RESUMO
Taniborbactam, a bicyclic boronate ß-lactamase inhibitor with activity against Klebsiella pneumoniae carbapenemase (KPC), Verona integron-encoded metallo-ß-lactamase (VIM), New Delhi metallo-ß-lactamase (NDM), extended-spectrum beta-lactamases (ESBLs), OXA-48, and AmpC ß-lactamases, is under clinical development in combination with cefepime. Susceptibility of 200 previously characterized carbapenem-resistant K. pneumoniae and 197 multidrug-resistant (MDR) Pseudomonas aeruginosa to cefepime-taniborbactam and comparators was determined by broth microdilution. For K. pneumoniae (192 KPC; 7 OXA-48-related), MIC90 values of ß-lactam components for cefepime-taniborbactam, ceftazidime-avibactam, and meropenem-vaborbactam were 2, 2, and 1 mg/L, respectively. For cefepime-taniborbactam, 100% and 99.5% of isolates of K. pneumoniae were inhibited at ≤16 mg/L and ≤8 mg/L, respectively, while 98.0% and 95.5% of isolates were susceptible to ceftazidime-avibactam and meropenem-vaborbactam, respectively. For P. aeruginosa, MIC90 values of ß-lactam components of cefepime-taniborbactam, ceftazidime-avibactam, ceftolozane-tazobactam, and meropenem-vaborbactam were 16, >8, >8, and >4 mg/L, respectively. Of 89 carbapenem-susceptible isolates, 100% were susceptible to ceftolozane-tazobactam, ceftazidime-avibactam, and cefepime-taniborbactam at ≤8 mg/L. Of 73 carbapenem-intermediate/resistant P. aeruginosa isolates without carbapenemases, 87.7% were susceptible to ceftolozane-tazobactam, 79.5% to ceftazidime-avibactam, and 95.9% and 83.6% to cefepime-taniborbactam at ≤16 mg/L and ≤8 mg/L, respectively. Cefepime-taniborbactam at ≤16 mg/L and ≤8 mg/L, respectively, was active against 73.3% and 46.7% of 15 VIM- and 60.0% and 35.0% of 20 KPC-producing P. aeruginosa isolates. Of all 108 carbapenem-intermediate/resistant P. aeruginosa isolates, cefepime-taniborbactam was active against 86.1% and 69.4% at ≤16 mg/L and ≤8 mg/L, respectively, compared to 59.3% for ceftolozane-tazobactam and 63.0% for ceftazidime-avibactam. Cefepime-taniborbactam had in vitro activity comparable to ceftazidime-avibactam and greater than meropenem-vaborbactam against carbapenem-resistant K. pneumoniae and carbapenem-intermediate/resistant MDR P. aeruginosa.
RESUMO
We characterized the molecular determinants of meropenem-vaborbactam (MV) non-susceptibility among non-metallo-ß-lactamase-producing KPC-Klebsiella pneumoniae (KPC-KP). Whole-genome sequencing was performed to identify mutations associated with MV non-susceptibility. Isolates with elevated MV MICs were found to have mutations encoding truncated or altered OmpK36 porins and increased blaKPC copy numbers. KPC-KP isolates with decreased susceptibility to MV were detected among a collection of isolates predating the availability of MV.
RESUMO
Bacterial infections routinely cause inflammation and thereby impair osseointegration of orthopedic implants. Acinetobacter spp., which cause osteomyelitis following trauma, on or off the battlefield, were, however, reported to cause neither osteomyelitis nor osteolysis in rodents. We therefore compared the effects of Acinetobacter strain M2 to those of Staphylococcus aureus in a murine implant infection model. Sterile implants and implants with adherent bacteria were inserted in the femur of mice. Bacterial burden, levels of proinflammatory cytokines, and osseointegration were measured. All infections were localized to the implant site. Infection with either S. aureus or Acinetobacter strain M2 increased the levels of proinflammatory cytokines and the chemokine CCL2 in the surrounding femurs, inhibited bone formation around the implant, and caused loss of the surrounding cortical bone, leading to decreases in both histomorphometric and biomechanical measures of osseointegration. Genetic deletion of TLR2 and TLR4 from the mice partially reduced the effects of Acinetobacter strain M2 on osseointegration but did not alter the effects of S. aureus. This is the first report that Acinetobacter spp. impair osseointegration of orthopedic implants in mice, and the murine model developed for this study will be useful for future efforts to clarify the mechanism of implant failure due to Acinetobacter spp. and to assess novel diagnostic tools or therapeutic agents.
