RESUMO
Enterococci are commensal members of the gastrointestinal tract and also major nosocomial pathogens. They possess both intrinsic and acquired resistance to many antibiotics, including intrinsic resistance to cephalosporins that target bacterial cell wall synthesis. These antimicrobial resistance traits make enterococcal infections challenging to treat. Moreover, prior therapy with antibiotics, including broad-spectrum cephalosporins, promotes enterococcal proliferation in the gut, resulting in dissemination to other sites of the body and subsequent infection. As a result, a better understanding of mechanisms of cephalosporin resistance is needed to enable development of new therapies to treat or prevent enterococcal infections. We previously reported that flow of metabolites through the peptidoglycan biosynthesis pathway is one determinant of enterococcal cephalosporin resistance. One factor that has been implicated in regulating flow of metabolites into cell wall biosynthesis pathways of other Gram-positive bacteria is GlmR. In enterococci, GlmR is encoded as the middle gene of a predicted 3-gene operon along with YvcJ and YvcL, whose functions are poorly understood. Here we use genetics and biochemistry to investigate the function of the enterococcal yvcJ-glmR-yvcL gene cluster. Our results reveal that YvcL is a DNA-binding protein that regulates expression of the yvcJ-glmR-yvcL operon in response to cell wall stress. YvcJ and GlmR bind UDP-GlcNAc and reciprocally regulate cephalosporin resistance in E. faecalis, and binding of UDP-GlcNAc by YvcJ appears essential for its activity. Reciprocal regulation by YvcJ/GlmR is essential for fitness during exposure to cephalosporin stress. Additionally, our results indicate that enterococcal GlmR likely acts by a different mechanism than the previously studied GlmR of Bacillus subtilis, suggesting that the YvcJ/GlmR regulatory module has evolved unique targets in different species of bacteria.
Assuntos
Resistência às Cefalosporinas , Cefalosporinas , Cefalosporinas/farmacologia , Cefalosporinas/metabolismo , Resistência às Cefalosporinas/genética , Antibacterianos/farmacologia , Enterococcus faecalis/genética , Óperon/genética , Difosfato de Uridina/metabolismoRESUMO
Hypermutation due to DNA mismatch repair (MMR) deficiencies can accelerate the development of antibiotic resistance in Pseudomonas aeruginosa. Whether hypermutators generate resistance through predominantly similar molecular mechanisms to wild-type (WT) strains is not fully understood. Here, we show that MMR-deficient P. aeruginosa can evolve resistance to important broad-spectrum cephalosporin/beta-lactamase inhibitor combination antibiotics through novel mechanisms not commonly observed in WT lineages. Using whole-genome sequencing (WGS) and transcriptional profiling of isolates that underwent in vitro adaptation to ceftazidime/avibactam (CZA), we characterized the detailed sequence of mutational and transcriptional changes underlying the development of resistance. Surprisingly, MMR-deficient lineages rapidly developed high-level resistance (>256 µg/mL) largely without corresponding fixed mutations or transcriptional changes in well-established resistance genes. Further investigation revealed that these isolates had paradoxically generated an early inactivating mutation in the mexB gene of the MexAB-OprM efflux pump, a primary mediator of CZA resistance in P. aeruginosa, potentially driving an evolutionary search for alternative resistance mechanisms. In addition to alterations in a number of genes not known to be associated with resistance, 2 mutations were observed in the operon encoding the RND efflux pump MexVW. These mutations resulted in a 4- to 6-fold increase in resistance to ceftazidime, CZA, cefepime, and ceftolozane-tazobactam when engineered into a WT strain, demonstrating a potentially important and previously unappreciated mechanism of resistance to these antibiotics in P. aeruginosa. Our results suggest that MMR-deficient isolates may rapidly evolve novel resistance mechanisms, sometimes with complex dynamics that reflect gene inactivation that occurs with hypermutation. The apparent ease with which hypermutators may switch to alternative resistance mechanisms for which antibiotics have not been developed may carry important clinical implications.
Assuntos
Pseudomonas aeruginosa , Inibidores de beta-Lactamases , Inibidores de beta-Lactamases/farmacologia , Pseudomonas aeruginosa/genética , Ceftazidima/farmacologia , Cefalosporinas/farmacologia , Antibacterianos/farmacologiaRESUMO
Antibacterial drug resistance of gram-negative bacteria (GNB) results in high morbidity and mortality of GNB infection, seriously threaten human health globally. Developing new antibiotics has become the critical need for dealing with drug-resistant bacterial infections. Cefiderocol is an iron carrier cephalosporin that achieves drug accumulation through a unique "Trojan horse" strategy into the bacterial periplasm. It shows high antibacterial activity against multidrug-resistant (MDR) Enterobacteriaceae and MDR non-fermentative bacteria. The application of cefiderocol offers new hope for treating clinical drug-resistant bacterial infections. However, limited clinical data and uncertainties about its resistance mechanisms constrain the choice of its therapeutic use. This review aimed to summarize the clinical applications, drug resistance mechanisms, and co-administration of cefiderocol.
