ABSTRACT
OXA-66 is a member of the OXA-51 subfamily of class D ß-lactamases native to the Acinetobacter genus that includes Acinetobacter baumannii, one of the ESKAPE pathogens and a major cause of drug-resistant nosocomial infections. Although both wild type OXA-66 and OXA-51 have low catalytic activity, they are ubiquitous in the Acinetobacter genomes. OXA-51 is also remarkably thermostable. In addition, newly emerging, single and double amino acid variants show increased activity against carbapenems, indicating that the OXA-51 subfamily is growing and gaining clinical significance. In this study, we used molecular dynamics simulations, X-ray crystallography, and thermal denaturation data to examine and compare the dynamics of OXA-66 wt and its gain-of-function variants: I129L (OXA-83), L167V (OXA-82), P130Q (OXA-109), P130A, and W222L (OXA-234). Our data indicate that OXA-66 wt also has a high melting temperature, and its remarkable stability is due to an extensive and rigid hydrophobic bridge formed by a number of residues around the active site and harbored by the three loops, P, Ω, and ß5-ß6. Compared to the WT enzyme, the mutants exhibit higher flexibility only in the loop regions, and are more stable than other robust carbapenemases, such as OXA-23 and OXA-24/40. All the mutants show increased rotational flexibility of residues I129 and W222, which allows carbapenems to bind. Overall, our data support the hypothesis that structural features in OXA-51 and OXA-66 promote evolution of multiple highly stable variants with increased clinical relevance in A. baumannii.
Subject(s)
Acinetobacter baumannii , Molecular Dynamics Simulation , beta-Lactamases , Acinetobacter baumannii/genetics , Acinetobacter baumannii/enzymology , beta-Lactamases/chemistry , beta-Lactamases/genetics , beta-Lactamases/metabolism , Crystallography, X-Ray , Enzyme Stability , Protein Conformation , Carbapenems/pharmacology , Carbapenems/metabolism , Evolution, Molecular , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Catalytic DomainABSTRACT
OBJECTIVES: Stenotrophomonas spp. intrinsically resistant to many ß-lactam antibiotics are found throughout the environment. CESS-1 identified in Stenotrophomonas sp. KCTC 12332 is an uncharacterized class A ß-lactamase. The goal of this study was to reveal biochemical and structural characteristics of CESS-1. METHODS: The hydrolytic activities of CESS-1 towards penicillins (penicillin G and ampicillin), cephalosporins (cephalexin, cefaclor, and cefotaxime), and carbapenems (imipenem and meropenem) was spectrophotometrically monitored. Structural information on E166Q mutants of CESS-1 acylated by cefaclor, cephalexin, or ampicillin were determined by X-ray crystallography. RESULTS: CESS-1 displayed hydrolytic activities toward penicillins and cephalosporins, with negligible activity toward carbapenems. Although cefaclor, cephalexin, and ampicillin have similar structures with identical R1 side chains, the catalytic parameters of CESS-1 toward them were distinct. The kcat values for cefaclor, cephalexin, and ampicillin were 1249.6 s-1, 204.3 s-1, and 69.8 s-1, respectively, with the accompanying KM values of 287.6 µM, 236.7 µM, and 28.8 µM, respectively. CONCLUSIONS: CESS-1 was able to discriminate between cefaclor and cephalexin with a single structural difference at C3 position: -Cl (cefaclor) and -CH3 (cephalexin). Structural comparisons among three E166Q mutants of CESS-1 acylated by cefaclor, cephalexin, or ampicillin, revealed that cooperative positional changes in the R1 side chain of substrates and their interaction with the ß5-ß6 loop affect the distance between Asn170 and the deacylating water at the acyl-enzyme intermediate state. This is directly associated with the differential hydrolytic activities of CESS-1 toward the three structurally similar ß-lactam antibiotics.
Subject(s)
Stenotrophomonas , beta-Lactamases , beta-Lactamases/genetics , beta-Lactamases/chemistry , beta-Lactamases/metabolism , Substrate Specificity , Crystallography, X-Ray , Stenotrophomonas/genetics , Stenotrophomonas/enzymology , Stenotrophomonas/metabolism , Stenotrophomonas/chemistry , Hydrolysis , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/metabolism , Carbapenems/pharmacology , Carbapenems/metabolism , Cephalosporins/metabolism , Cephalosporins/pharmacology , Penicillins/metabolism , Penicillins/pharmacology , KineticsABSTRACT
Carbapenem-resistant Acinetobacter baumannii infections have limited treatment options. Synthesis, transport and placement of lipopolysaccharide or lipooligosaccharide (LOS) in the outer membrane of Gram-negative bacteria are important for bacterial virulence and survival. Here we describe the cerastecins, inhibitors of the A. baumannii transporter MsbA, an LOS flippase. These molecules are potent and bactericidal against A. baumannii, including clinical carbapenem-resistant Acinetobacter baumannii isolates. Using cryo-electron microscopy and biochemical analysis, we show that the cerastecins adopt a serpentine configuration in the central vault of the MsbA dimer, stalling the enzyme and uncoupling ATP hydrolysis from substrate flipping. A derivative with optimized potency and pharmacokinetic properties showed efficacy in murine models of bloodstream or pulmonary A. baumannii infection. While resistance development is inevitable, targeting a clinically unexploited mechanism avoids existing antibiotic resistance mechanisms. Although clinical validation of LOS transport remains undetermined, the cerastecins may open a path to narrow-spectrum treatment modalities for important nosocomial infections.
