact of bedside interventions by an AS team (AST) on clinical and microbiological outcomes. This retrospective study enrolled patients with bloodstream infections (BSI) and long-term use of broad-spectrum antibiotics (more than 7 days). The main outcomes were 30-day and in-hospital mortality of patients with BSI. The secondary outcomes were the day of therapy (DOT) and susceptibility of antipseudomonal agents. Cases were classified into two groups: the pre-ASP group comprised cases between 2011 and 2013 and the post-ASP group, between 2014 and 2016. The outcomes were then compared between the two groups. Among the patients with all BSI (n = 1187), no significant differences in 30-day mortality were observed between those in the pre-ASP and post-ASP groups. However, in-hospital mortality was significantly lower in the post-ASP group than that in the pre-ASP group (24.8% vs. 18.0%; P = 0.004). Furthermore, the 30-day and in-hospital mortality of resistant gram-negative bacteraemia was significantly lower (20.4% vs.10.5%; P = 0.04 and 28.0% vs.16.1%; P = 0.03). The DOT of broad-spectrum antibiotics decreased except that of tazobactam/piperacillin. The susceptibilities of tazobactam/piperacillin, ceftazidime, cefepime, sulbactam/cefoperazone, gentamicin, ciprofloxacin levofloxacin, imipenem and meropenem were significantly better. Interventions by the AST can improve the clinical and microbiological outcomes, especially resistant gram-negative bacteria. Furthermore, this effect of our ASP can continue for a long term.

Treatment Outcomes of Stenotrophomonas maltophilia Bacteremia in Critically Ill Children: A Multicenter Experience.

OBJECTIVES: Stenotrophomonas maltophilia is a gram-negative opportunistic bacterium that may cause a myriad of clinical diseases in immunocompromised individuals. We aimed to describe the clinical characteristics, risk factors, mortality, and treatment of S. maltophilia bacteremia in critically ill children, a topic on which data are sparse. DESIGN: A multicenter observational retrospective study in which medical charts of critically ill children with S. maltophilia bacteremia were reviewed between 2012 and 2017. SETTING: Data were collected from each of the four largest PICUs nationwide, allocated in tertiary medical centers to which children with complex conditions are referred regularly. PATIENTS: A total of 68 suitable cases of S. maltophilia bacteremia were retrieved and reviewed. MEASUREMENTS AND MAIN RESULTS: The total occurrence rate of S. maltophilia isolation had increased significantly during the study period (r = 0.65; p = 0.02). The crude mortality was 42%, and the attributed mortality was 18%. Significant risk factors for mortality were a longer length of hospital stay prior to infection (33 d in nonsurvivors vs 28 in survivors; p = 0.03), a nosocomial source of infection (p = 0.02), presentation with septic shock (p < 0.001), and treatment with chemotherapy (p = 0.007) or carbapenem antibiotics (p = 0.05) prior to culture retrieval. On multivariate analysis, septic shock (odds ratio, 14.6; 95% CI, 1.45-147.05; p = 0.023) and being treated with chemotherapy prior to infection (odds ratio, 5.2; 95% CI, 1.59-17.19; p = 0.006)] were associated with mortality. The combination of ciprofloxacin, trimethoprim-sulfamethoxazole, and minocycline resulted in the longest survival time (p < 0.01). CONCLUSIONS: The significant attributed mortality associated with S. maltophilia bacteremia in critically ill children calls for an aggressive therapeutic approach. The findings of this investigation favor a combination of trimethoprim-sulfamethoxazole, ciprofloxacin, and minocycline.

Evaluation of the efficacy and safety of ceftazidime/avibactam in the treatment of Gram-negative bacterial infections: a systematic review and meta-analysis.