Assuntos
Cefiderocol , Infecções por Bactérias Gram-Negativas , Humanos , Sideróforos/farmacologia , Sideróforos/uso terapêutico , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Cefalosporinas/farmacologia , Cefalosporinas/uso terapêutico , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Infecções por Bactérias Gram-Negativas/microbiologia , Bactérias Gram-Negativas , Farmacorresistência Bacteriana Múltipla , Testes de Sensibilidade MicrobianaRESUMO
CTX-M ß-lactamases are a widespread source of resistance to ß-lactam antibiotics in Gram-negative bacteria. These enzymes readily hydrolyze penicillins and cephalosporins, including oxyimino-cephalosporins such as cefotaxime. To investigate the preference of CTX-M enzymes for cephalosporins, we examined eleven active-site residues in the CTX-M-14 ß-lactamase model system by alanine mutagenesis to assess the contribution of the residues to catalysis and specificity for the hydrolysis of the penicillin, ampicillin, and the cephalosporins cephalothin and cefotaxime. Key active site residues for class A ß-lactamases, including Lys73, Ser130, Asn132, Lys234, Thr216, and Thr235, contribute significantly to substrate binding and catalysis of penicillin and cephalosporin substrates in that alanine substitutions decrease both kcat and kcat/KM. A second group of residues, including Asn104, Tyr105, Asn106, Thr215, and Thr216, contribute only to substrate binding, with the substitutions decreasing only kcat/KM. Importantly, calculating the average effect of a substitution across the 11 active-site residues shows that the most significant impact is on cefotaxime hydrolysis while ampicillin hydrolysis is least affected, suggesting the active site is highly optimized for cefotaxime catalysis. Furthermore, we determined X-ray crystal structures for the apo-enzymes of the mutants N106A, S130A, N132A, N170A, T215A, and T235A. Surprisingly, in the structures of some mutants, particularly N106A and T235A, the changes in structure propagate from the site of substitution to other regions of the active site, suggesting that the impact of substitutions is due to more widespread changes in structure and illustrating the interconnected nature of the active site.
Assuntos
Domínio Catalítico , Cefalosporinas , Resistência a Medicamentos , Escherichia coli , beta-Lactamases , Ampicilina/metabolismo , Ampicilina/farmacologia , beta-Lactamases/química , beta-Lactamases/metabolismo , Catálise , Domínio Catalítico/genética , Cefotaxima/metabolismo , Cefotaxima/farmacologia , Cefalosporinas/metabolismo , Cefalosporinas/farmacologia , Resistência a Medicamentos/genética , Escherichia coli/efeitos dos fármacos , Escherichia coli/metabolismo , Mutagênese , Penicilinas/metabolismo , Penicilinas/farmacologia , beta-Lactamas/metabolismo , Modelos Moleculares , Estrutura Terciária de ProteínaRESUMO
In a retrospective multicenter study of 575 patients with bloodstream infections or pneumonia due to wild-type AmpC ß-lactamase-producing Enterobacterales, species with low in vitro mutation rates for AmpC derepression were associated with fewer treatment failures due to AmpC overproduction (adjusted hazard ratio, 0.5 [95% CI, .2-.9]). However, compared to cefepime/carbapenems, using third-generation cephalosporins as definitive therapy remained associated with this adverse outcome (15% vs 1%).
