scholarly journals Bactericidal Activity of ACH-702 against Nondividing and Biofilm Staphylococci

2012 ◽  
Vol 56 (7) ◽  
pp. 3812-3818 ◽  
Author(s):  
Steven D. Podos ◽  
Jane A. Thanassi ◽  
Melissa Leggio ◽  
Michael J. Pucci
Keyword(s):  
Protein Synthesis ◽  
Stationary Phase ◽  
Bactericidal Activity ◽  
Bacterial Infections ◽  
De Novo ◽  
Viable Cell ◽  
Bacterial Cells ◽  
Protein Synthesis Inhibitors ◽  
Content Type ◽  
Cell Counts

ABSTRACTMany bacterial infections involve slow or nondividing bacterial growth states and localized high cell densities. Antibiotics with demonstrated bactericidal activity rarely remain bactericidal at therapeutic concentrations under these conditions. The isothiazoloquinolone (ITQ) ACH-702 is a potent, bactericidal compound with activity against many antibiotic-resistant pathogens, including methicillin-resistantStaphylococcus aureus(MRSA). We evaluated its bactericidal activity under conditions where bacterial cells were not dividing and/or had slowed their growth. AgainstS. aureuscultures in stationary phase, ACH-702 showed concentration-dependent bactericidal activity and achieved a 3-log-unit reduction in viable cell counts within 6 h of treatment at ≥16× MIC values; in comparison, the bactericidal quinolone moxifloxacin and the additional comparator compounds vancomycin, linezolid, and rifampin at 16× to 32× MICs showed little or no bactericidal activity against stationary-phase cells. ACH-702 at 32× MIC retained bactericidal activity against stationary-phaseS. aureusacross a range of inoculum densities. ACH-702 did not kill cold-arrested cells yet remained bactericidal against cells arrested by protein synthesis inhibitors, suggesting that its bactericidal activity against nondividing cells requires active metabolism but notde novoprotein synthesis. ACH-702 also showed a degree of bactericidal activity at 16× MIC againstS. epidermidisbiofilm cells that was superior to that of moxifloxacin, rifampin, and vancomycin. The bactericidal activity of ACH-702 against stationary-phase staphylococci and biofilms suggests potential clinical utility in infections containing cells in these physiological states.

scholarly journals Pharmacokinetic and Pharmacodynamic Evaluation of P-873 versus Klebsiella pneumoniae in a Neutropenic Murine Thigh Infection Model

2013 ◽  
Vol 57 (4) ◽  
pp. 1971-1973 ◽  
Author(s):  
Lucinda M. Lamb ◽  
Jared L. Crandon ◽  
David P. Nicolau
Keyword(s):  
Protein Synthesis ◽  
Klebsiella Pneumoniae ◽  
Infection Model ◽  
Protein Synthesis Inhibitors ◽  
Content Type ◽  
Pharmacokinetic Properties

ABSTRACTP-873 is a novel compound in the RX-04 pyrrolocytosine series of protein synthesis inhibitors currently under development by Rib-X Pharmaceuticals. We evaluated the pharmacodynamic and pharmacokinetic properties of this compound againstKlebsiella pneumoniaeusing a murine neutropenic thigh infection model. P-873 demonstrated potent and rapidin vivoactivity against this organism with enhanced penetration and duration of exposure in thigh tissue.

scholarly journals The Bactericidal Activity and Spore Inhibition Effect of Manuka Honey against Clostridioides Difficile

Antibiotics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 684
Author(s):  
Lillian Yu ◽  
Reynal Palafox-Rosas ◽  
Brian Luna ◽  
Rosemary C. She
Keyword(s):  
Bactericidal Activity ◽  
Viable Cell ◽  
Manuka Honey ◽  
Inhibition Effect ◽  
Natural Substances ◽  
Clostridioides Difficile ◽  
Cell Counts ◽  
Colony Forming Units ◽  
Conventional Antibiotics ◽  
Drug Free