Data on the efficacy and safety of ceftazidime/avibactam (CAZ-AVI) are limited. A systematic review and meta-analysis was conducted to clarify the role of CAZ-AVI for patients with serious Gram-negative bacterial infections. The PubMed, EMBASE and Cochrane Library databases were searched for randomised controlled trials (RCTs) and cohort studies involving CAZ-AVI. Summary risk ratios (RRs) and 95% confidence intervals (CIs) were calculated using a fixed- or random-effects model. Twelve articles (4951 patients) were included, consisting of nine RCTs and three observational studies comparing CAZ-AVI with other regimens, e.g. carbapenems or colistin. CAZ-AVI showed a comparable clinical response (RR = 0.99, 95% CI 0.96-1.02; I2 = 0%) and non-inferior bacterial eradication (RR = 1.04, 95% CI 0.93-1.17; I2 = 79.1%) to carbapenems. No significant difference was detected between groups regarding mortality and adverse events. Moreover, subgroup analyses demonstrated that CAZ-AVI improved the clinical response (RR = 1.61, 95% CI 1.13-2.29) with reduced mortality (RR = 0.29, 95% CI 0.13-0.63) in patients infected by carbapenem-resistant Enterobacteriaceae versus comparators. Likewise, CAZ-AVI improved the clinical cure rate of bloodstream infections (RR = 2.11, 95% CI 1.54-2.88). An improved ability of CAZ-AVI in microbiological eradication was also detected in patients with complicated urinary tract infections (RR = 1.13, 95% CI 1.05-1.21). CAZ-AVI exhibited comparable efficacy and safety with carbapenems. Therefore, this agent might be a potential powerful agent for patients with serious Gram-negative bacterial infections.

Difficult-to-Treat Resistance in Gram-negative Bacteremia at 173 US Hospitals: Retrospective Cohort Analysis of Prevalence, Predictors, and Outcome of Resistance to All First-line Agents.

Background: Resistance to all first-line antibiotics necessitates the use of less effective or more toxic "reserve" agents. Gram-negative bloodstream infections (GNBSIs) harboring such difficult-to-treat resistance (DTR) may have higher mortality than phenotypes that allow for ≥1 active first-line antibiotic. Methods: The Premier Database was analyzed for inpatients with select GNBSIs. DTR was defined as intermediate/resistant in vitro to all ß-lactam categories, including carbapenems and fluoroquinolones. Prevalence and aminoglycoside resistance of DTR episodes were compared with carbapenem-resistant, extended-spectrum cephalosporin-resistant, and fluoroquinolone-resistant episodes using CDC definitions. Predictors of DTR were identified. The adjusted relative risk (aRR) of mortality was examined for DTR, CDC-defined phenotypes susceptible to ≥1 first-line agent, and graded loss of active categories. Results: Between 2009-2013, 471 (1%) of 45011 GNBSI episodes at 92 (53.2%) of 173 hospitals exhibited DTR, ranging from 0.04% for Escherichia coli to 18.4% for Acinetobacter baumannii. Among patients with DTR, 79% received parenteral aminoglycosides, tigecycline, or colistin/polymyxin-B; resistance to all aminoglycosides occurred in 33%. Predictors of DTR included urban healthcare and higher baseline illness. Crude mortality for GNBSIs with DTR was 43%; aRR was higher for DTR than for carbapenem-resistant (1.2; 95% confidence interval, 1.0-1.4; P = .02), extended-spectrum cephalosporin-resistant (1.2; 1.1-1.4; P = .001), or fluoroquinolone-resistant (1.2; 1.0-1.4; P = .008) infections. The mortality aRR increased 20% per graded loss of active first-line categories, from 3-5 to 1-2 to 0. Conclusion: Nonsusceptibility to first-line antibiotics is associated with decreased survival in GNBSIs. DTR is a simple bedside prognostic measure of treatment-limiting coresistance.

Effect of elevated imipenem/cilastatin minimum inhibitory concentrations on patient outcomes in Gram-negative bloodstream infections.

OBJECTIVES: Carbapenem minimum inhibitory concentration (MICs) are known to predict outcomes for patients with Gram-negative bacteraemia. However, limited data exist on how MICs influence such outcomes when organisms are classified as carbapenem-resistant. The purpose of this study was to evaluate the effect of increasing imipenem/cilastatin MICs on mortality in patients with Gram-negative bloodstream infection (BSI). METHODS: Patients with an imipenem/cilastatin-resistant (MIC>4mg/L) monomicrobial Gram-negative BSI were eligible for inclusion in the study and were assessed for baseline characteristics, organ function, microbiological data, timing and type of therapeutic treatment, and in-hospital mortality. RESULTS: A total of 62 patients with imipenem/cilastatin-resistant bacterial isolates (MIC>4mg/L) were retrospectively studied. Time to event analyses found no difference between patients who received carbapenem therapy and those who did not (P=0.10). After adjustment, patients receiving directed therapy were less likely to die (adjusted hazard ratio=0.35, 95% confidence interval 0.15-0.83; P<0.01), whereas higher modified Acute Physiology and Chronic Health Evaluation (APACHE) II score and days to positive culture were associated with non-survival. CONCLUSION: This study did not demonstrate a relationship between receipt of a carbapenem and mortality in patients with carbapenem-resistant Gram-negative BSI.

