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OBJECTIVES: To evaluate the effect of sub-growth-inhibitory concentrations of omadacycline on Staphylococcus aureus ATCC 10832 haemolytic activity in vitro. METHODS: Following determination of the MICs of omadacycline and comparator antibiotics, the strain was grown in the presence of individual antibiotics and the percentage of haemolysis assayed; 'washout' experiments were performed with omadacycline only. RESULTS: Omadacycline inhibited S. aureus haemolytic activity in vitro at sub-growth-inhibitory concentrations. Inhibition was maintained at least 4 h after removal of extracellular drug. CONCLUSIONS: Omadacycline's in vitro potency and suppression of virulence factors might contribute to its efficacy in the treatment of acute bacterial skin and skin structure infections and community-acquired bacterial pneumonia caused by virulent strains of S. aureus. This finding could be relevant for other organisms and virulence factors that depend on new protein synthesis.
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OBJECTIVE: Community-acquired bacterial pneumonia (CABP) is a major clinical burden worldwide. In the phase III OPTIC study (NCT02531438) in CABP, omadacycline was found to be non-inferior to moxifloxacin for investigator-assessed clinical response (IACR) at post-treatment evaluation (PTE, 5-10 days after last dose). This article reports the efficacy findings, as specified in the European Medicines Agency (EMA) guidance. METHODS: Patients were randomized 1:1 to omadacycline 100 mg intravenously (every 12 h for two doses, then every 24 h) with optional transition to 300 mg orally after 3 days, or moxifloxacin 400 mg intravenously (every 24 h) with optional transition to 400 mg orally after 3 days. The total treatment duration was 7-14 days. The primary endpoint for EMA efficacy analysis was IACR at PTE in patients with Pneumonia Patient Outcomes Research Team (PORT) risk class III and IV. RESULTS: In total, 660 patients were randomized as PORT risk class III and IV. Omadacycline was non-inferior to moxifloxacin at PTE. The clinical success rates were 88.4% and 85.2%, respectively [intent-to-treat population; difference 3.3; 97.5% confidence interval (CI) -2.7 to 9.3], and 92.5% and 90.5%, respectively (clinically evaluable population; difference 2.0; 97.5% CI 3.2-7.4). Clinical success rates with omadacycline and moxifloxacin were similar against identified pathogens and across key subgroups. CONCLUSIONS: Omadacycline was non-inferior to moxifloxacin for IACR at PTE, with high clinical success across pathogen types and patient subgroups.
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Antibacterianos/uso terapéutico , Infecciones Comunitarias Adquiridas/tratamiento farmacológico , Moxifloxacino/uso terapéutico , Neumonía Bacteriana/tratamiento farmacológico , Tetraciclinas/uso terapéutico , Administración Intravenosa , Anciano , Antibacterianos/administración & dosificación , Infecciones Comunitarias Adquiridas/microbiología , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Moxifloxacino/administración & dosificación , Neumonía Bacteriana/microbiología , Tetraciclinas/administración & dosificaciónRESUMEN
BACKGROUND: Many antibiotics require dosage adjustments in patients with renal impairment. In Phase III studies, omadacycline was non-inferior to moxifloxacin and linezolid in adults with community-acquired bacterial pneumonia (CABP) and acute bacterial skin and skin structure infections (ABSSSI), respectively. This analysis evaluated efficacy and safety measures from three omadacycline studies by patient renal function. METHODS: Patients were stratified as having normal renal function (creatinine clearance >89 mL/min), mild renal impairment (creatinine clearance 60-89 mL/min) or moderate renal impairment (creatinine clearance <60 mL/min); creatine clearance ≤30 mL/min (severe renal impairment) was an exclusion criterion. Efficacy endpoints were clinical success at the early clinical response (ECR) and post-treatment evaluation (PTE) time-points. Safety was evaluated as treatment-emergent adverse events (TEAEs) and laboratory measures. RESULTS: This subgroup analysis included 773 patients with CABP and 1339 patients with ABSSSI in intent-to-treat (ITT) and modified ITT populations, respectively. Clinical success rates were high at ECR and PTE across the studies (CABP 75-90%; ABSSSI 74-95%), and broadly similar between treatments, irrespective of renal function. Rates of TEAEs in patients with ABSSSI ranged from 33% to 52%, and were similar across renal function groups. In patients with CABP, higher rates were observed in patients with moderate renal impairment (56-61%) compared with patients with normal renal function or mild renal impairment (35-49%). The most common TEAEs were nausea and vomiting. CONCLUSIONS: Clinical success was similar across renal function groups, indicating no notable difference in the efficacy of omadacycline in patients with mild or moderate renal impairment. Omadacycline and comparators displayed similar safety profiles. CLINICALTRIALS. GOV REGISTRY: OPTIC (NCT02531438); OASIS-1 (NCT02378480); OASIS-2 (NCT02877927).
