scholarly journals Broadening the Spectrum of β-Lactam Antibiotics through Inhibition of Signal Peptidase Type I

2012 ◽  
Vol 56 (9) ◽  
pp. 4662-4670 ◽  
Author(s):  
Alex G. Therien ◽  
Joann L. Huber ◽  
Kenneth E. Wilson ◽  
Patrick Beaulieu ◽  
Alexandre Caron ◽  
...  
Keyword(s):  
Treatment Options ◽  
Signal Peptidase ◽  
Type I ◽  
New Agents ◽  
Content Type ◽  
Cyclic Depsipeptide ◽  
Serious Infections ◽  
Synthetic Derivative

ABSTRACTThe resistance of methicillin-resistantStaphylococcus aureus(MRSA) to all β-lactam classes limits treatment options for serious infections involving this organism. Our goal is to discover new agents that restore the activity of β-lactams against MRSA, an approach that has led to the discovery of two classes of natural product antibiotics, a cyclic depsipeptide (krisynomycin) and a lipoglycopeptide (actinocarbasin), which potentiate the activity of imipenem against MRSA strain COL. We report here that these imipenem synergists are inhibitors of the bacterial type I signal peptidase SpsB, a serine protease that is required for the secretion of proteins that are exported through the Sec and Tat systems. A synthetic derivative of actinocarbasin, M131, synergized with imipenem bothin vitroandin vivowith potent efficacy. Thein vitroactivity of M131 extends to clinical isolates of MRSA but not to a methicillin-sensitive strain. Synergy is restricted to β-lactam antibiotics and is not observed with other antibiotic classes. We propose that the SpsB inhibitors synergize with β-lactams by preventing the signal peptidase-mediated secretion of proteins required for β-lactam resistance. Combinations of SpsB inhibitors and β-lactams may expand the utility of these widely prescribed antibiotics to treat MRSA infections, analogous to β-lactamase inhibitors which restored the utility of this antibiotic class for the treatment of resistant Gram-negative infections.

scholarly journals ZN148 Is a Modular Synthetic Metallo-β-Lactamase Inhibitor That Reverses Carbapenem Resistance in Gram-Negative Pathogens In Vivo

2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Ørjan Samuelsen ◽  
Ove Alexander Høgmoen Åstrand ◽  
Christopher Fröhlich ◽  
Adam Heikal ◽  
Susann Skagseth ◽  
...  
Keyword(s):  
Active Site ◽  
Therapeutic Potential ◽  
Treatment Options ◽  
Carbapenem Resistance ◽  
Functional Space ◽  
Bactericidal Effect ◽  
Gram Negative ◽  
Content Type

ABSTRACT Carbapenem-resistant Gram-negative pathogens are a critical public health threat and there is an urgent need for new treatments. Carbapenemases (β-lactamases able to inactivate carbapenems) have been identified in both serine β-lactamase (SBL) and metallo-β-lactamase (MBL) families. The recent introduction of SBL carbapenemase inhibitors has provided alternative therapeutic options. Unfortunately, there are no approved inhibitors of MBL-mediated carbapenem-resistance and treatment options for infections caused by MBL-producing Gram-negatives are limited. Here, we present ZN148, a zinc-chelating MBL-inhibitor capable of restoring the bactericidal effect of meropenem and in vitro clinical susceptibility to carbapenems in >98% of a large international collection of MBL-producing clinical Enterobacterales strains (n = 234). Moreover, ZN148 was able to potentiate the effect of meropenem against NDM-1-producing Klebsiella pneumoniae in a murine neutropenic peritonitis model. ZN148 showed no inhibition of the human zinc-containing enzyme glyoxylase II at 500 μM, and no acute toxicity was observed in an in vivo mouse model with cumulative dosages up to 128 mg/kg. Biochemical analysis showed a time-dependent inhibition of MBLs by ZN148 and removal of zinc ions from the active site. Addition of exogenous zinc after ZN148 exposure only restored MBL activity by ∼30%, suggesting an irreversible mechanism of inhibition. Mass-spectrometry and molecular modeling indicated potential oxidation of the active site Cys221 residue. Overall, these results demonstrate the therapeutic potential of a ZN148-carbapenem combination against MBL-producing Gram-negative pathogens and that ZN148 is a highly promising MBL inhibitor that is capable of operating in a functional space not presently filled by any clinically approved compound.

