A1.19 Efficacy and safety of polymyxin B in the treatment of infections caused by multidrug-resistant Acinetobacter baumanii and Pseudomonas aeruginosa: A retrospective review

Cm-p5 is a snail-derived antimicrobial peptide, which demonstrated antifungal activity against the pathogenic strains of Candida albicans. Previously we synthetized a cyclic monomer as well as a parallel and an antiparallel dimer of Cm-p5 with improved antifungal activity. Considering the alarming increase of microbial resistance to conventional antibiotics, here we evaluated the antimicrobial activity of these derivatives against multiresistant and problematic bacteria and against important viral agents. The three peptides showed a moderate activity against Pseudomonas aeruginosa, Klebsiella pneumoniae Extended Spectrum β-Lactamase (ESBL), and Streptococcus agalactiae, with MIC values > 100 µg/mL. They exerted a considerable activity with MIC values between 25–50 µg/mL against Acinetobacter baumanii and Enterococcus faecium. In addition, the two dimers showed a moderate activity against Pseudomonas aeruginosa PA14. The three Cm-p5 derivatives inhibited a virulent extracellular strain of Mycobacterium tuberculosis, in a dose-dependent manner. Moreover, they inhibited Herpes Simplex Virus 2 (HSV-2) infection in a concentration-dependent manner, but had no effect on infection by the Zika Virus (ZIKV) or pseudoparticles of Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2). At concentrations of >100 µg/mL, the three new Cm-p5 derivatives showed toxicity on different eukaryotic cells tested. Considering a certain cell toxicity but a potential interesting activity against the multiresistant strains of bacteria and HSV-2, our compounds require future structural optimization.

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Evolution under low antibiotic concentrations: a risk for the selection of Pseudomonas aeruginosa multidrug resistant mutants in nature

10.1101/2021.04.21.440750 ◽

2021 ◽

Author(s):

Fernando Sanz-García ◽

Sara Hernando-Amado ◽

José Luis Martínez

Keyword(s):

Pseudomonas Aeruginosa ◽

Antibiotic Resistance ◽

Polymyxin B ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

Published Data ◽

Natural Ecosystems ◽

Clinical Value ◽

Drug Concentrations ◽

Resistant Mutants

ABSTRACTBACKGROUNDAntibiotic pollution of non-clinical environments might have a relevant impact on human health if resistant pathogens are selected. However, this potential risk is often overlooked, since drug concentrations in nature are usually below their minimal inhibitory concentrations (MICs). Albeit, antibiotic resistant bacteria can be selected even at sub-MIC concentrations, in a range that is dubbed the sub-MIC selective window, which depends on both the antibiotic and the pathogen.OBJECTIVESDetermine the sub-MIC selective windows of seven antibiotics of clinical relevance in the opportunistic pathogen Pseudomonas aeruginosa and evaluate the risk for selecting resistant mutants in nature, based on published data about the amount of antimicrobials detected in natural environments.METHODSWe conducted evolution experiments of P. aeruginosa PA14 in presence of sub-MIC concentrations of ceftazidime, amikacin, levofloxacin, ciprofloxacin, tetracycline, polymyxin B or imipenem, and measured drug susceptibility of the evolved populations.RESULTSSub-MIC selective window of quinolones was the largest, and the ones of polymyxin B and imipenem, the narrowest. Clinically relevant multidrug resistant (MDR) mutants (presenting MICs above EUCAST clinical breakpoints) arose within the sub-MIC selective windows of the majority of antibiotics tested, being these phenotypes probably mediated by efflux pumps′ activity.DISCUSSIONOur data show that the concentration of antibiotics reported in aquatic ecosystems -colonizable by P. aeruginosa- are, in occasions, higher than the ones able to select MDR mutants. This finding has implications for understanding the role of different ecosystems and conditions in the emergence of antibiotic resistance from a One-Health point of view. Further, it highlights the importance of delineating the sub-MIC selective windows for drugs of clinical value in pathogens with environmental niches, in order to evaluate the health risks due to antibiotic pollution of natural ecosystems and ultimately tackle antibiotic resistance.

