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1.
BMC Complement Altern Med ; 19(1): 119, 2019 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-31170971

RESUMO

BACKGROUND: Staphylococcus aureus is a notorious pathogen which often causes nosocomial and community attained infections. These infections steadily increased after evolving the resistance due to indecorous practice of antibiotics and now become a serious health issue. Ouabain is a Na+/K+-ATPase inhibitor that leads to increase the heart contraction in patients with congestive heart failure. METHODS: In the present study, in vitro antimicrobial effect of ouabain together with aminoglycosides was determined against clinical and non-clinical S. aureus strains. Using checkerboard, Gentamycin uptake and biofilm assays, we analysed he interactions of ouabain with aminoglycosides. RESULTS: Ouabain induced the staphylocidal potency of aminoglycosides by remarkably reducing the MIC of gentamycin (GEN) by 16 (0.25 µg/mL), 8 folds (0.5 µg/mL) amikacin (AMK); and 16 folds (1.0 µg/mL) with kanamycin (KAN), compared to their individual doses. OBN severely reduced cell viability within 60 min with GEN (1 µg/mL), KAN (2 µg/mL) and 90 min with AMK (1 µg/mL). This bactericidal effect was enhanced due to GEN uptake potentiated by 66% which led to increase the cell permeability as revealed by leakage of bacterial ATP and nitrocefin assay. The biofilm adherence disrupted by 80 and 50% at 5 mg/mL and 1.5 mg/mL OBN and 50 and 90% biofilm formation was inhibited at 5 mg/mL (MBIC50) and 10 mg/mL (MBIC90), respectively. Moreover, OBN with GEN further induced biofilm inhibition by 67 ± 5% at pH 7.0. CONCLUSIONS: Taken together, we established that OBN synergizes the antimicrobial activity of aminoglycosides that induces cell killing due to intracellular accumulation of GEN by disturbing cell homeostasis. It may be proven an effective approach for the treatment of staphylococcal infections.


Assuntos
Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Ouabaína/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Sinergismo Farmacológico , Testes de Sensibilidade Microbiana
2.
Fitoterapia ; 135: 107-113, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31048011

RESUMO

An examination of the endophytic fungus Trichoderma asperellum A-YMD-9-2 obtained from the marine red alga Gracilaria verrucosa led to the isolation of seven new chromanoid norbisabolane derivatives, trichobisabolins I-L (1-4) and trichaspsides C-E (5-7). Their structures and relative configurations were established on the basis of spectroscopic techniques, mainly including 1D/2D NMR and MS, and the absolute configuration of 1 was assigned by X-ray crystallographic analysis using Cu Kα radiation. All of these isolates feature a 1,9-epoxy ring system, and 5-7 represent the second occurrence of norbisabolane aminoglycosides. Compounds 1-7 exhibited potent inhibition of several marine phytoplankton species.


Assuntos
Aminoglicosídeos/farmacologia , Cromanos/farmacologia , Gracilaria/microbiologia , Trichoderma/química , Aminoglicosídeos/química , Aminoglicosídeos/isolamento & purificação , Cromanos/isolamento & purificação , Cristalografia por Raios X , Endófitos , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Trichoderma/fisiologia
3.
Microb Pathog ; 132: 150-155, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31059757

RESUMO

Tuberculosis is an airborne infectious disease caused by Mycobacterium tuberculosis which threatens the globe. Aminoglycosides {Amikacin (AK) & Kanamycin (KM)} are WHO recommended second-line anti-TB drugs used against the treatment of drug-resistant tuberculosis. Aminoglycosides target the steps of protein translation machinery of M.tuberculosis. Several mechanisms have been put forward to elucidate the phenomena of aminoglycosides resistance but our knowledge is still insufficient. The aim of the study was to understand the involvement of Mycobacterium tuberculosis universal stress protein (Rv2005c) in aminoglycosides resistance and virulence. To establish the relationship of universal stress protein Rv2005c with AK & KM resistance, Rv2005c was cloned, expressed in E.coli BL21 using pQE2 expression vector and antimicrobial drug susceptibility testing (DST) was carried out. STRING-10 was also used to predict the interacting protein partners of Rv2005c. DST showed that the minimum inhibitory concentration of induced recombinant cells (Rv2005c) were five and four folds shifted with AK and KM E-strips, respectively. STRING-10 showed the interacting protein partners of Rv2005c. Overexpression of Rv2005c leads to shifting in MIC which might be signifying its involvement in the survival/resistance of Mycobacteria by inhibiting/modulating the effects of AK and KM released from the E-strips. Interactome also suggests that Rv2005c and its interacting protein partners are cumulatively involved in M.tuberculosis resistance, stresses, and latency.