scholarly journals Reversal of Azole Resistance inCandida albicansby Sulfa Antibacterial Drugs

2017 ◽  
Vol 62 (3) ◽  
Author(s):  
Hassan E. Eldesouky ◽  
Abdelrahman Mayhoub ◽  
Tony R. Hazbun ◽  
Mohamed N. Seleem
Keyword(s):  
Treatment Options ◽  
Antifungal Drugs ◽  
Infection Model ◽  
Azole Resistance ◽  
Global Public Health ◽  
Sulfa Drugs ◽  
Antibacterial Drugs ◽  
Content Type

ABSTRACTInvasive candidiasis presents an emerging global public health challenge due to the emergence of resistance to the frontline treatment options, such as fluconazole. Hence, the identification of other compounds capable of pairing with fluconazole and averting azole resistance would potentially prolong the clinical utility of this important group. In an effort to repurpose drugs in the field of antifungal drug discovery, we explored sulfa antibacterial drugs for the purpose of reversing azole resistance inCandida. In this study, we assembled and investigated a library of 21 sulfa antibacterial drugs for their ability to restore fluconazole sensitivity inCandida albicans. Surprisingly, the majority of assayed sulfa drugs (15 of 21) were found to exhibit synergistic relationships with fluconazole by checkerboard assay with fractional inhibitory concentration index (ΣFIC) values ranging from <0.0312 to 0.25. Remarkably, five sulfa drugs were able to reverse azole resistance in a clinically achievable range. The structure-activity relationships (SARs) of the amino benzene sulfonamide scaffold as antifungal agents were studied. We also identified the possible mechanism of the synergistic interaction of sulfa antibacterial drugs with azole antifungal drugs. Furthermore, the ability of sulfa antibacterial drugs to inhibitCandidabiofilm by 40%in vitrowas confirmed. In addition, the effects of sulfa-fluconazole combinations onCandidagrowth kinetics and efflux machinery were explored. Finally, using aCaenorhabditis elegansinfection model, we demonstrated that the sulfa-fluconazole combination does possess potent antifungal activityin vivo, reducingCandidain infected worms by ∼50% compared to the control.

scholarly journals In VitroandIn VivoEvaluation of APX001A/APX001 and Other Gwt1 Inhibitors againstCryptococcus

2018 ◽  
Vol 62 (8) ◽  
Author(s):  
Karen Joy Shaw ◽  
Wiley A. Schell ◽  
Jonathan Covel ◽  
Gisele Duboc ◽  
C. Giamberardino ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Lung Tissue ◽  
Fungal Infections ◽  
Treatment Options ◽  
Content Type ◽  
Fungal Burden ◽  
Geographical Regions ◽  
Current Therapies

ABSTRACTCryptococcal meningitis (CM), caused primarily byCryptococcus neoformans, is uniformly fatal if not treated. Treatment options are limited, especially in resource-poor geographical regions, and mortality rates remain high despite current therapies. Here we evaluated thein vitroandin vivoactivity of several compounds, including APX001A and its prodrug, APX001, currently in clinical development for the treatment of invasive fungal infections. These compounds target the conserved Gwt1 enzyme that is required for the localization of glycosylphosphatidylinositol (GPI)-anchored cell wall mannoproteins in fungi. The Gwt1 inhibitors had low MIC values, ranging from 0.004 μg/ml to 0.5 μg/ml, against bothC. neoformansandC. gattii. APX001A and APX2020 demonstratedin vitrosynergy with fluconazole (fractional inhibitory concentration index, 0.37 for both). In a CM model, APX001 and fluconazole each alone reduced the fungal burden in brain tissue (0.78 and 1.04 log10CFU/g, respectively), whereas the combination resulted in a reduction of 3.52 log10CFU/g brain tissue. Efficacy, as measured by a reduction in the brain and lung tissue fungal burden, was also observed for another Gwt1 inhibitor prodrug, APX2096, where dose-dependent reductions in the fungal burden ranged from 5.91 to 1.79 log10CFU/g lung tissue and from 7.00 and 0.92 log10CFU/g brain tissue, representing the nearly complete or complete sterilization of lung and brain tissue at the higher doses. These data support the further clinical evaluation of this new class of antifungal agents for the treatment of CM.