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Antibacterianos/uso terapéutico , Neumonía Bacteriana/tratamiento farmacológico , Insuficiencia Renal/complicaciones , Enfermedades Cutáneas Bacterianas/tratamiento farmacológico , Tetraciclinas/uso terapéutico , Adulto , Anciano , Antibacterianos/efectos adversos , Infecciones Comunitarias Adquiridas/complicaciones , Infecciones Comunitarias Adquiridas/tratamiento farmacológico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neumonía Bacteriana/complicaciones , Enfermedades Cutáneas Bacterianas/complicaciones , Tetraciclinas/efectos adversosRESUMEN
BACKGROUND: Pathogen resistance and safety concerns limit oral antibiotic options for the treatment of acute bacterial skin and skin structure infections (ABSSSI). We aimed to compare the efficacy and safety of once-daily oral omadacycline, an aminomethylcycline antibiotic, versus twice-daily oral linezolid for treatment of ABSSSI. METHODS: In this phase 3, double-blind, randomised, non-inferiority study, eligible adults with ABSSSI at 33 sites in the USA were randomly assigned (1:1) to receive omadacycline (450 mg orally every 24 h over the first 48 h then 300 mg orally every 24 h) or linezolid (600 mg orally every 12 h) for 7-14 days. Randomisation was done via an interactive response system using a computer-generated schedule, and stratified by type of infection (wound infection, cellulitis or erysipelas, or major abscess) and receipt (yes or no) of allowed previous antibacterial treatment. Investigators, funders, and patients were masked to treatment assignments. Primary endpoints were early clinical response, 48-72 h after first dose, in the modified intention-to-treat (mITT) population (randomised patients without solely Gram-negative ABSSSI pathogens at baseline), and investigator-assessed clinical response at post-treatment evaluation, 7-14 days after the last dose, in the mITT population and clinically evaluable population (ie, mITT patients who had a qualifying infection as per study-entry criteria, received study drug, did not receive a confounding antibiotic, and had an assessment of outcome during the protocol-defined window). The safety population included randomised patients who received any amount of study drug. We set a non-inferiority margin of 10%. This study is registered with ClinicalTrials.gov, NCT02877927, and is complete. FINDINGS: Between Aug 11, 2016, and June 6, 2017, 861 participants were assessed for eligibility. 735 participants were randomly assigned, of whom 368 received omadacycline and 367 received linezolid. Omadacycline (315 [88%] of 360) was non-inferior to linezolid (297 [83%] of 360) for early clinical response (percentage-point difference 5·0, 95% CI -0·2 to 10·3) in the mITT population. For investigator-assessed clinical response at post-treatment evaluation, omadacycline was non-inferior to linezolid in the mITT (303 [84%] of 360 vs 291 [81%] of 360; percentage-point difference 3·3, 95% CI -2·2 to 9·0) and clinically evaluable (278 [98%] of 284 vs 279 [96%] of 292; 2·3, -0·5 to 5·8) populations. Mild to moderate nausea and vomiting were the most frequent treatment-emergent adverse events in omadacycline (111 [30%] of 368 and 62 [17%] of 368, respectively) and linezolid (28 [8%] of 367 and 11 [3%] of 367, respectively) groups. INTERPRETATION: Once-daily oral omadacycline was non-inferior to twice-daily oral linezolid in adults with ABSSSI, and was safe and well tolerated. Oral-only omadacycline represents a new treatment option for ABSSSI, with potential for reduction in hospital admissions and cost savings. FUNDING: Paratek Pharmaceuticals.