Subject(s)
Acinetobacter Infections , Acinetobacter baumannii , Anti-Bacterial Agents , Bacterial Proteins , Lipopolysaccharides , Acinetobacter baumannii/drug effects , Acinetobacter baumannii/metabolism , Lipopolysaccharides/metabolism , Animals , Acinetobacter Infections/microbiology , Acinetobacter Infections/drug therapy , Mice , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/metabolism , Biological Transport , Microbial Sensitivity Tests , Humans , Cryoelectron Microscopy , Carbapenems/pharmacology , Carbapenems/metabolism , Disease Models, Animal , Female , ATP-Binding Cassette TransportersABSTRACT
OXA-48 has rapidly disseminated worldwide and become one of the most common carbapenemases in many countries with more than 45 variants reported with, in some cases, significant differences in their hydrolysis profiles. The R214 residue, located in the ß5-ß6 loop, is crucial for the carbapenemase activity, as it stabilizes carbapenems in the active site and maintains the shape of the active site through interactions with D159. In this study, we have characterized a novel variant of OXA-48, OXA-933 with a single D159N change. To evaluate the importance of this residue, point mutations were generated (D159A, D159G, D159K, and D159W), kinetic parameters of OXA-933, OXA-48 D159G, and OXA-48 D159K were determined and compared to those of OXA-48 and OXA-244. The blaOXA-933 gene was borne on Tn2208, a 2,696-bp composite transposon made of two IS1 elements surrounded by 9 bp target site duplications and inserted into a non-self-transmissible plasmid pOXA-933 of 7,872 bp in size. Minimal inhibitory concentration values of E. coli expressing the blaOXA-933 gene or of its point mutant derivatives were lower for carbapenems (except for D159G) as compared to those expressing the blaOXA-48 gene. Steady-state kinetic parameters revealed lower catalytic efficiencies for expanded spectrum cephalosporins and carbapenems. A detailed structural analysis confirmed the crucial role of D159 in shaping the active site of OXA-48 enzymes by interacting with R214. Our work further illustrates the remarkable propensity of OXA-48-like carbapenemases to evolve through mutations at positions outside the ß5-ß6 loop, but interacting with key residues of it.
Subject(s)
Anti-Bacterial Agents , Carbapenems , Escherichia coli , Microbial Sensitivity Tests , Penicillins , beta-Lactamases , beta-Lactamases/genetics , beta-Lactamases/metabolism , Carbapenems/pharmacology , Carbapenems/metabolism , Hydrolysis , Anti-Bacterial Agents/pharmacology , Penicillins/metabolism , Escherichia coli/genetics , Escherichia coli/drug effects , Escherichia coli/metabolism , Kinetics , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Catalytic Domain , DNA Transposable Elements/genetics , Escherichia coli Proteins/genetics , Escherichia coli Proteins/metabolism , Point MutationABSTRACT
OBJETIVO: Estudiar los casos de colonización y/o infección por Klebsiella oxytoca productora de carbapenemasas (KOPC) en HM Sanchinarro en 2018. MÉTODO: Estudio descriptivo retrospectivo de los pacientes con KOPC. La información se obtuvo de la historia clínica digital del programa informático HOSMA de HM Hospitales. El análisis estadístico se realizó con SPSS 24.0. RESULTADOS: Se analizaron 76 ingresos en 46 pacientes. El 76,6% fueron varones con media de edad de 68,5 años, 16,5 días de estancia y 12 de aislamiento específico. El 75,5% ingresó a cargo de Ci-rugía General, Oncología Médica o Medicina Interna. El 81,1% evolucionó favorablemente y el 17% fueron éxitus. El 86% falleció por shock séptico por KOPC. El patrón de resistencia predominante fue clase D-OXA 48 (71,4%). Los antibióticos más utilizados fueron meropenem, piperacilina-tazobactam, y levofloxacino. CONCLUSIONES: El sexo masculino, edad avanzada y comorbilidad son los factores de riesgo fundamentales. Shock séptico por KOPC es causa frecuente de éxitos
OBJECTIVE: Reviewing reported cases of carbapenem-producing Klebsiella oxytoca (CPKO) colonization or infection in patients attended in HM Sanchinarro in 2018. METHODS: A descriptive, retrospective study of patients with CPKO was carried out. Information was obtained from digital medical records in soft-ware HOSMA used in HM Hospitales. Statistical analysis was performed with SPSS 24.0.RESULTS: 76 admissions to hospital related to 46 were analyzed. 76,6% were male with mean age 68,5 years. Average hospital stay was 16,5 days and aver-age contact or droplet isolation, 12 days. 75,5% were admitted in General Surgery, Medical Oncology or Internal Medicine. 81,1% developed favourably and 17% died. The main cause in death was septic shock by CPKO (86%). Dominant resistance patterns was class D-OXA 48 (71,4%). The most prescribed anti-biotics were meronem, piperacillin-tazobactam and levofloxacin. CONCLUSIONS: Male sex, advanced age and comorbidity are key risk factors. Septic shock by CPKO cause death frequently
Subject(s)
Humans , Male , Female , Young Adult , Adult , Middle Aged , Aged , Aged, 80 and over , Klebsiella Infections/microbiology , Klebsiella Infections/epidemiology , Klebsiella oxytoca/isolation & purification , Carbapenems/metabolism , Carbapenem-Resistant Enterobacteriaceae/isolation & purification , Retrospective Studies , Klebsiella Infections/drug therapy , Anti-Bacterial Agents/therapeutic use , Disease Outbreaks , Risk Factors , Age Factors , Spain/epidemiology , Shock, Septic/microbiologyABSTRACT