scholarly journals Assessment of Mycobacterium tuberculosis Pantothenate Kinase Vulnerability through Target Knockdown and Mechanistically Diverse Inhibitors

2014 ◽  
Vol 58 (6) ◽  
pp. 3312-3326 ◽  
Author(s):  
B. K. Kishore Reddy ◽  
Sudhir Landge ◽  
Sudha Ravishankar ◽  
Vikas Patil ◽  
Vikas Shinde ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Present Report ◽  
Kinetic Studies ◽  
Antimycobacterial Activity ◽  
Type I ◽  
Pantothenate Kinase ◽  
Content Type ◽  
Rate Limiting Step

ABSTRACTPantothenate kinase (PanK) catalyzes the phosphorylation of pantothenate, the first committed and rate-limiting step toward coenzyme A (CoA) biosynthesis. In our earlier reports, we had established that the type I isoform encoded by thecoaAgene is an essential pantothenate kinase inMycobacterium tuberculosis, and this vital information was then exploited to screen large libraries for identification of mechanistically different classes of PanK inhibitors. The present report summarizes the synthesis and expansion efforts to understand the structure-activity relationships leading to the optimization of enzyme inhibition along with antimycobacterial activity. Additionally, we report the progression of two distinct classes of inhibitors, the triazoles, which are ATP competitors, and the biaryl acetic acids, with a mixed mode of inhibition. Cocrystallization studies provided evidence of these inhibitors binding to the enzyme. This was further substantiated with the biaryl acids having MIC against the wild-typeM. tuberculosisstrain and the subsequent establishment of a target link with an upshift in MIC in a strain overexpressing PanK. On the other hand, the ATP competitors had cellular activity only in aM. tuberculosisknockdown strain with reduced PanK expression levels. Additionally,in vitroandin vivosurvival kinetic studies performed with aM. tuberculosisPanK (MtPanK) knockdown strain indicated that the target levels have to be significantly reduced to bring in growth inhibition. The dual approaches employed here thus established the poor vulnerability of PanK inM. tuberculosis.

scholarly journals Hydroxylamine and Carboxymethoxylamine Can Inhibit Toxoplasma gondii Growth through an Aspartate Aminotransferase-Independent Pathway

2020 ◽  
Vol 64 (3) ◽  
Author(s):  
Jixu Li ◽  
Huanping Guo ◽  
Eloiza May Galon ◽  
Yang Gao ◽  
Seung-Hun Lee ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Drug Targets ◽  
Protozoan Parasite ◽  
Cell Types ◽  
Lytic Cycle ◽  
Type I ◽  
Content Type ◽  
Mechanism Of Inhibition

ABSTRACT Toxoplasma gondii is an obligate intracellular protozoan parasite and a successful parasitic pathogen in diverse organisms and host cell types. Hydroxylamine (HYD) and carboxymethoxylamine (CAR) have been reported as inhibitors of aspartate aminotransferases (AATs) and interfere with the proliferation in Plasmodium falciparum. Therefore, AATs are suggested as drug targets against Plasmodium. The T. gondii genome encodes only one predicted AAT in both T. gondii type I strain RH and type II strain PLK. However, the effects of HYD and CAR, as well as their relationship with AAT, on T. gondii remain unclear. In this study, we found that HYD and CAR impaired the lytic cycle of T. gondii in vitro, including the inhibition of invasion or reinvasion, intracellular replication, and egress. Importantly, HYD and CAR could control acute toxoplasmosis in vivo. Further studies showed that HYD and CAR could inhibit the transamination activity of rTgAAT in vitro. However, our results confirmed that deficiency of AAT in both RH and PLK did not reduce the virulence in mice, although the growth ability of the parasites was affected in vitro. HYD and CAR could still inhibit the growth of AAT-deficient parasites. These findings indicated that HYD and CAR inhibition of T. gondii growth and control of toxoplasmosis can occur in an AAT-independent pathway. Overall, further studies focusing on the elucidation of the mechanism of inhibition are warranted. Our study hints at new substrates of HYD and CAR as potential drug targets to inhibit T. gondii growth.

