Visualizing Borrelia burgdorferi infection using a small molecule imaging probe.

In vivo diagnostic imaging of bacterial infections is currently reliant on targeting their metabolic pathways, an ineffective method to identify microbial species with low metabolic activity. Here we establish HS-198 as a small molecule-fluorescent conjugate that selectively targets the highly conserved bacterial protein, HtpG (High temperature protein G), within B. burgdorferi, the bacterium responsible for Lyme Disease. We describe the use of HS-198 to target morphologic forms of B. burgdorferi in both the logarithmic growth phase and the metabolically dormant stationary phase as well as in inactivated spirochetes. Furthermore, in a murine infection model, systemically injected HS-198 identified B. burgdorferi as revealed by imaging in post necropsy tissue sections. These findings demonstrate how small molecule probes directed at conserved bacterial protein targets can function to identify the microbe using non-invasive imaging and potentially as scaffolds to deliver antimicrobial agents to the pathogen.

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Visualizing Borrelia burgdorferi infection using a small molecule imaging probe

10.1101/2020.09.04.284067 ◽

2020 ◽

Author(s):

Madeline G Sell ◽

David A. Alcorta ◽

Andrew E. Padilla ◽

Dakota W. Nollner ◽

Nicole R. Hasenkampf ◽

...

Keyword(s):

Small Molecule ◽

Bacterial Infections ◽

Antimicrobial Agents ◽

Infection Model ◽

Bacterial Protein ◽

Logarithmic Growth Phase ◽

Protein Targets ◽

Non Invasive ◽

Small Molecule Probes

AbstractIn vivo diagnostic imaging of bacterial infections is currently reliant on targeting their metabolic pathways, an ineffective method to identify microbial species with low metabolic activity. Here we establish HS-198 as a small molecule-fluorescent conjugate that selectively targets the highly conserved bacterial protein, HtpG (High temperature protein G), within B. burgdorferi, the bacteria responsible for Lyme Disease. We describe the use of HS-198 to target morphologic forms of B. burgdorferi in both the logarithmic growth phase and the metabolically dormant stationary phase. Furthermore, in a murine infection model, systemically injected HS-198 identified B. burgdorferi as revealed by imaging in post necropsy tissue sections. These findings demonstrate how small molecule probes directed at conserved bacterial protein targets can function to identify the microbe using non-invasive imaging and potentially as scaffolds to deliver antimicrobial agents to the pathogen.

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In VitroandIn VivoActivities of Novel, Semisynthetic Thiopeptide Inhibitors of Bacterial Elongation Factor Tu

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00582-11 ◽

2011 ◽

Vol 55 (11) ◽

pp. 5277-5283 ◽

Cited By ~ 18

Author(s):

J. A. Leeds ◽

M. J. LaMarche ◽

J. T. Brewer ◽

S. M. Bushell ◽

G. Deng ◽

...

Keyword(s):

Bacterial Infections ◽

Elongation Factor ◽

Infection Model ◽

Elongation Factor Tu ◽

Bacterial Protein ◽

Preclinical Development ◽

Gram Positive ◽

Content Type

ABSTRACTRecently, we identified aminothiazole derivatives of GE2270 A. These novel semisynthetic congeners, like GE2270 A, target the essential bacterial protein elongation factor Tu (EF-Tu). Medicinal chemistry optimization of lead molecules led to the identification of preclinical development candidates 1 and 2. These cycloalklycarboxylic acid derivatives show activity against difficult to treat Gram-positive pathogens and demonstrate increased aqueous solubility compared to GE2270 A. We describe here thein vitroandin vivoactivities of compounds 1 and 2 compared to marketed antibiotics. Compounds 1 and 2 were potent against clinical isolates of methicillin-resistantStaphylococcus aureusand vancomycin-resistant enterococci (MIC90≤ 0.25 μg/ml) but weaker against the streptococci (MIC90≥ 4 μg/ml). Like GE2270 A, the derivatives inhibited bacterial protein synthesis and selected for spontaneous loss of susceptibility via mutations in thetufgene, encoding EF-Tu. The mutants were not cross-resistant to other antibiotic classes. In a mouse systemic infection model, compounds 1 and 2 protected mice from lethalS. aureusinfections with 50% effective doses (ED50) of 5.2 and 4.3 mg/kg, respectively. Similarly, compounds 1 and 2 protected mice from lethal systemicE. faecalisinfections with ED50of 0.56 and 0.23 mg/kg, respectively. In summary, compounds 1 and 2 are activein vitroandin vivoactivity against difficult-to-treat Gram-positive bacterial infections and represent a promising new class of antibacterials for use in human therapy.