INTRODUCTION: The carbapenem inactivation method (CIM) is a cost-effective assay for detecting carbapenemases. However, its interpretation is unclear for Pseudomonas spp. We evaluate its accuracy when meropenem is changed to imipenem. METHODS: We analyzed 266 P. aeruginosa isolates. The CIM method consists of: resuspend bacterial colonies (a full 10 μ,L loop) in 400 μ,L water, in which a 10 μ,g disk of meropenem/imipenem is immersed. After 2 h of incubation (35°C), remove the disk, place it onto a Mueller-Hinton agar plate previously inoculated with Escherichia coli (ATCC 25922), and incubate at 35 ̊C between 18-24 h. Interpretation criteria (mm of inhibition zone): ≤ 19 mm, positive; ≥ 25 mm negative; 20-24 mm, undetermined. RESULTS: Imipenem improves the sensitivity and specificity of CIM when compared to meropenem (99.4% and 98.9%, vs. 91.9% and 94.7%, respectively). CONCLUSIONS: The accuracy of CIM for carbapenemase detection in P. aeruginosa is increased with the use of imipenem
INTRODUCCIÓN: El método de inactivación del carbapenem (CIM, por sus siglas en inglés) se utiliza para detectar carbapenemasas, pero su interpretación no está clara para Pseudomonas spp. Se evaluó la precisión del método utilizando imipenem en lugar de meropenem. MÉTODOS: Se estudiaron 266 aislados de P. aeruginosa. El CIM consiste en: suspender colonias bacterianas (un asa de 10 μ,l) en 400 μ,l de agua en los que se sumerge un disco de 10 μ,g de meropenem/imipenem. Tras 2 h de incubación (35°C) se saca el disco y es transferido a agar Mueller-Hinton, previamente inoculado con Escherichia coli (ATCC 25922) e incubado a 35°C entre 18-24h. Criterios de interpretación (mm halo de inhibición): ≤ 19 mm positivo; ≥ 25 mm negativo y 20-24 mm indeterminado. RESULTADOS: Imipenem mejora la sensibilidad y especificidad del CIM frente a meropenem (99,4 y 98,9% vs. 91,9 y 94,7%, respectivamente). CONCLUSIONES: La precisión del CIM para la detección de carbapenemasas en P. aeruginosa mejora al utilizar imipenem
Subject(s)
Humans , Carbapenems/pharmacology , Imipenem/pharmacology , Pseudomonas aeruginosa/isolation & purification , Meropenem/pharmacology , Carbapenems/metabolism , Sensitivity and Specificity , Microbial Sensitivity TestsABSTRACT
Introducción: En los últimos años se ha observado un incremento de la resistencia a fluoroquinolonas en enterobacterias, estando asociado significativamente a la resistencia a betalactámicos. Nuestro objetivo fue conocer la prevalencia de mecanismos cromosómicos y plasmídicos de resistencia a quinolonas en aislados productores de betalactamasas de claseC adquiridas y/o carbapenemasas. Métodos: Se evaluó la presencia de mecanismos cromosómicos y plasmídicos de resistencia a quinolonas [mutaciones en la región determinante de resistencia a quinolonas de gyrA y parCy genes qnr, aac(6')-Ib-cr y qepA] en 289 aislados de enterobacterias productoras de betalactamasas de claseC adquiridas y/o carbapenemasas recogidos entre febrero y julio de 2009 en 35 hospitales españoles. Resultados: Se detectaron determinantes plasmídicos en 92 aislados (31,8%); en 83 aislados (28,7%) se detectó algún gen qnr, y en 20 (7%), la variante aac(6')-Ib-cr. El gen qnr más prevalente fue qnrB4 (20%), asociado en la mayoría de los casos a DHA-1. El 14,6% de los aislados con una CMI de ciprofloxacino superior a 0,25mg/l no presentaban mutaciones en gyrA ni parC, detectándose en el 90% de los mismos algún determinante plasmídico de resistencia a quinolonas. Conclusión: qnrB4 fue el determinante plasmídico más prevalente, claramente asociado a DHA-1. Los mecanismos plasmídicos en asociación con mecanismos cromosómicos diferentes a las mutaciones en los genes de las topoisomerasas (sobreexpresión de bombas de expulsión, alteración del lipopolisacárido o disminución de porinas) pueden dar lugar a valores de CMI de ciprofloxacino que superan los puntos de corte establecidos por los principales comités internacionales de definición de puntos de corte para interpretación de datos de sensibilidad (AU)
Background: Quinolone resistance in Enterobacteriaceae species has increased over the past few years, and is significantly associated to beta-lactam resistance. The aim of this study was to evaluate the prevalence of chromosomal- and plasmid-mediated quinolone resistance in acquired AmpC Beta-lactamase and/or carbapenemase-producing Enterobacteriaceae isolates. Methods: The presence of chromosomal- and plasmid-mediated quinolone resistance mechanisms [mutations in the quinolone resistance determining region (QRDR) of gyrA and parC and qnr, aac(6')-Ib-cr and qepA genes] was evaluated in 289 isolates of acquired AmpC Beta -lactamase- and/or carbapenemase-producing Enterobacteriaceae collected between February and July 2009 in 35 Spanish hospitals. Results: Plasmid mediated quinolone resistance (PMQR) genes were detected in 92 isolates (31.8%), qnr genes were detected in 83 isolates (28.7%), and the aac(6')-Ib-cr gene was detected in 20 isolates (7%). qnrB4 gene was the most prevalent qnr gene detected (20%), associated, in most cases, with DHA-1. Only 14.6% of isolates showed no mutations in gyrA or parC with a ciprofloxacin MIC of 0.5mg/L or higher, whereas PMQR genes were detected in 90% of such isolates. Conclusion: qnrB4 gene was the most prevalent PMQR gene detected, and was significantly associated with acquired AmpC Beta -lactamase DHA-1. PMQR determinants in association with other chromosomal-mediated quinolone resistance mechanisms, different to mutations in gyrA and parC (increased energy-dependent efflux, altered lipopolysaccharide or porin loss), could lead to ciprofloxacin MIC values that exceed breakpoints established by the main international committees to define clinical antimicrobial susceptibility breakpoints (AU)