Assuntos
Aminoglicosídeos/farmacologia , Antígenos de Bactérias/genética , Proteínas de Bactérias/genética , DNA Bacteriano/isolamento & purificação , Farmacorresistência Bacteriana Múltipla/genética , Amicacina/farmacologia , Antígenos de Bactérias/metabolismo , Antituberculosos/farmacologia , Proteínas de Bactérias/metabolismo , Clonagem Molecular , DNA Bacteriano/genética , Regulação Bacteriana da Expressão Gênica , Canamicina/farmacologia , Testes de Sensibilidade Microbiana , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/metabolismo , Mapas de Interação de Proteínas , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico
4.
Mar Drugs ; 17(4)2019 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-31010150

RESUMO

Spirotetronates are actinomyces-derived polyketides that possess complex structures and exhibit potent and unexplored bioactivities. Due to their anticancer and antimicrobial properties, they have potential as drug hits and deserve further study. In particular, abyssomicin C and tetrocarcin A have shown significant promise against antibiotic-resistant S. aureus and tuberculosis, as well as for the treatment of various lymphomas and solid tumors. Improved synthetic routes to these compounds, particularly the class II spirotetronates, are needed to access sufficient quantities for structure optimization and clinical applications.


Assuntos
Aminoglicosídeos/química , Compostos Bicíclicos Heterocíclicos com Pontes/química , Policetídeos/química , Compostos de Espiro/química , Aminoglicosídeos/farmacologia , Antibacterianos/química , Antibacterianos/farmacologia , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Descoberta de Drogas , Humanos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Policetídeos/metabolismo , Policetídeos/farmacologia , Compostos de Espiro/metabolismo , Compostos de Espiro/farmacologia
5.
mSphere ; 4(2)2019 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-30842268

RESUMO

The two-component system TctD-TctE is important for regulating the uptake of tricarboxylic acids in Pseudomonas aeruginosa TctD-TctE accomplishes this through derepression of the gene opdH, which encodes a tricarboxylic acid-specific porin. Previous work from our lab revealed that TctD-TctE in P. aeruginosa also has a role in resistance to aminoglycoside antibiotics. The aim of this study was to further characterize the role of TctD-TctE in P. aeruginosa in the presence of citric acid. Here it was found that deletion of P. aeruginosa PA14 TctD-TctE (ΔtctED) resulted in a 4-fold decrease in the biofilm bactericidal concentrations of the aminoglycosides tobramycin and gentamicin when citric acid was present in nutrient media. Tobramycin accumulation assays demonstrated that deletion of TctD-TctE resulted in an increase in the amount of tobramycin retained in biofilm cells. The PA14 wild type responded to increasing concentrations of citric acid by producing less biofilm. In contrast, the amount of ΔtctED mutant biofilm formation remained constant or enhanced. Furthermore, the ΔtctED strain was incapable of growing on citric acid as a sole carbon source and was highly reduced in its ability to grow in the presence of citric acid even when an additional carbon source was available. Use of phenotypic and genetic microarrays found that this growth deficiency of the ΔtctED mutant is unique to citric acid and that multiple metabolic genes are dysregulated. This work demonstrates that TctD-TctE in P. aeruginosa has a role in biofilm development that is dependent on citric acid and that is separate from the previously characterized involvement in resistance to antibiotics.IMPORTANCE Nutrient availability is an important contributor to the ability of bacteria to establish successful infections in a host. Pseudomonas aeruginosa is an opportunistic pathogen in humans causing infections that are difficult to treat. In part, its success is attributable to a high degree of metabolic versatility. P. aeruginosa is able to sense and respond to varied and limited nutrient stress in the host environment. Two-component systems are important sensors-regulators of cellular responses to environmental stresses, such as those encountered in the host. This work demonstrates that the response by the two-component system TctD-TctE to the presence of citric acid has a role in biofilm formation, aminoglycoside susceptibility, and growth in P. aeruginosa.


Assuntos
Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Biofilmes/crescimento & desenvolvimento , Ácido Cítrico/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/genética , Proteínas de Bactérias/genética , Biofilmes/efeitos dos fármacos , Deleção de Genes , Regulação Bacteriana da Expressão Gênica , Tobramicina/farmacologia
6.
Anticancer Res ; 39(3): 1197-1204, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30842150