Assuntos
Antibacterianos , Proteínas de Bactérias , Infecções por Enterobacteriaceae , Enterobacteriaceae , Taxa de Mutação , beta-Lactamases , Humanos , beta-Lactamases/genética , beta-Lactamases/metabolismo , Proteínas de Bactérias/genética , Estudos Retrospectivos , Antibacterianos/uso terapêutico , Antibacterianos/farmacologia , Enterobacteriaceae/genética , Enterobacteriaceae/efeitos dos fármacos , Enterobacteriaceae/enzimologia , Infecções por Enterobacteriaceae/tratamento farmacológico , Infecções por Enterobacteriaceae/microbiologia , Pessoa de Meia-Idade , Masculino , Feminino , Testes de Sensibilidade Microbiana , Bacteriemia/tratamento farmacológico , Bacteriemia/microbiologia , Idoso , Cefalosporinas/uso terapêutico , Cefalosporinas/farmacologiaRESUMO
Phage-antibiotic combinations (PAC) offer a potential solution for treating refractory daptomycin-nonsusceptible (DNS) methicillin-resistant Staphylococcus aureus (MRSA) infections. We examined PAC activity against two well-characterized DNS MRSA strains (C4 and C37) in vitro and ex vivo. PACs comprising daptomycin (DAP) ± ceftaroline (CPT) and a two-phage cocktail (Intesti13 + Sb-1) were evaluated for phage-antibiotic synergy (PAS) against high MRSA inoculum (109 CFU/mL) using (i) modified checkerboards (CB), (ii) 24-h time-kill assays (TKA), and (iii) 168-h ex vivo simulated endocardial vegetation (SEV) models. PAS was defined as a fractional inhibitory concentration ≤0.5 in CB minimum inhibitory concentration (MIC) or a ≥2 log10 CFU/mL reduction compared to the next best regimen in time-kill assays and SEV models. Significant differences between regimens were assessed by analysis of variance with Tukey's post hoc modification (α = 0.05). CB assays revealed PAS with Intesti13 + Sb-1 + DAP ± CPT. In 24-h time-kill assays against C4, Intesti13 + Sb-1 + DAP ± CPT demonstrated synergistic activity (-Δ7.21 and -Δ7.39 log10 CFU/mL, respectively) (P < 0.05 each). Against C37, Intesti13 + Sb-1 + CPT ± DAP was equally effective (-Δ7.14 log10 CFU/mL each) and not significantly different from DAP + Intesti13 + Sb-1 (-Δ6.65 log10 CFU/mL). In 168-h SEV models against C4 and C37, DAP ± CPT + the phage cocktail exerted synergistic activities, significantly reducing bio-burdens to the detection limit [2 log10 CFU/g (-Δ7.07 and -Δ7.11 log10 CFU/g, respectively)] (P < 0.001). At 168 h, both models maintained stable MICs, and no treatment-emergent phage resistance occurred with DAP or DAP + CPT regimens. The two-phage cocktail demonstrated synergistic activity against two DNS MRSA isolates in combination with DAP + CPT in vitro and ex vivo. Further in vivo PAC investigations are needed.
Assuntos
Daptomicina , Staphylococcus aureus Resistente à Meticilina , Daptomicina/farmacologia , Cefalosporinas/farmacologia , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Ceftarolina , Testes de Sensibilidade MicrobianaRESUMO
Cefiderocol is a siderophore cephalosporin designed to target multi-drug-resistant Gram-negative bacteria. Previously, the emergence of cefiderocol non-susceptibility has been associated with mutations in the chromosomal cephalosporinase (PDC) along with mutations in the PirA and PiuA/D TonB-dependent receptor pathways. Here, we report a clinical case of cefiderocol-resistant P. aeruginosa that emerged in a patient during treatment. This resistance was associated with mutations not previously reported, suggesting potential novel pathways to cefiderocol resistance.
Assuntos
Cefiderocol , Infecções por Pseudomonas , Humanos , Antibacterianos/farmacologia , Cefiderocol/farmacologia , Cefalosporinas/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Bactérias Gram-Negativas , Testes de Sensibilidade Microbiana , Monobactamas/farmacologia , Pseudomonas aeruginosa , Infecções por Pseudomonas/tratamento farmacológicoRESUMO
Extracellular bacterial metabolites have potential as markers of bacterial growth and resistance emergence but have not been evaluated in dynamic in vitro studies. We investigated the dynamic metabolomic footprint of a multidrug-resistant hypermutable Pseudomonas aeruginosa isolate exposed to ceftolozane/tazobactam as continuous infusion (4.5 g/day, 9 g/day) in a hollow-fiber infection model over 7-9 days in biological replicates (n = 5). Bacterial samples were collected at 0, 7, 23, 47, 71, 95, 143, 167, 191, and 215 h, the supernatant quenched, and extracellular metabolites extracted. Metabolites were analyzed via untargeted metabolomics, including hierarchical clustering and correlation with quantified total and resistant bacterial populations. The time-courses of five (of 1,921 detected) metabolites from enriched pathways were mathematically modeled. Absorbed L-arginine and secreted L-ornithine were highly correlated with the total bacterial population (r -0.79 and 0.82, respectively, P<0.0001). Ribose-5-phosphate, sedoheptulose-7-phosphate, and trehalose-6-phosphate correlated with the resistant subpopulation (0.64, 0.64, and 0.67, respectively, P<0.0001) and were likely secreted due to resistant growth overcoming oxidative and osmotic stress induced by ceftolozane/tazobactam. Using pharmacokinetic/pharmacodynamic-based transduction models, these metabolites were successfully modeled based on the total or resistant bacterial populations. The models well described the abundance of each metabolite across the differing time-course profiles of biological replicates, based on bacterial killing and, importantly, resistant regrowth. These proof-of-concept studies suggest that further exploration is warranted to determine the generalizability of these findings. The metabolites modeled here are not exclusive to bacteria. Future studies may use this approach to identify bacteria-specific metabolites correlating with resistance, which would ultimately be extremely useful for clinical translation.