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Novispirin G10-Induced Lung Toxicity in a Klebsiella pneumoniae Infection Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.47.12.3901-3906.2003 ◽

2003 ◽

Vol 47 (12) ◽

pp. 3901-3906 ◽

Cited By ~ 11

Author(s):

Karen H. Bartlett ◽

Paul B. McCray ◽

Peter S. Thorne

Keyword(s):

Klebsiella Pneumoniae ◽

Bacterial Infections ◽

Antimicrobial Agents ◽

Ex Vivo ◽

Intratracheal Instillation ◽

Lung Toxicity ◽

Infection Model ◽

Culturable Bacteria ◽

Markers Of Inflammation

ABSTRACT Mammalian cathelicidins are a class of innate antimicrobial peptides isolated from leukocytes and epithelial cells that aid host defense against bacterial infections. Synthetic analogs of cathelicidins offer the promise of potent broad-spectrum antimicrobial efficacy. We developed a combined lung infection and ex vivo whole-blood assay model to characterize the toxicity and efficacy of synthetic cathelicidin-derived peptides. Male C57BL/6 mice were administered saline or Klebsiella pneumoniae by intratracheal instillation. Five hours later, the Klebsiella-infected mice were instilled with saline, tobramycin (1 mg/kg of body weight or 10 mg/kg), novispirin G10 (0.4 mg/kg), or a combination of tobramycin (1 mg/kg) and G10 (0.4 mg/kg). At 24 h, bronchoalveolar lavage fluid (BAL) was collected for analysis of culturable bacteria and for markers of inflammation and lung toxicity. Blood samples were analyzed for circulating cytokines. Recovery of Klebsiella from the lung, recruitment of neutrophils, and production of interleukin-6 (IL-6) in BAL samples were highly correlated (r = 0.68 and 0.84, respectively; P < 0.01). Animals treated with G10 or G10 plus tobramycin had increased hemoglobin (P < 0.001) and protein (P < 0.001) levels compared to those for Klebsiella-infected or tobramycin-alone-treated animals. The levels of circulating IL-6 in mice infected with Klebsiella were 1000- to 10,000-fold higher than in the noninfected controls. The highest levels of IL-6 were measured in mice given G10 alone or in combination with tobramycin. These studies demonstrated that G10 was relatively nontoxic in saline-treated mice but was highly toxic in mice infected with Klebsiella. This finding establishes the importance of investigating candidate antimicrobial agents in an in vivo infection model.

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Mechanistic insights into synergy between nalidixic acid and tetracycline against clinical isolates of Acinetobacter baumannii and Escherichia coli

Communications Biology ◽

10.1038/s42003-021-02074-5 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Amit Gaurav ◽

Varsha Gupta ◽

Sandeep K. Shrivastava ◽

Ranjana Pathania

Keyword(s):

Escherichia Coli ◽

Acinetobacter Baumannii ◽

Nalidixic Acid ◽

Bacterial Infections ◽

Clinical Isolates ◽

Hospital Environment ◽

Infection Model ◽

Drug Resistant ◽

E Coli

AbstractThe increasing prevalence of antimicrobial resistance has become a global health problem. Acinetobacter baumannii is an important nosocomial pathogen due to its capacity to persist in the hospital environment. It has a high mortality rate and few treatment options. Antibiotic combinations can help to fight multi-drug resistant (MDR) bacterial infections, but they are rarely used in the clinics and mostly unexplored. The interaction between bacteriostatic and bactericidal antibiotics are mostly reported as antagonism based on the results obtained in the susceptible model laboratory strain Escherichia coli. However, in the present study, we report a synergistic interaction between nalidixic acid and tetracycline against clinical multi-drug resistant A. baumannii and E. coli. Here we provide mechanistic insight into this dichotomy. The synergistic combination was studied by checkerboard assay and time-kill curve analysis. We also elucidate the mechanism behind this synergy using several techniques such as fluorescence spectroscopy, flow cytometry, fluorescence microscopy, morphometric analysis, and real-time polymerase chain reaction. Nalidixic acid and tetracycline combination displayed synergy against most of the MDR clinical isolates of A. baumannii and E. coli but not against susceptible isolates. Finally, we demonstrate that this combination is also effective in vivo in an A. baumannii/Caenorhabditis elegans infection model (p < 0.001)

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In VivoEfficacy of Anuran Trypsin Inhibitory Peptides against Staphylococcal Skin Infection and the Impact of Peptide Cyclization

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04324-14 ◽

2015 ◽

Vol 59 (4) ◽

pp. 2113-2121 ◽

Cited By ~ 9

Author(s):

U. Malik ◽

O. N. Silva ◽

I. C. M. Fensterseifer ◽

L. Y. Chan ◽

R. J. Clark ◽

...

