RESUMEN
The therapeutic activity of ceftobiprole medocaril, the prodrug of ceftobiprole, was compared to that of vancomycin, daptomycin, and the combination of a subtherapeutic dose of ceftobiprole and vancomycin in a rat model of infective endocarditis due to methicillin-resistant Staphylococcus aureus (MRSA) (ATCC 43300) or glycopeptide-intermediate Staphylococcus aureus (GISA) (NRS4 and HIP 5836) strains. The minimum bactericidal concentrations of ceftobiprole, vancomycin, and daptomycin at bacterial cell densities similar to those encountered in the cardiac vegetation in the rat endocarditis model were 2, >64, and 8 µg/ml, respectively, for MRSA ATCC 43300 and 4, >64, and 8 µg/ml, respectively, for the GISA strain. Ceftobiprole medocaril administered in doses of 100 mg/kg of body weight given intravenously (i.v.) twice a day (BID) every 8 h (q8h) (equivalent to a human therapeutic dose of ceftobiprole [500 mg given three times a day [TID]) was the most effective monotherapy, eradicating nearly 5 log(10) CFU/g MRSA or 6 log(10) CFU/g GISA organisms from the cardiac vegetation and had the highest incidence of sterile vegetation compared to the other monotherapies in the endocarditis model. In in vitro time-kill studies, synergistic effects were observed with ceftobiprole and vancomycin on MRSA and GISA strains, and in vivo synergy was noted with combinations of subtherapeutic doses of these agents for the same strains. Additionally, sterile vegetations were achieved in 33 and 60%, respectively, of the animals infected with MRSA ATCC 43300 or GISA NRS4 receiving ceftobiprole-vancomycin combination therapy. In summary, ceftobiprole was efficacious both as monotherapy and in combination with vancomycin in treating MRSA and GISA infections in a rat infective endocarditis model and warrants further evaluation.
Asunto(s)
Antibacterianos/farmacología , Cefalosporinas/farmacología , Daptomicina/farmacología , Endocarditis Bacteriana/tratamiento farmacológico , Infecciones Estafilocócicas/tratamiento farmacológico , Staphylococcus aureus/efectos de los fármacos , Vancomicina/farmacología , Animales , Antibacterianos/sangre , Cefalosporinas/sangre , Daptomicina/sangre , Cálculo de Dosificación de Drogas , Sinergismo Farmacológico , Endocarditis Bacteriana/microbiología , Femenino , Humanos , Inyecciones Intravenosas , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/crecimiento & desarrollo , Pruebas de Sensibilidad Microbiana , Ratas , Ratas Sprague-Dawley , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/crecimiento & desarrollo , Vancomicina/sangreRESUMEN
The new broad-spectrum fluoroquinolone JNJ-Q2 displays in vitro activity against Gram-negative and Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA) and ciprofloxacin-resistant MRSA isolates. Tested with isogenic methicillin-susceptible S. aureus (MSSA) and MRSA strains bearing quinolone-resistant target mutations, JNJ-Q2 displayed MICs ≤ 0.12 µg/ml, values 16- to 32-fold lower than those determined for moxifloxacin. Overexpression of the NorA efflux pump did not impact JNJ-Q2 MICs. Inhibition of S. aureus DNA gyrase and DNA topoisomerase IV enzymes demonstrated that JNJ-Q2 was more potent than comparators against wild-type enzymes and enzymes carrying quinolone-resistant amino acid substitutions, and JNJ-Q2 displayed equipotent activity against both enzymes. In serial-passage studies comparing resistance selection in parallel MRSA cultures by ciprofloxacin and JNJ-Q2, ciprofloxacin readily selected for mutants displaying MIC values of 128 to 512 µg/ml, which were observed within 18 to 24 days of passage. In contrast, cultures passaged in the presence of JNJ-Q2 displayed MICs ≤ 1 µg/ml for a minimum of 27 days of serial passage. A mutant displaying a JNJ-Q2 MIC of 4 µg/ml was not observed until after 33 days of passage. Mutant characterization revealed that ciprofloxacin-passaged cultures with MICs of 256 to 512 µg/ml carried only 2 or 3 quinolone resistance-determining region (QRDR) mutations. Cultures passaged with JNJ-Q2 selection for up to 51 days displayed MICs of 1 to 64 µg/ml and carried between 4 and 9 target mutations. Established in vitro biofilms of wild-type or ciprofloxacin-resistant MRSA exposed to JNJ-Q2 displayed greater decreases in bacterial counts (7 days of exposure produced 4.5 to >7 log(10) CFU decreases) than biofilms exposed to ciprofloxacin, moxifloxacin, rifampin, or vancomycin.