RESUMO

BACKGROUND/AIM: Triple-negative breast cancers (TNBC) lack expression of three important receptors, and have limited treatment options. High expression of junctional adhesion molecule-A (JAM-A) has been linked with aggressive tumor phenotypes including TNBC. This study aimed to evaluate the bioactivity of a JAM-A-down-regulating compound, Tetrocarcin-A, in TNBC. MATERIALS AND METHODS: TNBC cell viability, colony formation and xenograft growth were examined in Tetrocarcin-A-treated HCC38 human cells, 4T1 mouse cells or patient-derived primary cells. Protein expression of cell fate signaling effectors was examined by immunoblotting (versus transient JAM-A gene silencing). Apoptotic pathways were investigated in parallel. RESULTS: Tetrocarcin-A reduced TNBC cell viability in vitro and in an in ovo/semi-in vivo xenograft model. Tetrocarcin-A-induced JAM-A down-regulation and reduced ERK phosphorylation, followed by c-FOS phosphorylation on its transcription-regulating residue, which down-regulated several inhibitor of apoptosis (IAP) proteins and induced caspase-dependent intrinsic pathway of apoptosis. CONCLUSION: Tetrocarcin-A merits further investigation as a novel anti-tumor agent in TNBC.


Assuntos
Aminoglicosídeos/farmacologia , Antineoplásicos/farmacologia , Proteínas Inibidoras de Apoptose/metabolismo , Neoplasias de Mama Triplo Negativas/metabolismo , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Embrião de Galinha , Membrana Corioalantoide , Regulação para Baixo , Inativação Gênica , Humanos , Molécula A de Adesão Juncional/genética , Camundongos , RNA Interferente Pequeno/genética , Neoplasias de Mama Triplo Negativas/genética
7.
BMC Infect Dis ; 19(1): 167, 2019 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-30770727

RESUMO

BACKGROUND: To evaluate the in vitro activities of plazomicin and comparator aminoglycosides and elucidate the underlying aminoglycoside resistance mechanisms among carbapenemase-producing K. pneumoniae isolates collected during a nationwide surveillance study in Greek hospitals. METHODS: Three hundred single-patient carbapenemase-producing K. pneumoniae isolates were studied, including 200 KPC-, 50 NDM-, 21 VIM-, 14 KPC & VIM-, 12 OXA-48-, two NDM & OXA- and one KPC & OXA-producing isolates. Susceptibility testing was performed by broth microdilution, and minimum inhibitory concentrations (MICs) interpreted per EUCAST breakpoints. Carbapenemase-, aminoglycoside modifying enzyme- and 16S rRNA methylase- encoding genes were detected by PCR. RESULTS: Of 300 isolates tested, 5.7% were pandrug resistant and 29.3% extensively drug resistant. Plazomicin inhibited 87.0% of the isolates at ≤2 mg/L, with MIC50/MIC90 of 0.5/4 mg/L. Apramycin (a veterinary aminoglycoside) inhibited 86.7% of the isolates at ≤8 mg/L and was the second most active drug after plazomicin, followed by gentamicin (S, 43%; MIC50/MIC90, 4/> 256) and amikacin (S, 18.0%; MIC50/MIC90, 32/128). Twenty-three (7.7%) isolates (16 KPC-, 6 VIM- and one KPC & OXA-48-producers) exhibited MICs ≥64 mg/L for plazomicin, and harbored rmtB (n = 22) or armA (n = 1). AAC(6')-Іb was the most common aminoglycoside modifying enzyme (84.7%), followed by AAC(3΄)-IIa (25.3%), while those two enzymes were co-produced by 21.4% of the isolates. CONCLUSIONS: Plazomicin retains activity against most carbapenemase-producing K. pneumoniae isolated from Greek hospitals, with MICs consistently lower than those of the other aminoglycosides, even in the presence of aminoglycoside modifying enzymes. Dissemination of 16S- rRNA methylases in 8% of the isolates is an unwelcome event that needs strict infection control measures and rigorous stewardship interventions.


Assuntos
Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Infecções por Klebsiella/epidemiologia , Klebsiella pneumoniae/efeitos dos fármacos , Sisomicina/análogos & derivados , Amicacina , Proteínas de Bactérias , Enterobacteriáceas Resistentes a Carbapenêmicos/isolamento & purificação , Carbapenêmicos , Gentamicinas , Grécia/epidemiologia , Hospitais , Humanos , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/isolamento & purificação , Metiltransferases , Testes de Sensibilidade Microbiana , RNA Ribossômico 16S , Sisomicina/farmacologia , beta-Lactamases
8.
Diagn Microbiol Infect Dis ; 94(2): 199-201, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30638654
9.
Molecules ; 24(3)2019 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-30691073

RESUMO

Mycobacterium tuberculosis (Mtb) has recently surpassed HIV/AIDS as the leading cause of death by a single infectious agent. The standard therapeutic regimen against tuberculosis (TB) remains a long, expensive process involving a multidrug regimen, and the prominence of multidrug-resistant (MDR), extensively drug-resistant (XDR), and totally drug-resistant (TDR) strains continues to impede treatment success. An underexplored class of natural products-the capuramycin-type nucleoside antibiotics-have been shown to have potent anti-TB activity by inhibiting bacterial translocase I, a ubiquitous and essential enzyme that functions in peptidoglycan biosynthesis. The present review discusses current literature concerning the biosynthesis and chemical synthesis of capuramycin and analogs, seeking to highlight the potential of the capuramycin scaffold as a favorable anti-TB therapeutic that warrants further development.