Keyword(s):

Antimicrobial Agents ◽

Cyclic Peptide ◽

Sequence Similarity ◽

Infection Model ◽

Content Type ◽

Wide Range ◽

Inhibitory Activities ◽

The Impact

ABSTRACTStaphylococcus aureusis a virulent pathogen that is responsible for a wide range of superficial and invasive infections. Its resistance to existing antimicrobial drugs is a global problem, and the development of novel antimicrobial agents is crucial. Antimicrobial peptides from natural resources offer potential as new treatments against staphylococcal infections. In the current study, we have examined the antimicrobial properties of peptides isolated from anuran skin secretions and cyclized synthetic analogues of these peptides. The structures of the peptides were elucidated by nuclear magnetic resonance (NMR) spectroscopy, revealing high structural and sequence similarity with each other and with sunflower trypsin inhibitor 1 (SFTI-1). SFTI-1 is an ultrastable cyclic peptide isolated from sunflower seeds that has subnanomolar trypsin inhibitory activity, and this scaffold offers pharmaceutically relevant characteristics. The five anuran peptides were nonhemolytic and noncytotoxic and had trypsin inhibitory activities similar to that of SFTI-1. They demonstrated weakin vitroinhibitory activities againstS. aureus, but several had strong antibacterial activities againstS. aureusin anin vivomurine wound infection model. pYR, an immunomodulatory peptide fromRana sevosa, was the most potent, with complete bacterial clearance at 3 mg · kg−1. Cyclization of the peptides improved their stability but was associated with a concomitant decrease in antimicrobial activity. In summary, these anuran peptides are promising as novel therapeutic agents for treating infections from a clinically resistant pathogen.

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TSPphg Lysin from the Extremophilic Thermus Bacteriophage TSP4 as a Potential Antimicrobial Agent against Both Gram-Negative and Gram-Positive Pathogenic Bacteria

Viruses ◽

10.3390/v12020192 ◽

2020 ◽

Vol 12 (2) ◽

pp. 192 ◽

Cited By ~ 6

Author(s):

Feng Wang ◽

Xinyu Ji ◽

Qiupeng Li ◽

Guanling Zhang ◽

Jiani Peng ◽

...

Keyword(s):

Bacterial Infections ◽

Pathogenic Bacteria ◽

Infection Model ◽

Bacterial Cells ◽

Skin Damage ◽

Gram Positive ◽

Antibiotic Resistant ◽

Gram Negative

New strategies against antibiotic-resistant bacterial pathogens are urgently needed but are not within reach. Here, we present in vitro and in vivo antimicrobial activity of TSPphg, a novel phage lysin identified from extremophilic Thermus phage TSP4 by sequencing its whole genome. By breaking down the bacterial cells, TSPphg is able to cause bacteria destruction and has shown bactericidal activity against both Gram-negative and Gram-positive pathogenic bacteria, especially antibiotic-resistant strains of Klebsiella pneumoniae, in which the complete elimination and highest reduction in bacterial counts by greater than 6 logs were observed upon 50 μg/mL TSPphg treatment at 37 °C for 1 h. A murine skin infection model further confirmed the in vivo efficacy of TSPphg in removing a highly dangerous and multidrug-resistant Staphylococcus aureus from skin damage and in accelerating wound closure. Together, our findings may offer a therapeutic alternative to help fight bacterial infections in the current age of mounting antibiotic resistance, and to shed light on bacteriophage-based strategies to develop novel anti-infectives.

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Anti-Inflammatory and Antibacterial Activity Constituents from the Stem of Cinnamomum validinerve

Molecules ◽

10.3390/molecules25153382 ◽

2020 ◽

Vol 25 (15) ◽

pp. 3382 ◽

Cited By ~ 1

Author(s):

Chi-Lung Yang ◽

Ho-Cheng Wu ◽

Tsong-Long Hwang ◽

Chu-Hung Lin ◽

Yin-Hua Cheng ◽

...