Asunto(s)
Antibacterianos/farmacología , Fluoroquinolonas/farmacología , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Antibacterianos/química , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Ciprofloxacina/farmacología , Girasa de ADN/genética , Topoisomerasa de ADN IV/genética , Farmacorresistencia Bacteriana/genética , Fluoroquinolonas/química , Humanos , Meticilina/farmacología , Staphylococcus aureus Resistente a Meticilina/crecimiento & desarrollo , Pruebas de Sensibilidad Microbiana/estadística & datos numéricos , Mutación , Pase Seriado , Staphylococcus aureus/crecimiento & desarrolloRESUMEN
BACKGROUND: Antibiotic resistance is problematic in Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii, and is often associated with serious infections. Carbapenems are often one of the few remaining therapeutic options, so it is important to monitor carbapenem activity against these pathogens and to identify resistance mechanisms. METHODS: Carbapenem susceptibilities were determined for 14â359 Enterobacteriaceae, 3614 P. aeruginosa and 994 A. baumannii from the USA (2007-09). Klebsiella pneumoniae with doripenem MICs ≥2 mg/L (nâ=â88), and P. aeruginosa (nâ=â452), A. baumannii (nâ=â349) and other enterics (nâ=â13) with doripenem MICs ≥4 mg/L were screened for carbapenem resistance mechanisms. RESULTS: Doripenem/meropenem and imipenem susceptibilities for Enterobacteriaceae were >99% and 89%, respectively. Doripenem susceptibility (2007-09) for P. aeruginosa was 87.4%-84.1%; comparable to meropenem and higher than imipenem. For A. baumannii, doripenem susceptibility (2007-09) was 63%-58.2%; lower than imipenem and meropenem. Resistant K. pneumoniae had KPC and lacked porins OmpK35/OmpK36. In 2009, 3.4% of all K. pneumoniae possessed KPC. Five other enterics and one P. aeruginosa possessed KPC. Resistance mechanisms in P. aeruginosa were loss of porin OprD (90%), efflux (55%) and elevated AmpC activity (25%). Acquired carbapenemases OXA-23/-24 were present in 48% of resistant A. baumannii. VIM metallo-ß-lactamases were present in three P. aeruginosa and one A. baumannii isolates. CONCLUSIONS: Doripenem and meropenem were more active than imipenem against Enterobacteriaceae and P. aeruginosa from the USA. Carbapenem resistance mechanisms included serine carbapenemases, elevated AmpC activity, efflux and porin deficiencies occurring mostly in P. aeruginosa. Metallo-ß-lactamases were found in <0.1% of isolates.