Assuntos
Aminoglicosídeos/biossíntese , Aminoglicosídeos/síntese química , Antituberculosos/síntese química , Aminoglicosídeos/farmacologia , Antituberculosos/metabolismo , Antituberculosos/farmacologia , Bactérias/genética , Bactérias/metabolismo , Biocatálise , Produtos Biológicos/síntese química , Produtos Biológicos/metabolismo , Produtos Biológicos/farmacologia , Descoberta de Drogas , Humanos , Redes e Vias Metabólicas , Família Multigênica , Mycobacterium tuberculosis/efeitos dos fármacos , Relação Estrutura-Atividade
10.
Diagn Microbiol Infect Dis ; 94(1): 73-77, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30661726

RESUMO

Aminoglycoside-nonsusceptible isolates of Escherichia coli, Klebsiella, Proteus, and Enterobacter species (480/3675) from US hospitals collected during 2014-2015 were screened for 16S rRNA methyltransferase and aminoglycoside-modifying enzyme (AME) genes. Only 5 isolates had high aminoglycoside MICs and carried 16S rRNA methyltransferases. AME genes were observed among 89.7% (426/475) of isolates and the most common genes were aac(3)-IIa (n = 270) and aac(6')-Ib (n = 269). Among other genes, ant(2″)-Ia, aac(3)-Iva, and aph(3')-VIa were observed among 36, 23, and 3 isolates, respectively. Forty-nine (10.3%) isolates yielded negative results for the investigated AME genes. Plazomicin (MIC50/90, 0.5/1 µg/ml) inhibited 99.3% of the AME-carrying isolates at its susceptible breakpoint while amikacin, gentamicin, and tobramycin inhibited 90.1%, 20.9%, and 18.3%, respectively. Plazomicin was approved by the US Food and Drug Administration in June 2018 for the treatment of complicated urinary tract infections when limited treatment options are available. This agent displayed activity against isolates carrying AMEs that were resistance to other aminoglycosides and comparator agents.


Assuntos
Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Enterobacteriaceae/efeitos dos fármacos , Sisomicina/análogos & derivados , Proteínas de Bactérias/genética , Enterobacteriaceae/enzimologia , Enterobacteriaceae/genética , Enterobacteriaceae/isolamento & purificação , Infecções por Enterobacteriaceae/microbiologia , Enzimas/genética , Hospitais , Testes de Sensibilidade Microbiana , Sisomicina/farmacologia , Estados Unidos
11.
Oncol Rep ; 41(1): 475-482, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30542729

RESUMO

Apoptosis induction and differentiation of promyelocytic leukemic cells into mature cells are major strategies for the drug-based treatment of leukemia. Lidamycin (LDM) which is a member of the enediyne antibiotic family exhibits extreme cytotoxicity. In the present study, the induction of apoptosis and differentiation in human chronic myeloid leukemia K562 cells by low concentrations of lidamycin were investigated. K562 cells were treated with lidamycin at various concentrations for 48 h, and accumulated in the metaphase as determined in previous experiments. Cell viability was determined using a Cell Counting Kit-8 (CCK-8) assay and the IC50 value of lidamycin was 0.1±3.2 nM. Induction of apoptosis was investigated morphologically by acridine orange/ethidium bromide (AO/EtBr) staining. Growth inhibition and apoptosis induction were observed in cells treated with low concentrations of lidamycin. In addition, western blot analysis revealed that treatment of the K562 cells with lidamycin at low concentrations upregulated the expression of caspase-8 and caspase-3. The induction of differentiation in human chronic myeloid leukemia K562 cells by lidamycin at low concentrations was also investigated. The nitroblue tetrazolium reduction ability of K562 cells was increased following treatment with lidamycin. Low concentrations of lidamycin triggered erythroid differentiation among K562 cells, indicated by morphological changes, increased hemoglobin content, and the expression of cell surface antigens such as CD71. Additionally the expression of GATA-binding factor 1 (GATA-1) protein in low concentration lidamycin-treated K562 cells was increased. The results of the present study suggest that a low-concentration lidamycin exerts effects on apoptosis and erythroid differentiation induction by increasing the expression of caspases and GATA-1 protein. Lidamycin may serve a positive role in relevant targeted chemotherapy and may represent a potential candidate for chronic myelogenous leukemia differentiation-inducing treatment.