scholarly journals Interferon-Stimulated Gene (ISG)-Expression Screening Reveals the Specific Antibunyaviral Activity of ISG20

2018 ◽  
Vol 92 (13) ◽  
Author(s):  
Junjie Feng ◽  
Arthur Wickenhagen ◽  
Matthew L. Turnbull ◽  
Veronica V. Rezelj ◽  
Felix Kreher ◽  
...  
Keyword(s):  
Viral Infections ◽  
Rhesus Macaques ◽  
Type I ◽  
Emerging Viruses ◽  
Content Type ◽  
Expression Screening ◽  
Interferon Stimulated Genes ◽  
Life Threatening

ABSTRACT Bunyaviruses pose a significant threat to human health, prosperity, and food security. In response to viral infections, interferons (IFNs) upregulate the expression of hundreds of interferon-stimulated genes (ISGs), whose cumulative action can potently inhibit the replication of bunyaviruses. We used a flow cytometry-based method to screen the ability of ∼500 unique ISGs from humans and rhesus macaques to inhibit the replication of Bunyamwera orthobunyavirus (BUNV), the prototype of both the Peribunyaviridae family and the Bunyavirales order. Candidates possessing antibunyaviral activity were further examined using a panel of divergent bunyaviruses. Interestingly, one candidate, ISG20, exhibited potent antibunyaviral activity against most viruses examined from the Peribunyaviridae , Hantaviridae , and Nairoviridae families, whereas phleboviruses ( Phenuiviridae ) largely escaped inhibition. Similar to the case against other viruses known to be targeted by ISG20, the antibunyaviral activity of ISG20 is dependent upon its functional RNase activity. Through use of an infectious virus-like particle (VLP) assay (based on the BUNV minigenome system), we confirmed that gene expression from all 3 viral segments is strongly inhibited by ISG20. Using in vitro evolution, we generated a substantially ISG20-resistant BUNV and mapped the determinants of ISG20 sensitivity/resistance. Taking all the data together, we report that ISG20 is a broad and potent antibunyaviral factor but that some bunyaviruses are remarkably ISG20 resistant. Thus, ISG20 sensitivity/resistance may influence the pathogenesis of bunyaviruses, many of which are emerging viruses of clinical or veterinary significance. IMPORTANCE There are hundreds of bunyaviruses, many of which cause life-threatening acute diseases in humans and livestock. The interferon (IFN) system is a key component of innate immunity, and type I IFNs limit bunyaviral propagation both in vitro and in vivo . Type I IFN signaling results in the upregulation of hundreds of IFN-stimulated genes (ISGs), whose concerted action generates an “antiviral state.” Although IFNs are critical in limiting bunyaviral replication and pathogenesis, much is still unknown about which ISGs inhibit bunyaviruses. Using ISG-expression screening, we examined the ability of ∼500 unique ISGs to inhibit Bunyamwera orthobunyavirus (BUNV), the prototypical bunyavirus. Using this approach, we identified ISG20, an interferon-stimulated exonuclease, as a potent inhibitor of BUNV. Interestingly, ISG20 possesses highly selective antibunyaviral activity, with multiple bunyaviruses being potently inhibited while some largely escape inhibition. We speculate that the ability of some bunyaviruses to escape ISG20 may influence their pathogenesis.

scholarly journals Endocarditis Caused by Highly Penicillin-Resistant Viridans Group Streptococci: Still Room for Vancomycin-Based Regimens