Asunto(s)
Antibacterianos/farmacología , Carbapenémicos/farmacología , Enterobacteriaceae/efectos de los fármacos , Enterobacteriaceae/genética , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/genética , Acinetobacter baumannii/aislamiento & purificación , Proteínas Bacterianas/genética , Doripenem , Farmacorresistencia Bacteriana Múltiple , Enterobacteriaceae/aislamiento & purificación , Genotipo , Imipenem/farmacología , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/aislamiento & purificación , Estudios Longitudinales , Meropenem , Pruebas de Sensibilidad Microbiana , Porinas/deficiencia , Porinas/genética , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/aislamiento & purificación , Tienamicinas/farmacología , Estados Unidos , beta-Lactamasas/genéticaRESUMEN
Induction of mecA by ceftobiprole and oxacillin in 18 methicillin-resistant Staphylococcus aureus clinical isolates with various SCCmec cassettes was examined using reverse transcriptase PCR. The magnitude of mecA induction, 3- to 65-fold for ceftobiprole and 2- to 69-fold for oxacillin, did not correlate with ceftobiprole MICs (
Asunto(s)
Antibacterianos/farmacología , Proteínas Bacterianas/genética , Cefalosporinas/farmacología , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/genética , Oxacilina/farmacología , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Regulación Bacteriana de la Expresión Génica/genética , Proteínas de Unión a las Penicilinas , Reacción en Cadena de la PolimerasaRESUMEN
Single-step Pseudomonas aeruginosa mutants, selected with ceftobiprole, ceftazidime, or cefepime, were generated at frequencies of 10(-6) to <10(-9) at two and four times the MIC. The chromosomal AmpC ß-lactamase activity was increased in all ceftazidime-selected mutants. Mutants selected with cefepime either increased AmpC activity or upregulated expression of the mexXY efflux genes. Mutants selected with ceftobiprole did not overexpress AmpC; 90% of these produced elevated levels of mexXY RNA, indicating that increased efflux, not AmpC derepression, is the predominant response to ceftobiprole during first-step mutations in P. aeruginosa.
Asunto(s)
Antibacterianos/farmacología , Proteínas Bacterianas/genética , Ceftazidima/farmacología , Cefalosporinas/farmacología , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/aislamiento & purificación , beta-Lactamasas/genética , Cefepima , Pruebas de Sensibilidad Microbiana , Mutación , Pseudomonas aeruginosa/enzimología , Pseudomonas aeruginosa/genéticaRESUMEN
The stability of doripenem to hydrolysis by beta-lactamases from molecular classes A to D was compared to the stability for imipenem and meropenem. Doripenem was stable to hydrolysis by extended-spectrum beta-lactamases and AmpC type beta-lactamases and demonstrated high affinity for the AmpC enzymes. For the serine carbapenemases SME-3 and KPC-2 and metallo-beta-lactamases IMP-1 and VIM-2, doripenem hydrolysis was generally 2- to 150-fold slower than imipenem hydrolysis. SPM-1 hydrolyzed meropenem and doripenem fourfold faster than imipenem.
Asunto(s)
Antibacterianos/farmacología , Carbapenémicos/farmacología , Inhibidores Enzimáticos/farmacología , Imipenem/farmacología , Tienamicinas/farmacología , Inhibidores de beta-Lactamasas , Bacterias/efectos de los fármacos , Bacterias/enzimología , Doripenem , Hidrólisis , Cinética , Meropenem , Pruebas de Sensibilidad MicrobianaRESUMEN
In phase 3 clinical trials for ceftobiprole treatment of complicated skin and skin structure infections, 1,219 gram-positive and 276 gram-negative aerobic baseline pathogens were identified. Ceftobiprole inhibited all staphylococcal isolates, including methicillin-resistant strains, at MICs of =4 mug/ml. Against Enterobacteriaceae and Pseudomonas aeruginosa isolates, the potency of ceftobiprole was similar to that of cefepime.
Asunto(s)
Antibacterianos/farmacología , Cefalosporinas/farmacología , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Grampositivas/efectos de los fármacos , Enfermedades Cutáneas Bacterianas/microbiología , Enterobacteriaceae/clasificación , Enterobacteriaceae/efectos de los fármacos , Infecciones por Bacterias Gramnegativas/microbiología , Infecciones por Bacterias Grampositivas/microbiología , Humanos , Pruebas de Sensibilidad Microbiana , Pseudomonas aeruginosa/efectos de los fármacos , Staphylococcus/clasificación , Staphylococcus/efectos de los fármacosRESUMEN
Infections caused by multidrug-resistant Gram-negative pathogens play a major role in the morbidity and mortality of hospitalized patients. The rise of resistance to current antibiotic therapies has made the discovery of new agents urgent. One of the major antibiotic resistance mechanisms utilized by more than 15 species of Gram-negative bacterial cells is the Resistance Nodulation Division (RND) efflux pump, which eliminates several classes of antibiotics such as penicillins and cephalosporin macrolides aminoglycosides, fluoroquinolonesx and tetracyclines. Here we describe a multistep process to identify compounds that inhibit the RND-type efflux pumps. This involves measuring the inhibition of accumulation of ethidium bromide in E. coli or Haemophilus influenzae cells and confirming that the inhibition is specific for the efflux pumps by using genetic constructs and biochemical methods to measure nonspecific inhibition due to e.g. intrinsic antibacterial activity or membrane disruption. In whole bacterial cells synergism antagonism or indifference of the combination of an antibiotic with the putative inhibitor is determined and this is then confirmed by quantitating viable bacterial cells in liquid culture over 24 h.