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Antibacterianos/administración & dosificación , Antibacterianos/uso terapéutico , Linezolid/administración & dosificación , Linezolid/uso terapéutico , Enfermedades Cutáneas Bacterianas/tratamiento farmacológico , Tetraciclinas/administración & dosificación , Tetraciclinas/uso terapéutico , Administración Oral , Adulto , Antibacterianos/efectos adversos , Método Doble Ciego , Femenino , Humanos , Tiempo de Internación , Linezolid/efectos adversos , Masculino , Persona de Mediana Edad , Náusea/etiología , Tetraciclinas/efectos adversos , Resultado del Tratamiento , Vómitos/etiologíaRESUMEN
Omadacycline, an aminomethylcycline antibiotic, is approved as once-daily intravenous (i.v.) and oral (p.o.) monotherapy for acute bacterial skin and skin structure infections and for community-acquired bacterial pneumonia, and it is under development for treatment of urinary tract infection (UTI). This is a phase 1b, randomized, open-label study of omadacycline in women with cystitis (defined as UTI symptoms and a positive urine leukocyte esterase test). Patients received omadacycline for 5 days (group 1: 200 mg intravenously on day 1, then 300 mg orally every 24 h [q24h]; group 2: 300 mg orally every 12 h [q12h] on day 1, then 300 mg orally q24h; group 3: 450 mg orally q12h on day 1, then 450 mg orally q24h). Blood and urine samples were collected over 5 days. Investigator-assessed clinical response was determined at end of treatment (EOT; day 6) and posttreatment evaluation (PTE; 5 to 9 days after last dosing). A total of 31 women were treated. At steady state (day 5), the range of mean omadacycline urine concentrations over 24 h across the groups was 17.94 to 48.12 µg/ml. The most common treatment-emergent adverse events were gastrointestinal (including nausea [60% to 73%] and vomiting [20% to 40%]) and were generally mild and transient. Investigator-determined clinical success was observed in 94% and 84% of patients at EOT and PTE, respectively, with similar results across groups. A favorable microbiological response at PTE was observed in 78% of patients who had a baseline pathogen. Omadacycline is partially excreted in urine and appears to be safe and well tolerated. These preliminary results indicate that omadacycline warrants further evaluation in larger controlled UTI studies.
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Cistitis/tratamiento farmacológico , Cistitis/orina , Tetraciclinas/uso terapéutico , Tetraciclinas/orina , Adulto , Anciano , Femenino , Humanos , Persona de Mediana Edad , Tetraciclinas/efectos adversos , Infecciones Urinarias/tratamiento farmacológico , Infecciones Urinarias/orina , Adulto JovenRESUMEN
BACKGROUND: Acute bacterial skin and skin-structure infections are associated with substantial morbidity and health care costs. Omadacycline, an aminomethylcycline antibiotic that can be administered once daily either orally or intravenously, is active against pathogens that commonly cause such infections, including antibiotic-resistant strains. METHODS: In this double-blind trial, we randomly assigned adults with acute bacterial skin and skin-structure infections (in a 1:1 ratio) to receive omadacycline (100 mg given intravenously every 12 hours for two doses, then 100 mg given intravenously every 24 hours) or linezolid (600 mg given intravenously every 12 hours). A transition to oral omadacycline (300 mg every 24 hours) or oral linezolid (600 mg every 12 hours) was allowed after 3 days; the total treatment duration was 7 to 14 days. The primary end point was an early clinical response at 48 to 72 hours, defined as survival with a reduction in lesion size of at least 20% without rescue antibacterial therapy. A secondary end point was an investigator-assessed clinical response at the post-treatment evaluation 7 to 14 days after the last dose, with clinical response defined as survival with resolution or improvement in signs or symptoms of infection to the extent that further antibacterial therapy was unnecessary. For both end points, the noninferiority margin was 10 percentage points. RESULTS: In the modified intention-to-treat population, omadacycline (316 patients) was noninferior to linezolid (311 patients) with respect to early clinical response (rate of response, 84.8% and 85.5%, respectively; difference, -0.7 percentage points; 95% confidence interval [CI], -6.3 to 4.9). Omadacycline also was noninferior to linezolid with respect to investigator-assessed clinical response at the post-treatment evaluation in the modified intention-to-treat population (rate of response, 86.1% and 83.6%, respectively; difference, 2.5 percentage points; 95% CI, -3.2 to 8.2) and in the clinical per-protocol population (96.3% and 93.5%, respectively; difference, 2.8 percentage points; 95% CI, -1.0 to 6.9). In both groups, the efficacy of the trial drug was similar for methicillin-susceptible and methicillin-resistant Staphylococcus aureus infections. Adverse events were reported in 48.3% of the patients in the omadacycline group and in 45.7% of those in the linezolid group; the most frequent adverse events in both groups were gastrointestinal (in 18.0% and 15.8% of the patients in the respective groups). CONCLUSIONS: Omadacycline was noninferior to linezolid for the treatment of acute bacterial skin and skin-structure infections and had a similar safety profile. (Funded by Paratek Pharmaceuticals; OASIS-1 ClinicalTrials.gov number, NCT02378480 .).
