Activity of Aztreonam in Combination with Avibactam, Clavulanate, Relebactam, and Vaborbactam against Multidrug-Resistant Stenotrophomonas maltophilia.

The intrinsic L1 metallo- and L2 serine-ß-lactamases in Stenotrophomonas maltophilia make it naturally multidrug resistant and difficult to treat. There is a need to identify novel treatment strategies for this pathogen, especially against isolates resistant to first-line agents. Aztreonam in combination with avibactam has demonstrated potential, although data on other aztreonam-ß-lactamase inhibitor (BLI) combinations are lacking. Additionally, molecular mechanisms for reduced susceptibility to these combinations have not been explored. The objectives of this study were to evaluate and compare the in vitro activities and to understand the mechanisms of resistance to aztreonam in combination with avibactam, clavulanate, relebactam, and vaborbactam against S. maltophilia A panel of 47 clinical S. maltophilia strains nonsusceptible to levofloxacin and/or trimethoprim-sulfamethoxazole were tested against each aztreonam-BLI combination via broth microdilution, and 6 isolates were then evaluated in time-kill analyses. Three isolates with various aztreonam-BLI MICs were subjected to whole-genome sequencing and quantitative reverse transcriptase PCR. Avibactam restored aztreonam susceptibility in 98% of aztreonam-resistant isolates, compared to 61, 71, and 15% with clavulanate, relebactam, and vaborbactam, respectively. The addition of avibactam to aztreonam resulted in a ≥2-log10-CFU/ml decrease at 24 h versus aztreonam alone against 5/6 isolates compared to 1/6 with clavulanate, 4/6 with relebactam, and 2/6 with vaborbactam. Molecular analyses revealed that decreased susceptibility to aztreonam-avibactam was associated with increased expression of genes encoding L1 and L2, as well as the efflux pump (smeABC). Aztreonam-avibactam is the most promising BLI-combination against multidrug-resistant S. maltophilia Decreased susceptibility may be due to the combination of overexpressed ß-lactamases and efflux pumps. Further studies evaluating this combination against S. maltophilia are warranted.

Activity of Cefiderocol Alone and in Combination with Levofloxacin, Minocycline, Polymyxin B, or Trimethoprim-Sulfamethoxazole against Multidrug-Resistant Stenotrophomonas maltophilia.

The production of an L1 metallo-ß-lactamase and an L2 serine active-site ß-lactamase precludes the use of ß-lactams for the treatment of Stenotrophomonas maltophilia infections. Preclinical data suggest that cefiderocol is the first approved ß-lactam with reliable activity against S. maltophilia, but data on strains resistant to current first-line agents are limited, and no studies have assessed cefiderocol-based combinations. The objective of this study was to evaluate and compare the in vitro activity of cefiderocol alone and in combination with levofloxacin, minocycline, polymyxin B, or trimethoprim-sulfamethoxazole (TMP-SMZ) against a collection of highly resistant clinical S. maltophilia isolates. For this purpose, the MICs of cefiderocol, ceftazidime, levofloxacin, minocycline, polymyxin B, and TMP-SMZ for 37 S. maltophilia isolates not susceptible to levofloxacin and/or TMP-SMZ were determined. Nine strains with various cefiderocol MICs were then tested in time-kill experiments with cefiderocol alone and in combination with comparators. The only agents for which susceptibility rates exceeded 40% were cefiderocol (100%) and minocycline (97.3%). Cefiderocol displayed the lowest MIC50 and MIC90 values (0.125 and 0.5 mg/liter, respectively). In time-kill experiments, synergy was observed when cefiderocol was combined with levofloxacin, minocycline, polymyxin B, or TMP-SMZ against 4/9 (44.4%), 6/9 (66.7%), 5/9 (55.5%), and 6/9 (66.7%) isolates, respectively. These data suggest that cefiderocol displays potent in vitro activity against S. maltophilia, including strains resistant to currently preferred agents. Future dynamic and in vivo studies of cefiderocol alone and in combination are warranted to further define cefiderocol's synergistic capabilities and its place in therapy for S. maltophilia infections.

Activity of Imipenem-Relebactam and Meropenem-Vaborbactam against Carbapenem-Resistant, SME-Producing Serratia marcescens.