Assuntos
Antibacterianos , Infecções por Pseudomonas , Humanos , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Pseudomonas aeruginosa , Testes de Sensibilidade Microbiana , Tazobactam/farmacologia , Cefalosporinas/farmacologia , Infecções por Pseudomonas/tratamento farmacológico , Infecções por Pseudomonas/microbiologia , Farmacorresistência Bacteriana MúltiplaRESUMO
Mycobacterium abscessus (MAB) infections pose a growing public health threat. Here, we assessed the in vitro activity of the boronic acid-based ß-lactamase inhibitor, vaborbactam, with different ß-lactams against 100 clinical MAB isolates. Enhanced activity was observed with meropenem and ceftaroline with vaborbactam (1- and >4-fold MIC50/90 reduction). CRISPRi-mediated blaMAB gene knockdown showed a fourfold MIC reduction to ceftaroline but not the other ß-lactams. Our findings demonstrate vaborbactam's potential in combination therapy against MAB infections.
Assuntos
Antibacterianos , Ácidos Borônicos , Cefoxitina , Ceftarolina , Cefalosporinas , Imipenem , Meropeném , Testes de Sensibilidade Microbiana , Mycobacterium abscessus , Mycobacterium abscessus/efeitos dos fármacos , Meropeném/farmacologia , Ácidos Borônicos/farmacologia , Antibacterianos/farmacologia , Cefalosporinas/farmacologia , Imipenem/farmacologia , Cefoxitina/farmacologia , Humanos , Infecções por Mycobacterium não Tuberculosas/tratamento farmacológico , Infecções por Mycobacterium não Tuberculosas/microbiologia , Inibidores de beta-Lactamases/farmacologiaRESUMO
We report the emergence of cefiderocol resistance in a blaOXA-72 carbapenem-resistant Acinetobacter baumannii isolate from a sacral decubitus ulcer. Cefiderocol was initially used; however, a newly approved sulbactam-durlobactam therapy with source control and flap coverage was successful in treating the infection. Laboratory investigation revealed cefiderocol resistance mediated by ISAba36 insertion into the siderophore receptor pirA.
Assuntos
Infecções por Acinetobacter , Acinetobacter baumannii , Antibacterianos , Carbapenêmicos , Cefiderocol , Cefalosporinas , Testes de Sensibilidade Microbiana , Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/genética , Antibacterianos/farmacologia , Humanos , Cefalosporinas/farmacologia , Infecções por Acinetobacter/tratamento farmacológico , Infecções por Acinetobacter/microbiologia , Carbapenêmicos/farmacologia , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Sulbactam/farmacologia , Masculino , Farmacorresistência Bacteriana Múltipla/genética , Compostos Azabicíclicos/farmacologia , Elementos de DNA Transponíveis/genética , Proteínas da Membrana Bacteriana ExternaRESUMO
The siderophore-cephalosporin cefiderocol (FDC) presents a promising treatment option for carbapenem-resistant (CR) P. aeruginosa (PA). FDC circumvents traditional porin and efflux-mediated resistance by utilizing TonB-dependent receptors (TBDRs) to access the periplasmic space. Emerging FDC resistance has been associated with loss of function mutations within TBDR genes or the regulatory genes controlling TBDR expression. Further, difficulties with antimicrobial susceptibility testing (AST) and unexpected negative clinical treatment outcomes have prompted concerns for heteroresistance, where a single lineage isolate contains resistant subpopulations not detectable by standard AST. This study aimed to evaluate the prevalence of TBDR mutations among clinical isolates of P. aeruginosa and the phenotypic effect on FDC susceptibility and heteroresistance. We evaluated the sequence of pirR, pirS, pirA, piuA, or piuD from 498 unique isolates collected before the introduction of FDC from four clinical sites in Portland, OR (1), Houston, TX (2), and Santiago, Chile (1). At some clinical sites, TBDR mutations were seen in up to 25% of isolates, and insertion, deletion, or frameshift mutations were predicted to impair protein function were seen in 3% of all isolates (n = 15). Using population analysis profile testing, we found that P. aeruginosa with major TBDR mutations were enriched for a heteroresistant phenotype and undergo a shift in the susceptibility distribution of the population as compared to susceptible strains with wild-type TBDR genes. Our results indicate that mutations in TBDR genes predate the clinical introduction of FDC, and these mutations may predispose to the emergence of FDC resistance.