Assuntos
Acinetobacter baumannii , Osteomielite , Infecções Estafilocócicas , Animais , Citocinas/uso terapêutico , Camundongos , Osseointegração , Osteomielite/etiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureusRESUMO
Plazomicin was tested against 697 recently acquired carbapenem-resistant Klebsiella pneumoniae isolates from the Great Lakes region of the United States. Plazomicin MIC50 and MIC90 values were 0.25 and 1 mg/liter, respectively; 680 isolates (97.6%) were susceptible (MICs of ≤2 mg/liter), 9 (1.3%) intermediate (MICs of 4 mg/liter), and 8 (1.1%) resistant (MICs of >32 mg/liter). Resistance was associated with rmtF-, rmtB-, or armA-encoded 16S rRNA methyltransferases in all except 1 isolate.
Assuntos
Antibacterianos/farmacologia , Enterobacteriáceas Resistentes a Carbapenêmicos/efeitos dos fármacos , Klebsiella pneumoniae/efeitos dos fármacos , Metiltransferases/genética , Sisomicina/análogos & derivados , Adulto , Idoso , Proteínas de Bactérias/metabolismo , Farmacorresistência Bacteriana/genética , Feminino , Humanos , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/isolamento & purificação , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Sisomicina/farmacologia , Estados Unidos , beta-Lactamases/metabolismoRESUMO
Unlike for classes A and B, a standardized amino acid numbering scheme has not been proposed for the class C (AmpC) ß-lactamases, which complicates communication in the field. Here, we propose a scheme developed through a collaborative approach that considers both sequence and structure, preserves traditional numbering of catalytically important residues (Ser64, Lys67, Tyr150, and Lys315), is adaptable to new variants or enzymes yet to be discovered and includes a variation for genetic and epidemiological applications.
Assuntos
Proteínas de Bactérias/classificação , Bactérias Gram-Negativas/genética , Bactérias Gram-Positivas/genética , Mutação , Terminologia como Assunto , Resistência beta-Lactâmica/genética , beta-Lactamases/classificação , Sequência de Aminoácidos , Antibacterianos/química , Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Expressão Gênica , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/enzimologia , Bactérias Gram-Positivas/efeitos dos fármacos , Bactérias Gram-Positivas/enzimologia , Cooperação Internacional , Estrutura Secundária de Proteína , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Inibidores de beta-Lactamases/química , Inibidores de beta-Lactamases/farmacologia , beta-Lactamases/genética , beta-Lactamases/metabolismo , beta-Lactamas/química , beta-Lactamas/farmacologiaRESUMO
BACKGROUND: Overcoming ß-lactam resistance in pathogens such as Pseudomonas aeruginosa is a major clinical challenge. Rapid molecular diagnostics (RMDs) have the potential to inform selection of empiric therapy in patients infected by P. aeruginosa. METHODS: In this study, we used a heterogeneous collection of 197 P. aeruginosa that included multidrug-resistant isolates to determine whether 2 representative RMDs (Acuitas Resistome test and VERIGENE gram-negative blood culture test) could identify susceptibility to 2 newer ß-lactam/ß-lactamase inhibitor (BL-BLI) combinations, ceftazidime/avibactam (CZA) and ceftolozane/tazobactam (TOL/TAZO). RESULTS: We found that the studied RMD platforms were able to correctly identify BL-BLI susceptibility (susceptibility sensitivity, 100%; 95% confidence interval [CI], 97%, 100%) for both BLs-BLIs. However, their ability to detect resistance to these BLs-BLIs was lower (resistance sensitivity, 66%; 95% CI, 52%, 78% for TOL/TAZO and 33%; 95% CI, 20%, 49% for CZA). CONCLUSIONS: The diagnostic platforms studied showed the most potential in scenarios where a resistance gene was detected or in scenarios where a resistance gene was not detected and the prevalence of resistance to TOL/TAZO or CZA is known to be low. Clinicians need to be mindful of the benefits and risks that result from empiric treatment decisions that are based on resistance gene detection in P. aeruginosa, acknowledging that such decisions are impacted by the prevalence of resistance, which varies temporally and geographically.