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Antibacterianos/uso terapéutico , Linezolid/uso terapéutico , Enfermedades Cutáneas Bacterianas/tratamiento farmacológico , Tetraciclinas/uso terapéutico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Antibacterianos/efectos adversos , Método Doble Ciego , Esquema de Medicación , Farmacorresistencia Bacteriana , Femenino , Humanos , Infusiones Intravenosas , Análisis de Intención de Tratar , Linezolid/efectos adversos , Masculino , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Persona de Mediana Edad , Enfermedades Cutáneas Bacterianas/microbiología , Tetraciclinas/efectos adversos , Adulto JovenRESUMEN
BACKGROUND: Omadacycline, a new once-daily aminomethylcycline antibiotic agent that can be administered intravenously or orally, reaches high concentrations in pulmonary tissues and is active against common pathogens that cause community-acquired bacterial pneumonia. METHODS: In a double-blind trial, we randomly assigned (in a 1:1 ratio) adults with community-acquired bacterial pneumonia (Pneumonia Severity Index risk class II, III, or IV) to receive omadacycline (100 mg intravenously every 12 hours for two doses, then 100 mg intravenously every 24 hours), or moxifloxacin (400 mg intravenously every 24 hours). A transition to oral omadacycline (300 mg every 24 hours) or moxifloxacin (400 mg every 24 hours), respectively, was allowed after 3 days; the total treatment duration was 7 to 14 days. The primary end point was early clinical response, defined as survival with improvement in at least two of four symptoms (cough, sputum production, pleuritic chest pain, and dyspnea) and no worsening of symptoms at 72 to 120 hours, without receipt of rescue antibacterial therapy. A secondary end point was investigator-assessed clinical response at a post-treatment evaluation 5 to 10 days after the last dose, with clinical response defined as resolution or improvement in signs or symptoms to the extent that further antibacterial therapy was unnecessary. A noninferiority margin of 10 percentage points was used. RESULTS: The intention-to-treat population included 386 patients in the omadacycline group and 388 patients in the moxifloxacin group. Omadacycline was noninferior to moxifloxacin for early clinical response (81.1% and 82.7%, respectively; difference, -1.6 percentage points; 95% confidence interval [CI], -7.1 to 3.8), and the rates of investigator-assessed clinical response at the post-treatment evaluation were 87.6% and 85.1%, respectively (difference, 2.5 percentage points; 95% CI, -2.4 to 7.4). Adverse events that emerged after treatment initiation were reported in 41.1% of the patients in the omadacycline group and 48.5% of the patients in the moxifloxacin group; the most frequent events were gastrointestinal (10.2% and 18.0%, respectively), and the largest difference was for diarrhea (1.0% and 8.0%). Twelve deaths (8 in the omadacycline group and 4 in the moxifloxacin group) occurred during the trial. CONCLUSIONS: Omadacycline was noninferior to moxifloxacin for the treatment of community-acquired bacterial pneumonia in adults. (Funded by Paratek Pharmaceuticals; OPTIC ClinicalTrials.gov number, NCT02531438 .).