The Serratia marcescens enzyme (SME) is a chromosomally encoded carbapenemase with no known optimal treatment. Various ß-lactam/ß-lactamase inhibitors and comparators were evaluated against 8 SME producers via broth microdilution. Four isolates were subsequently tested via time-kill analyses. All isolates were resistant to imipenem, imipenem-relebactam, and meropenem but susceptible to ceftazidime, ceftazidime-avibactam, and meropenem-vaborbactam. Ceftazidime, imipenem-relebactam, and meropenem-vaborbactam were bactericidal against 3, 0, and 4 isolates, respectively. Meropenem-vaborbactam may be a potential option for severe SME-producing infections.

Activity of Potential Alternative Treatment Agents for Stenotrophomonas maltophilia Isolates Nonsusceptible to Levofloxacin and/or Trimethoprim-Sulfamethoxazole.

Stenotrophomonas maltophilia is difficult to treat due to the production of multiple intrinsic and acquired mechanisms of resistance. Trimethoprim-sulfamethoxazole (TMP-SMZ) and the fluoroquinolones have traditionally been considered the drugs of choice but are plagued by increasing resistance and adverse drug effects. The objective of this study was to evaluate the in vitro activities of 12 clinically relevant antimicrobials against clinical S. maltophilia isolates nonsusceptible to levofloxacin and/or TMP-SMZ. A diverse panel of 41 clinical S. maltophilia isolates collected through the SENTRY Antimicrobial Surveillance Program from 2008 to 2018 was evaluated against ceftazidime, ceftazidime-avibactam, chloramphenicol, delafloxacin, levofloxacin, moxifloxacin, eravacycline, minocycline, omadacycline, polymyxin B, and tigecycline. MICs were determined in triplicate via reference broth microdilution and interpreted according to CLSI guidelines where available. MIC distributions and susceptibilities were also compared across infection type, acquisition setting, and geographic origin. Susceptibilities to levofloxacin and TMP-SMZ were 29.3% and 36.6%, respectively. Minocycline displayed the highest susceptibility rate overall (92.7%) and the lowest MIC90 value (4 mg/liter) of any of the 12 agents tested. Only 3 isolates were resistant to levofloxacin, TMP-SMZ, and minocycline. Polymyxin B and tigecycline were the second most active agents. No significant differences were observed in MIC distributions across the 3 strata evaluated. These data demonstrate that few antimicrobials, old or new, maintain reliable activity against resistant S. maltophilia The role of minocycline in the treatment of infections due to S. maltophilia warrants further clinical investigation given its potent in vitro activity and favorable adverse effect profile.

Searching for the Optimal Treatment for Metallo- and Serine-ß-Lactamase Producing Enterobacteriaceae: Aztreonam in Combination with Ceftazidime-avibactam or Meropenem-vaborbactam.

Objective: Metallo-ß-lactamase (MBL)-producing Enterobacteriaceae, particularly those that co-harbor serine ß-lactamases, are a serious emerging public health threat given their rapid dissemination and the limited number of treatment options. Pre-clinical and anecdotal clinical data support the use of aztreonam in combination with ceftazidime-avibactam against these pathogens, but other aztreonam-based combinations have not been explored. The objective of this study was to evaluate the in vitro activity and compare synergy between aztreonam in combination with ceftazidime-avibactam and meropenem-vaborbactam against serine and MBL-producing Enterobacteriaceae via time-kill analyses. Methods: 8 clinical Enterobacteriaceae strains (4 Escherichia coli and 4 Klebsiella pneumoniae) co-producing NDM and at least one serine ß-lactamase were used for all experiments. Drugs were tested alone, in dual ß-lactam combinations, and in triple drug combinations against all strains. Results: All strains were resistant to ceftazidime-avibactam and meropenem-vaborbactam and 7/8 (87.5%) strains were resistant to aztreonam. Aztreonam combined with ceftazidime-avibactam was synergistic against all 7 aztreonam-resistant strains. Aztreonam combined with meropenem-vaborbactam was synergistic against all aztreonam-resistant strains with the exception of an OXA-232-producing K. pneumoniae strain. Neither triple combination was synergistic against the aztreonam-susceptible strain. Likewise, neither dual ß-lactam combination was synergistic against any strain. Conclusions: These data suggest that aztreonam plus meropenem-vaborbactam has similar activity to aztreonam plus ceftazidime-avibactam against Enterobacteriaceae producing NDM and other non-OXA-48-like serine ß-lactamases. Confirmation of these findings in future in vitro and in vivo models is warranted.

Pharmacokinetics and Dialytic Clearance of Isavuconazole During In Vitro and In Vivo Continuous Renal Replacement Therapy.