Clostridioides difficile colitis overgrowth occurs when the normal gut microbiome becomes disrupted, often due to antibiotics. Effective treatment remains elusive, due partly to the persistence of its spores in the gut. Natural substances like manuka honey offer an alternative antimicrobial mechanism of action to conventional antibiotics. We investigated the antibiotic activity of manuka honey against 20 C. difficile isolates. The minimum inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBC) of manuka honeys of methylglyoxal (MGO) grades 30+, 100+, 250+, and 400+ were determined based on broth microdilution. Sporicidal activity was assessed in a range of honey concentrations by enumerating total viable cell and spore counts at 0–96 h after organism inoculation. The MICs of C. difficile ranged from 4% to >30% (w/v). MIC50 for the four MGO grades were similar at 10–14%. MBC results for the majority of isolates were distributed bimodally at MBC/MIC ratios ≤4 or MBC >30%. Growth kinetics in honey showed total viable cell counts remaining >105 colony-forming units (CFU)/mL at all time points, whereas spore counts remained within 1-log of baseline (102 CFU/mL) in honey but steadily increased in the drug-free control to >105 CFU/mL by 96 h. Manuka honey demonstrated variable inhibitory and bactericidal activity against C. difficile. MGO grade had no noticeable impact on overall MIC distributions or bactericidal activity. Although manuka honey could inhibit spore proliferation, it did not eradicate spores completely.

scholarly journals The Urinary Antibiotic 5-Nitro-8-Hydroxyquinoline (Nitroxoline) Reduces the Formation and Induces the Dispersal of Pseudomonas aeruginosa Biofilms by Chelation of Iron and Zinc

2012 ◽  
Vol 56 (11) ◽  
pp. 6021-6025 ◽  
Author(s):  
A. Sobke ◽  
M. Klinger ◽  
B. Hermann ◽  
S. Sachse ◽  
S. Nietzsche ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Broad Spectrum ◽  
Viable Cell ◽  
Antibiofilm Activity ◽  
Content Type ◽  
Cell Counts ◽  
Iron And Zinc ◽  
Chelation Of Iron

ABSTRACTSince cations have been reported as essential regulators of biofilm, we investigated the potential of the broad-spectrum antimicrobial and cation-chelator nitroxoline as an antibiofilm agent. Biofilm mass synthesis was reduced by up to 80% at sub-MIC nitroxoline concentrations inPseudomonas aeruginosa, and structures formed were reticulate rather than compact. In preformed biofilms, viable cell counts were reduced by 4 logs at therapeutic concentrations. Complexation of iron and zinc was demonstrated to underlie nitroxoline's potent antibiofilm activity.

scholarly journals Simultaneous Rapid Detection and Serotyping of Cronobacter sakazakii Serotypes O1, O2, and O3 by Using Specific Monoclonal Antibodies

2016 ◽  
Vol 82 (8) ◽  
pp. 2300-2311 ◽  
Author(s):  
Eva J. Scharinger ◽  
Richard Dietrich ◽  
Ina Kleinsteuber ◽  
Erwin Märtlbauer ◽  
Kristina Schauer
Keyword(s):  
Monoclonal Antibodies ◽  
Rapid Detection ◽  
Foodborne Pathogen ◽  
Cross Reactivity ◽  
Antigenic Determinants ◽  
Powdered Infant Formula ◽  
Bacterial Cells ◽  
Cronobacter Sakazakii ◽  
Content Type ◽  
Cell Counts

ABSTRACTCronobacter sakazakiiis a foodborne pathogen associated with rare but often lethal infections in neonates. Powdered infant formula (PIF) represents the most frequent source of infection. Out of the identified serotypes (O1 to O7), O1, O2, and O3 are often isolated from clinical and PIF samples. Serotype-specific monoclonal antibodies (MAbs) suitable for application in enzyme immunoassays (EIAs) for the rapid detection ofC. sakazakiihave not yet been developed. In this study, we created specific MAbs with the ability to bind toC. sakazakiiof serotypes O1, O2, and O3. Characterization by indirect EIAs, immunofluorescence, motility assays, and immunoblotting identified lipopolysaccharide (LPS) and exopolysaccharide (EPS) as the antigenic determinants of the MAbs. The established sandwich EIAs were highly sensitive and were able to detect between 2 × 103and 9 × 106CFU/ml. Inclusivity tests confirmed that 93% of serotype O1 strains, 100% of O2 strains, and 87% of O3 strains were detected at low cell counts. No cross-reactivity with >100 strains ofCronobacterspp. and otherEnterobacteriaceaewas observed, except for that withC. sakazakiiserotype O3 andCronobactermuytjensiiserotype O1. Moreover, the sandwich EIAs detectedC. sakazakiiin PIF samples artificially contaminated with 1 to 10 bacterial cells per 10 g of sample after 15 h of preenrichment. The use of these serotype-specific MAbs not only allows the reliable detection ofC. sakazakiistrains but also enables simultaneous serotyping in a simple sandwich EIA method.

scholarly journals Phosphorylation and internalization of gp130 occur after IL-6 activation of Jak2 kinase in hepatocytes.