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Antibacterianos/uso terapéutico , Moxifloxacino/uso terapéutico , Neumonía Bacteriana/tratamiento farmacológico , Tetraciclinas/uso terapéutico , Adulto , Anciano , Anciano de 80 o más Años , Antibacterianos/efectos adversos , Bacterias/aislamiento & purificación , Infecciones Comunitarias Adquiridas/tratamiento farmacológico , Método Doble Ciego , Esquema de Medicación , Femenino , Hospitalización , Humanos , Infusiones Intravenosas , Análisis de Intención de Tratar , Masculino , Persona de Mediana Edad , Moxifloxacino/efectos adversos , Neumonía Bacteriana/microbiología , Tetraciclinas/efectos adversosRESUMEN
Omadacycline, a first-in-class aminomethylcycline antibiotic, is related to tetracyclines but is structurally modified to circumvent mechanisms of resistance to tetracyclines. Omadacycline demonstrates potent activity against a broad range of pathogens, including drug-resistant strains, and is in late-stage development for treatment of acute bacterial skin and skin structure infections and community-acquired bacterial pneumonia. Previous studies support an intravenous-to-oral transition regimen with 300-mg once-daily oral dosing. This phase 1 study investigated the pharmacokinetics and safety/tolerability of multiple oral omadacycline doses higher than 300 mg. Using a 3-period crossover design, healthy adults were randomized to receive oral omadacycline at 300, 450, and 600 mg in variable sequence (n = 26) or placebo (n = 7) once daily for 5 consecutive days per period. In plasma, omadacycline maximum concentration and total exposure increased with increasing dose but were less than dose proportional. The kinetics of omadacycline plasma accumulation were similar between dose levels; exposure on day 5 was â¼50% higher than that on day 1. Omadacycline plasma concentrations on day 1 of 450-mg dosing were similar to those on day 5 of 300-mg dosing. All doses were generally well tolerated, but the 600-mg dose was associated with more gastrointestinal adverse events.
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Antibacterianos/farmacocinética , Tetraciclinas/farmacocinética , Administración Oral , Adolescente , Adulto , Antibacterianos/sangre , Área Bajo la Curva , Método Doble Ciego , Esquema de Medicación , Cálculo de Dosificación de Drogas , Femenino , Voluntarios Sanos , Humanos , Masculino , Persona de Mediana Edad , Seguridad del Paciente , Tetraciclinas/sangreRESUMEN
Many antibiotics require dose adjustments in patients with renal impairment and/or in those undergoing hemodialysis. Omadacycline, the first aminomethylcycline antibiotic in late-stage clinical development, displays activity against a broad spectrum of bacterial pathogens, including drug-resistant strains. Data from completed phase 3 studies of omadacycline for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP) showed intravenous (i.v.) to once-daily oral omadacycline to be clinically effective and well tolerated. To determine if the dosing of omadacycline should be adjusted in patients with impaired renal function, a phase 1 study examining the pharmacokinetics (PK) and safety of i.v. omadacycline (100 mg) was conducted in subjects with end-stage renal disease (ESRD) on stable hemodialysis (n = 8) and in matched healthy subjects (n = 8). i.v. administration of omadacycline produced similar plasma concentration-time profiles in subjects with ESRD and healthy subjects. Further, in subjects with ESRD, similar values of the PK parameters were observed when omadacycline was administered i.v. after or before dialysis. The mean area under the concentration-time curve from time zero extrapolated to infinity in plasma was 10.30 µg · h/ml when omadacycline was administered to ESRD subjects after dialysis, 10.20 µg · h/ml when omadacycline was administered to ESRD subjects before dialysis, and 9.76 µg · h/ml when omadacycline was administered to healthy subjects. The mean maximum observed concentration of omadacycline in plasma in ESRD subjects was 1.88 µg/ml when it was administered after dialysis and 2.33 µg/ml when it was administered before dialysis, and in healthy subjects it was 1.92 µg/ml. The 100-mg i.v. dose of omadacycline was generally safe and well tolerated in both ESRD and healthy subjects. This study demonstrates that no dose adjustment is necessary for omadacycline in patients with impaired renal function or on days when patients are receiving hemodialysis.