Assuntos
Antibacterianos/uso terapêutico , Compostos Azabicíclicos/uso terapêutico , Ceftazidima/uso terapêutico , Cefalosporinas/uso terapêutico , Farmacorresistência Bacteriana Múltipla , Técnicas de Diagnóstico Molecular/normas , Infecções por Pseudomonas/tratamento farmacológico , Tazobactam/uso terapêutico , Antibacterianos/farmacologia , Combinação de Medicamentos , Genótipo , Humanos , Testes de Sensibilidade Microbiana , Técnicas de Diagnóstico Molecular/métodos , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Sensibilidade e Especificidade , Resistência beta-Lactâmica , Inibidores de beta-Lactamases/farmacologia , Inibidores de beta-Lactamases/uso terapêuticoRESUMO
The activity of the siderophore cephalosporin cefiderocol is targeted against carbapenem-resistant Gram-negative bacteria. In this study, the activity of cefiderocol against characterized carbapenem-resistant Acinetobacter baumannii complex, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, and Enterobacteriaceae strains was determined by microdilution in iron-depleted Mueller-Hinton broth. The MIC90s against A. baumannii, S. maltophilia, and P. aeruginosa were 1, 0.25, and 0.5 mg/liter, respectively. Against Enterobacteriaceae, the MIC90 was 1 mg/liter for the group harboring OXA-48-like, 2 mg/liter for the group harboring KPC-3, and 8 mg/liter for the group harboring TEM/SHV ESBL, NDM, and KPC-2.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Cefalosporinas/farmacologia , Enterobacteriaceae/efeitos dos fármacos , Pseudomonas aeruginosa/efeitos dos fármacos , Stenotrophomonas maltophilia/efeitos dos fármacos , beta-Lactamases/genética , Acinetobacter baumannii/enzimologia , Acinetobacter baumannii/genética , Acinetobacter baumannii/crescimento & desenvolvimento , Meios de Cultura , Enterobacteriaceae/enzimologia , Enterobacteriaceae/genética , Enterobacteriaceae/crescimento & desenvolvimento , Expressão Gênica , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Infecções por Bactérias Gram-Negativas/microbiologia , Humanos , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/enzimologia , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/crescimento & desenvolvimento , Sideróforos/farmacologia , Stenotrophomonas maltophilia/enzimologia , Stenotrophomonas maltophilia/genética , Stenotrophomonas maltophilia/crescimento & desenvolvimento , Resistência beta-Lactâmica/efeitos dos fármacos , Resistência beta-Lactâmica/genética , beta-Lactamases/metabolismo , CefiderocolRESUMO
Background: Extremely drug-resistant (XDR) Acinetobacter baumannii is one of the most commonly encountered, highly resistant pathogens requiring novel therapeutic interventions. Methods: We developed C8, a monoclonal antibody (mAb), by immunizing mice with sublethal inocula of a hypervirulent XDR clinical isolate. Results: C8 targets capsular carbohydrate on the bacterial surface, enhancing opsonophagocytosis. Treating with a single dose of C8 as low as 0.5 µg/mouse (0.0167 mg/kg) markedly improved survival in lethal bacteremic sepsis and aspiration pneumonia models of XDR A. baumannii infection. C8 was also synergistic with colistin, substantially improving survival compared to monotherapy. Treatment with C8 significantly reduced blood bacterial density, cytokine production (tumor necrosis factor α, interleukin [IL] 6, IL-1ß, and IL-10), and sepsis biomarkers. Serial in vitro passaging of A. baumannii in the presence of C8 did not cause loss of mAb binding to the bacteria, but did result in emergence of less-virulent mutants that were more susceptible to macrophage uptake. Finally, we developed a highly humanized variant of C8 that retains opsonophagocytic activity in murine and human macrophages and rescued mice from lethal infection. Conclusions: We describe a promising and novel mAb as therapy for lethal, XDR A. baumannii infections, and demonstrate that it synergistically improves outcomes in combination with antibiotics.