1994 ◽  
Vol 5 (7) ◽  
pp. 819-828 ◽  
Author(s):  
Y Wang ◽  
G M Fuller
Keyword(s):  
Protein Synthesis ◽  
Cell Surface ◽  
De Novo ◽  
Cell Types ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Protein Synthesis Inhibitors ◽  
Different Cell Types ◽  
Kinetics Of

Recent evidence has shown that members of the Jak kinase family are activated after IL-6 binds to its receptor complex, leading to a tyrosine phosphorylation of gp130, the IL-6 signal-transducing subunit. The different members of the IL-6 cytokine subfamily induce distinct patterns of Jak-Tyk phosphorylation in different cell types. Using monospecific antibodies to gp130, Jak2 kinase, and phosphotyrosine, we investigated the kinetics of IL-6 stimulation of members of this pathway in primary hepatocytes. Our findings show that Jak 2 is maximally activated within 2 min of exposure to IL-6, followed by gp130 phosphorylation that reaches its peak in another 2 min then declines to basal level by 60 min. In vitro phosphorylation experiments show that activated Jak 2 is able to phosphorylate both native gp130 and a fusion peptide containing its cytoplasmic domain, demonstrating gp130 is a direct substrate of Jak 2 kinase. Experiments designed to explore the cell surface expression of gp130 show that > or = 2 h are required to get a second round of phosphorylation after the addition of more cytokines. This finding suggests that activated gp130 is internalized from the cell surface after IL-6 stimulation. Additional experiments using protein synthesis inhibitors reveal that new protein synthesis is required to get a second cycle of gp130 phosphorylation indicating gp130 must be synthesized de novo and inserted into the membrane. These findings provide strong evidence that down regulation of the IL-6 signal in hepatocytes involves the internalization and cytosol degradation of gp130.

scholarly journals Tools for Characterizing Bacterial Protein Synthesis Inhibitors

2013 ◽  
Vol 57 (12) ◽  
pp. 5994-6004 ◽  
Author(s):  
Cédric Orelle ◽  
Skylar Carlson ◽  
Bindiya Kaushal ◽  
Mashal M. Almutairi ◽  
Haipeng Liu ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Mode Of Action ◽  
Rapid Identification ◽  
Protein Synthesis Inhibitors ◽  
Drug Induced ◽  
Content Type ◽  
Antibiotic Action ◽  
Bacterial Ribosome ◽  
Culture Extract ◽  
Bacterial Protein Synthesis

ABSTRACTMany antibiotics inhibit the growth of sensitive bacteria by interfering with ribosome function. However, discovery of new protein synthesis inhibitors is curbed by the lack of facile techniques capable of readily identifying antibiotic target sites and modes of action. Furthermore, the frequent rediscovery of known antibiotic scaffolds, especially in natural product extracts, is time-consuming and expensive and diverts resources that could be used toward the isolation of novel lead molecules. In order to avoid these pitfalls and improve the process of dereplication of chemically complex extracts, we designed a two-pronged approach for thecharacterization ofinhibitors ofproteinsynthesis (ChIPS) that is suitable for the rapid identification of the site and mode of action on the bacterial ribosome. First, we engineered antibiotic-hypersensitiveEscherichia colistrains that contain only one rRNA operon. These strains are used for the rapid isolation of resistance mutants in which rRNA mutations identify the site of the antibiotic action. Second, we show that patterns of drug-induced ribosome stalling on mRNA, monitored by primer extension, can be used to elucidate the mode of antibiotic action. These analyses can be performed within a few days and provide a rapid and efficient approach for identifying the site and mode of action of translation inhibitors targeting the bacterial ribosome. Both techniques were validated using a bacterial strain whose culture extract, composed of unknown metabolites, exhibited protein synthesis inhibitory activity; we were able to rapidly detect the presence of the antibiotic chloramphenicol.