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Efficacy of Antibiotic Combinations against Multidrug-Resistant Pseudomonas aeruginosa in Automated Time-Lapse Microscopy and Static Time-Kill Experiments

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02111-19 ◽

2020 ◽

Vol 64 (6) ◽

Cited By ~ 2

Author(s):

Anna Olsson ◽

Pikkei Wistrand-Yuen ◽

Elisabet I. Nielsen ◽

Lena E. Friberg ◽

Linus Sandegren ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Time Lapse ◽

Polymyxin B ◽

Multidrug Resistant ◽

Positive Interactions ◽

Synergistic Activity ◽

Content Type ◽

Time Lapse Microscopy ◽

Time Kill ◽

Antibiotic Combination

ABSTRACT Antibiotic combination therapy is used for severe infections caused by multidrug-resistant (MDR) Gram-negative bacteria, yet data regarding which combinations are most effective are lacking. This study aimed to evaluate the in vitro efficacy of polymyxin B in combination with 13 other antibiotics against four clinical strains of MDR Pseudomonas aeruginosa. We evaluated the interactions of polymyxin B in combination with amikacin, aztreonam, cefepime, chloramphenicol, ciprofloxacin, fosfomycin, linezolid, meropenem, minocycline, rifampin, temocillin, thiamphenicol, or trimethoprim by automated time-lapse microscopy using predefined cutoff values indicating inhibition of growth (≤106 CFU/ml) at 24 h. Promising combinations were subsequently evaluated in static time-kill experiments. All strains were intermediate or resistant to polymyxin B, antipseudomonal β-lactams, ciprofloxacin, and amikacin. Genes encoding β-lactamases (e.g., blaPAO and blaOXA-50) and mutations associated with permeability and efflux were detected in all strains. In the time-lapse microscopy experiments, positive interactions were found with 39 of 52 antibiotic combination/bacterial strain setups. Enhanced activity was found against all four strains with polymyxin B used in combination with aztreonam, cefepime, fosfomycin, minocycline, thiamphenicol, and trimethoprim. Time-kill experiments showed additive or synergistic activity with 27 of the 39 tested polymyxin B combinations, most frequently with aztreonam, cefepime, and meropenem. Positive interactions were frequently found with the tested combinations, against strains that harbored several resistance mechanisms to the single drugs, and with antibiotics that are normally not active against P. aeruginosa. Further study is needed to explore the clinical utility of these combinations.

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Analysis of Susceptibility Patterns of Pseudomonas aeruginosa and Isolation, Characterization of Lytic Bacteriophages Targeting Multi Drug Resistant Pseudomonas aeruginosa

Biomedical & Pharmacology Journal ◽

10.13005/bpj/1471 ◽

2018 ◽

Vol 11 (2) ◽

pp. 1105-1117 ◽

Cited By ~ 2

Author(s):

Shri Natrajan Arumugam ◽

Akarsh Chickamagalur Rudraradhya ◽

Sathish Sadagopan ◽

Sunilkumar Sukumaran ◽

Ganesh Sambasivam ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Host Range ◽

Polymyxin B ◽

Multidrug Resistant ◽

Clinical Isolates ◽

Dilution Method ◽

Drug Resistant ◽

Susceptibility Pattern ◽

Infectivity Rate

Pseudomonas aeruginosa is known to be a major cause of Hospital Acquired Infections leading to high mortality in immune-compromised patients. Due to precipitous rise in antibiotic resistance, bacteriophages are significant alternative therapeutic approach for treatment and to combat resistance development. Objective of the current study was to identify MDR Pseudomonas aeruginosa from clinical isolates and to isolate bacteriophages from sewage samples against these MDR Pseudomonas aeruginosa strains. One hundred and forty-four Pseudomonas isolates were tested for their susceptibility pattern with 13 different antibiotics by micro-broth dilution method. Frequency of multidrug resistant (MDR) and Extensive Drug resistant (XDR) of Pseudomonas aeruginosa were found to be 35.5% and 23.6%, respectively. 7.61% isolates were identified as Pan drug resistant (PDR). Rate of susceptibility pattern were Piperacillin/Tazobactam 75%, Polymyxin B 74.6%, Meropenem 73.6%, Colistin 69.2%, Cefepime 54.9%, Ciprofloxacin 54.2%, Gentamicin 54.2%, Aztreonam 53.5%, Tobramycin 47.9%, Ticarcillin/Clavulanic acid 46.9%, Ertapenem 45.8%, Ceftazidime 40.3% and Imipenem 39.2%. Ninety-four bacteriophages were isolated from sewage samples against Pseudomonas aeruginosa PAO1/ATCC9027/clinical strains and host range testing study was carried out with all MDR clinical isolates. Among 51 MDR strains 34 strains were infected by phages. Phage infectivity rate were calculated for individual phages based on their host range infectivity results. AP025 and AP006 phages exhibited good infectivity rate of 39% and 30% respectively against MDR strains. Combination of 5 phages (AP002, AP006, AP011, AP025 and AP067) lysed 62.7% of the strains. Based on the obtained results, phages could be employed for treatment of infections caused by MDR strains with substantiated in-vivo experiments.