Assuntos
Infecções por Acinetobacter/tratamento farmacológico , Acinetobacter baumannii/efeitos dos fármacos , Anticorpos Monoclonais/farmacologia , Sepse/tratamento farmacológico , Animais , Antibacterianos/farmacologia , Biomarcadores/sangue , Colistina/farmacologia , Citocinas/sangue , Modelos Animais de Doenças , Farmacorresistência Bacteriana Múltipla , Células HL-60 , Humanos , Macrófagos/imunologia , Macrófagos/microbiologia , Masculino , Camundongos , Camundongos Endogâmicos C3H , Sepse/microbiologia , Resultado do TratamentoRESUMO
Background: Carbapenem resistance is a critical healthcare challenge worldwide. Particularly concerning is the widespread dissemination of Klebsiella pneumoniae carbapenemase (KPC). Klebsiella pneumoniae harboring blaKPC (KPC-Kpn) is endemic in many areas including the United States, where the epidemic was primarily mediated by the clonal dissemination of Kpn ST258. We postulated that the spread of blaKPC in other regions occurs by different and more complex mechanisms. To test this, we investigated the evolution and dynamics of spread of KPC-Kpn in Colombia, where KPC became rapidly endemic after emerging in 2005. Methods: We sequenced the genomes of 133 clinical isolates recovered from 24 tertiary care hospitals located in 10 cities throughout Colombia, between 2002 (before the emergence of KPC-Kpn) and 2014. Phylogenetic reconstructions and evolutionary mapping were performed to determine temporal and genetic associations between the isolates. Results: Our results indicate that the start of the epidemic was driven by horizontal dissemination of mobile genetic elements carrying blaKPC-2, followed by the introduction and subsequent spread of clonal group 258 (CG258) isolates containing blaKPC-3. Conclusions: The combination of 2 evolutionary mechanisms of KPC-Kpn within a challenged health system of a developing country created the "perfect storm" for sustained endemicity of these multidrug-resistant organisms in Colombia.
Assuntos
Enterobacteriáceas Resistentes a Carbapenêmicos/genética , Epidemias , Evolução Molecular , Infecções por Klebsiella/epidemiologia , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/genética , Enterobacteriáceas Resistentes a Carbapenêmicos/isolamento & purificação , Cidades/epidemiologia , Colômbia/epidemiologia , DNA Bacteriano/química , DNA Bacteriano/genética , Transmissão de Doença Infecciosa , Transferência Genética Horizontal , Humanos , Sequências Repetitivas Dispersas , Klebsiella pneumoniae/classificação , Klebsiella pneumoniae/isolamento & purificação , Epidemiologia Molecular , Filogenia , Análise de Sequência de DNA , Centros de Atenção Terciária , Sequenciamento Completo do GenomaRESUMO
Background: Polymyxins including colistin are an important "last-line" treatment for infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKp). Increasing use of colistin has led to resistance to this cationic antimicrobial peptide. Methods: A cohort nested within the Consortium on Resistance against Carbapenems in Klebsiella pneumoniae (CRACKLE) was constructed of patients with infection, or colonization with CRKp isolates tested for colistin susceptibility during the study period of December, 2011 to October, 2014. Reference colistin resistance determination as performed by broth macrodilution was compared to results from clinical microbiology laboratories (Etest) and to polymyxin resistance testing. Each patient was included once, at the time of their first colistin-tested CRKp positive culture. Time to 30-day in-hospital all-cause mortality was evaluated by Kaplan-Meier curves and Cox proportional hazard modeling. Results: In 246 patients with CRKp, 13% possessed ColR CRKp. ColR was underestimated by Etest (very major error rate = 35%, major error rate = 0.4%). A variety of rep-PCR strain types were encountered in both the ColS and the ColR groups. Carbapenem resistance was mediated primarily by blaKPC-2 (46%) and blaKPC-3 (50%). ColR was associated with increased hazard for in-hospital mortality (aHR 3.48; 95% confidence interval, 1.73-6.57; P < .001). The plasmid-associated ColR genes, mcr-1 and mcr-2 were not detected in any of the ColR CRKp. Conclusions: In this cohort, 13% of patients with CRKp presented with ColR CRKp. The apparent polyclonal nature of the isolates suggests de novo emergence of ColR in this cohort as the primary factor driving ColR. Importantly, mortality was increased in patients with ColR isolates.