2019 ◽  
Vol 63 (8) ◽  
Author(s):  
Juan M. Pericàs ◽  
Ruvandhi Nathavitharana ◽  
Cristina Garcia-de-la-Mària ◽  
Carles Falces ◽  
Juan Ambrosioni ◽  
...  
Keyword(s):  
Bactericidal Activity ◽  
Treatment Options ◽  
Content Type ◽  
High Level ◽  
Viridans Group Streptococci ◽  
Time Kill

ABSTRACT Optimal treatment options remain unknown for infective endocarditis (IE) caused by penicillin-resistant (PEN-R) viridans group streptococcal (VGS) strains. The aims of this study were to report two cases of highly PEN-R VGS IE, perform a literature review, and evaluate various antibiotic combinations in vitro and in vivo. The following combinations were tested by time-kill studies and in the rabbit experimental endocarditis (EE) model: PEN-gentamicin, ceftriaxone-gentamicin, vancomycin-gentamicin, daptomycin-gentamicin, and daptomycin-ampicillin. Case 1 was caused by Streptococcus parasanguinis (PEN MIC, 4 μg/ml) and was treated with vancomycin plus cardiac surgery. Case 2 was caused by Streptococcus mitis (PEN MIC, 8 μg/ml) and was treated with 4 weeks of vancomycin plus gentamicin, followed by 2 weeks of vancomycin alone. Both patients were alive and relapse-free after ≥6 months follow-up. For the in vitro studies, except for daptomycin-ampicillin, all combinations demonstrated both synergy and bactericidal activity against the S. parasanguinis isolate. Only PEN-gentamicin, daptomycin-gentamicin, and daptomycin-ampicillin demonstrated both synergy and bactericidal activity against the S. mitis strain. Both strains developed high-level daptomycin resistance (HLDR) during daptomycin in vitro passage. In the EE studies, PEN alone failed to clear S. mitis from vegetations, while ceftriaxone and vancomycin were significantly more effective (P < 0.001). The combination of gentamicin with PEN or vancomycin increased bacterial eradication compared to that with the respective monotherapies. In summary, two patients with highly PEN-R VGS IE were cured using vancomycin-based therapy. In vivo, regimens of gentamicin plus either β-lactams or vancomycin were more active than their respective monotherapies. Further clinical studies are needed to confirm the role of vancomycin-based regimens for highly PEN-R VGS IE. The emergence of HLDR among these strains warrants caution in the use of daptomycin therapy for VGS IE.

scholarly journals Arsenic Trioxide Negatively Affects Echinococcus granulosus

2015 ◽  
Vol 59 (11) ◽  
pp. 6946-6951 ◽  
Author(s):  
Bo Wang ◽  
Yufeng Jiang ◽  
Zhuo Wang ◽  
Fangfang Li ◽  
Guoqiang Xing ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Arsenic Trioxide ◽  
Echinococcus Granulosus ◽  
Treatment Options ◽  
Small Sample ◽  
Content Type ◽  
Transmission Electron ◽  
New Strategy

ABSTRACTSpillage of cyst contents during surgery is the major cause of recurrences of hydatidosis, also called cystic echinococcosis (CE). Currently, many scolicidal agents are used for inactivation of the cyst contents. However, due to complications in the use of those agents, new and more-effective treatment options are urgently needed. The aim of this study was to investigate thein vitroefficacy of arsenic trioxide (ATO) againstEchinococcus granulosusprotoscolices. Protoscolices ofE. granulosuswere incubatedin vitrowith 2, 4, 6, and 8 μmol/liter ATO; viability of protoscolices was assessed daily by microscopic observation of movements and 0.1% eosin staining. A small sample from each culture was processed for scanning and transmission electron microscopy. ATO demonstrated a potent ability to kill protoscolices, suggesting that ATO may represent a new strategy in treating hydatid cyst echinococcosis. However, thein vivoefficacy and possible side effects of ATO need to be explored.

