phenylalanine-arginine-beta-naphthylamide and Enterobacteriaceae-Infections

There is urgent need for new therapeutic strategies to fight the global threat of antibiotic resistance. The focus of this Perspective is on chemical agents that target the most common mechanisms of antibiotic resistance such as enzymatic inactivation of antibiotics, changes in cell permeability, and induction/activation of efflux pumps. Here we assess the current landscape and challenges in the treatment of antibiotic resistance mechanisms at both bacterial cell and community levels. We also discuss the potential clinical application of chemical inhibitors of antibiotic resistance mechanisms as add-on treatments for serious drug-resistant infections. Enzymatic inhibitors, such as the derivatives of the β-lactamase inhibitor avibactam, are closer to the clinic than other molecules. For example, MK-7655, in combination with imipenem, is in clinical development for the treatment of infections caused by carbapenem-resistant Enterobacteriaceae and Pseudomonas aeruginosa, which are difficult to treat. In addition, other molecules targeting multidrug-resistance mechanisms, such as efflux pumps, are under development and hold promise for the treatment of multidrug resistant infections.

Topics: Azabicyclo Compounds; beta-Lactamase Inhibitors; Drug Resistance, Microbial; Enterobacteriaceae Infections; Humans; Imipenem; Pseudomonas Infections

An interregional surveillance program was conducted in the northwestern part of France to determine the prevalence of carbapenem-nonsusceptible Enterobacteriaceae (CNSE) isolates and their susceptibility to ceftazidime-avibactam and aztreonam-avibactam combinations. Nonduplicate CNSE clinical isolates were prospectively collected from six hospitals between June 2012 and November 2013. MICs of ceftazidime and aztreonam, alone or combined with a fixed concentration of avibactam (4 μg/ml), and those of carbapenems (comparator agents) were determined. MICs of ertapenem in combination with phenylalanine arginine-naphthylamide dihydrochloride (PAβN) were also determined to assess active efflux. Genes encoding carbapenemases, plasmid-mediated AmpC enzymes, extended-spectrum β-lactamases (ESBLs), and major outer membrane proteins (OMPs) were amplified and sequenced. OMPs were also extracted for SDS-PAGE analysis. Among the 139 CNSE isolates, mainly Enterobacter spp. and Klebsiella pneumoniae, 123 (88.4%) were ertapenem nonsusceptible, 12 (8.6%) exhibited reduced susceptibility to all carbapenems, and 4 Proteeae isolates (2.9%) were resistant to imipenem. Carbapenemase production was detected in only two isolates (producing OXA-48 and IMI-3). In contrast, OMP deficiency, in association with AmpCs and/or ESBLs (mainly CTX-M-9, SHV-12, and CTX-M-15), was largely identified among CNSE isolates. The ceftazidime-avibactam and aztreonam-avibactam combinations exhibited potent activity against CNSE isolates (MIC50/MIC90, 1/1 μg/ml and 0.5/0.5 μg/ml, respectively) compared to that of ceftazidime and aztreonam alone (MIC50/MIC90, 512/512 μg/ml and 128/512 μg/ml, respectively). This study reveals the in vitro activity of ceftazidime-avibactam and aztreonam-avibactam combinations against a large collection of porin-deficient enterobacterial isolates that are representative of the CNSE recovered in the northern part of France.

Topics: Anti-Bacterial Agents; Azabicyclo Compounds; Aztreonam; Bacterial Outer Membrane Proteins; beta-Lactamases; beta-Lactams; Ceftazidime; Dipeptides; Drug Combinations; Drug Resistance, Multiple, Bacterial; Enterobacteriaceae; Enterobacteriaceae Infections; Epidemiological Monitoring; Ertapenem; France; Gene Expression; Humans; Microbial Sensitivity Tests; Plasmids; Prevalence; Prospective Studies

The aim of this study was to obtain a better understanding regarding the origin of recurrent contamination by Enterobacter gergoviae in diverse cosmetic formula. We studied 65 isolates collected from various sources (clinical, food, cosmetics).. RAPD analysis using AP12H, REP and ERIC-PCR was carried out for epidemiological typing. Evaluation of susceptibility to preservatives currently used in cosmetics for a representative panel of collection strains was measured. Preservative efficacy was evaluated by minimum inhibitory concentrations and minimum bactericidal concentrations (MBCs).. Eighty per cent of isolates was unrelated. E. gergoviae showed significant levels of resistance to preservatives. MBC was higher than maximum permitted concentrations imposed by European Commission (EC). Association of preservatives showed in rare case additive effects, and no synergic effects were observed.. Most of the cosmetic formulations are contaminated with unrelated E. gergoviae strains. Maximum allowed concentrations for sodium benzoate are inefficient to limit proliferation and control adaptability to this bacterium in cosmetic products. Efflux mechanisms should be involved in methylisothiazolinone-chloromethylisothiazolinone and triclosan adaptation.