Assuntos
Aminoglicosídeos/farmacologia , Antibióticos Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Enedi-Inos/farmacologia , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Aminoglicosídeos/uso terapêutico , Antibióticos Antineoplásicos/uso terapêutico , Antígenos CD/metabolismo , Caspase 3/metabolismo , Caspase 8/metabolismo , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Enedi-Inos/uso terapêutico , Fator de Transcrição GATA1/metabolismo , Hemoglobinas/metabolismo , Humanos , Células K562 , Nitroazul de Tetrazólio/metabolismo , Receptores da Transferrina/metabolismo
12.
Eur J Med Chem ; 163: 381-393, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30530174

RESUMO

The development of new ligands that have comparable or enhanced therapeutic efficacy relative to current drugs is vital to the health of the global community in the short and long term. One strategy to accomplish this goal is to functionalize sites on current antimicrobials to enhance specificity and affinity while abating resistance mechanisms of infectious organisms. Herein, we report the synthesis of a series of pyrene-neomycin B (PYR-NEO) conjugates, their binding affinity to A-site RNA targets, resistance to aminoglycoside-modifying enzymes (AMEs), and antibacterial activity against a wide variety of bacterial strains of clinical relevance. PYR-NEO conjugation significantly alters the affinities of NEO for bacterial A-site targets. The conjugation of PYR to NEO significantly increased the resistance of NEO to AME modification. PYR-NEO conjugates exhibited broad-spectrum activity towards Gram-positive bacteria, including improved activity against NEO-resistant methicillin-resistant Staphylococcus aureus (MRSA) strains.


Assuntos
Aminoglicosídeos/farmacologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Infecções Estafilocócicas/tratamento farmacológico , Animais , Sítios de Ligação , Framicetina/química , Bactérias Gram-Positivas/efeitos dos fármacos , Humanos , Ligação Proteica , Pirenos/química , Proteínas Ribossômicas
13.
Eur Urol Focus ; 5(1): 10-12, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30555037
14.
Microbiol Res ; 216: 108-119, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30269850

RESUMO

We previously reported that inactivation of a universally conserved dimethyl adenosine transferase (KsgA) attenuates virulence and increases sensitivity to oxidative and osmotic stress in Salmonella Enteritidis. Here, we show a role of KsgA in cell-envelope fitness as a potential mechanism underlying these phenotypes in Salmonella. We assessed structural integrity of the cell-envelope by transmission electron microscopy, permeability barrier function by determining intracellular accumulation of ethidium bromide and electrophysical properties by dielectrophoresis, an electrokinetic tool, in wild-type and ksgA knock-out mutants of S. Enteritidis. Deletion of ksgA resulted in disruption of the structural integrity, permeability barrier and distorted electrophysical properties of the cell-envelope. The cell-envelope fitness defects were alleviated by expression of wild-type KsgA (WT-ksgA) but not by its catalytically inactive form (ksgAE66A), suggesting that the dimethyl transferase activity of KsgA is important for cell-envelope fitness in S. Enteritidis. Upon expression of WT-ksgA and ksgAE66A in inherently permeable E. coli cells, the former strengthened and the latter weakened the permeability barrier, suggesting that KsgA also contributes to the cell-envelope fitness in E. coli. Lastly, expression of ksgAE66A exacerbated the cell-envelope fitness defects, resulting in impaired S. Enteritidis interactions with human intestinal epithelial cells, and human and avian phagocytes. This study shows that KsgA contributes to cell-envelope fitness and opens new avenues to modulate cell-envelopes via use of KsgA-antagonists.


Assuntos
Parede Celular/metabolismo , Metiltransferases/metabolismo , Salmonella enteritidis/enzimologia , Salmonella enteritidis/metabolismo , Salmonella enteritidis/patogenicidade , Aminoglicosídeos/farmacologia , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Células CACO-2 , Escherichia coli/genética , Escherichia coli/metabolismo , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica , Técnicas de Inativação de Genes , Interações Hospedeiro-Patógeno , Humanos , Macrófagos/microbiologia , Metiltransferases/genética , Testes de Sensibilidade Microbiana , Mutação , Permeabilidade , Salmonella enteritidis/genética , Células THP-1 , Virulência
15.
Eur J Med Chem ; 157: 1512-1525, 2018 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-30282323