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2151. Biofilm and Metallo-β-Lactamase (MBL) Production Among Imipenem-Resistant Pseudomonas aeruginosa and Acinetobacter spp.

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.1831 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S729-S730

Author(s):

Yang Metok ◽

Supram Hosuru Subramanya ◽

Upendra Thapa Shrestha ◽

Leandro Reus Rodrigues Perez ◽

Nabaraj Adhikari ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Hospital Setting ◽

Polymyxin B ◽

Microtiter Plate ◽

Multidrug Resistant ◽

High Rate ◽

Bacterial Strains ◽

Microbiological Techniques ◽

Acinetobacter Spp ◽

Imipenem Resistance

Abstract Background Pseudomonas aeruginosa and Acinetobacter spp. head the list of hospital-acquired infections. Resistance to carbapenem as reserve drug is under threat with the emergence of Metallo-β-lactamase (MBL) and biofilm producing bacterial strains. This study was thus undertaken to determine the rate of MBL and biofilm production among imipenem-resistant P. aeruginosa (IRPA) and imipenem-resistant Acinetobacter spp. (IRAS) isolates. Methods A total of 79 P. aeruginosa and 117 Acinetobacter spp. were isolated from different clinical specimens of patients visiting Manipal Teaching Hospital, Pokhara Nepal from July 2016 to January 2017. Isolation, identification and antibiotic susceptibility testing of the isolates were performed by standard microbiological techniques. Combined disc test and Epsilometer test (E-test) were employed to detect MBL in IRPA and IRAS isolates. Microtiter plate using crystal violet method was employed for detection of biofilm in imipenem-resistant isolates. Results 9 (11.4%) of P. aeruginosa and 49 (41.9%) of Acinetobacter spp. were Multidrug Resistant (MDR). Similarly, 22 (27.8%) of P. aeruginosa and 23 (19.7%) of Acinetobacter spp. were Extensively Drug Resistant (XDR). Imipenem resistance was detected among 15 (19%) P. aeruginosa and 57 (48.7%) Acinetobacter spp. isolates. 8 (53.3%) of IRPA and 22 (38.6%) of IRAS isolates were MBL producers while all (100%) of IRPA and 47 (82.5%) of IRAS were biofilm producers. All the biofilm producer IRPA isolates were XDR and 62.5% of XDR IRAS strains were moderate biofilm producers. However, 80% of IRPA, 49.1% of IRAS and 63% of both MBL producer isolates were weak biofilm formers. Polymyxin B and ampicillin-sulbactam showed a better degree of susceptibility against MBL cum biofilm producer IRPA and IRAS isolates respectively. Conclusion The study showed high propensity of IRPA and IRAS to form biofilm, which is strongly associated with higher drug resistance. Such high rate of MBL and biofilm producing P. aeruginosa and Acinetobacter spp. alarms the rapid spread of such strains in our hospital setting. Disclosures All authors: No reported disclosures.

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Adaptive and Mutational Responses to Peptide Dendrimer Antimicrobials in Pseudomonas aeruginosa

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02040-19 ◽

2020 ◽

Vol 64 (4) ◽

Cited By ~ 3

Author(s):

Fatma Ben Jeddou ◽

Léna Falconnet ◽

Alexandre Luscher ◽

Thissa Siriwardena ◽

Jean-Louis Reymond ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Lipid A ◽