Subject(s)
Humans , Quinolones/pharmacology , beta-Lactamases/therapeutic use , Fluoroquinolones/pharmacology , Enterobacteriaceae/enzymology , Bacterial Proteins/classification , Carbapenems/metabolism , Spain/epidemiology , Enterobacteriaceae/isolation & purification , Enterobacteriaceae Infections/diagnosis , Bacterial Proteins/therapeutic use , Bacterial Proteins/analysis , Plasmids/therapeutic use , Microbial Sensitivity Tests/methods , Ofloxacin/therapeutic useABSTRACT
An investigation was carried out into the genetic mechanisms responsible for multidrug resistance in nine carbapenem-resistant Pseudomonas aeruginosaisolates from different hospitals in Recife, Brazil. Susceptibility to antimicrobial agents was determined by broth microdilution. Polymerase chain reaction (PCR) was employed to detect the presence of genes encoding β-lactamases, aminoglycoside-modifying enzymes (AMEs), 16S rRNA methylases, integron-related genes and OprD. Expression of genes coding for efflux pumps and AmpC cephalosporinase were assessed by quantitative PCR. The outer membrane proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The blaSPM-1, blaKPC-2 and blaGES-1 genes were detected in P. aeruginosaisolates in addition to different AME genes. The loss of OprD in nine isolates was mainly due to frameshift mutations, premature stop codons and point mutations. An association of loss of OprD with the overexpression of MexAB-OprM and MexXY-OprM was observed in most isolates. Hyper-production of AmpC was also observed in three isolates. Clonal relationship of the isolates was determined by repetitive element palindromic-PCR and multilocus sequence typing. Our results show that the loss of OprD along with overexpression of efflux pumps and β-lactamase production were responsible for the multidrug resistance in the isolates analysed.
Subject(s)
Humans , Carbapenems/metabolism , Drug Resistance, Multiple, Bacterial/genetics , Mutation , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/genetics , beta-Lactam Resistance/genetics , beta-Lactamases/metabolism , Aminoglycosides/metabolism , Amphotericin B/analogs & derivatives , Amphotericin B/metabolism , Antifungal Agents/metabolism , Brazil , Cephalosporinase/classification , Cephalosporinase/metabolism , Codon, Nonsense/metabolism , Enzyme Activation/genetics , Frameshift Mutation/genetics , Gene Expression Regulation, Bacterial/genetics , Membrane Transport Proteins/metabolism , Methyltransferases/metabolism , Nucleotidyltransferases/metabolism , Point Mutation/genetics , Porins/metabolism , Pseudomonas aeruginosa/enzymology , Pseudomonas aeruginosa/isolation & purification , Repetitive Sequences, Nucleic Acid , beta-Lactamases/geneticsABSTRACT
Infections produced by carbapenemase-producing Enterobacteriaceae (CPE) are increasing worldwide. Therapeutic options are scarce because many of these bacteria are resistant to other antimicrobial groups. Furthermore, the dissemination of some carbapenemases and CPE is occurring rapidly. Health care authorities should be aware of the relevance of this problem, and coordinated surveillance and control strategies at all levels of the health system should be undertaken. The Spanish Society of Clinical Microbiology and Infectious Diseases (SEIMC) and The Spanish Network for Research on Infectious Diseases (REIPI, Institute of Health Carlos III, Ministry of Health, Spain) has selected a panel of Spanish experts on infections caused by CPE from the areas of clinical microbiology, infectious diseases and public health to review and discuss the most controversial issues regarding this increasing threat (AU)
Las infecciones causadas por enterobacterias productoras de carbapenemasas (EPC) están aumentando en el mundo entero. Las posibilidades terapéuticas son escasas, puesto que estas bacterias suelen ser resistentes a diferentes grupos de antibacterianos. Además, la diseminación de algunos tipos de carbapenemasas y de EPC está ocurriendo con mucha rapidez. Las autoridades sanitarias deberían ser conscientes de la relevancia de este problema y coordinar medidas de vigilancia y control en todos los ámbitos sanitarios. La Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica (SEIMC) y la Red Española de Investigación en Patología Infecciosa (REIPI; Instituto de Salud Carlos III, Ministerio de Sanidad, España) han seleccionado un panel de expertos en infecciones producidas por EPC que provienen del campo de la microbiología clínica, enfermedades infecciosas y salud pública para revisar y discutir los aspectos más controvertidos de esta amenaza (AU)
Subject(s)
Humans , Anti-Bacterial Agents/metabolism , Bacterial Proteins/metabolism , Carbapenems/metabolism , Drug Resistance, Multiple, Bacterial/genetics , Enterobacteriaceae Infections/microbiology , Enterobacteriaceae/enzymology , beta-Lactamases/metabolism , beta-Lactam Resistance/genetics , Global Health , Public Health , SpainABSTRACT