RESUMO

Amphiphilic aminoglycosides (AAGs) constitute a new class of antibacterial compounds targeting the bacterial membranes. We have identified the 3',6-dinonyl neamine 9 as a broad spectrum antibacterial AAG. Here, we report on the synthesis, antibacterial activity and eukaryotic cytotoxicity of new 3',6-dialkyl neamines designed in order to finely delineate the structure-activity relationships relating their activity to a lipophilicity window. New broad-spectrum antibacterial derivatives were obtained carrying two identical linear or branched alkyl groups or two different linear alkyl groups. Two fluorescent antibacterial 3',6-heterodialkyl neamines carrying a pyrenylbutyl fluorophore were also identified as potential tools for mechanistic study. Homodialkyl and heterodialkyl neamines appeared to be more active on Gram-negative bacteria than dinaphthylalkyl neamines. However, branched dialkyl neamines or heterodialkyl derivatives were found to be more cytotoxic on mammalian cells than 9. The exposure of P. aeruginosa over one month to half-MIC of one of the most active derivatives 9 demonstrated the high difficulty of resistance emergence to AAGs.


Assuntos
Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Células Eucarióticas/efeitos dos fármacos , Framicetina/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Tensoativos/farmacologia , Aminoglicosídeos/síntese química , Aminoglicosídeos/química , Antibacterianos/síntese química , Antibacterianos/química , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Framicetina/síntese química , Framicetina/química , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Pseudomonas aeruginosa/crescimento & desenvolvimento , Relação Estrutura-Atividade , Tensoativos/síntese química , Tensoativos/química
16.
Transplant Proc ; 50(7): 2170-2175, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30177131

RESUMO

INTRODUCTION: Aminoglycoside resistance (AR) is common in health care-associated methicillin-resistant Staphylococcus aureus (HA-MRSA). AR is most often associated with the production of antibiotic modifying enzymes: bidomain AAC(6')-Ie/APH(2″)-Ia acetyltransferase and phosphotransferase, ANT(4')-Ia nucleotidyltransferase, and APH(3″)-IIIa phosphotransferase. AIM: Determination of aminoglycoside sensitivity, presence of genes encoding enzymes, and molecular typing of HA-MRSA strains derived from patients hospitalized in surgical and transplantation wards. MATERIALS AND METHODS: Fifty-four HA-MRSA strains, isolated from various materials from patients in the surgical and transplantation wards of Warsaw's clinical hospital, hospitalized between 1991 and 2007. The MIC values of gentamicin-GEN/tobramycin-TOB/amikacin-AK/netilmicin-NET were determined by the E-test (CLSI/EUCAST). Genes mecA/aacA-aphD/aadD/aph(3″)-IIIa were detected using PCR. SCCmec types were determined according to the Oliveira method and the sequence type (ST)/clonal complex (CC) by the MLST method. RESULTS: Of the isolates tested, 36 (66.7%) showed resistance to at least one aminoglycoside: TOB (57.4%), GEN (53.7%), AK (55.6%), NET (24.1%). The aacA-aphD gene was present in 29 MRSA-GEN-R (most often in combination with aadD, 15/29 or aph(3″)-IIIa, 10/29); the aacA-aphD gene was the only determinant of resistance in 1 isolate. The AR variants mainly belonged to the CC8 clonal complex (ST239/247/241/254/8) and most frequently contained SCCmec type III (3A) cassettes. CONCLUSIONS: Resistance to at least one aminoglycoside was present in 66.7% of HA-MRSA and in more than 22% to all of them. The presence of the aacA-aphD gene was sufficient to express the resistance phenotype to GEN/TOB/AK/NET. Resistant isolates were closely related to each other.


Assuntos
Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Proteínas de Bactérias/efeitos dos fármacos , Canamicina Quinase/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Amicacina/farmacologia , Proteínas de Bactérias/isolamento & purificação , Gentamicinas/farmacologia , Unidades Hospitalares , Hospitais , Humanos , Canamicina Quinase/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Netilmicina/farmacologia , Nucleotidiltransferases/efeitos dos fármacos , Nucleotidiltransferases/isolamento & purificação , Proteínas de Ligação às Penicilinas/efeitos dos fármacos , Proteínas de Ligação às Penicilinas/isolamento & purificação , Estudos Retrospectivos , Infecções Estafilocócicas , Tobramicina/farmacologia
17.
mSphere ; 3(4)2018 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-30111627