Polymyxin B ◽

Multidrug Resistant ◽

Sensor Kinase ◽

Loss Of Function ◽

Adaptive Responses ◽

Kinase Gene ◽

Polyamine Biosynthesis ◽

Content Type

ABSTRACT Colistin (polymyxin E) is a last-resort antibiotic against multidrug-resistant isolates of Pseudomonas aeruginosa. However, the nephro-toxicity of colistin limits its use, spurring the interest in novel antimicrobial peptides (AMP). Here, we show that the synthetic AMP-dendrimer G3KL (MW 4,531.38 Da, 15 positive charges, MIC = 8 mg/liter) showed faster killing than polymyxin B (Pmx-B) with no detectable resistance selection in P. aeruginosa strain PA14. Spontaneous mutants selected on Pmx-B, harboring loss of function mutations in the PhoQ sensor kinase gene, showed increased Pmx-B MICs and arnB operon expression (4-amino-l-arabinose addition to lipid A), but remained susceptible to dendrimers. Two mutants carrying a missense mutation in the periplasmic loop of the PmrB sensor kinase showed increased MICs for Pmx-B (8-fold) and G3KL (4-fold) but not for the dendrimer T7 (MW 4,885.64 Da, 16 positive charges, MIC = 8 mg/liter). The pmrB mutants showed increased expression of the arnB operon as well as of the speD2-speE2-PA4775 operon, located upstream of pmrAB, and involved in polyamine biosynthesis. Exogenous supplementation with the polyamines spermine and norspermine increased G3KL and T7 MICs in a phoQ mutant background but not in the PA14 wild type. This suggests that both addition of 4-amino-l-arabinose and secretion of polyamines are required to reduce susceptibility to dendrimers, probably neutralizing the negative charges present on the lipid A and the 2-keto-3-deoxyoctulosonic acid (KDO) sugars of the lipopolysaccharide (LPS), respectively. We further show by transcriptome analysis that the dendrimers G3KL and T7 induce adaptive responses through the CprRS two-component system in PA14.

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Efficacy and Safety of Colistin for the Treatment of Infections Caused by Multidrug-Resistant Isolates of Pseudomonas Aeruginosa Sensitive to Colistin in Patients with Haematological Malignancy; a Matched-Pair Analysis.

Blood ◽

10.1182/blood.v110.11.2283.2283 ◽

2007 ◽

Vol 110 (11) ◽

pp. 2283-2283

Author(s):

Nadira Durakovic ◽

Ana Boban ◽

Mirando Mrsic ◽

Dubravka Sertic ◽

Ranka Serventi Seiwerth ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Renal Function ◽

Haematological Malignancy ◽

Multidrug Resistant ◽

Matched Pair ◽

Control Group ◽

Efficacy And Safety ◽

Matched Pair Analysis ◽

Significant Difference ◽

Pair Analysis

Abstract Infections due to multidrug-resistant (MDR) Gram-negative bacteria have been increasing and they are an important cause of nosocomial morbidity and mortality, especially in immunocompromised patients. In order to determine efficacy and safety of colistin (colistimethate sodium) use in the treatment of MDR Pseudomonas aeruginosa sensitive to colistin, a comparison of renal function, other toxicities, and outcome of therapy was done between a group of patients treated with colistin and patients treated with other antipseudomonas drugs as control group. A group of 26 patients that was hospitalized in our institution between February 2002 and December 2006 and treated with intravenous colistin for an infection caused by MDR P.aeruginosa was compared in a matched-pair analysis to a group of 26 patients treated with other antipseudomonas drugs. Patients were 52% male and 48% female; mean age was 37 years (range 17–63). All of the patients were treated for haematological malignancy, most received intensive chemotherapy regimens (44%), 19% received allogeneic and 31% autologous transplants. Groups of patients did not differ in age, sex, disease, or kind of treatment received. All of the patients in both groups had clinical signs of sepsis; in 69% of patients from colistin group and 84% from control group P.aeruginosa was isolated from blood, and in 27% and 12% it was isolated from skin lesions that had clinical presentation of echtyma gangrenosum, respectively. Patients treated with colistin received 3 MU of colistin every 8 hours for a mean (± SD) duration of 12.5 (± 5.4) days. Due to nature of their disease, and severity of infections, all of the patients received more than two other possibly nephrotoxic drugs; in colistin group 4 other concomitant drugs, on control group 3; most frequently vancomycin, cefepime, amikacine, garamycine and amphotericine B deoxycholate was used. Of 26 patients receiving colistin, 76.9% of patients had the drug discontinued after successful clearance of infection, while in control group 65.4% of patients had the drug discontinued due to same reason. Only one patient had displayed neurological toxicity (Jacksons attack with secondary generalisation), but the drug was not discontinued, dose was modified, patient had no further attacks. There was no statistically significant difference in the level of serum creatinine, creatinine clearance (calculated), or potassium levels between prior to therapy and after treatment discontinuation between groups. One patient treated with colistin developed renal failure and was subjected to continuous venovenous hemodiafiltration; of note is that at the time colistin introduction patient already had impaired renal function. In one patient drug was discontinued due to suspected allergic reaction. No other adverse events of colistin therapy were noted. Colistin is an effective antimicrobial drug for the treatment of severe infections caused by MDR P.aeruginosa in haematological patients. The safety profile observed is acceptable in these severe life-threatening infections, in matched-pair analysis it did not display greater toxicity than other antipseudomonas drugs. Further studies are needed to better address the treatment of MDR P. aeruginosa, naimely the optimal dose and schedule, also route of administration of colistin, as well as drug-to-drug interactions.