The most important mechanism of carbapenem resistance in Enterobacteriaceae is the production of carbapenemases, although resistance can also result from the synergistic activity between AmpC-type or (to a lesser extent) extended-spectrum beta-lactamases combined with decreased outer membrane permeability. Three major molecular classes of carbapenemases are recognized: A, B and D. Classes A and D are serine-beta-lactamases, whereas class B are metallo-beta-lactamases (their hydrolytic activity depends on the presence of zinc). In addition to carbapenems, carbapenemases also hydrolyze other beta-lactams, but the concrete substrate profile depends on the enzyme type. In general terms, class A enzymes are to some extent inhibited by clavulanic acid, and class B enzymes do not affect monobactams and are inhibited by zinc chelators. Given Enterobacteriaceae producing carbapenemases usually also contain gene coding for other mechanisms of resistance to beta-lactams, it is not unusual for the organisms to present complex beta-lactam resistance phenotypes. Additionally, these organisms frequently contain other genes that confer resistance to quinolones, aminoglycosides, tetracyclines, sulphonamides and other families of antimicrobial agents, which cause multiresistance or even panresistance. Currently, the most important type of class A carbapenemases are KPC enzymes, whereas VIM, IMP and (particularly) NDM in class B and OXA-48 (and related) in class D are the more relevant enzymes. Whereas some enzymes are encoded by chromosomal genes, most carbapenemases are plasmid-mediated (with genes frequently located in integrons), which favors the dissemination of the enzymes. Detailed information of the genetic platforms and the context of the genes coding for the most relevant enzymes will be presented in this review (AU)
El mecanismo más importante de resistencia a carbapenémicos en enterobacterias es la producción de carbapenemasas, aunque dicha resistencia también puede deberse a la combinación de betalactamasas tipo AmpC o, en menor medida, de espectro extendido, combinadas con disminución de la permeabilidad de la membrana externa. Se conocen 3 tipos moleculares de carbapenemasas: A, B y D. Las de las clases A y D son betalactamasas de serina, mientras que las de clase B son metalobetalactamasas (su actividad depende del cinc). Las carbapenemasas también hidrolizan otros betalactámicos, además de carbapenémicos, pero el perfil de sustrato concreto depende de la enzima considerada. En términos generales, las enzimas de clase A se inhiben en mayor o menor medida por ácido clavulánico y las de clase B no afectan a los monobactámicos y se inhiben por quelantes del cinc. Las enterobacterias que producen carbapenemasas, generalmente contienen otros genes de resistencia a betalactámicos y no es raro que presenten fenotipos de resistencia a betalactámicos complejos. Además, estos organismos frecuentemente contienen genes de resistencia a quinolonas, aminoglucósidos, tetraciclinas, sulfonamidas y otros antimicrobianos, causando multirresistencia o incluso panresistencia. Actualmente, las carbapenemasas más importantes de clase A son KPC, las de clase B son VIM, IMP, y en especial NDM, y las de clase D, OXA-48 y similares. Aunque algunas enzimas están codificadas por genes cromosómicos, la mayoría están mediadas por plásmidos (y los correspondientes genes con frecuencia se encuentran en integrones), lo cual favorece la diseminación de estas enzimas. En esta revisión se presenta información detallada sobre las plataformas y los contextos genéticos de los genes que codifican las enzimas más relevantes (AU)
Subject(s)
Humans , Anti-Bacterial Agents/metabolism , Bacterial Proteins/classification , Carbapenems/metabolism , Drug Resistance, Multiple, Bacterial/genetics , Enterobacteriaceae Infections/microbiology , Enterobacteriaceae/enzymology , beta-Lactamases/classification , beta-Lactam Resistance/genetics , Global Health , Zinc/pharmacology , Genes, Bacterial , Substrate Specificity , Clavulanic Acid/pharmacology , Plasmids/geneticsABSTRACT
The dissemination of carbapenemase-producing Enterobacteriaceae has occurred very quickly and has crossed borders rapidly between countries and continents. In some areas, it has exceeded the holding capacity of health systems, reaching epidemic proportions. This form of dissemination has not been the same for all enzymes, with KPC, NDM and OXA-48 genes having a greater ability to spread. These enzymes have primarily been spread clonally in the case of KPC-producing Klebsiella pneumoniae from the initial epicenter located in New York, with a very small number of strains causing outbreaks. For NDM and OXA48, these resistance determinants have been vehiculized by clones with a high transmission capacity; however, simultaneous horizontal transmission is also playing an important role. The most important identified reservoirs are colonized or infected individuals from endemic areas or centers with outbreaks, but the contaminated goods from these endemic areas also play a part. An international effort is needed to control the spread of these multiresistant pathogens (AU)