A novel probiotic Bacillus siamensis B44v isolated from Thai pickled vegetables (Phak-dong) for potential use as a feed supplement in aquaculture.

The use of probiotic bacteria to control bacterial infection in farmed fish is of clear practical interest. The aims of this study were to isolate and select a probiotic Bacillus sp. and to evaluate the effects of its supplementation on the growth and disease resistance of hybrid catfish. Bacillus siamensis strain B44v, selectively isolated from Thai pickled vegetables (Phak-dong), displayed a high potential as a probiotic in catfish culture. This bacterium produced a bacteriocin-like substance and exhibited a broad-spectrum antibacterial activity inhibiting both Gram-positive and Gram-negative bacteria, especially the fish pathogens Aeromonas hydrophila and Streptococcus agalactiae. The susceptibility to all 14 antibiotics tested implies its less possibility to be the antibiotic-resistant bacterium. Bacillus siamensis strain B44v possessed interesting adhesion properties, as shown by its high percentages of hydrophobicity (64.8%), auto-agglutination (73.8%), co-aggregation (67.2% with A. hydrophila FW52 and 63.5% with S. agalactiae F3S), and mucin binding (88.7%). The strain B44v survived simulated gastrointestinal conditions and produced protease and cellulase enzymes. Hybrid catfish (C. macrocephalus × C. gariepinus) were employed in the feed-trial experiments. Fish fed diet containing strain B44v (107 CFU/g feed) displayed not only no mortality but also growth improvement. At the end of the feed trial, fish were challenged by an intraperitoneal injection of Aeromonas hydrophila FW52. The Bacillus siamensis strain B44v fed fish survived (75.0%; p < 0.05) better than the controls (36.7%; p < 0.05) after a two week challenge. These collective results present for the first time the potential of Bacillus siamensis strain B44v for use as a bacterial probiotic in aquaculture.

From Bench-Top to Bedside: A Prospective In Vitro Antibiotic Combination Testing (iACT) Service to Guide the Selection of Rationally Optimized Antimicrobial Combinations against Extensively Drug Resistant (XDR) Gram Negative Bacteria (GNB).

INTRODUCTION: Combination therapy is increasingly utilized against extensively-drug resistant (XDR) Gram negative bacteria (GNB). However, choosing a combination can be problematic as effective combinations are often strain-specific. An in vitro antibiotic combination testing (iACT) service, aimed to guide the selection of individualized and rationally optimized combination regimens within 48 hours, was developed. We described the role and feasibility of the iACT service in guiding individualized antibiotic combination selection in patients with XDR-GNB infections. METHODS: A retrospective case review was performed in two Singapore hospitals from April 2009-June 2014. All patients with XDR-GNB and antibiotic regimen guided by iACT for clinical management were included. The feasibility and role of the prospective iACT service was evaluated. The following patient outcomes were described: (i) 30-day in-hospital all-cause and infection-related mortality, (ii) clinical response, and (iii) microbiological eradication in patients with bloodstream infections. RESULTS: From 2009-2014, the iACT service was requested by Infectious Disease physicians for 39 cases (20 P. aeruginosa, 13 A. baumannii and 6 K. pneumoniae). Bloodstream infection was the predominant infection (36%), followed by pneumonia (31%). All iACT recommendations were provided within 48h from request for the service. Prior to iACT-guided therapy, most cases were prescribed combination antibiotics empirically (90%). Changes in the empiric antibiotic regimens were recommended in 21 (54%) cases; in 14 (36%) cases, changes were recommended as the empiric regimens were found to be non-bactericidal in vitro. In 7 (18%) cases, the number of antibiotics used in combination empirically was reduced by the iACT service. Overall, low 30-day infection-related mortality (15%) and high clinical response (82%) were observed. Microbiological eradication was observed in 79% of all bloodstream infections. CONCLUSIONS: The iACT service can be feasibly employed to guide the timely selection of rationally optimized combination regimens, and played a role in reducing indiscreet antibiotic use.

Influence of Colistin Dose on Global Cure in Patients with Bacteremia Due to Carbapenem-Resistant Gram-Negative Bacilli.