The pharmacokinetics (PK) and dialytic clearance of isavuconazole in vitro and in 7 solid organ transplant patients undergoing continuous renal replacement therapy (CRRT) were evaluated. In vivo, mean (± SD) plasma PK parameters of isavuconazole were: C max 4.00±1.45 mg/L, C min 1.76±0.76 mg/L, t ½ 48.36±29.78 h, Vss 288.78±182.11 L, CLss 4.85±3.79 L/h, and AUC 54.01±20.98 mg ⋅ h/L. Transmembrane clearance represented just 0.7% of the total isavuconazole clearance. These data suggest that isavuconazole is not readily removed by CRRT and no dose adjustments are necessary.

Protective effect of Propolfenol® on induced oxidative stress in human spermatozoa.

The propolis extract was shown to possess the capacity to protect sperm membrane from the deleterious action of oxidative attack. Oxidative stress can induce propagation of a lipid peroxidation (LPO) chain reaction because spermatozoa contain high concentration of unsaturated fatty acids. This study aimed at evaluating in vitro the possible toxicity and/or the antioxidant properties of Propolfenol® in ejaculated human spermatozoa. A colorimetric assay determined the total flavonoid content by spectrophotometry and a high-performance liquid chromatography-diode array detection analysis the quantity of galangin, pinocembrin and caffeic acid phenylethilic ester (CAPE). Sperm parameters such as motility, vitality and DNA integrity were assessed utilising optical microscopy. The antioxidant properties Propolfenol® against LPO induced by tert-Butyl Hydroperoxide were evaluated using the C11-BODIPY581/591 probe. Chemical analysis of Propolfenol® revealed low quantities of galangin, pinocembrin and CAPE; cyclic voltammetry experiments showed that Propolfenol® may exert an antioxidant activity. A protective action of Propolfenol® (20 and 100 µg/ml) on induced LPO in human spermatozoa was detected. Propolfenol® may be proposed as the supplement in media for sperm preparation techniques or cryopreservation to counteract the increased presence of reactive oxygen species generated by these methods.

Co-administration of elvitegravir/cobicistat/tenofovir disoproxil fumarate/emtricitabine and atazanavir in treatment-experienced HIV patients.

We report the use of elvitegravir 150 mg/cobicistat 150 mg/tenofovir disoproxil fumarate 300 mg/emtricitabine 200 mg (EVG/COBI/TDF/FTC) once daily, in addition to once-daily atazanavir (ATV) 300 mg, in treatment-experienced patients with human immunodeficiency virus (HIV). Due to limited data available on the co-administration of these agents, our objective was to evaluate and monitor safety and efficacy of this regimen in patients who developed resistance or intolerance to conventional antiretroviral therapy (ART). This short report included offenders incarcerated in the Illinois Department of Corrections who were ≥18 years, HIV-infected, had documented antiretroviral resistance, and received EVG/COBI/TDF/FTC + ATV once daily. Based on previous ART, resistance patterns and current medications, seven patients were initiated on once-daily therapy consisting of EVG/COBI/TDF/FTC and ATV. Due to extensive resistance, two of the seven patients were also started on abacavir (ABC) 600 mg daily in addition to EVG/COBI/TDF/FTC and ATV. Of the seven patients, one had ART changed due to concerns of resistance based on a genotype, one experienced a decline in renal function that warranted a change in therapy, and one is currently virologically suppressed on a combination of EVG/COBI/TDF/FTC, ATV, and ABC. The remaining four patients remain virologically suppressed on EVG/COBI/TDF/FTC + ATV. Therapy consisting of EVG/COBI/TDF/FTC and ATV may be a viable option for some treatment-experienced HIV-infected patients. Further studies evaluating the safety, efficacy, and pharmacokinetics of this therapy are warranted, given the lack of information currently available.

Nanoscale dielectric microscopy of non-planar samples by lift-mode electrostatic force microscopy.

Lift-mode electrostatic force microscopy (EFM) is one of the most convenient imaging modes to study the local dielectric properties of non-planar samples. Here we present the quantitative analysis of this imaging mode. We introduce a method to quantify and subtract the topographic crosstalk from the lift-mode EFM images, and a 3D numerical approach that allows for extracting the local dielectric constant with nanoscale spatial resolution free from topographic artifacts. We demonstrate this procedure by measuring the dielectric properties of micropatterned SiO2 pillars and of single bacteria cells, thus illustrating the wide applicability of our approach from materials science to biology.

Liver function in workers exposed of the cosmetics industry.