Assuntos
Antibacterianos/uso terapêutico , Colistina/uso terapêutico , Infecções por Klebsiella/tratamento farmacológico , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Resistência beta-Lactâmica , Idoso , Antibacterianos/farmacologia , Carbapenêmicos/farmacologia , Carbapenêmicos/uso terapêutico , Colistina/farmacologia , Comorbidade , Feminino , Humanos , Estimativa de Kaplan-Meier , Infecções por Klebsiella/diagnóstico , Infecções por Klebsiella/mortalidade , Klebsiella pneumoniae/classificação , Klebsiella pneumoniae/genética , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Filogenia , Modelos de Riscos Proporcionais , beta-Lactamases/genéticaRESUMO
Among Gram-negative bacteria, carbapenem-resistant infections pose a serious and life-threatening challenge. Here, the CRACKLE network reports a sentinel detection and characterization of a carbapenem-resistant Klebsiella pneumoniae ST147 isolate harboring blaNDM-5 and blaOXA-181 from a young man who underwent abdominal surgery in India. blaNDM-5 was located on an IncFII plasmid of ≈90 kb, whereas blaOXA-181 was chromosomally encoded. Resistome and genome analysis demonstrated multiple copies of the transposable element IS26 and a "hot-spot region" in the IncFII plasmid.
Assuntos
Klebsiella pneumoniae/enzimologia , Klebsiella pneumoniae/patogenicidade , beta-Lactamases/metabolismo , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Carbapenêmicos/farmacologia , Carbapenêmicos/uso terapêutico , Humanos , Índia , Infecções por Klebsiella/tratamento farmacológico , Infecções por Klebsiella/microbiologia , Masculino , Testes de Sensibilidade Microbiana , Plasmídeos/genética , beta-Lactamases/genéticaRESUMO
Based upon knowledge of the hydrolytic profile of major ß-lactamases found in Gram-negative bacteria, we tested the efficacy of the combination of ceftazidime-avibactam (CAZ-AVI) with aztreonam (ATM) against carbapenem-resistant enteric bacteria possessing metallo-ß-lactamases (MBLs). Disk diffusion and agar-based antimicrobial susceptibility testing were initially performed to determine the in vitro efficacy of a unique combination of CAZ-AVI and ATM against 21 representative Enterobacteriaceae isolates with a complex molecular background that included blaIMP, blaNDM, blaOXA-48, blaCTX-M, blaAmpC, and combinations thereof. Time-kill assays were conducted, and the in vivo efficacy of this combination was assessed in a murine neutropenic thigh infection model. By disk diffusion assay, all 21 isolates were resistant to CAZ-AVI alone, and 19/21 were resistant to ATM. The in vitro activity of CAZ-AVI in combination with ATM against diverse Enterobacteriaceae possessing MBLs was demonstrated in 17/21 isolates, where the zone of inhibition was ≥21 mm. All isolates demonstrated a reduction in CAZ-AVI agar dilution MICs with the addition of ATM. At 2 h, time-kill assays demonstrated a ≥4-log10-CFU decrease for all groups that had CAZ-AVI with ATM (8 µg/ml) added, compared to the group treated with CAZ-AVI alone. In the murine neutropenic thigh infection model, an almost 4-log10-CFU reduction was noted at 24 h for CAZ-AVI (32 mg/kg every 8 h [q8h]) plus ATM (32 mg/kg q8h) versus CAZ-AVI (32 mg/kg q8h) alone. The data presented herein require us to carefully consider this new therapeutic combination to treat infections caused by MBL-producing Enterobacteriaceae.