La diseminación de enterobacterias productoras de carbapenemasas ha sucedido muy deprisa y ha cruzado rápidamente los límites entre países y continentes. En algunas áreas ha excedido la capacidad de manejo de los sistemas sanitarios, alcanzando proporciones epidémicas. Esta forma de diseminación no ha sido la misma para todas las enzimas, siendo los genes KPC, NDM y OXA-48 los que tienen una mayor capacidad de diseminación. Estas enzimas se han extendido principalmente de forma clónica en el caso de la Klebsiella pneumoniae productora de KPC desde el epicentro inicial localizado en Nueva York, con un número muy pequeño de cepas causantes del brote. En el caso de NDM y OXA-48, estos determinantes de resistencia han sido vehiculizados por clones con una alta capacidad de transmisión; no obstante, la transmisión horizontal simultánea está jugando también un papel importante. Los reservorios identificados más importantes son los individuos colonizados o infectados procedentes de las áreas o centros epidémicos con brotes, pero los productos contaminados procedentes de estas áreas también juegan un papel. Se necesita un esfuerzo internacional para controlar la diseminación de estos patógenos multirresistentes (AU)
Subject(s)
Humans , Bacterial Proteins/metabolism , Enterobacteriaceae Infections/epidemiology , Enterobacteriaceae/enzymology , Drug Resistance, Multiple, Bacterial/genetics , beta-Lactamases/metabolism , beta-Lactam Resistance/genetics , Disease Reservoirs , Anti-Bacterial Agents/metabolism , Carbapenems/metabolism , Community-Acquired Infections , Cross Infection , Global Health , International Cooperation , Clone Cells/enzymologyABSTRACT
In recent years, Enterobacteriaceae isolates have increased their potential to become highly drug resistant by acquiring resistance to carbapenems, primarily due to the production of acquired carbapenemases. The carbapenemases detected in Enterobacteriaceae are largely of the KPC, VIM, NDM, IMP and OXA-48 types. Although the epidemiological origin and geographic distribution of carbapenemases are clearly different, they all first appeared in the late 20th Century. Only a decade later, these enzymes have already become established and have expanded globally. An important epidemiological change has occurred in Spain in recent years, characterized by a rapid increase in the number of cases of carbapenemase-producing Enterobacteriaceae (CPE), causing both nosocomial outbreaks and single infections. The impact of CPE in Spain is primarily due to OXA-48- producing and VIM-1-producing Klebsiella pneumoniae isolates, although other species such as Escherichia coli and Enterobacter cloacae are also increasing. The emergence of CPE as a cause of community-onset infections is a matter of great concern. Taking into account recent experience, and considering the fact that increasing numbers of patients are becoming infected by CPE and reservoirs of carbapenemases are growing globally, the trend of the CPE epidemic points toward a rise in its incidence. To prevent a massive CPE pandemic, a well-coordinated response from all health professionals and national and supranational authorities is clearly needed (AU)
En los últimos años, los aislamientos clínicos de enterobacterias resistentes a múltiples antibióticos, incluyendo los antibióticos carbapenémicos, han aumentado debido principalmente a la producción de carbapenemasas. Las principales carbapenemasas detectadas en enterobacterias pertenecen a los tipos KPC, VIM, NDM, IMP y OXA-48. Aunque el origen epidemiológico y la distribución geográfica de las diferentes carbapenemasas son diversos, todas aparecieron en los últimos años del siglo XX. Solo una década más tarde, estas enzimas ya se han establecido y expandido a nivel mundial. En España se ha producido un importante cambio epidemiológico en los últimos años caracterizado por un aumento rápido del número de casos de enterobacterias productoras de carbapenemasas (EPC), causando tanto brotes nosocomiales como infecciones esporádicas. En la actualidad, el mayor impacto de las EPC en España es debido a las cepas de Klebsiella pneumoniae productoras de OXA-48 o VIM-1, aunque la prevalencia de otras especies como Escherichia coli y Enterobacter cloacae también está aumentando. La aparición de EPC como causa de infecciones de inicio en la comunidad es un asunto de gran preocupación. Teniendo en cuenta las últimas tendencias detectadas y el aumento de los reservorios de carbapenemasas a nivel mundial, la evolución futura de la incidencia de las EPC no parece ser otra que la del aumento tanto en infecciones nosocomiales como en las adquiridas en la comunidad. Para prevenir una pandemia por EPC es necesaria una respuesta rotunda, bien coordinada y protocolizada de todos los profesionales sanitarios y autoridades nacionales y supranacionales implicadas (AU)
Subject(s)
Humans , Anti-Bacterial Agents/metabolism , Bacterial Proteins/metabolism , Carbapenems/metabolism , Drug Resistance, Multiple, Bacterial/genetics , Enterobacteriaceae/enzymology , Enterobacteriaceae Infections/microbiology , beta-Lactamases/metabolism , beta-Lactam Resistance/genetics , Cross Infection , Community-Acquired Infections , Forecasting , Spain , Infection Control , International Cooperation , Global Health , Evolution, MolecularABSTRACT