Assuntos
Antibacterianos , Proteínas de Bactérias , Cefiderocol , Testes de Sensibilidade Microbiana , Mutação , Pseudomonas aeruginosa , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/efeitos dos fármacos , Antibacterianos/farmacologia , Humanos , Proteínas de Bactérias/genética , Cefalosporinas/farmacologia , Proteínas de Membrana/genética , Infecções por Pseudomonas/microbiologia , Infecções por Pseudomonas/tratamento farmacológico , Farmacorresistência Bacteriana/genéticaRESUMO
We subjected seven P. aeruginosa isolates to a 10-day serial passaging against five antipseudomonal agents to evaluate resistance levels post-exposure and putative resistance mechanisms in terminal mutants were analyzed by whole-genome sequencing analysis. Meropenem (mean, 38-fold increase), cefepime (14.4-fold), and piperacillin-tazobactam (52.9-fold) terminal mutants displayed high minimum inhibitory concentration (MIC) values compared to those obtained after exposure to ceftolozane-tazobactam (11.4-fold) and ceftazidime-avibactam (5.7-fold). Fewer isolates developed elevated MIC values for other ß-lactams and agents belonging to other classes when exposed to meropenem in comparison to other agents. Alterations in nalC and nalD, involved in the upregulation of the efflux pump system MexAB-OprM, were common and observed more frequently in isolates exposed to ceftazidime-avibactam and meropenem. These alterations, along with ones in mexR and amrR, provided resistance to most ß-lactams and levofloxacin but not imipenem. The second most common gene altered was mpl, which is involved in the recycling of the cell wall peptidoglycan. These alterations were mainly noted in isolates exposed to ceftolozane-tazobactam and piperacillin-tazobactam but also in one cefepime-exposed isolate. Alterations in other genes known to be involved in ß-lactam resistance (ftsI, oprD, phoP, pepA, and cplA) and multiple genes involved in lipopolysaccharide biosynthesis were also present. The data generated here suggest that there is a difference in the mechanisms selected for high-level resistance between newer ß-lactam/ß-lactamase inhibitor combinations and older agents. Nevertheless, the isolates exposed to all agents displayed elevated MIC values for other ß-lactams (except imipenem) and quinolones tested mainly due to alterations in the MexAB-OprM regulators that extrude these agents.
Assuntos
Antibacterianos , Compostos Azabicíclicos , Ceftazidima , Meropeném , Testes de Sensibilidade Microbiana , Combinação Piperacilina e Tazobactam , Pseudomonas aeruginosa , Tazobactam , Inibidores de beta-Lactamases , beta-Lactamas , Antibacterianos/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/genética , Inibidores de beta-Lactamases/farmacologia , Compostos Azabicíclicos/farmacologia , Meropeném/farmacologia , Tazobactam/farmacologia , Ceftazidima/farmacologia , beta-Lactamas/farmacologia , Combinação Piperacilina e Tazobactam/farmacologia , Combinação de Medicamentos , Cefalosporinas/farmacologia , Cefepima/farmacologia , Humanos , Piperacilina/farmacologia , Sequenciamento Completo do Genoma , Farmacorresistência Bacteriana Múltipla/genéticaRESUMO
CERTAIN-1 was a Phase 3, double-blind, randomized, parallel group study of the efficacy and safety of cefepime-taniborbactam versus meropenem in the treatment of adults with complicated urinary tract infection (cUTI), including acute pyelonephritis. We determined susceptibility of Enterobacterales and Pseudomonas aeruginosa baseline pathogens to cefepime-taniborbactam and comparators and characterized ß-lactam resistance mechanisms. Microbiologic response and clinical response were assessed in patient subsets defined by baseline pathogens that were of cefepime-, multidrug-, or carbapenem-resistant phenotype or that carried ß-lactamase genes. Among Enterobacterales baseline pathogens, 26.8%, 4.1%, and 3.0% carried genes for extended-spectrum ß-lactamases (ESBLs), AmpC, and carbapenemases, respectively. Within each treatment group, while composite success rates at Test of Cure in resistant subsets by pathogen species were similar to those by pathogen overall, composite success rates in meropenem patients were numerically lower for cefepime-resistant Escherichia coli (9/19; 47.4%) and ESBL E. coli (13/25; 52.0%) compared with E. coli overall (62/100; 62.0%). Cefepime-taniborbactam achieved composite success in 7/8 (87.5%) patients with carbapenem-resistant Enterobacterales and 8/9 (88.9%) patients with Enterobacterales with a carbapenemase gene (5 OXA-48-group; 2 KPC-3; 2 NDM-1). Cefepime-taniborbactam also achieved composite success in 8/16 (50.0%) patients and clinical success in 13/16 (81.3%) patients with P. aeruginosa; corresponding rates were 4/7 (57.1%) and 6/7 (85.7%) for meropenem. Cefepime-taniborbactam demonstrated efficacy in adult cUTI patients with cefepime-, multidrug-, and carbapenem-resistant pathogens including pathogens with ESBL, AmpC, and carbapenemase genes. CLINICAL TRIALS: This study is registered with ClinicalTrials.gov as NCT03840148.