Assuntos
Antibacterianos/farmacologia , Compostos Azabicíclicos/farmacologia , Aztreonam/farmacologia , Ceftazidima/farmacologia , Infecções por Enterobacteriaceae/tratamento farmacológico , Enterobacteriaceae/efeitos dos fármacos , Animais , Contagem de Colônia Microbiana , Ciclofosfamida , Esquema de Medicação , Combinação de Medicamentos , Quimioterapia Combinada , Enterobacteriaceae/enzimologia , Enterobacteriaceae/genética , Enterobacteriaceae/crescimento & desenvolvimento , Infecções por Enterobacteriaceae/microbiologia , Feminino , Expressão Gênica , Humanos , Infecções por Klebsiella/complicações , Infecções por Klebsiella/tratamento farmacológico , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/enzimologia , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/crescimento & desenvolvimento , Camundongos , Testes de Sensibilidade Microbiana , Neutropenia/induzido quimicamente , Neutropenia/complicações , Neutropenia/tratamento farmacológico , Neutropenia/microbiologia , Plasmídeos/química , Plasmídeos/metabolismo , Infecções dos Tecidos Moles/complicações , Infecções dos Tecidos Moles/tratamento farmacológico , Infecções dos Tecidos Moles/microbiologia , Coxa da Perna , Resistência beta-Lactâmica/efeitos dos fármacos , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , beta-Lactamases/metabolismoRESUMO
The widespread dissemination of carbapenem-resistant Acinetobacter spp. has created significant therapeutic challenges. At present, rapid molecular diagnostics (RMDs) that can identify this phenotype are not commercially available. Two RMD platforms, PCR combined with electrospray ionization mass spectrometry (PCR/ESI-MS) and molecular beacons (MB), for detecting genes conferring resistance/susceptibility to carbapenems in Acinetobacter spp. were evaluated. An archived collection of 200 clinical Acinetobacter sp. isolates was tested. Predictive values for susceptibility and resistance were estimated as a function of susceptibility prevalence and were based on the absence or presence of beta-lactamase (bla) NDM, VIM, IMP, KPC, and OXA carbapenemase genes (e.g., blaOXA-23, blaOXA-24/40, and blaOXA-58 found in this study) against the reference standard of MIC determinations. According to the interpretation of MICs, 49% (n = 98) of the isolates were carbapenem resistant (as defined by either resistance or intermediate resistance to imipenem). The susceptibility sensitivities (95% confidence interval [CI]) for imipenem were 82% (74%, 89%) and 92% (85%, 97%) for PCR/ESI-MS and MB, respectively. Resistance sensitivities (95% CI) for imipenem were 95% (88%, 98%) and 88% (80%, 94%) for PCR/ESI-MS and MB, respectively. PRIMERS III establishes that RMDs can discriminate between carbapenem resistance and susceptibility in Acinetobacter spp. In the context of a known prevalence of resistance, SPVs and RPVs can inform clinicians regarding the best choice for empiric antimicrobial therapy against this multidrug-resistant pathogen.
Assuntos
Acinetobacter/genética , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Carbapenêmicos/farmacologia , Testes de Sensibilidade Microbiana/métodos , Patologia Molecular/métodos , Resistência beta-Lactâmica , beta-Lactamases/genética , Acinetobacter/efeitos dos fármacos , Acinetobacter/enzimologia , Primers do DNA , Humanos , Valor Preditivo dos Testes , Sensibilidade e Especificidade , Fatores de TempoRESUMO
The medical community needs systematic and pragmatic approaches for evaluating the benefit-risk trade-offs of diagnostics that assist in medical decision making. Benefit-Risk Evaluation of Diagnostics: A Framework (BED-FRAME) is a strategy for pragmatic evaluation of diagnostics designed to supplement traditional approaches. BED-FRAME evaluates diagnostic yield and addresses 2 key issues: (1) that diagnostic yield depends on prevalence, and (2) that different diagnostic errors carry different clinical consequences. As such, evaluating and comparing diagnostics depends on prevalence and the relative importance of potential errors. BED-FRAME provides a tool for communicating the expected clinical impact of diagnostic application and the expected trade-offs of diagnostic alternatives. BED-FRAME is a useful fundamental supplement to the standard analysis of diagnostic studies that will aid in clinical decision making.