Infections caused by carbapenem-producing Enterobacteriaceae (CPE) can present as several infectious syndromes, but they primarily present as respiratory, urinary and blood stream infections (primary or catheter-related) that are usually found as nosocomial or healthcare-associated infections. The risk of CPE infection is influenced by individual factors, such as the length of the hospital stay and their exposure to invasive procedures and/or to antimicrobials. Of note, exposure to several antimicrobials, not only carbapenems, has been linked to CPE colonization; the duration of antibiotic exposure is one of the primary drivers of CPE acquisition. Individual risk factors must be considered jointly with the local epidemiology of these microorganisms in healthcare institutions. Overall, these infections have a high associated mortality. Mortality is influenced by host factors (e.g., age, comorbidity and immune deficiency), infection-related variables (e.g., type and severity of the infection) and treatment-related factors such as the delay in the initiation of appropriate antimicrobial therapy and the use or monotherapy or combined antimicrobial therapy. Gaining knowledge concerning the epidemiology, clinical features and prognostic features of CPE infection could be useful for improving infection prevention and for the management of patients with infections caused by these microorganisms (AU)
Las infecciones causadas por enterobacterias productoras de carbapenemasas (EPC) se pueden presentar con diferentes cuadros clínicos, aunque suelen ser más frecuentes las infecciones respiratorias, urinarias y la bacteriemia, ya sea primaria o asociada a catéter. Su adquisición es habitualmente nosocomial o relacionada con la asistencia sanitaria. El riesgo de presentar infección por EPC se relaciona con factores individuales como la duración del ingreso hospitalario y la exposición a procedimientos invasivos o antibióticos. El tratamiento previo con diversos antimicrobianos, además de carbapenemas, y en especial su duración son factores de riesgo esenciales para su adquisición. Estos factores individuales se deben valorar teniendo en cuenta la epidemiología local de las EPC en el medio sanitario. La mortalidad global de las infecciones causadas por EPC es generalmente elevada y se relaciona con factores del huésped (edad, inmunodepresión y enfermedades subyacentes), la infección (localización y gravedad) y el tratamiento antibiótico (retraso en el inicio de terapia adecuada y uso de monoterapia o terapia combinada). Un mayor conocimiento de la epidemiología, la presentación clínica y los factores pronósticos de las infecciones causadas por EPC debe contribuir a mejorar su prevención y manejo global (AU)
Subject(s)
Humans , Anti-Bacterial Agents/metabolism , Bacterial Proteins/metabolism , Carbapenems/metabolism , Enterobacteriaceae Infections/microbiology , Drug Resistance, Multiple, Bacterial/genetics , beta-Lactamases/metabolism , beta-Lactam Resistance/genetics , Risk Factors , Postoperative Complications/microbiology , Comorbidity , Cross Infection/epidemiology , Carrier State/epidemiology , Endemic DiseasesABSTRACT
No disponible
Subject(s)
Humans , Pseudomonas aeruginosa/isolation & purification , Pseudomonas Infections/microbiology , Carbapenems/metabolism , Carbapenems/therapeutic use , Public Health/methods , Public Health/trendsABSTRACT
Las metalo-βeta-lactamasas (MBL) que producen las bacterias gram-negativas son un creciente problema de salud pública en todo el mundo. Las pruebas de detección para la identificación rápida y específica de estos patógenos son esenciales y deben ser incluídas entre los diagnósticos de rutina de los laboratorios. Este estudio tiene como objetivo determinar la frecuencia de MBL en aislamientos de Pseudomona aeruginosa resistentes a carbapenem y evaluar la precisión de diferentes pruebas en la detección de la producción de MBL. Entre enero de 2001 y diciembre de 2008 un total de 142 cepas de P. aeruginosa no susceptibles a imipenem fueron aisladas de muestras clínicas provenientes de pacientes hospitalizados. Estas cepas fueron examinadas por PCR, prueba de MBL-E, prueba de sinergia de doble disco (DDS), y prueba de disco combinado (DC). La concentración inhibitoria mínima (CIM; g/ml) se determinó mediante dilución en agar. Se realizó electroforesis en gel de campo pulsado (PFGE) a todas las muestras. La secuenciación se realizó para confirmar y definir la variante de MBL y subtipo. Por PCR y análisis de secuencia de ADN, 93 cepas fueron confirmadas como positivas para MBL. A su vez, 91 cepas fueron confirmadas para el gen blaSPM-1, 1 cepa para el gen bla IMP-1, y 1 cepa para el gen bla IMP-16. La prueba de PFGE muestra un patrón clonal. Se evaluó la sensibilidad, especificidad, valores predictivos positivos y negativos para todas las pruebas. El ensayo DDS (CAZ-MPA) fue el método óptimo para la detección de la producción de MBL en las cepas de P. aeruginosa. Sin embargo, los resultados del ensayo de DC (IMP/EDTA) mostraron una estrecha concordancia con los de la DDS. Adicionalmente, el ensayo de DC permitió una interpretación más objetiva de los resultados, no requiriendo el uso de una sustancia tóxica