scholarly journals UVC Light Prophylaxis for Cutaneous Wound Infections in Mice

2012 ◽  
Vol 56 (7) ◽  
pp. 3841-3848 ◽  
Author(s):  
Tianhong Dai ◽  
Barbara Garcia ◽  
Clinton K. Murray ◽  
Mark S. Vrahas ◽  
Michael R. Hamblin
Keyword(s):  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Light Exposure ◽  
Dna Lesions ◽  
Bacterial Cells ◽  
Wound Infections ◽  
Content Type ◽  
Cutaneous Wound ◽  
Thickness Skin

ABSTRACTUVC light has long been known to be highly germicidal but has not been much developed as a therapy for infections. This study investigated the potential of UVC light for the prophylaxis of infections developing in highly contaminated superficial cutaneous wounds.In vitrostudies demonstrated that the pathogenic bacteriaPseudomonas aeruginosaandStaphylococcus aureuswere inactivated at UVC light exposures much lower than those needed for a similar effect on mammalian keratinocytes. Mouse models of partial-thickness skin abrasions infected with bioluminescentP. aeruginosaandS. aureuswere developed. Approximately 107bacterial cells were inoculated onto wounds measuring 1.2 by1.2 cm on the dorsal surfaces of mice. UVC light was delivered at 30 min after bacterial inoculation. It was found that for both bacterial infections, UVC light at a single radiant exposure of 2.59 J/cm2reduced the bacterial burden in the infected mouse wounds by approximately 10-fold in comparison to those in untreated mouse wounds (P< 0.00001). Furthermore, UVC light increased the survival rate of mice infected withP. aeruginosaby 58.3% (P= 0.0023) and increased the wound healing rate in mice infected withS. aureusby 31.2% (P< 0.00001). DNA lesions were observed in the UVC light-treated mouse wounds; however, the lesions were extensively repaired by 48 h after UVC light exposure. These results suggested that UVC light may be used for the prophylaxis of cutaneous wound infections.

scholarly journals Subpopulations of Stressed Yersinia pseudotuberculosis Preferentially Survive Doxycycline Treatment within Host Tissues

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Jasmine Ramirez Raneses ◽  
Alysha L. Ellison ◽  
Bessie Liu ◽  
Kimberly M. Davis
Keyword(s):  
Bacterial Growth ◽  
Intraperitoneal Injection ◽  
Bacterial Infections ◽  
Yersinia Pseudotuberculosis ◽  
Antibiotic Administration ◽  
Bacterial Cells ◽  
Fluorescent Reporter ◽  
Content Type ◽  
Drug Concentrations ◽  
Host Tissues

ABSTRACT Severe systemic bacterial infections result in colonization of deep tissues, which can be very difficult to eliminate with antibiotics. It remains unclear if this is because antibiotics are not reaching inhibitory concentrations within tissues, if subsets of bacteria are less susceptible to antibiotics, or if both contribute to limited treatment efficacy. To detect exposure to doxycycline (Dox) present in deep tissues following treatment, we generated a fluorescent transcriptional reporter derived from the tet operon to specifically detect intracellular tetracycline exposure at the single bacterial cell level. Dox exposure was detected in the spleen 2 h after intraperitoneal injection, and by 4 h postinjection, this treatment resulted in a significant decrease in viable Yersinia pseudotuberculosis bacteria in the spleen. Nitric oxide-stressed bacteria preferentially survived treatment, suggesting that stress was sufficient to alter Dox susceptibility. Many bacteria (∼10%) survived a single dose of Dox, and the antibiotic accumulated at the periphery of microcolonies to growth inhibitory concentrations until 48 h posttreatment. After this time point, antibiotic concentrations decreased and bacterial growth resumed. Dox-treated mice eventually succumbed to the infection, albeit with significantly prolonged survival relative to that of untreated mice. These results indicate that Dox delivery by intraperitoneal injection results in rapid diffusion of inhibitory concentrations of antibiotic into the spleen, but stressed cells preferentially survive drug treatment, and bacterial growth resumes once drug concentrations decrease. This fluorescent reporter strategy for antibiotic detection could easily be modified to detect the concentration of additional antimicrobial compounds within host tissues following drug administration. IMPORTANCE Bacterial infections are very difficult to treat when bacteria spread into the bloodstream and begin to replicate within deep tissues, such as the spleen. Subsets of bacteria can survive antibiotic treatment, but it remains unclear if this survival is because of limited drug diffusion into tissues, or if there are changes within the bacteria, promoting survival of some bacterial cells. Here, we have developed a fluorescent reporter to detect doxycycline (Dox) diffusion into host tissues, and we show that Dox impacts the bacterial population within hours of administration and inhibits bacterial growth for 48 h. However, bacterial growth resumes when antibiotic concentrations decrease. Subsets of bacteria, stressed by the host response to infection, survive Dox treatment at a higher rate. These results provide critical information about the dynamics that occur within deep tissues following antibiotic administration and suggest that subsets of bacteria are predisposed to survive inhibitory concentrations of antibiotic before exposure.