Assuntos
Sistemas de Apoio a Decisões Clínicas , Diagnóstico por Computador , Medição de Risco/métodos , Actinobacteria , Antibacterianos/uso terapêutico , Farmacorresistência Bacteriana , Infecções por Bactérias Gram-Positivas/tratamento farmacológico , Humanos , Modelos Estatísticos , PrevalênciaRESUMO
BACKGROUND: Rapid molecular diagnostic (RMD) platforms may lead to better antibiotic use. Our objective was to develop analytical strategies to enhance the interpretation of RMDs for clinicians. METHODS: We compared the performance characteristics of 4 RMD platforms for detecting resistance against ß-lactams in 72 highly resistant isolates of Escherichia coli and Klebsiella pneumoniae (PRIMERS I). Subsequently, 2 platforms were used in a blinded study in which a heterogeneous collection of 196 isolates of E. coli and K. pneumoniae (PRIMERS II) were examined. We evaluated the genotypic results as predictors of resistance or susceptibility against ß-lactam antibiotics. We designed analytical strategies and graphical representations of platform performance, including discrimination summary plots and susceptibility and resistance predictive values, that are readily interpretable by practitioners to inform decision-making. RESULTS: In PRIMERS I, the 4 RMD platforms detected ß-lactamase (bla) genes and identified susceptibility or resistance in >95% of cases. In PRIMERS II, the 2 platforms identified susceptibility against extended-spectrum cephalosporins and carbapenems in >90% of cases; however, against piperacillin/tazobactam, susceptibility was identified in <80% of cases. Applying the analytical strategies to a population with 15% prevalence of ceftazidime-resistance and 5% imipenem-resistance, RMD platforms predicted susceptibility in >95% of cases, while prediction of resistance was 69%-73% for ceftazidime and 41%-50% for imipenem. CONCLUSIONS: RMD platforms can help inform empiric ß-lactam therapy in cases where bla genes are not detected and the prevalence of resistance is known. Our analysis is a first step in bridging the gap between RMDs and empiric treatment decisions.
Assuntos
Antibacterianos/uso terapêutico , Infecções por Enterobacteriaceae/tratamento farmacológico , Escherichia coli/efeitos dos fármacos , Klebsiella pneumoniae/efeitos dos fármacos , Testes de Sensibilidade Microbiana/métodos , Técnicas de Diagnóstico Molecular/métodos , Resistência beta-Lactâmica , Infecções por Enterobacteriaceae/microbiologia , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Técnicas de Genotipagem/métodos , Humanos , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/isolamento & purificação , Fatores de TempoRESUMO
We report complete genome sequences of four blaNDM-1-harboring Gram-negative multidrug-resistant (MDR) isolates from Colombia. The blaNDM-1 genes were located on 193-kb Inc FIA, 178-kb Inc A/C2, and 47-kb (unknown Inc type) plasmids. Multilocus sequence typing (MLST) revealed that these isolates belong to sequence type 10 (ST10) (Escherichia coli), ST392 (Klebsiella pneumoniae), and ST322 and ST464 (Acinetobacter baumannii and Acinetobacter nosocomialis, respectively). Our analysis identified that the Inc A/C2 plasmid in E. coli contained a novel complex transposon (Tn125 and Tn5393 with three copies of blaNDM-1) and a recombination "hot spot" for the acquisition of new resistance determinants.