Assuntos
Antibacterianos , Cefepima , Cefalosporinas , Meropeném , Testes de Sensibilidade Microbiana , Infecções Urinárias , beta-Lactamases , Humanos , Meropeném/uso terapêutico , Meropeném/farmacologia , Cefepima/uso terapêutico , Cefepima/farmacologia , Antibacterianos/uso terapêutico , Antibacterianos/farmacologia , Infecções Urinárias/tratamento farmacológico , Infecções Urinárias/microbiologia , Cefalosporinas/uso terapêutico , Cefalosporinas/farmacologia , beta-Lactamases/genética , Adulto , Feminino , Masculino , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/genética , Pessoa de Meia-Idade , Método Duplo-Cego , Proteínas de Bactérias/genética , Genótipo , Fenótipo , Idoso , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Resultado do Tratamento , Ácidos Borínicos , Ácidos CarboxílicosRESUMO
In contrast to the epidemiology 10 years earlier at our hospital when the epidemic restriction endonuclease analysis (REA) group strain BI accounted for 72% of Clostridioides difficile isolates recovered from first-episode C. difficile infection (CDI) cases, BI represented 19% of first-episode CDI isolates in 2013-2015. Two additional REA group strains accounted for 31% of isolates (Y, 16%; DH, 12%). High-level resistance to fluoroquinolones and azithromycin was more common among BI isolates than among DH, Y, and non-BI/DH/Y isolates. Multivariable analysis revealed that BI cases were 2.47 times more likely to be associated with fluoroquinolone exposure compared to non-BI cases (95% confidence interval [CI]: 1.12-5.46). In addition, the odds of developing a CDI after third- or fourth-generation cephalosporin exposure was 2.83 times for DH cases than for non-DH cases (95% CI: 1.06-7.54). Fluoroquinolone use in the hospital decreased from 2005 to 2015 from a peak of 113 to a low of 56 antimicrobial days/1,000 patient days. In contrast, cephalosporin use increased from 42 to 81 antimicrobial days/1,000 patient days. These changes correlated with a decrease in geometric mean MIC for ciprofloxacin (61.03 to 42.65 mg/L, P = 0.02) and an increase in geometric mean MIC for ceftriaxone (40.87 to 86.14 mg/L, P < 0.01) among BI isolates. The BI strain remained resistant to fluoroquinolones, but an overall decrease in fluoroquinolone use and increase in cephalosporin use were associated with a decrease in the prevalence of BI, an increased diversity of C. difficile strain types, and the emergence of strains DH and Y.
Assuntos
Antibacterianos , Clostridioides difficile , Infecções por Clostridium , Fluoroquinolonas , Testes de Sensibilidade Microbiana , Clostridioides difficile/efeitos dos fármacos , Clostridioides difficile/isolamento & purificação , Humanos , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Infecções por Clostridium/epidemiologia , Infecções por Clostridium/microbiologia , Infecções por Clostridium/tratamento farmacológico , Fluoroquinolonas/farmacologia , Fluoroquinolonas/uso terapêutico , Masculino , Feminino , Idoso , Prevalência , Pessoa de Meia-Idade , Proibitinas , Hospitais , Surtos de Doenças , Azitromicina/uso terapêutico , Azitromicina/farmacologia , Infecção Hospitalar/microbiologia , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/tratamento farmacológico , Idoso de 80 Anos ou mais , Cefalosporinas/uso terapêutico , Cefalosporinas/farmacologiaRESUMO
Traditionally, cephalothin susceptibility results were used to predict the susceptibility of additional cephalosporins; however, in 2013-2014, the Clinical and Laboratory Standards Institute (CLSI) revisited this practice and determined that cefazolin is a more accurate proxy than cephalothin for uncomplicated urinary tract infections (uUTIs). Therefore, a cefazolin surrogacy breakpoint was established to predict the susceptibility of seven oral cephalosporins for Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis in the context of uUTIs. Clinical microbiology laboratories face several operational challenges when implementing the cefazolin surrogacy breakpoint, which may lead to confusion for the best path forward. Here, we review the historical context and data behind the surrogacy breakpoints, review PK/PD profiles for oral cephalosporins, discuss challenges in deploying the breakpoint, and highlight the limited clinical outcome data in this space.
Assuntos
Cefazolina , Infecções Urinárias , Humanos , Cefazolina/farmacologia , Cefazolina/uso terapêutico , Cefalosporinas/farmacologia , Cefalotina , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Testes de Sensibilidade Microbiana , Infecções Urinárias/tratamento farmacológico , Infecções Urinárias/microbiologia , Escherichia coli , MonobactamasRESUMO
There are increasing reports of carbapenem-resistant Enterobacterales (CRE) that test as cefepime-susceptible (S) or susceptible-dose dependent (SDD). However, there are no data to compare the cefepime testing performance of BD Phoenix automated susceptibility system (BD Phoenix) and disk diffusion (DD) relative to reference broth microdilution (BMD) against carbapenemase-producing (CPblaKPC-CRE) and non-producing (non-CP CRE) isolates. Cefepime susceptibility results were interpreted according to CLSI M100Ed32. Essential agreement (EA), categorical agreement (CA), minor errors (miEs), major errors (MEs), and very major errors (VMEs) were calculated for BD Phoenix (NMIC-306 Gram-negative panel) and DD relative to BMD. Correlates were also analyzed by the error rate-bounded method. EA and CA for CPblaKPC-CRE isolates (n = 64) were <90% with BD Phoenix while among non-CP CRE isolates (n = 58), EA and CA were 96.6%, and 79.3%, respectively. CA was <90% with DD for both cohorts. No ME or VME was observed for either isolate cohort; however, miEs were >10% for CPblaKPC-CRE and non-CP CRE with BD Phoenix and DD tests. For error rate-bounded method, miEs were <40% for IHigh + 1 to ILow - 1 ranges for CPblaKPC-CRE and non-CP CRE with BD Phoenix. Regarding disk diffusion, miEs were unacceptable for all MIC ranges among CPblaKPC-CRE. For non-CP CRE isolates, only IHigh + 1 to ILow - 1 range was acceptable at 37.2%. Using this challenge set of genotypic-phenotypic discordant CRE, the BD Phoenix MICs and DD susceptibility results trended higher (toward SDD and resistant phenotypes) relative to reference BMD results yielding lower CA. These results were more prominent among CPblaKPC-CRE than non-CP CRE.