Keyword(s):

Bacterial Infections ◽

Immune Cell ◽

Intraperitoneal Administration ◽

In Vitro Study ◽

Human Neutrophils ◽

Infection Model ◽

Ic50 Values ◽

Anti Inflammatory

One new dibenzocycloheptene, validinol (1), and one butanolide firstly isolated from the natural source, validinolide (2), together with 17 known compounds were isolated from the stem of Cinnamomum validinerve. Among the isolates, lincomolide A (3), secosubamolide (7), and cinnamtannin B1 (19) exhibited potent inhibition on both superoxide anion generation (IC50 values of 2.98 ± 0.3 µM, 4.37 ± 0.38 µM, and 2.20 ± 0.3 µM, respectively) and elastase release (IC50 values of 3.96 ± 0.31 µM, 3.04 ± 0.23 µM, and 4.64 ± 0.71 µM, respectively) by human neutrophils. In addition, isophilippinolide A (6), secosubamolide (7), and cinnamtannin B1 (19) showed bacteriostatic effects against Propionibacterium acnes in in vitro study, with minimal inhibitory concentration (MIC) values at 16 μg/mL, 16 μg/mL, and 500 μg/mL, respectively. Further investigations using the in vivo ear P. acnes infection model showed that the intraperitoneal administration of the major component cinnamtannin B1 (19) reduced immune cell infiltration and pro-inflammatory cytokines TNF-α and IL-6 at the infection sites. The results demonstrated the potential of cinnamtannin B1 (19) for acne therapy. In summary, these results demonstrated the anti-inflammatory potentials of Formosan C. validinerve during bacterial infections.

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Bioorthogonal cyclization-mediated in situ self-assembly of small-molecule probes for imaging caspase activity in vivo

Nature Chemistry ◽

10.1038/nchem.1920 ◽

2014 ◽

Vol 6 (6) ◽

pp. 519-526 ◽

Cited By ~ 248

Author(s):

Deju Ye ◽

Adam J. Shuhendler ◽

Lina Cui ◽

Ling Tong ◽

Sui Seng Tee ◽

...

Keyword(s):

Small Molecule ◽

Self Assembly ◽

Caspase Activity ◽

Small Molecule Probes

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Recent advances in stimuli-responsive in situ self-assembly of small molecule probes for in vivo imaging of enzymatic activity

Biomaterials Science ◽

10.1039/d0bm00895h ◽

2021 ◽

Cited By ~ 1

Author(s):

Yuqi Wang ◽

Jianhui Weng ◽

Xidan Wen ◽

Yuxuan Hu ◽

Deju Ye

Keyword(s):

Enzymatic Activity ◽

Small Molecule ◽

Self Assembly ◽

In Vivo Imaging ◽

Molecular Probes ◽

Stimuli Responsive ◽

Small Molecule Probes ◽

Recent Advances

Stimuli-responsive in situ self-assembly of small molecule probes into nanostructures has been promising for the construction of molecular probes for in vivo imaging.

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Fusidic Acid-Resistant Mutants of Salmonella enterica Serovar Typhimurium with Low Fitness In Vivo Are Defective in RpoS Induction

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.47.12.3743-3749.2003 ◽

2003 ◽

Vol 47 (12) ◽

pp. 3743-3749 ◽

Cited By ~ 33

Author(s):

Mirjana Macvanin ◽

Johanna Björkman ◽

Sofia Eriksson ◽

Mikael Rhen ◽

Dan I. Andersson ◽

...

Keyword(s):

Protein Synthesis ◽

Fusidic Acid ◽

Salmonella Enterica ◽

Antimicrobial Agents ◽

Relative Fitness ◽

Infection Model ◽

Macrophage Infection ◽

Serovar Typhimurium

ABSTRACT Mutants of Salmonella enterica serovar Typhimurium resistant to fusidic acid (Fusr) have mutations in fusA, the gene encoding translation elongation factor G (EF-G). Most Fusr mutants have reduced fitness in vitro and in vivo, in part explained by mutant EF-G slowing the rate of protein synthesis and growth. However, some Fusr mutants with normal rates of protein synthesis still suffer from reduced fitness in vivo. As shown here, Fusr mutants could be similarly ranked in their relative fitness in mouse infection models, in a macrophage infection model, in their relative hypersensitivity to hydrogen peroxide in vivo and in vitro, and in the amount of RpoS production induced upon entry into the stationary phase. We identify a reduced ability to induce production of RpoS (σs) as a defect associated with Fusr strains. Because RpoS is a regulator of the general stress response, and an important virulence factor in Salmonella, an inability to produce RpoS in appropriate amounts can explain the low fitness of Fusr strains in vivo. The unfit Fusr mutants also produce reduced levels of the regulatory molecule ppGpp in response to starvation. Because ppGpp is a positive regulator of RpoS production, we suggest that a possible cause of the reduced levels of RpoS is the reduction in ppGpp production associated with mutant EF-G. The low fitness of Fusr mutants in vivo suggests that drugs that can alter the levels of global regulators of gene expression deserve attention as potential antimicrobial agents.

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