RESUMO

Heteroresistance is a phenomenon where a subpopulation of cells exhibits higher levels of antibiotic resistance than the general population. Analysis of tobramycin resistance in Acinetobacter baumannii AB5075 using Etest strips demonstrated that colonies with increased resistance arose at high frequency within the zone of growth inhibition. The presence of a resistant subpopulation was confirmed by population analysis profiling (PAP). The tobramycin-resistant subpopulation was cross resistant to gentamicin but not amikacin. The increased tobramycin resistance phenotype was highly unstable, and cells reverted to a less resistant population at frequencies of 60 to 90% after growth on nonselective media. Furthermore, the frequency of the resistant subpopulation was not increased by preincubation with subinhibitory concentrations of tobramycin. The tobramycin-resistant subpopulation was shown to replicate during the course of antibiotic treatment, demonstrating that these were not persister cells. In A. baumannii AB5075, a large plasmid (p1AB5075) carries aadB, a 2″-nucleotidyltransferase that confers resistance to both tobramycin and gentamicin but not amikacin. The aadB gene is part of an integron and is carried adjacent to four additional resistance genes that are all flanked by copies of an integrase gene. In isolates with increased resistance, this region was highly amplified in a RecA-dependent manner. However, in a recA mutant, colonies with unstable tobramycin resistance arose by a mechanism that did not involve amplification of this region. These data indicate that tobramycin heteroresistance occurs by at least two mechanisms in A. baumannii, and future studies to determine its effect on patient outcomes are warranted.IMPORTANCEAcinetobacter baumannii has become an important pathogen in hospitals worldwide, where the incidence of these infections has been increasing. A. baumannii infections have become exceedingly difficult to treat due to a rapid increase in the frequency of multidrug- and pan-resistant isolates. This has prompted the World Health Organization to list A. baumannii as the top priority for the research and development of new antibiotics. This study reports for the first time a detailed analysis of aminoglycoside heteroresistance in A. baumannii We define the mechanistic basis for heteroresistance, where the aadB(ant2″)Ia gene encoding an aminoglycoside adenylyltransferase becomes highly amplified in a RecA-dependent manner. Remarkably, this amplification of 20 to 40 copies occurs stochastically in 1/200 cells in the absence of antibiotic selection. In addition, we provide evidence for a second RecA-independent mechanism for aminoglycoside heteroresistance. This study reveals that aminoglycoside resistance in A. baumannii is far more complex than previously realized and has important implications for the use of aminoglycosides in treating A. baumannii infections.


Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Amicacina/farmacologia , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Gentamicinas/farmacologia , Humanos , Integrons , Nucleotidiltransferases/genética , Plasmídeos , Tobramicina/farmacologia
18.
Proc Natl Acad Sci U S A ; 115(32): 8191-8196, 2018 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-30038002

RESUMO

Bacteria respond to zinc starvation by replacing ribosomal proteins that have the zinc-binding CXXC motif (C+) with their zinc-free (C-) paralogues. Consequences of this process beyond zinc homeostasis are unknown. Here, we show that the C- ribosome in Mycobacterium smegmatis is the exclusive target of a bacterial protein Y homolog, referred to as mycobacterial-specific protein Y (MPY), which binds to the decoding region of the 30S subunit, thereby inactivating the ribosome. MPY binding is dependent on another mycobacterial protein, MPY recruitment factor (MRF), which is induced on zinc depletion, and interacts with C- ribosomes. MPY binding confers structural stability to C- ribosomes, promoting survival of growth-arrested cells under zinc-limiting conditions. Binding of MPY also has direct influence on the dynamics of aminoglycoside-binding pockets of the C- ribosome to inhibit binding of these antibiotics. Together, our data suggest that zinc limitation leads to ribosome hibernation and aminoglycoside resistance in mycobacteria. Furthermore, our observation of the expression of the proteins of C- ribosomes in Mycobacterium tuberculosis in a mouse model of infection suggests that ribosome hibernation could be relevant in our understanding of persistence and drug tolerance of the pathogen encountered during chemotherapy of TB.


Assuntos
Antibióticos Antituberculose/farmacologia , Proteínas de Bactérias/metabolismo , Mycobacterium tuberculosis/fisiologia , Proteínas Ribossômicas/metabolismo , Tuberculose/tratamento farmacológico , Zinco/deficiência , Aminoglicosídeos/farmacologia , Animais , Microscopia Crioeletrônica , Modelos Animais de Doenças , Farmacorresistência Bacteriana , Feminino , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Testes de Sensibilidade Microbiana , Modelos Moleculares , Mycobacterium smegmatis/efeitos dos fármacos , Mycobacterium smegmatis/fisiologia , Mycobacterium tuberculosis/efeitos dos fármacos , Biossíntese de Proteínas/fisiologia , Ribossomos/metabolismo , Ribossomos/ultraestrutura , Tuberculose/microbiologia , Tuberculose/patologia
19.
J Med Microbiol ; 67(9): 1402-1409, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30052178