Assuntos
Antibacterianos , Enterobacteriáceas Resistentes a Carbapenêmicos , Cefepima , Testes de Sensibilidade Microbiana , Cefepima/farmacologia , Antibacterianos/farmacologia , Testes de Sensibilidade Microbiana/métodos , Humanos , Enterobacteriáceas Resistentes a Carbapenêmicos/efeitos dos fármacos , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão/métodos , Infecções por Enterobacteriaceae/microbiologia , Cefalosporinas/farmacologiaRESUMO
BACKGROUND: Antimicrobial activity of antibiotics can be impacted by pH, enhancing or reducing their bactericidal properties. Cefiderocol, a novel cephalosporin antibiotic that is among others indicated for the treatment of complicated urinary tract infections (cUTIs), lacks data on activity in urine. METHODS: Pooled human urine (iron levels â¼0.05 mg/L/24 h), CAMHB and iron-depleted CAMHB (ID-CAMHB) at pH 5, 7 and 8 served as media. MIC testing was done according to EUCAST with the broth microdilution method for 17 clinical isolates of Escherichia coli and ATCC 25922 (including isolates with ESBL activity), 17 clinical isolates of Klebsiella pneumoniae and ATCC 700603 (also with ESBL), and 6 clinical isolates of Pseudomonas aeruginosa and ATCC 27853. Time-kill curves (TKCs) were performed for selected strains at pH 5, 7 and 8 in urine. RESULTS: MIC values in urine, CAMHB and ID-CAMHB exhibited isolate-specific variations when assessed under identical pH conditions, ranging from a 1-fold dilution to changes of up to 4-fold dilutions in either direction. Median MICs of cefiderocol were up to 50-fold higher in pH 5 than in pH 7 for P. aeruginosa isolates and 32-fold higher in E. coli and K. pneumoniae isolates. TKCs with 650 and 1300 mg/L cefiderocol in urine showed that ATCC strains were efficiently eradicated despite the pH set. CONCLUSIONS: Acidic pH had a significant negative impact on cefiderocol activity. Yet, after a recommended IV administration of 2 g cefiderocol every 8 h, a concentration of approximately 1300 mg/L can be achieved in urine, suggesting that efficient killing of all tested pathogens could have been possible even under acidic conditions in vivo.
Assuntos
Cefiderocol , Cefalosporinas , Humanos , Cefalosporinas/farmacologia , Cefalosporinas/uso terapêutico , Escherichia coli , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Monobactamas , Ferro , Pseudomonas aeruginosa , Klebsiella pneumoniae , Concentração de Íons de Hidrogênio , Testes de Sensibilidade MicrobianaRESUMO
BACKGROUND: Antimicrobial use (AMU) in primary care is a contributing factor to the emergence of antimicrobial-resistant bacteria. We assessed the potential effects of AMU on the prevalence of a combination of resistance phenotypes in bacteraemic Escherichia coli in outpatient care settings between primary care facilities ('clinics') and hospitals. METHODS: Population-weighted total AMU calculated from the national database was expressed as DDDs per 1000 inhabitants per day (DID). National data for all routine microbiological test results were exported from the databases of a major commercial clinical laboratory, including 16 484 clinics, and the Japan Nosocomial Infections Surveillance, including 1947 hospitals. AMU and the prevalence of combinations of resistance phenotypes in bacteraemic E. coli isolates were compared between clinics and hospitals. RESULTS: The five most common bacteria isolated from patients with bacteraemia were the same in clinics, outpatient settings and inpatient settings in hospitals, with E. coli as the most frequent. Oral third-generation cephalosporins and fluoroquinolones were the top two AMU outpatient drugs, except for macrolides, and resulted in at least three times higher AMU in clinics than in hospitals. The percentage of E. coli isolates resistant to both drugs in clinics (18.7%) was 5.6% higher than that in hospitals (13.1%) (P < 10-8). CONCLUSIONS: Significant AMU, specifically of oral third-generation cephalosporins and fluoroquinolones, in clinics is associated with a higher prevalence of E. coli isolates resistant to both drugs. This study provides a basis for national interventions to reduce inappropriate AMU in primary care settings.