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Antibacterianos/farmacocinética , Insuficiencia Renal/metabolismo , Tetraciclinas/efectos adversos , Tetraciclinas/farmacocinética , Administración Intravenosa/métodos , Adulto , Anciano , Antibacterianos/efectos adversos , Área Bajo la Curva , Bacterias/efectos de los fármacos , Estudios de Casos y Controles , Femenino , Humanos , Fallo Renal Crónico/metabolismo , Masculino , Pruebas de Sensibilidad Microbiana/métodos , Persona de Mediana Edad , Diálisis Renal/métodos , Tetraciclinas/administración & dosificaciónRESUMEN
The steady-state concentrations of omadacycline and tigecycline in the plasma, epithelial lining fluid (ELF), and alveolar cells (AC) of 58 healthy adult subjects were obtained. Subjects were administered either omadacycline at 100 mg intravenously (i.v.) every 12 h for two doses followed by 100 mg i.v. every 24 h for three doses or tigecycline at an initial dose of 100 mg i.v. followed by 50 mg i.v. every 12 h for six doses. A bronchoscopy and bronchoalveolar lavage were performed once in each subject following the start of the fifth dose of omadacycline at 0.5, 1, 2, 4, 8, 12, or 24 h and after the start of the seventh dose of tigecycline at 2, 4, 6, or 12 h. The value of the area under the concentration-time curve (AUC) from time zero to 24 h postdosing (AUC0-24) (based on mean concentrations) in ELF and the ratio of the ELF to total plasma omadacycline concentration based on AUC0-24 values were 17.23 mg · h/liter and 1.47, respectively. The AUC0-24 value in AC was 302.46 mg · h/liter, and the ratio of the AC to total plasma omadacycline concentration was 25.8. In comparison, the values of the AUC from time zero to 12 h postdosing (AUC0-12) based on the mean concentrations of tigecycline in ELF and AC were 3.16 and 38.50 mg · h/liter, respectively. The ratio of the ELF and AC to total plasma concentrations of tigecycline based on AUC0-12 values were 1.71 and 20.8, respectively. The pharmacokinetic advantages of higher and sustained concentrations of omadacycline compared to those of tigecycline in plasma, ELF, and AC suggest that omadacycline is a promising antibacterial agent for the treatment of lower respiratory tract bacterial infections caused by susceptible pathogens.
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Células Epiteliales Alveolares/química , Antibacterianos/farmacocinética , Líquido del Lavado Bronquioalveolar/química , Minociclina/análogos & derivados , Tetraciclinas/farmacocinética , Adulto , Antibacterianos/sangre , Área Bajo la Curva , Lavado Broncoalveolar , Broncoscopía , Femenino , Voluntarios Sanos , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Minociclina/efectos adversos , Minociclina/sangre , Minociclina/farmacocinética , Alveolos Pulmonares/citología , Tetraciclinas/efectos adversos , Tetraciclinas/sangre , TigeciclinaRESUMEN
With increasing resistance to existing antimalarials, there is an urgent need to discover new drugs at affordable prices for countries in which malaria is endemic. One approach to the development of new antimalarial drugs is to improve upon existing antimalarial agents, such as the tetracyclines. Tetracyclines exhibit potent, albeit relatively slow, action against malaria parasites, and doxycycline is used for both treatment (with other agents) and prevention of malaria. We synthesized 18 novel 7-position modified tetracycline derivatives and screened them for activity against cultured malaria parasites. Compounds with potent in vitro activity and other favorable drug properties were further tested in a rodent malaria model. Ten compounds inhibited the development of cultured Plasmodium falciparum with a 50% inhibitory concentration (IC50) after 96 h of incubation of <30 nM, demonstrating activity markedly superior to that of doxycycline (IC50 at 96 h of 320 nM). Most compounds showed little mammalian cell cytotoxicity and no evidence of in vitro phototoxicity. In a murine Plasmodium berghei model, 13 compounds demonstrated improved activity relative to that of doxycycline. In summary, 7-position modified tetracyclines offer improved activity against malaria parasites compared to doxycycline. Optimized compounds may allow lower doses for treatment and chemoprophylaxis. If safety margins are adequate, dosing in children, the group at greatest risk for malaria in countries in which it is endemic, may be feasible.