Asunto(s)
Antibacterianos/análisis , Transporte Biológico Activo/efectos de los fármacos , Inhibidores Enzimáticos/análisis , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/antagonistas & inhibidores , Antibacterianos/aislamiento & purificación , Antibacterianos/farmacología , Proteínas de la Membrana Bacteriana Externa/antagonistas & inhibidores , Proteínas Bacterianas/análisis , Proteínas Bacterianas/antagonistas & inhibidores , Farmacorresistencia Bacteriana/efectos de los fármacos , Inhibidores Enzimáticos/aislamiento & purificación , Inhibidores Enzimáticos/farmacología , Escherichia coli/efectos de los fármacos , Etidio/metabolismo , Haemophilus influenzae/efectos de los fármacos , Humanos , Pruebas de Sensibilidad MicrobianaRESUMEN
The ability of enterococci to acquire resistance to antibiotics and form biofilms in vivo makes these infections, endocarditis in particular, especially difficult to treat. A collection of clinical enterococcal isolates was screened for the presence of various virulence determinants and in an in vitro assay for biofilm formation. Isolates were chosen for the presence or absence of the genes for Esp and gelatinase and different in vitro biofilm phenotypes, and were evaluated in a rat model of endocarditis; all colonized vegetations to similar degrees. Treatment with vancomycin resulted in a 2.7-log reduction in colony-forming unit (CFU) in vegetations for an esp(+)/gel(-) strain, compared with no reduction in CFU for an esp(+)/gel(+) or an esp(-)/gel(-) isolate. These results suggest that although there may not be an absolute role for individual virulence determinants in infectivity, combinations of factors may play a role in allowing a biofilm infection to be more resistant to therapy.
Asunto(s)
Proteínas Bacterianas/genética , Biopelículas/efectos de los fármacos , Endocarditis Bacteriana/tratamiento farmacológico , Enterococcus faecalis/patogenicidad , Resistencia a la Vancomicina , Animales , Válvula Aórtica/microbiología , Biopelículas/crecimiento & desarrollo , Recuento de Colonia Microbiana , Endocarditis Bacteriana/microbiología , Enterococcus faecalis/efectos de los fármacos , Enterococcus faecalis/genética , Enterococcus faecalis/crecimiento & desarrollo , Gelatinasas/genética , Infecciones por Bacterias Grampositivas/tratamiento farmacológico , Infecciones por Bacterias Grampositivas/microbiología , Humanos , Masculino , Proteínas de la Membrana/genética , Ratas , Ratas Sprague-Dawley , Vancomicina/farmacología , Vancomicina/uso terapéutico , Resistencia a la Vancomicina/genética , Virulencia/genéticaRESUMEN
Klebsiella pneumoniae carbapenemases (KPCs) have previously been identified in distinct geographic locations. We report the spread of KPC-2 to upstate New York. Our intention is to alert clinicians to problems encountered in identifying KPC-containing isolates. Possible errors as a result of inferring susceptibility of untested carbapenems from the routine antibiogram using agar-based methodology or microdilution testing are discussed.