The increasing prevalence of multidrug-resistant (MDR) nosocomial infections accounts for increased morbidity and mortality of such infections. Infections with MDR Gram-negative isolates are frequently treated with colistin. Based on recent pharmacokinetic studies, current colistin dosing regimens may result in a prolonged time to therapeutic concentrations, leading to suboptimal and delayed effective treatment. In addition, studies have demonstrated an association between an increased colistin dose and improved clinical outcomes. However, the specific dose at which these outcomes are observed is unknown and warrants further investigation. This retrospective study utilized classification and regression tree (CART) analysis to determine the dose of colistin most predictive of global cure at day 7 of therapy. Patients were assigned to high- and low-dose cohorts based on the CART-established breakpoint. The secondary outcomes included microbiologic outcomes, clinical cure, global cure, lengths of intensive care unit (ICU) and hospital stays, and 7- and 28-day mortalities. Additionally, safety outcomes focused on the incidence of nephrotoxicity associated with high-dose colistin therapy. The CART-established breakpoint for high-dose colistin was determined to be >4.4 mg/kg of body weight/day, based on ideal body weight. This study evaluated 127 patients; 45 (35%) received high-dose colistin, and 82 (65%) received low-dose colistin. High-dose colistin was associated with day 7 global cure (40% versus 19.5%; P = 0.013) in bivariate and multivariate analyses (odds ratio [OR] = 3.40; 95% confidence interval [CI], 1.37 to 8.45; P = 0.008). High-dose colistin therapy was also associated with day 7 clinical cure, microbiologic success, and mortality but not with the development of acute kidney injury. We concluded that high-dose colistin (>4.4 mg/kg/day) is independently associated with day 7 global cure.

Comparisons between patients with trimethoprim-sulfamethoxazole-susceptible and trimethoprim-sulfamethoxazole-resistant Stenotrophomonas maltophilia monomicrobial bacteremia: A 10-year retrospective study.

BACKGROUND/PURPOSE: The impact of bacteremia due to the resistance of Stenotrophomonas maltophilia to trimethoprim-sulfamethoxazole (TMP-SXT) is uncertain. This study compared the clinical characteristics and outcomes of patients with TMP-SXT-susceptible (TSSSM) and TMP-SXT-resistant S. maltophilia (TSRSM) monomicrobial bacteremia. METHODS: The medical records of adult patients with TSSSM and TSRSM monomicrobial bacteremia from January 2004 to December 2013 were reviewed and classified into two groups, namely, TSSSM and TSRSM. RESULTS: There were 184 patients with monomicrobial S. maltophilia bacteremia. The mean age was 68.3 years. Most patients were males (72.8%), had high Charlson Comorbidity Index scores, previously prescribed antimicrobial agents, and indwelling medical devices. The 14-day and in-hospital mortality rates were 23.9% and 47.2%, respectively. There were 128 patients (69.6%) with TSSSM and 56 (30.4%) with TSRSM. The incidence of TSSSM bacteremia increased during the study period. The TSSSM and TSRSM groups had similar demographic and clinical characteristics and no significant differences in 14-day and in-hospital mortality (24.2% vs. 23.2%, p = 0.833; 50.0% vs. 41.1%, p = 0.264, respectively). Patients with TSSSM bacteremia had an increased risk of septic shock (p = 0.044) and neutropenia (p = 0.028) at bacteremia onset. Logistic regression analysis indicated that acquisition of TMP-SXT resistance was an independent risk factor for prolonged hospitalization (p = 0.018) and catheter-related S. maltophilia bacteremia was inversely associated with prolonged hospitalization after bacteremia (p = 0.032). CONCLUSION: There were no significant differences in mortality for patients with TSSSM and TSRSM bacteremia, but patients with TSRSM bacteremia were associated with prolonged hospitalization after bacteremia onset.

Chlorophytum borivilianum Polysaccharide Fraction Provokes the Immune Function and Disease Resistance of Labeo rohita against Aeromonas hydrophila.

The present study aimed to investigate the effects of Chlorophytum borivilianum polysaccharide (CBP), as a dietary supplement administered at varying concentrations with feed (basal diet), on various cytokine-related responses in Labeo rohita fingerlings. Immune parameters and immune-related gene expressions were measured at 3rd, 4th, and 5th week after feeding. The results revealed that dietary administration of CBP at 0.2% and 0.4% for 4 weeks significantly upregulated serum lysozyme and phagocytic activity. Complement C3 and respiratory burst activity (RBA) were significantly higher after 4 weeks of CBP feeding. The immune related genes IL-8, IL-1ß, TNF-α, and iNOS were downregulated (P < 0.05) in groups with 0.2% and 0.4% CBP supplemented diets at week 4. Expression of anti-inflammatory cytokines (IL-10 and TGF-ß) was also downregulated (P < 0.5) after 4 weeks of feeding with 0.2% to 0.8% CBP. However, five weeks of CBP administration had no significant effect on immune gene expression, except TNF-α and IL-8. Fish fed with 0.4% CBP for 4 weeks showed maximum resistance against Aeromonas hydrophila (73.3% survival) compared to control. From these results, we recommend that CBP administration at 0.4% for 4 weeks could effectively improve immune response and disease resistance in L. rohita.