scholarly journals Arrested Protein Synthesis Increases Persister-Like Cell Formation

2013 ◽  
Vol 57 (3) ◽  
pp. 1468-1473 ◽  
Author(s):  
Brian W. Kwan ◽  
John A. Valenta ◽  
Michael J. Benedik ◽  
Thomas K. Wood
Keyword(s):  
Protein Synthesis ◽  
Bacterial Infections ◽  
Clinical Medicine ◽  
Cell Formation ◽  
Low Frequency ◽  
Atp Synthesis ◽  
Initial Population ◽  
Bacterial Persistence ◽  
Content Type ◽  
Chemical Pretreatments

ABSTRACTBiofilms are associated with a wide variety of bacterial infections and pose a serious problem in clinical medicine due to their inherent resilience to antibiotic treatment. Within biofilms, persister cells comprise a small bacterial subpopulation that exhibits multidrug tolerance to antibiotics without undergoing genetic change. The low frequency of persister cell formation makes it difficult to isolate and study persisters, and bacterial persistence is often attributed to a quiescent metabolic state induced by toxins that are regulated through toxin-antitoxin systems. Here we mimic toxins via chemical pretreatments to induce high levels of persistence (10 to 100%) from an initial population of 0.01%. Pretreatment ofEscherichia coliwith (i) rifampin, which halts transcription, (ii) tetracycline, which halts translation, and (iii) carbonyl cyanidem-chlorophenylhydrazone, which halts ATP synthesis, all increased persistence dramatically. Using these compounds, we demonstrate that bacterial persistence results from halted protein synthesis and from environmental cues.

Temporal phases of long-term potentiation (LTP): myth or fact?

2015 ◽  
Vol 26 (5) ◽  
pp. 507-546 ◽  
Author(s):  
Abdul-Karim Abbas ◽  
Agnès Villers ◽  
Laurence Ris
Keyword(s):  
Protein Synthesis ◽  
De Novo ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Long Term Memory ◽  
Protein Synthesis Inhibitor ◽  
Protein Synthesis Inhibitors ◽  
Early Protein ◽  
Term Potentiation

AbstractLong-term potentiation (LTP) remains the most widely accepted model for learning and memory. In accordance with this belief, the temporal differentiation of LTP into early and late phases is accepted as reflecting the differentiation of short-term and long-term memory. Moreover, during the past 30 years, protein synthesis inhibitors have been used to separate the early, protein synthesis-independent (E-LTP) phase and the late, protein synthesis-dependent (L-LTP) phase. However, the role of these proteins has not been formally identified. Additionally, several reports failed to show an effect of protein synthesis inhibitors on LTP. In this review, a detailed analysis of extensive behavioral and electrophysiological data reveals that the presumed correspondence of LTP temporal phases to memory phases is neither experimentally nor theoretically consistent. Moreover, an overview of the time courses of E-LTP in hippocampal slices reveals a wide variability ranging from <1 h to more than 5 h. The existence of all these conflictual findings should lead to a new vision of LTP. We believe that the E-LTP vs. L-LTP distinction, established with protein synthesis inhibitor studies, reflects a false dichotomy. We suggest that the duration of LTP and its dependency on protein synthesis are related to the availability of a set of proteins at synapses and not to the de novo synthesis of plasticity-related proteins. This availability is determined by protein turnover kinetics, which is regulated by previous and ongoing electrical activities and by energy store availability.

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