BACKGROUND: The purpose of this study is to assess whether occupational exposure to substances used in the cosmetic factories may cause effects on the liver and blood counts in exposed workers. METHODS: The study included 48 exposed workers and 86 unexposed controls. All workers included in the study underwent blood count, white blood count, total, direct and indirect bilirubin, transaminases, alkaline phosphatase and cholinesterase. The differences between the means and frequencies were compared using the Student's t-test and chi-square test with Yates correction and were considered significant when the p value was <0.05. RESULTS: The analysis of the results shows that 35.4% of workers in the cosmetics industry had liver test values above the range. We noted a statistically significant higher prevalence of GPT (p <0.05) and total bilirubin (p <0.05) in the workers of the cosmetics industry compared with the control group. CONCLUSIONS: The results obtained suggest that occupational exposure to low doses of substances used in the cosmetic industry is able to influence some liver parameters in occupationally exposed workers.

Bone marrow transplantation from alternative donors for thalassemia: HLA-phenotypically identical relative and HLA-nonidentical sibling or parent transplants.

Twenty-nine patients with thalassemia and a median age of 6 years (range 1.1-33 years) were given a BMT from an alternative donor. Six of the 29 donors were HLA-phenotypically identical and two were mismatched relatives, 13 were mismatched siblings and eight were mismatched parents. Six patients received no antigen (relatives), 15 patients one antigen, five patients two antigen and three patients three antigen disparate grafts. Twenty-three patients were in class 2 or class 3, whereas six patients were in class 1. Thirteen patients were given BUCY, nine patients BUCY plus ALG, six patients BUCY plus TBI or TLI and one patient BUCY with prior cytoreductive-immunosuppressive treatment as conditioning. As GVHD prophylaxis four patients received MTX, 22 CsA + MTX + methylprednisolone (MP) and three patients CsA + MP. Thirteen of 29 patients (44.8%) had sustained engraftment. The probability of graft failure or rejection was 55%. There were no significant differences between antigen disparities and graft failure. The incidence of grade II-IV acute GVHD was 47.3% and chronic GVHD was 37.5%. The incidence of acute GVHD was higher in patients receiving one or two antigen disparate in the GVHD direction grafts (vs no antigen) (P EQ 0.04; odds ratio 10.8; 95% CI 1.5-115). The probability of overall and event-free survival was 65% and 21%, respectively, with median follow-up of 7.5 years (range 0.6-17 years) for surviving patients. The degree of HLA disparity between patient and donor did not have a significant effect on survival. The incidence of nonhematologic toxicity was low. Transplant-related mortality was 34%. GVHD (acute or chronic) was a major contributing cause of death (50%) followed by infections (30%). We conclude that at present, due to high graft failure and GVHD rates, BMT from alternative donors should be restricted to patients who have poor life expectancies because they cannot receive adequate conventional treatment or because of alloimmunization to minor blood antigens.

The central venous catheter in a bone marrow transplant unit: an unresolved problem.

Bone marrow transplantation (BMT) is feasible with a bearable risk and discomfort for patients only if good venous access is provided. Therefore a major task for nurses of a BMT unit is management of a patient's central venous catheter. There is not general agreement about the procedure of handling a CVC and infection prophylaxis. We collected data from some Italian BMT and hematology units by means of a questionnaire. The responses to this questionnaire were not comparable except for some particulars. Each center has its own ritual procedure; even the use of sterile gloves while handling the most dangerous connections of the catheter is not the rule everywhere. It is noteworthy that only a minority of physicians are able to handle a catheter correctly.

Liver damage among shoe repairers.

BACKGROUND: The risk of hepatotoxicity in the shoe industry has already been suggested, however, there has been no investigation among the craftsmen who repair shoes. METHODS: A group of 33 shoe repairers who work in supermarkets, and who use the same glues which contain mixtures of potentially hepatotoxic solvents were identified. A control group of 61 workers not exposed to hepatotoxic substances was also examined. All participants completed a questionnaire designed to identify potential risk factors and the main non-occupational confounding factors for hepatotoxicity. Laboratory tests, commonly used in clinical practice, were done to check whether they were useful markers of hepatotoxicity due to exposure to solvent mixtures, and to investigate which tests should be used in the screening campaigns. RESULTS: The exposed workers had a higher prevalence of elevated mean alanine aminotransferase (ALT), aspartate aminotransferase (AST), conjugated bilirubin (P=0.0001), and alkaline phosphatase (AP) (P=0.004) than controls did. The number of workers who had values outside the upper limit of normal for our laboratory was significantly higher (ALT P=0.034, AST P=0. 037, conjugated bilirubin P=0.014). Exposed workers all had a ratio of ALT to AST greater than 1, with a mean of 1.5; it was > 1.6 in more than half the exposed workers. CONCLUSIONS: The findings suggest that there is the possibility of liver involvement among even asymptomatic shoe repairers, and that periodic liver screening may be useful; furthermore, use of these tests (especially the ratio of ALT to AST) for craftsmen who repair shoes, and are exposed to solvent mixtures, is advisable even when environmental monitoring indicates levels below the threshold limit values (TLVs).