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Comparative Metabolomics and Transcriptomics Reveal Multiple Pathways Associated with Polymyxin Killing in Pseudomonas aeruginosa

mSystems ◽

10.1128/msystems.00149-18 ◽

2019 ◽

Vol 4 (1) ◽

Cited By ~ 13

Author(s):

Mei-Ling Han ◽

Yan Zhu ◽

Darren J. Creek ◽

Yu-Wei Lin ◽

Alina D. Gutu ◽

...

Keyword(s):

Oxidative Stress ◽

Pseudomonas Aeruginosa ◽

Lipid A ◽

Therapeutic Option ◽

Polymyxin B ◽

Multidrug Resistant ◽

Central Carbon Metabolism ◽

Dynamic Interactions ◽

Content Type ◽

Comparative Metabolomics

ABSTRACT Polymyxins are a last-line therapy against multidrug-resistant Pseudomonas aeruginosa; however, resistance to polymyxins has been increasingly reported. Therefore, understanding the mechanisms of polymyxin activity and resistance is crucial for preserving their clinical usefulness. This study employed comparative metabolomics and transcriptomics to investigate the responses of polymyxin-susceptible P. aeruginosa PAK (polymyxin B MIC, 1 mg/liter) and its polymyxin-resistant pmrB mutant PAKpmrB6 (MIC, 16 mg/liter) to polymyxin B (4, 8, and 128 mg/liter) at 1, 4, and 24 h, respectively. Our results revealed that polymyxin B at 4 mg/liter induced different metabolic and transcriptomic responses between polymyxin-susceptible and -resistant P. aeruginosa. In strain PAK, polymyxin B significantly activated PmrAB and the mediated arn operon, leading to increased 4-amino-4-deoxy-L-arabinose (L-Ara4N) synthesis and the addition to lipid A. In contrast, polymyxin B did not increase lipid A modification in strain PAKpmrB6. Moreover, the syntheses of lipopolysaccharide and peptidoglycan were significantly decreased in strain PAK but increased in strain PAKpmrB6 due to polymyxin B treatment. In addition, 4 mg/liter polymyxin B significantly perturbed phospholipid and fatty acid levels and induced oxidative stress in strain PAK, but not in PAKpmrB6. Notably, the increased trehalose-6-phosphate levels indicate that polymyxin B potentially caused osmotic imbalance in both strains. Furthermore, 8 and 128 mg/liter polymyxin B significantly elevated lipoamino acid levels and decreased phospholipid levels but without dramatic changes in lipid A modification in wild-type and mutant strains, respectively. Overall, this systems study is the first to elucidate the complex and dynamic interactions of multiple cellular pathways associated with the polymyxin mode of action against P. aeruginosa. IMPORTANCE Pseudomonas aeruginosa has been highlighted by the recent WHO Global Priority Pathogen List due to multidrug resistance. Without new antibiotics, polymyxins remain a last-line therapeutic option for this difficult-to-treat pathogen. The emergence of polymyxin resistance highlights the growing threat to our already very limited antibiotic armamentarium and the urgency to understand the exact mechanisms of polymyxin activity and resistance. Integration of the correlative metabolomics and transcriptomics results in the present study discovered that polymyxin treatment caused significant perturbations in the biosynthesis of lipids, lipopolysaccharide, and peptidoglycan, central carbon metabolism, and oxidative stress. Importantly, lipid A modifications were surprisingly rapid in response to polymyxin treatment at clinically relevant concentrations. This is the first study to reveal the dynamics of polymyxin-induced cellular responses at the systems level, which highlights that combination therapy should be considered to minimize resistance to the last-line polymyxins. The results also provide much-needed mechanistic information which potentially benefits the discovery of new-generation polymyxins.

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