Evaluation of the type I signal peptidase as antibacterial target for biofilm-associated infections of Staphylococcus epidermidis

Microbiology ◽  
2009 ◽  
Vol 155 (11) ◽  
pp. 3719-3729 ◽  
Author(s):  
Katrijn Bockstael ◽  
Nick Geukens ◽  
Lieve Van Mellaert ◽  
Piet Herdewijn ◽  
Jozef Anné ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Functional Activity ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Antimicrobial Treatment ◽  
Signal Peptidase ◽  
Temperature Sensitive ◽  
Type I

The development of antibacterial resistance is inevitable and is a major concern in hospitals and communities. Moreover, biofilm-grown bacteria are less sensitive to antimicrobial treatment. In this respect, the Gram-positive Staphylococcus epidermidis is an important source of nosocomial biofilm-associated infections. In the search for new antibacterial therapies, the type I signal peptidase (SPase I) serves as a potential target for development of antibacterials with a novel mode of action. This enzyme cleaves off the signal peptide from secreted proteins, making it essential for protein secretion, and hence for bacterial cell viability. S. epidermidis encodes three putative SPases I (denoted Sip1, Sip2 and Sip3), of which Sip1 lacks the catalytic lysine. In this report, we investigated the active S. epidermidis SPases I in more detail. Sip2 and Sip3 were found to complement a temperature-sensitive Escherichia coli lepB mutant, demonstrating their in vivo functional activity. In vitro functional activity of purified Sip2 and Sip3 proteins and inhibition of their activity by the SPase I inhibitor arylomycin A2 were further illustrated using a fluorescence resonance energy transfer (FRET)-based assay. Furthermore, we demonstrated that SPase I not only is an attractive target for development of novel antibacterials against free-living bacteria, but also is a feasible target for biofilm-associated infections.

scholarly journals Immunoadjuvant Chemotherapy of Visceral Leishmaniasis in Hamsters Using Amphotericin B-Encapsulated Nanoemulsion Template-Based Chitosan Nanocapsules

2013 ◽  
Vol 57 (4) ◽  
pp. 1714-1722 ◽  
Author(s):  
Shalini Asthana ◽  
Anil K. Jaiswal ◽  
Pramod K. Gupta ◽  
Vivek K. Pawar ◽  
Anuradha Dube ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Amphotericin B ◽  
Leishmania Donovani ◽  
Transforming Growth Factor ◽  
Treatment Options ◽  
Interleukin 12 ◽  
Necrosis Factor Alpha ◽  
Content Type

ABSTRACTThe accessible treatment options for life-threatening neglected visceral leishmaniasis (VL) disease have problems with efficacy, stability, adverse effects, and cost, making treatment a complex issue. Here we formulated nanometric amphotericin B (AmB)-encapsulated chitosan nanocapsules (CNC-AmB) using a polymer deposition technique mediated by nanoemulsion template fabrication. CNC-AmB exhibited good steric stabilityin vitro, where the chitosan content was found to be efficient at preventing destabilization in the presence of protein and Ca2+. A toxicity study on the model cell line J774A and erythrocytes revealed that CNC-AmB was less toxic than commercialized AmB formulations such as Fungizone and AmBisome. The results ofin vitro(macrophage-amastigote system; 50% inhibitory concentration [IC50], 0.19 ± 0.04 μg AmB/ml) andin vivo(Leishmania donovani-infected hamsters; 86.1% ± 2.08% parasite inhibition) experiments in conjunction with effective internalization by macrophages illustrated the efficacy of CNC-AmB at augmenting antileishmanial properties. Quantitative mRNA analysis by real-time PCR (RT-PCR) showed that the improved effect was synergized with the upregulation of tumor necrosis factor alpha (TNF-α), interleukin-12 (IL-12), and inducible nitric oxide synthase and with the downregulation of transforming growth factor β (TGF-β), IL-10, and IL-4. These research findings suggest that a cost-effective CNC-AmB immunoadjuvant chemotherapeutic delivery system could be a viable alternative to the current high-cost commercial lipid-based formulations.

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