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Antimaláricos/farmacología , Malaria/tratamiento farmacológico , Malaria/prevención & control , Plasmodium berghei/efectos de los fármacos , Tetraciclinas/farmacología , Animales , Resistencia a Medicamentos , Ratones , Pruebas de Sensibilidad ParasitariaRESUMEN
LcrF (VirF), a transcription factor in the multiple adaptational response (MAR) family, regulates expression of the Yersinia type III secretion system (T3SS). Yersinia pseudotuberculosis lcrF-null mutants showed attenuated virulence in tissue culture and animal models of infection. Targeting of LcrF offers a novel, antivirulence strategy for preventing Yersinia infection. A small molecule library was screened for inhibition of LcrF-DNA binding in an in vitro assay. All of the compounds lacked intrinsic antibacterial activity and did not demonstrate toxicity against mammalian cells. A subset of these compounds inhibited T3SS-dependent cytotoxicity of Y. pseudotuberculosis toward macrophages in vitro. In a murine model of Y. pseudotuberculosis pneumonia, two compounds significantly reduced the bacterial burden in the lungs and afforded a dramatic survival advantage. The MAR family of transcription factors is well conserved, with members playing central roles in pathogenesis across bacterial genera; thus, the inhibitors could have broad applicability.
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Proteínas Bacterianas/antagonistas & inhibidores , Bencimidazoles/farmacología , Neumonía Bacteriana/patología , Factores de Transcripción/antagonistas & inhibidores , Infecciones por Yersinia pseudotuberculosis/patología , Yersinia pseudotuberculosis/efectos de los fármacos , Yersinia pseudotuberculosis/patogenicidad , Animales , Antibacterianos/administración & dosificación , Antibacterianos/síntesis química , Antibacterianos/química , Antibacterianos/farmacología , Proteínas Bacterianas/metabolismo , Bencimidazoles/administración & dosificación , Bencimidazoles/síntesis química , Bencimidazoles/química , Línea Celular , Modelos Animales de Enfermedad , Femenino , Humanos , Pulmón/microbiología , Macrófagos/microbiología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Neumonía Bacteriana/tratamiento farmacológico , Neumonía Bacteriana/microbiología , Neumonía Bacteriana/mortalidad , Factores de Transcripción/metabolismo , Resultado del Tratamiento , Virulencia , Yersinia pseudotuberculosis/metabolismo , Infecciones por Yersinia pseudotuberculosis/tratamiento farmacológico , Infecciones por Yersinia pseudotuberculosis/microbiología , Infecciones por Yersinia pseudotuberculosis/mortalidadRESUMEN
ExsA is a multiple adaptational response (MAR) transcription factor, regulating the expression of a virulence determinant, the type III secretion system (T3SS) in Pseudomonas aeruginosa. Non-cytotoxic, non-antibacterial N-hydroxybenzimidazoles were identified as effective inhibitors of ExsA-DNA binding, and their potential utility as anti-virulence agents for P. aeruginosa was demonstrated in a whole cell assay. Select N-hydroxybenzimidazole inhibitors were stable in an in vitro human liver microsomal assay.
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Bencimidazoles/antagonistas & inhibidores , Pseudomonas aeruginosa/efectos de los fármacos , Factores de Transcripción/antagonistas & inhibidores , Virulencia/efectos de los fármacos , Humanos , Microsomas Hepáticos/efectos de los fármacos , Pseudomonas aeruginosa/metabolismo , Pseudomonas aeruginosa/patogenicidadRESUMEN
LcrF, a multiple adaptational response (MAR) transcription factor, regulates virulence in Yersinia pestis and Yersinia pseudotuberculosis. In a search for small molecule inhibitors of LcrF, an acrylic amide series of N-hydroxybenzimidazoles was synthesized and the SAR (structure-activity relationship) was examined. Selected test compounds demonstrated inhibitory activity in a primary cell-free LcrF-DNA binding assay as well as in a secondary whole cell assay (type III secretion system dependent Y. pseudotuberculosis cytotoxicity assay). The inhibitors exhibited no measurable antibacterial activity in vitro, confirming that they do not target bacterial growth. These results demonstrate that N-hydroxybenzimidazole inhibitors, exemplified by 14, 22, and 36, are effective antivirulence agents and have the potential to prevent infections caused by Yersinia spp.