Stenotrophomonas maltophilia bloodstream infection in patients with hematologic malignancies: a retrospective study and in vitro activities of antimicrobial combinations.

BACKGROUND: Stenotrophomonas maltophilia causes serious infections in immunocompromised hosts. Here, we analyzed the clinical characteristics of S. maltophilia bloodstream infection (BSI) in patients with hematologic malignancies and evaluated in vitro synergistic effects of antimicrobial combinations. METHODS: We retrospectively reviewed all consecutive episodes of S. maltophilia BSIs in adult hematologic patients from June 2009 to May 2014, with in vitro susceptibility and synergy tests using high-throughput bioluminescence assay performed for available clinical isolates. RESULTS: Among 11,004 admissions during 5-year period, 31 cases were identified as S. maltophilia BSIs. The incidence rate of S. maltophilia BSI was 0.134 cases/1,000 patient-days. Overall and attributable mortality of S. maltophilia BSI was 64.5% and 38.7%, respectively. Severe neutropenia (adjusted hazard ratio [HR] 5.24, p =0.013), shock at the onset of BSI (adjusted HR 6.05, p <0.001), and pneumonia (adjusted HR 3.15, p =0.017) were independent risk factors for mortality. In vitro susceptibilities to ceftazidime, levofloxacin, ticarcillin-clavulanic acid (TIM) and trimethoprim-sulfamethoxazole (SXT) were 11.1%, 44.0%, 40.7%, and 88.9%, respectively. MIC50/MIC90 for moxifloxacin and tigecycline were 1/4 mg/L and 4/8 mg/L. The 50% and 90% fractional inhibitory concentrations (FIC(50)/FIC(90)) of clinical isolates against a combination of SXT and TIM were 0.500/0.750. For SXT plus levofloxacin or moxifloxacin, FIC(50)/FIC(90) were 0.625/1.000 and 0.625/0.625, respectively. CONCLUSION: S. maltophilia BSIs show high mortality, which is related to severe neutropenia, shock, and S. maltophilia pneumonia. Based upon drug susceptibility testing, the primary treatment of choice for S. maltophilia BSIs should be SXT in hematologic patients, rather than quinolones, with combination therapies including SXT serving as a feasible treatment option.

Impact of combination antimicrobial therapy on mortality risk for critically ill patients with carbapenem-resistant bacteremia.

There are limited treatment options for carbapenem-resistant Gram-negative infections. Currently, there are suggestions in the literature that combination therapy should be used, which frequently includes antibiotics to which the causative pathogen demonstrates in vitro resistance. This case-control study evaluated risk factors associated with all-cause mortality rates for critically ill patients with carbapenem-resistant Gram-negative bacteremia. Adult patients who were admitted to an intensive care unit with sepsis and a blood culture positive for Gram-negative bacteria resistant to a carbapenem were included. Patients with polymicrobial, recurrent, or breakthrough infections were excluded. Included patients were classified as survivors (controls) or nonsurvivors (cases) at 30 days after the positive blood culture. Of 302 patients screened, 168 patients were included, of whom 90 patients died (53.6% [cases]) and 78 survived (46.4% [controls]) at 30 days. More survivors received appropriate antibiotics (antibiotics with in vitro activity) than did nonsurvivors (93.6% versus 53.3%; P < 0.01). Combination therapy, defined as multiple appropriate agents given for 48 h or more, was more common among survivors than nonsurvivors (32.1% versus 7.8%; P < 0.01); however, there was no difference in multiple-agent use when in vitro activity was not considered (including combinations with carbapenems) (87.2% versus 80%; P = 0.21). After adjustment for baseline factors with multivariable logistic regression, combination therapy was independently associated with decreased risk of death (odds ratio, 0.19 [95% confidence interval, 0.06 to 0.56]; P < 0.01). These data suggest that combination therapy with multiple agents with in vitro activity is associated with improved survival rates for critically ill patients with carbapenem-resistant Gram-negative bacteremia. However, that association is lost if in vitro activity is not considered.