Asunto(s)
Bacteriemia/microbiología , Proteínas Bacterianas/metabolismo , Farmacorresistencia Bacteriana Múltiple/fisiología , Klebsiella pneumoniae/metabolismo , Neumonía Bacteriana/microbiología , beta-Lactamasas/metabolismo , Adulto , Humanos , Fallo Renal Crónico/complicaciones , Fallo Renal Crónico/terapia , Trasplante de Riñón , Klebsiella pneumoniae/aislamiento & purificación , Masculino , New York , Neumonía Bacteriana/complicacionesRESUMEN
The aim of this study was to evaluate the in vitro efficacy of ceftobiprole and comparator antibiotics, either alone or in combination, in staphylococcal MBEC™ (minimum biofilm eradication concentration) and colony biofilm assays at dilutions of the maximum free-drug plasma concentration attained during clinical use (fCmax). Staphylococci tested included meticillin-susceptible and meticillin-resistant Staphylococcus aureus (n=6) and Staphylococcus epidermidis (n=2). Relative to no-drug controls, after 7 days of exposure ceftobiprole concentrations from 1/4 fCmax to fCmax generally decreased CFUs in MBEC or colony biofilms of S. aureus isolates by ca. 1.5log10 to ≥2.5log10. Gentamicin reduced colony biofilm CFUs by ≥1.4log10 at these concentrations with gentamicin-susceptible isolates. Following 7 days of exposure, vancomycin and rifampicin were ineffective as single agents or in combination in the colony model, but yielded CFU decreases from 0 to 5log10 in the MBEC model. Treatment of biofilms with rifampicin for 7 days yielded rifampicin-resistant mutants, and the selection of rifampicin resistance was inhibited by co-treatment with ceftobiprole. Thus, ceftobiprole alone or in combination demonstrated promising activity against biofilms of meticillin-susceptible and -resistant staphylococci at clinically relevant concentrations. In contrast, vancomycin and rifampicin, two agents used clinically for the treatment of biofilm infections, tested separately or together gave inconsistent results and generally had little impact on cell viability.
Asunto(s)
Antibacterianos/farmacología , Biopelículas/efectos de los fármacos , Cefalosporinas/farmacología , Staphylococcus aureus/efectos de los fármacos , Staphylococcus epidermidis/efectos de los fármacos , Recuento de Colonia Microbiana , Humanos , Pruebas de Sensibilidad Microbiana , Staphylococcus aureus/crecimiento & desarrollo , Staphylococcus aureus/fisiología , Staphylococcus epidermidis/crecimiento & desarrollo , Staphylococcus epidermidis/fisiología , Factores de TiempoRESUMEN
INTRODUCTION: A mouse intracerebral challenge model is used for potency testing of whole-cell pertussis (wP) vaccines. We investigated the use of a mouse nasopharyngeal challenge model, which better reflects the clinical features of pertussis disease, to differentiate between efficacy of wP vaccines. METHODS: Efficacy of three wP vaccines (Quinvaxem(®), Easyfive(®) and Pentavac(®)) was tested in the nasopharyngeal challenge model. Mice were vaccinated at 4 and 7 weeks and challenged with Bordetella pertussis at 9 weeks. Vaccine efficacy was determined based on CFU in the lungs 5 days after challenge. RESULTS: The mouse nasopharyngeal challenge model has the capacity to differentiate between the efficacy of whole cell pertussis vaccines. CONCLUSION: The mouse nasopharyngeal challenge model could be considered as a potency and release assay for wP vaccines. Whether this model directly correlates with clinical vaccine efficacy requires further investigations. Whether this model directly correlates with clinical vaccine efficacy requires further investigations. The mouse nasopharyngeal challenge model could be considered as a potency and release assay for wP vaccines.