[125I]His-neurokinin A binds selectively to NK2 receptors of the B-type in rat small intestine smooth muscle membranes.

The high-affinity, reversible binding of [125I]His-neurokinin A (NKA) to rat small intestine smooth muscle membranes was investigated. Endogenous neurokinin agonists, selective neurokinin analogues, both agonist and antagonist, were used to define the selectivity of the binding. Both the endogenous and selective neurokinin analogue agonists displayed orders of potency indicating that [125I]His-NKA was binding to NK2 receptors. The use of recently developed NK2-selective antagonists indicated that the NK2 receptors present in this preparation were similar to those described in hamster trachea preparations (NK2B), and not endothelium-denuded rabbit pulmonary artery (NK2A). The absence of NK2A receptors and the predominance of NK2B was confirmed by blocking experiments using MEN10376 and L659877. Low-affinity binding of NKA was also observed with this preparation, which was not sensitive to the NK2-selective agonist, [beta-Ala8]NKA4-10. This was shown not to be due to the presence of NK1 or NK3 receptors by using selective agonists for NK1 and NK3 to block any such receptors. (No evidence for the presence of these receptors was obtained during these blocking experiments.) Guanylylimidodiphosphate appears to discriminate between the high- and low-affinity binding sites for NKA. It was thus concluded that high-affinity binding of [125I]His-NKA to rat small intestine smooth muscle membranes was selective for NK2B receptors. No evidence was found for the binding of [125I]His-NKA to NK1, NK3 or NK2A receptors.

Immunologic recovery in thalassemic marrow graft recipients following high-dose busulfan and cyclophosphamide.

T lymphocyte subsets, mitogenic response, and immunoglobulin levels were studied in peripheral blood from 95 thalassemic patients before and at different times after bone marrow transplantation. With the exception of patients receiving more than 100 transfusion units before transplant, who showed an increased percentage of CD8-positive cells, thalassemic patients were essentially immunologically normal. Depressed lymphocyte proliferative response to phytohemagglutinin, concanavalin-A, and pokeweed mitogen; decreased IgG, IgM and IgA levels; and abnormal T subpopulation distribution were observed early after transplant. Long-term transplanted patients showed complete recovery of the immunological profile with the exception of the IgA levels, which were significantly decreased up to 2 years after transplant.

Fetal liver transplantation in the mini-pig.

After the characterisation of the hematological and immunological status of the mini-pig fetus at different gestational ages of development was performed, two different groups of animals receiving 800 rads of TBI given by a radioactive cobalt source at a dose/rate of 5/6 rad/min or 750 rads of TBI given by a Linear Accelerator at a dose/rate of 25/26 rad/min, both in a single dose exposure, were transplanted with a pool of allogeneic fetal liver cells whose age ranged between 55 and 75 days of gestation. In the first group 1 animal out of 6 is alive and well 30 months post-transplant. In the second group one of the nine transplanted animals survived 78 days. Engraftment was proved by the presence of the donor chromosome in the proliferating bone marrow cells in one animal.

Effect of two cyclophosphamide derivatives on hemopoietic progenitor cells and pluripotential stem cells.

The studies described herein were undertaken to help define the effects of certain cyclophosphamide derivatives that have been used for selective removal of leukemic cells from marrow samples used for autologous transplantation. We have tested the effect of 4-HC and another cyclophosphamide congener, ASTA-Z 7557, on pluripotent stem cells (CFU-S) and committed progenitor cells (CFU-GM) in mice. The CFU-S were evaluated by the spleen colony assay at eight days and 12 days after transplant. The eight-day colonies are transient in nature, rapidly growing, mainly erythroid, and lack pluripotential precursors. The 12-day colonies are believed to provide a measure of hemopoietic stem cells as they slowly grow and do contain primitive precursors. Our data show that at the maximum dose levels tested, both drugs caused a 100% loss of CFU-GM and about 80%-95% inhibition of early transient CFU-S. In contrast, about 70% of the pluripotent 12-day CFU-S were spared. These data appear to explain the hemopoietic recovery seen in man after transplantation with marrow cells treated with 4-HC despite their relative absence of hemopoietic progenitor cells.