Topics: Dipeptides; Drug Resistance, Bacterial; Enterobacter; Enterobacteriaceae Infections; Humans; Microbial Sensitivity Tests; Preservatives, Pharmaceutical; Random Amplified Polymorphic DNA Technique

A series of amine-alkyl derivatives of 5-arylidenehydantoin 3-21 was evaluated for their ability to improve antibiotic effectiveness in two strains of Gram-negative Enterobacter aerogenes: the reference strain (ATCC-13048) and the chloramphenicol-resistant derivative over-producing the AcrAB-TolC efflux pump (CM-64). Three antibiotics, chloramphenicol, nalidixic acid and sparfloxacin were used as markers of efflux pump activity. New compounds (5-16) were obtained within 3-4 step synthesis using Knoevenagel condensation, Mitsunobu reaction and microwave aided N-alkylation. Molecular modeling based structure-activity relationship (SAR) studies were performed. The most active compounds: (Z)-5-(4-(diethylamino)benzylidene)-3-(2-hydroxy-3-(4-(2-hydroxyethyl)piperazin-1-yl)propyl)imidazolidine-2,4-dione (14) and (Z)-5-(2,4-dimethoxybenzylidene)-3-(2-hydroxy-3-(isopropylamino)propyl)imidazolidine-2,4-dione (15) induced fourfold decrease of minimal inhibition concentration (MIC) of all tested antibiotics in the strain CM-64 overexpressing the AcrAB-TolC pump.

Topics: Amines; Anti-Bacterial Agents; Drug Resistance, Multiple, Bacterial; Enterobacter aerogenes; Enterobacteriaceae Infections; Humans; Hydantoins; Models, Molecular

The report concerns the molecular epidemiology, cyclohexane tolerance and Phe-Arg-β-naphtylamide (PAβN) susceptibility of multidrug-resistant Enterobacter cloacae isolates, with high-level fluoroquinolone resistance collected from healthcare facilities in a nationwide survey. A total of 113 multidrug-resistant E. cloacae isolates (recovered in 1997-2005) were subjected to disc diffusion tests, ERIC-PCR and XbaI PFGE. Representatives of the ERIC-types (n = 67) were tested further with cyclohexane and PAβN, using ciprofloxacin as the substrate. Forty-four per cent of the isolates were derived from the urinary tract, 19% from the bloodstream, 17% from the respiratory tract, and 15% from wound infections. Four ERIC-types (A, B, C and D) were distinguished, but 109 isolates were found to belong to a single, epidemic ERIC type: A. PFGE results suggested that the epidemic-type isolates were of monoclonal origin. Forty-two patients were involved in four outbreaks caused by the epidemic-type strains. Eighty-one cases were found to be nosocomial. At least fourfold reduction in ciprofloxacin MICs was found in the presence of PAβN in 79% of representative isolates (representing types A, C and D); an eightfold or greater reduction in ciprofloxacin MICs in the presence of PAβN (PAβN+) was found in 37% of representative isolates, representing types A and C. Eighty-five per cent of the representative isolates were found to be cyclohexane-tolerant, representing types A, C and D. This is the first report of a wide distribution of cyclohexane-tolerant or PAβN+ strains of E. cloacae. These feature-indicators of adaptive mechanisms that help bacteria to survive in hospital wards may have contributed to the nationwide spread of type A strains.

Topics: Anti-Bacterial Agents; Bacterial Typing Techniques; Ciprofloxacin; Cyclohexanes; Dipeptides; Disk Diffusion Antimicrobial Tests; Drug Resistance, Multiple, Bacterial; Electrophoresis, Gel, Pulsed-Field; Enterobacter cloacae; Enterobacteriaceae Infections; Humans; Hungary; Polymerase Chain Reaction

1-(1-Naphthylmethyl)-piperazine (NMP) has been shown to reverse multidrug resistance (MDR) in Escherichia coli overexpressing RND type efflux pumps, but there is no data on its activity in Enterobacteriaceae other than E. coli.. The antimicrobial susceptibilities of laboratory strains and 167 clinical isolates of Enterobacteriaceae to a variety of antimicrobial agents were determined in the absence and presence of NMP and, for comparison, of Phe-Arg-beta-naphthylamide (PAbetaN), another putative efflux pump inhibitor (EPI). A 4-fold or greater reduction of the MIC after EPI addition was considered significant.. NMP consistently reduced the MIC of linezolid in Citrobacter freundii, Enterobacter aerogenes and Klebsiella pneumoniae clinical isolates. Significant effects of NMP addition in >50% of tested isolates were also seen for levofloxacin, tetracycline and chloramphenicol in E. aerogenes, and for levofloxacin and tetracycline in K. pneumoniae, whereas no or minor effects were observed in Serratia marcescens. MDR reversal by NMP was more likely in isolates with decreased susceptibility to fluoroquinolones. In most fluoroquinolone-resistant strains the activity was sufficient to render isolates drug-susceptible at clinically achievable concentrations. The activity of PAbetaN was different from that of NMP, suggesting different modes of action of the two putative EPIs.. NMP has moderate activity in reversing MDR in many but not all members of the Enterobacteriaceae family including clinical isolates. Its effects on resistance reversal depend on bacterial species and drug, and are different from those seen with PAbetaN.

Topics: Anti-Bacterial Agents; Culture Media; Dipeptides; Drug Resistance, Multiple, Bacterial; Enterobacteriaceae; Enterobacteriaceae Infections; Fluorescent Dyes; Membrane Transport Proteins; Microbial Sensitivity Tests; Piperazines; Pyronine