Asunto(s)
Vacuna contra la Tos Ferina/inmunología , Tos Ferina/inmunología , Administración Intranasal , Animales , Anticuerpos Antibacterianos/análisis , Anticuerpos Antibacterianos/biosíntesis , Bordetella pertussis/inmunología , Ensayo de Unidades Formadoras de Colonias , Inmunoglobulina G/análisis , Ratones , Vacuna contra la Tos Ferina/administración & dosificaciónAsunto(s)
Aminoaciltransferasas/genética , Proteínas Bacterianas/genética , Carbapenémicos/farmacología , Mutación/genética , Proteínas de Unión a las Penicilinas/genética , Peptidil Transferasas/genética , Streptococcus pneumoniae/genética , beta-Lactamas/farmacología , Aminoaciltransferasas/química , Aminoaciltransferasas/metabolismo , Proteínas Bacterianas/metabolismo , Doripenem , Humanos , Mutación/efectos de los fármacos , Proteínas de Unión a las Penicilinas/química , Proteínas de Unión a las Penicilinas/metabolismo , Penicilinas/metabolismo , Peptidil Transferasas/metabolismo , Unión Proteica/efectos de los fármacos , Unión Proteica/genética , Estructura Terciaria de Proteína , Streptococcus pneumoniae/efectos de los fármacos , Streptococcus pneumoniae/enzimología , Estados Unidos/epidemiologíaRESUMEN
ß-Lactamase inhibitors (clavulanic acid, sulbactam, and tazobactam) contribute significantly to the longevity of the ß-lactam antibiotics used to treat serious infections. In the quest to design more potent compounds and to understand the mechanism of action of known inhibitors, 6ß-(hydroxymethyl)penicillanic acid sulfone (6ß-HM-sulfone) was tested against isolates expressing the class A TEM-1 ß-lactamase and a clinically important variant of the AmpC cephalosporinase of Pseudomonas aeruginosa, PDC-3. The addition of the 6ß-HM-sulfone inhibitor to ampicillin was highly effective. 6ß-HM-sulfone inhibited TEM-1 with an IC(50) of 12 ± 2 nM and PDC-3 with an IC(50) of 180 ± 36 nM, and displayed lower partition ratios than commercial inhibitors, with partition ratios (k(cat)/k(inact)) equal to 174 for TEM-1 and 4 for PDC-3. Measured for 20 h, 6ß-HM-sulfone demonstrated rapid, first-order inactivation kinetics with the extent of inactivation being related to the concentration of inhibitor for both TEM-1 and PDC-3. Using mass spectrometry to gain insight into the intermediates of inactivation of this inhibitor, 6ß-HM-sulfone was found to form a major adduct of +247 ± 5 Da with TEM-1 and +245 ± 5 Da with PDC-3, suggesting that the covalently bound, hydrolytically stabilized acyl-enzyme has lost a molecule of water (HOH). Minor adducts of +88 ± 5 Da with TEM-1 and +85 ± 5 Da with PDC-3 revealed that fragmentation of the covalent adduct can result but appeared to occur slowly with both enzymes. 6ß-HM-sulfone is an effective and versatile ß-lactamase inhibitor of representative class A and C enzymes.
Asunto(s)
Antibacterianos/farmacología , Proteínas Bacterianas/metabolismo , Sulbactam/análogos & derivados , Sulbactam/farmacología , beta-Lactamasas/metabolismo , Antibacterianos/química , Proteínas Bacterianas/antagonistas & inhibidores , Proteínas Bacterianas/genética , Dominio Catalítico , Simulación por Computador , Escherichia coli/efectos de los fármacos , Escherichia coli/enzimología , Escherichia coli/genética , Modelos Moleculares , Estructura Molecular , Conformación Proteica , Pseudomonas aeruginosa/enzimología , Sulbactam/química , Inhibidores de beta-Lactamasas , beta-Lactamasas/genéticaRESUMEN
Meticillin-resistant Staphylococcus aureus (MRSA) isolates from two worldwide ceftobiprole Phase 3 clinical trials for the treatment of complicated skin and skin-structure infections were characterised by clonality, staphylococcal cassette chromosome mec (SCCmec) type and the presence of Panton-Valentine leukocidin (PVL). PVL was predominantly found in US isolates (196/231 vs. 13/110 non-US isolates). SCCmec type IV was the most common (253/329) owing to the predominance of clone USA300 in isolates from the USA (197/226). In Europe, SCCmec type III was the most prevalent (30/74). Ceftobiprole minimum inhibitory concentrations (MICs) ranged from 0.25 microg/mL to 4 microg/mL, with MICs Asunto(s)
Antibacterianos/uso terapéutico
, Cefalosporinas/uso terapéutico
, Staphylococcus aureus Resistente a Meticilina/clasificación
, Staphylococcus aureus Resistente a Meticilina/genética
, Infecciones Cutáneas Estafilocócicas/tratamiento farmacológico
, Infecciones Cutáneas Estafilocócicas/microbiología
, Técnicas de Tipificación Bacteriana/métodos
, Análisis por Conglomerados
, Dermatoglifia del ADN/métodos
, ADN Bacteriano/genética
, Europa (Continente)
, Genotipo
, Humanos
, Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos
, Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación
, Pruebas de Sensibilidad Microbiana
, Estados Unidos
RESUMEN
Doripenem, a parenteral carbapenem, exhibited high affinity for penicillin-binding protein 2 (PBP2) and PBP3 in Pseudomonas aeruginosa and PBP2 in Escherichia coli, the primary PBPs whose inhibition leads to cell death. This PBP affinity profile correlates with the broad-spectrum gram-negative activity observed with doripenem.