RESUMO

PURPOSE: Clostridium difficile infection (CDI) is an increasing cause of nosocomial diarrhoea worldwide, which has been partly attributed to the emergence of hypervirulent strains including C. difficile BI/NAP1/ribotype 027 and BK/NAP7/ribotype 078. Cadazolid is a new antibiotic currently in late-stage clinical studies for the treatment of CDI. The present study evaluated the in vitro bactericidal effect of cadazolid and comparator antibiotics against four C. difficile strains. The data demonstrate the potent and bactericidal activity of cadazolid against different ribotypes of C. difficile. METHODOLOGY: MICs for test antibiotics were determined in brain- heart infusion-supplemented broth (BHIS) containing 5 g l-1 yeast extract and 0.025 % (w/v) l-cysteine. Time-kill kinetics to investigate the rate of killing of each antibiotic at sub- and supra-MIC concentrations were performed at concentrations of 0.5, 1, 2, 4, 8 or 16× the MIC of cadazolid, vancomycin and fidaxomicin at intervals over a 48 h period.Results/key findings. Cadazolid-mediated killing of C. difficile was faster and occurred at lower concentrations than observed for vancomycin, while potency and killing was largely comparable to those observed for fidaxomicin. Notably, cadazolid also displayed a potent bactericidal effect against fluoroquinolone-resistant hypervirulent ribotype 027 and 078 strains. C. difficile spore formation was largely inhibited by all three antibiotics at concentrations >1× MIC; however, none were able to eliminate spores effectively, which were present at the start of the experiment. CONCLUSION: The data presented here demonstrate the potent in vitro bactericidal activity of cadazolid against different ribotypes of C. difficile, although on a limited set of strains.


Assuntos
Antibacterianos/farmacologia , Clostridium difficile/efeitos dos fármacos , Oxazolidinonas/farmacologia , Aminoglicosídeos/farmacologia , Infecções por Clostridium/microbiologia , Clostridium difficile/química , Clostridium difficile/classificação , Clostridium difficile/crescimento & desenvolvimento , Fidaxomicina , Humanos , Cinética , Testes de Sensibilidade Microbiana , Ribotipagem , Vancomicina/farmacologia
20.
Lett Appl Microbiol ; 67(4): 329-336, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29981154

RESUMO

Whole genome sequencing was utilized to investigate the genomic profile of Vibrio cholerae O1 strains, isolated from symptomatic patients in a low-income urban area of Dhaka, Bangladesh. Comparative genomics using bioinformatics tools were applied to identify major virulence factors, biotype and antimicrobial resistance genes in three V. cholerae O1 strains (VC-1, 2 and 3) isolated from two case patients. A phylogenetic SNP (single nucleotide polymorphism)-based analysis was conducted to infer the relatedness to V. cholerae O1 strains isolated elsewhere. The V. cholerae strains were the El Tor variant carrying ctxB1 (standard classical genotype). SNP-based global phylogeny revealed that the three isolates were strictly clonal and the closest neighbouring genomes were epidemic clones of V. cholerae O1 isolated in 2010 from cholera patients in Pakistan. All strains harboured the integrase gene of the SXT element (intSXT ), antimicrobial resistance genes for aminoglycosides, phenicol, sulphonamide and trimethoprim except VC-1 that lacked sulphonamide resistance genes. The multilocus sequence typing (MLST) revealed that the strains belonged to sequence type, ST69. The study provides knowledge on current genetic traits of clinical V. cholerae O1 circulating in urban household clusters of Bangladesh which may help in predicting emergence of new pandemic strains in Bangladesh. SIGNIFICANCE AND IMPACT OF THE STUDY: Vibrio cholerae has frequently experienced genetic changes with rapid evolution of pandemic clones in the Ganges Delta region. Whole genome sequencing can reveal genetic information of current pathogenic V. cholerae in Bangladesh which includes cefotaxime genotypes, virulence factors, altered antimicrobial resistance pattern as well as mobile genetic element compared to global pandemic strains. This study data could be used in planning future surveillance strategies in Ganges Delta region by informing new epidemiology of current outbreak strains.


Assuntos
Cólera/epidemiologia , Cólera/microbiologia , Farmacorresistência Bacteriana Múltipla/genética , Genoma Bacteriano/genética , Vibrio cholerae O1 , Adulto , Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Bangladesh/epidemiologia , Pré-Escolar , Toxina da Cólera/genética , Surtos de Doenças , Feminino , Genômica/métodos , Genótipo , Humanos , Tipagem de Sequências Multilocus , Filogenia , Polimorfismo de Nucleotídeo Único/genética , Sulfonamidas/farmacologia , Trimetoprima/farmacologia , Vibrio cholerae O1/efeitos dos fármacos , Vibrio cholerae O1/genética , Vibrio cholerae O1/isolamento & purificação , Sequenciamento Completo do Genoma/métodos , Adulto Jovem
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