Assuntos
Anti-Infecciosos , Bacteriemia , Humanos , Escherichia coli , Japão/epidemiologia , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Anti-Infecciosos/farmacologia , Fluoroquinolonas/farmacologia , Bacteriemia/tratamento farmacológico , Bacteriemia/epidemiologia , Cefalosporinas/farmacologia , Atenção Primária à Saúde , Farmacorresistência BacterianaRESUMO
OBJECTIVES: An Escherichia coli isolate, WGS1363, showed resistance to piperacillin/tazobactam but susceptibility to cephalosporins and contained a previously unrecognized ß-lactamase, CTX-M-255, as the only acquired ß-lactamase. CTX-M-255 was identical to CTX-M-27 except for a G239S substitution. Here, we characterize the hydrolytic spectrum of CTX-M-255 and a previously reported ß-lactamase, CTX-M-178, also containing a G239S substitution and compare it to their respective parental enzymes, CTX-M-27 and CTX-M-15. METHODS: All ß-lactamase genes were expressed in E. coli TOP10 and MICs to representative ß-lactam-antibiotics were determined. Furthermore, blaCTX-M-15, blaCTX-M-27, blaCTX-M-178 and blaCTX-M-255 with C-terminal His-tag fusions were affinity purified for enzyme kinetic assays determining Michaelis-Menten kinetic parameters against representative ß-lactam-antibiotics and IC50s of clavulanate, sulbactam, tazobactam and avibactam. RESULTS: TOP10-transformants expressing blaCTX-M-178 and blaCTX-M-255 showed resistance to penicillin/ß-lactamase combinations and susceptibility to cephalothin and cefotaxime in contrast to transformants expressing blaCTX-M-15 and blaCTX-M-27. Determination of enzyme kinetic parameters showed that CTX-M-178 and CTX-M-255 both lacked hydrolytic activity against cephalosporins and showed impaired hydrolytic efficiency against penicillin antibiotics compared to their parental enzymes. Both enzymes appeared more active against piperacillin compared to benzylpenicillin and ampicillin. Compared to their parental enzymes, IC50s of ß-lactamase-inhibitors were increased more than 1000-fold for CTX-M-178 and CTX-M-255. CONCLUSIONS: CTX-M-178 and CTX-M-255, both containing a G239S substitution, conferred resistance to piperacillin/tazobactam and may be characterized as inhibitor-resistant CTX-M ß-lactamases. Inhibitor resistance was accompanied by loss of activity against cephalosporins and monobactams. These findings add to the necessary knowledge base for predicting antibiotic susceptibility from genotypic data.
Assuntos
Antibacterianos , Inibidores de beta-Lactamases , Inibidores de beta-Lactamases/farmacologia , Antibacterianos/farmacologia , Escherichia coli , beta-Lactamases/genética , Penicilinas/farmacologia , Cefalosporinas/farmacologia , Tazobactam/farmacologia , Piperacilina/farmacologia , Monobactamas , Combinação Piperacilina e Tazobactam , Testes de Sensibilidade MicrobianaRESUMO
BACKGROUND: Patients infected with difficult-to-treat Pseudomonas aeruginosa are likely to receive meropenem (MEM) empirically before escalation to ceftolozane/tazobactam (C/T). We assessed whether pre-exposure to MEM affected C/T resistance development on C/T exposure. MATERIALS AND METHODS: Nine clinical P. aeruginosa isolates were exposed to MEM 16â mg/L for 72â h. Then, isolates were serially passaged in the presence of C/T (concentration of 10â mg/L) for 72â h as two groups: an MEM-exposed group inoculated with MEM pre-exposed isolates and a non-MEM control group. At 24â h intervals, samples were plated on drug-free and drug-containing agar (C/T concentration 16/8â mg/L) and incubated to quantify bacterial densities (log10 cfu/mL). Growth on C/T agar indicated resistance development, and resistant population was calculated by dividing the cfu/mL on C/T plates by the cfu/mL on drug-free agar. RESULTS: At 72â h, resistant populations were detected in 6/9 isolates. In five isolates, MEM exposure significantly increased the prevalence of ceftolozane/tazobactam-resistance development; the percentages of resistance population were 100%, 100%, 53.5%, 31% and 3% for the MEM-exposed versus 0%, 0%, 2%, 0.35% and ≤0.0003% in the unexposed groups. One isolate had a similar resistant population at 72â h between the two groups. The remaining isolates showed no development of resistance, regardless of previous MEM exposure. CONCLUSIONS: MEM exposure may pre-dispose to C/T resistance development and thus limit the therapeutic utility of this ß-lactam/ß-lactamase inhibitor. Resistance may be a result of stress exposure or molecular-level mutations conferring cross-resistance. Further in vivo studies are needed to assess clinical implications of these findings.