Asunto(s)
Antibacterianos/metabolismo , Carbapenémicos/metabolismo , Escherichia coli/metabolismo , Proteínas de Unión a las Penicilinas/metabolismo , Pseudomonas aeruginosa/metabolismo , beta-Lactamas/metabolismo , Antibacterianos/farmacología , Proteínas Bacterianas/metabolismo , Carbapenémicos/farmacología , Doripenem , Escherichia coli/efectos de los fármacos , Proteínas de Escherichia coli/metabolismo , Humanos , Concentración 50 Inhibidora , Pruebas de Sensibilidad Microbiana , Pseudomonas aeruginosa/efectos de los fármacos , beta-Lactamas/farmacologíaRESUMEN
The interactions of ceftobiprole with purified beta-lactamases from molecular classes A, B, C, and D were determined and compared with those of benzylpenicillin, cephaloridine, cefepime, and ceftazidime. Enzymes were selected from functional groups 1, 2a, 2b, 2be, 2d, 2e, and 3 to represent beta-lactamases from organisms within the antibacterial spectrum of ceftobiprole. Ceftobiprole was refractory to hydrolysis by the common staphylococcal PC1 beta-lactamase, the class A TEM-1 beta-lactamase, and the class C AmpC beta-lactamase but was labile to hydrolysis by class B, class D, and class A extended-spectrum beta-lactamases. Cefepime and ceftazidime followed similar patterns. In most cases, the hydrolytic stability of a substrate correlated with the MIC for the producing organism. Ceftobiprole and cefepime generally had lower MICs than ceftazidime for AmpC-producing organisms, particularly AmpC-overexpressing Enterobacter cloacae organisms. However, all three cephalosporins were hydrolyzed very slowly by AmpC cephalosporinases, suggesting that factors other than beta-lactamase stability contribute to lower ceftobiprole and cefepime MICs against many members of the family Enterobacteriaceae.
Asunto(s)
Antibacterianos/metabolismo , Bacterias/enzimología , Cefalosporinas/metabolismo , beta-Lactamasas/metabolismo , Bacterias/efectos de los fármacos , Cefepima , Ceftazidima/metabolismo , Hidrólisis , Cinética , Pruebas de Sensibilidad Microbiana , Espectrofotometría Ultravioleta , beta-Lactamasas/clasificación , beta-Lactamasas/aislamiento & purificaciónRESUMEN
Ceftobiprole exhibited tight binding to PBP2a in methicillin-resistant Staphylococcus aureus, PBP2x in penicillin-resistant Streptococcus pneumoniae, and PBP3 and other essential penicillin-binding proteins in methicillin-susceptible S. aureus, Escherichia coli, and Pseudomonas aeruginosa. Ceftobiprole also bound well to PBP2 in the latter organisms, contributing to the broad-spectrum antibacterial activity against gram-negative and gram-positive bacteria.