Assuntos
Acinetobacter baumannii/enzimologia , Acinetobacter baumannii/genética , Epidemiologia Molecular/métodos , Acinetobacter/efeitos dos fármacos , Acinetobacter/enzimologia , Acinetobacter/genética , Acinetobacter baumannii/efeitos dos fármacos , Colômbia , DNA Bacteriano/genética , Farmacorresistência Bacteriana/genética , Escherichia coli/efeitos dos fármacos , Escherichia coli/enzimologia , Escherichia coli/genética , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/enzimologia , Klebsiella pneumoniae/genética , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Plasmídeos/genéticaRESUMO
BACKGROUND: Acinetobacter baumannii is one of the most antibiotic-resistant pathogens. Defining mechanisms driving pathogenesis is critical to enable new therapeutic approaches. METHODS: We studied virulence differences across a diverse panel of A. baumannii clinical isolates during murine bacteremia to elucidate host-microbe interactions that drive outcome. RESULTS: We identified hypervirulent strains that were lethal at low intravenous inocula and achieved very high early, and persistent, blood bacterial densities. Virulent strains were nonlethal at low inocula but lethal at 2.5-fold higher inocula. Finally, relatively avirulent (hypovirulent) strains were nonlethal at 20-fold higher inocula and were efficiently cleared by early time points. In vivo virulence correlated with in vitro resistance to complement and macrophage uptake. Depletion of complement, macrophages, and neutrophils each independently increased bacterial density of the hypovirulent strain but insufficiently to change lethality. However, disruption of all 3 effector mechanisms enabled early bacterial densities similar to hypervirulent strains, rendering infection 100% fatal. CONCLUSIONS: The lethality of A. baumannii strains depends on distinct stages. Strains resistant to early innate effectors are able to establish very high early bacterial blood density, and subsequent sustained bacteremia leads to Toll-like receptor 4-mediated hyperinflammation and lethality. These results have important implications for translational efforts to develop therapies that modulate host-microbe interactions.
Assuntos
Infecções por Acinetobacter/imunologia , Acinetobacter baumannii/imunologia , Bacteriemia/imunologia , Imunidade Inata/imunologia , Interações Microbianas/imunologia , Infecções por Acinetobacter/microbiologia , Animais , Antibacterianos/imunologia , Bacteriemia/microbiologia , Farmacorresistência Bacteriana Múltipla/imunologia , Macrófagos/imunologia , Macrófagos/microbiologia , Camundongos , Camundongos Endogâmicos C3H , Neutrófilos/imunologia , Neutrófilos/microbiologia , Virulência/imunologia , Fatores de Virulência/imunologiaRESUMO
Pseudomonas aeruginosa is a notoriously difficult-to-treat pathogen that is a common cause of severe nosocomial infections. Investigating a collection of ß-lactam-resistant P. aeruginosa clinical isolates from a decade ago, we uncovered resistance to ceftazidime-avibactam, a novel ß-lactam/ß-lactamase inhibitor combination. The isolates were systematically analyzed through a variety of genetic, biochemical, genomic, and microbiological methods to understand how resistance manifests to a unique drug combination that is not yet clinically released. We discovered that avibactam was able to inactivate different AmpC ß-lactamase enzymes and that blaPDC regulatory elements and penicillin-binding protein differences did not contribute in a major way to resistance. By using carefully selected combinations of antimicrobial agents, we deduced that the greatest barrier to ceftazidime-avibactam is membrane permeability and drug efflux. To overcome the constellation of resistance determinants, we show that a combination of antimicrobial agents (ceftazidime/avibactam/fosfomycin) targeting multiple cell wall synthetic pathways can restore susceptibility. In P. aeruginosa, efflux, as a general mechanism of resistance, may pose the greatest challenge to future antibiotic development. Our unexpected findings create concern that even the development of antimicrobial agents targeted for the treatment of multidrug-resistant bacteria may encounter clinically important resistance. Antibiotic therapy in the future must consider these factors.
Assuntos
Antibacterianos/farmacologia , Compostos Azabicíclicos/farmacologia , Ceftazidima/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Fosfomicina/farmacologia , Bactérias Gram-Negativas , Humanos , Testes de Sensibilidade MicrobianaRESUMO
Genome sequencing of carbapenem-resistant Klebsiella pneumoniae isolates from regional U.S. hospitals was used to characterize strain diversity and the bla(KPC) genetic context. A phylogeny based on core single-nucleotide variants (SNVs) supports a division of sequence type 258 (ST258) into two distinct groups. The primary differences between the groups are in the capsular polysaccharide locus (cps) and their plasmid contents. A strict association between clade and KPC variant was found. The bla(KPC) gene was found on variants of two plasmid backbones. This study indicates that highly similar K. pneumoniae subpopulations coexist within the same hospitals over time.