Asunto(s)
Antibacterianos/química , Antibacterianos/farmacología , Proteínas Bacterianas/antagonistas & inhibidores , Bencimidazoles/química , Bencimidazoles/farmacología , Transactivadores/antagonistas & inhibidores , Yersinia pestis/efectos de los fármacos , Yersinia pseudotuberculosis/efectos de los fármacos , Animales , Antibacterianos/síntesis química , Antibacterianos/uso terapéutico , Proteínas Bacterianas/metabolismo , Bencimidazoles/síntesis química , Bencimidazoles/uso terapéutico , Línea Celular , Sistema Libre de Células/metabolismo , ADN/metabolismo , Descubrimiento de Drogas , Concentración 50 Inhibidora , Ratones , Peste/tratamiento farmacológico , Relación Estructura-Actividad , Transactivadores/metabolismo , Virulencia/efectos de los fármacos , Yersinia pestis/patogenicidad , Yersinia pseudotuberculosis/patogenicidadRESUMEN
Pseudomonas aeruginosa, an important cause of opportunistic infections in humans, delivers bacterial cytotoxins by type III secretion directly into the host cell cytoplasm, resulting in disruption of host cell signaling and host innate immunity. However, little is known about the fate of the toxins themselves following injection into the host cytosol. Here, we show by both in vitro and in vivo studies that the host ubiquitin ligase Cbl-b interacts with the type III-secreted effector exotoxin T (ExoT) and plays a key role in vivo in limiting bacterial dissemination mediated by ExoT. We demonstrate that, following polyubiquitination, ExoT undergoes regulated proteasomal degradation in the host cell cytosol. ExoT interacts with the E3 ubiquitin ligase Cbl-b and Crk, the substrate for the ExoT ADP ribosyltransferase (ADPRT) domain. The efficiency of degradation is dependent upon the activity of the ADPRT domain. In mouse models of acute pneumonia and systemic infection, Cbl-b is specifically required to limit the dissemination of ExoT-producing bacteria whereas c-Cbl plays no detectable role. To the best of our knowledge, this represents the first identification of a mammalian gene product that is specifically required for in vivo resistance to disease mediated by a type III-secreted effector.
Asunto(s)
ADP Ribosa Transferasas/toxicidad , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Toxinas Bacterianas/toxicidad , Exotoxinas/toxicidad , Proteínas Activadoras de GTPasa/toxicidad , Proteínas Proto-Oncogénicas c-cbl/metabolismo , Pseudomonas aeruginosa/patogenicidad , ADP Ribosa Transferasas/química , ADP Ribosa Transferasas/metabolismo , Proteínas Adaptadoras Transductoras de Señales/deficiencia , Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas Adaptadoras Transductoras de Señales/inmunología , Animales , Toxinas Bacterianas/química , Toxinas Bacterianas/metabolismo , Exotoxinas/química , Exotoxinas/metabolismo , Proteínas Activadoras de GTPasa/química , Proteínas Activadoras de GTPasa/metabolismo , Células HeLa , Humanos , Inmunidad Innata , Técnicas In Vitro , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Infecciones Oportunistas/inmunología , Infecciones Oportunistas/metabolismo , Infecciones Oportunistas/microbiología , Complejo de la Endopetidasa Proteasomal/metabolismo , Estructura Terciaria de Proteína , Proteínas Proto-Oncogénicas c-cbl/deficiencia , Proteínas Proto-Oncogénicas c-cbl/genética , Proteínas Proto-Oncogénicas c-cbl/inmunología , Proteínas Proto-Oncogénicas c-crk/metabolismo , Infecciones por Pseudomonas/inmunología , Infecciones por Pseudomonas/metabolismo , Infecciones por Pseudomonas/microbiología , Ubiquitina/metabolismo , VirulenciaRESUMEN
MarA, SoxS and Rob are transcription factors belonging to the AraC family. While these proteins have been associated historically with control of multiple antibiotic resistance, and tolerance to oxidative stress agents and organic solvents, only a paucity of experimental data support a role in regulating virulence. Clinical Escherichia coli isolates, and isogenic strains lacking marA, soxS and rob, were studied in a murine model of ascending pyelonephritis, which is a clinically relevant model of urinary tract infection. Organisms lacking all three transcription factors (triple knockouts) were significantly less virulent than parental strains, and complementation studies demonstrated that the addition of marA, soxS and rob individually restored wild-type virulence in the triple-knockout strain. Deletion of soxS or rob alone was more detrimental than the removal of marA. Thus, all three proteins contribute to virulence in vivo.