Asunto(s)
Proteínas Bacterianas/metabolismo , Cefalosporinas/metabolismo , Proteínas de Escherichia coli/metabolismo , Bacterias Gramnegativas/metabolismo , Proteínas de Unión a las Penicilinas/metabolismo , Concentración 50 Inhibidora , Pruebas de Sensibilidad Microbiana , Pseudomonas aeruginosa/química , Pseudomonas aeruginosa/metabolismo , Staphylococcus aureus/química , Staphylococcus aureus/metabolismo , Streptococcus pneumoniae/química , Streptococcus pneumoniae/metabolismoRESUMEN
The activities of ceftobiprole and other beta-lactams were examined with 30 Streptococcus pneumoniae isolates containing multiple pbp1a, pbp2b, and pbp2x mutations. The highest ceftobiprole MIC was 1 microg/ml, while the comparator MICs were 16 to 64 microg/ml. Fifty percent inhibitory concentrations for penicillin-binding protein 2x were 0.5 microg/ml (ceftobiprole) and 4 microg/ml (ceftriaxone) in a penicillin- and ceftriaxone-resistant isolate.
Asunto(s)
Antibacterianos/farmacología , Cefalosporinas/farmacología , Mutación , Proteínas de Unión a las Penicilinas/genética , Streptococcus pneumoniae/efectos de los fármacos , beta-Lactamas/farmacología , Secuencias de Aminoácidos , Aminoaciltransferasas/genética , Proteínas Bacterianas/genética , Humanos , Pruebas de Sensibilidad Microbiana , Proteínas de Unión a las Penicilinas/química , Proteínas de Unión a las Penicilinas/metabolismo , Peptidil Transferasas/genética , Streptococcus pneumoniae/genética , Streptococcus pneumoniae/aislamiento & purificación , Estados Unidos , Resistencia betalactámicaRESUMEN
Clinical isolates of Klebsiella pneumoniae resistant to carbapenems and essentially all other antibiotics (multidrug resistant) are being isolated from some hospitals in New York City with increasing frequency. A highly related pair of K. pneumoniae strains isolated on the same day from one patient in a hospital in New York City were studied for antibiotic resistance. One (KP-2) was resistant to imipenem, meropenem, and sulopenem (MICs of 16 to 32 microg/ml) while the other (KP-1) was susceptible (MIC of 0.5 microg/ml); both contained the bla(ACT-1), bla(SHV-1), and bla(TEM-1) beta-lactamases. bla(ACT-1) in both strains was encoded on a large approximately 150-kb plasmid. Both isolates contained an identical class 1 integron encoding resistance to aminoglycosides and chloramphenicol. They each had identical insertions in ompK35 and ompK36, resulting in disruption of these key porin genes. The carbapenem-resistant and -susceptible isolates were extensively studied for differences in the structural and regulatory genes for the operons acrRAB, marORAB, romA-ramA, soxRS, micF, micC, phoE, phoBR, rpoS, and hfq. No changes were detected between the isolates except for a significant down-regulation of ompK37, phoB, and phoE in KP-2 as deduced from reverse transcription-PCR analysis of mRNA and polyacrylamide gel electrophoresis separation of outer membrane proteins. Backcross analysis was conducted using the wild-type phoE gene cloned into the vector pGEM under regulation of its native promoter as well as the lacZ promoter following transformation into the resistant KP-2 isolate. The wild-type gene reversed carbapenem resistance only when under control of the heterologous lacZ promoter. In the background of ompK35-ompK36 gene disruption, the up-regulation of phoE in KP-1 apparently compensated for porin loss and conferred carbapenem susceptibility. Down-regulation of phoE in KP-2 may represent the normal state of this gene, or it may have been selected from KP-1 in vivo under antibiotic pressure, generating the carbapenem-resistant clone. This is the first study in the Enterobacteriaceae where expression of the phosphate-regulated PhoE porin has been associated with resistance to antimicrobials. Our results with this pair of Klebsiella clinical isolates highlight the complex and evolving nature of multiple drug resistance in this species.