Metallo-βeta-lactamase (MBL)-producing gram-negative bacteria are an increasing public health concern worldwide. Screening tests for the rapid and specific identification of these pathogens are essential, and should be included among routine diagnostics in laboratories. This study aimed to determine the MBL frequency among carbapenem-resistant Pseudomonas aeruginosa isolates, and to evaluate the accuracy of different tests in screening for MBL production. From January 2001 to December 2008, a total of 142 imipenem-non-susceptible P. aeruginosa strains were isolated from distinct clinical samples from hospitalized patients. These isolates were examined by PCR, MBL E-test, double-disk synergy test (DDST), and combined disk (CD) test. The minimal inhibitory concentration (MIC; μg/mL) was determined by agar dilution, and pulsed field gel electrophoresis (PFGE) was performed on all samples. Sequencing was performed to confirm and define the MBL variant and subtype. Using PCR and DNA sequence analysis, 93 strains were confirmed positive for MBLs, 91 strains for the blaSPM-1 gene, 1 strain for the blaIMP-1 gene, and 1 strain for the blaIMP-16 gene. PFGE displayed a clonal pattern. The sensitivities, specificities, positive and negative predictive values were evaluated for all tests. The DDST assay (CAZ-MPA) was the optimal method for screening MBL production in P. aeruginosa strains. However, the results of the CD assay (IMP/EDTA) showed close agreement with those of the DDST. In addition, the CD assay allowed a more objective interpretation and did not require the use of a toxic substance
Subject(s)
Humans , Male , Female , Pseudomonas aeruginosa , Pseudomonas aeruginosa/isolation & purification , Carbapenems/metabolism , Carbapenems/therapeutic use , Bacteria/isolation & purification , Public Health/methods , Polymerase Chain Reaction/methods , Polymerase Chain Reaction/standards , Polymerase Chain Reaction , Drug Synergism , ROC CurveABSTRACT
OBJETIVO: Describir el uso de carbapenémicos en pacientes pediátricos hospitalizados fuera de las unidades de cuidados intensivos y oncohematología, y evaluar la adecuación de su prescripción a un protocolo terapéutico. PACIENTES Y MÉTODOS: Estudio retrospectivo observacional, entre enero de 2009 y diciembre de 2010, sobre la utilización de carbapenémicos en niños hospitalizados, por patología infecciosa comunitaria y relacionada con asistencia sanitaria, en el área infantil del Hospital Universitari Vall d'Hebrón, en Barcelona, excluyendo las unidades de cuidados intensivos, neonatología y oncohematología. Se recogieron datos clínicos y de consumo de antibióticos, facilitados por el Servicio de Farmacia. RESULTADOS: Cumplían los criterios de inclusión 51 episodios. En el 31,4% se indicó un carbapenémico como tratamiento empírico inicial; en el resto fue como tratamiento de rescate. Se adecúan a las indicaciones del protocolo el 70,6% de las prescripciones empíricas y el 87,5% de las dirigidas. Globalmente, el 77,6% de las prescripciones de un carbapenémico se ajustaron a las indicaciones del protocolo. En los pacientes con un ingreso previo o una enfermedad de base la prescripción empírica tiene una mejor adecuación. Factores como el diagnóstico al ingreso, la edad o la antibioterapia previa al ingreso no mostraron ninguna tendencia respecto a la indicación empírica de un carbapenémico. CONCLUSIONES: La existencia de un protocolo de indicaciones de tratamiento con carbapenémicos establecido desde 2007 en el hospital ha permitido unos resultados de adecuación de la prescripción significativamente superiores a los obtenidos en otros estudios
OBJECTIVE: To describe the use of carbapenems in children hospitalised outside intensive care and onco-haematology units, and assess adherence to a therapeutic protocol. PATIENTS AND METHODS: A retrospective observational study was conducted on the use of carbapenems between January 2009 and December 2010. The study included children with a community-acquired infectious disease or a health care-associated infectious disease, and who were admitted to paediatric areas of the Vall d'Hebron University Hospital (Barcelona, Spain), other than intensive care, neonatology and onco-haematology units. Clinical data were collected and antibiotic consumption data were provided by the Pharmacy Department. RESULTS: A total of 51 episodes fulfilled the inclusion criteria. Carbapenem as initial empirical treatment was indicated in 31.4%, and applied as rescue therapy in the remainder. The instructions of the protocol were adhered to in 70.6% of the empirical and 87.5% of the targeted prescriptions (77.6% overall). A better match was found for empirical carbapenem in patients with a previous admission or underlying condition. Factors such as diagnosis, age or antibiotic use prior to admission did not affect the empirical indication of carbapenem. CONCLUSIONS: The establishment of a treatment protocol with carbapenem indications in our centre since 2007 has yielded significantly better results on the appropriateness of the prescription than those obtained in other studies
Subject(s)
Humans , Male , Female , Child , Carbapenems/metabolism , Carbapenems/therapeutic use , Anti-Infective Agents/therapeutic use , Community-Acquired Infections/complications , Community-Acquired Infections/immunology , Community-Acquired Infections/microbiology , Clinical Protocols , Community Medicine/methods , Retrospective StudiesABSTRACT
La emergencia y diseminación de enterobacterias productoras de carbapenemasas, como paradigma actual de la resistencia extensa y de la panresistencia a antibióticos, en nuestro ámbito sanitario es una grave amenaza para la salud de los pacientes y para la salud pública. El máximo impacto de esta problemática se debe a la dispersión de cepas de Klebsiella pneumoniae productoras de OXA-48 y VIM-1. Estas evidencias llevan a los miembros de un panel representativo de los Grupos de Estudio de la Infección Hospitalaria y de los Mecanismos de Acción y de la Resistencia a Antimicrobianos de la Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica (GEIH/GEMARA-SEIMC) a posicionarse exponiendo la necesidad de una respuesta rotunda, coordinada y protocolizada por parte de todos los profesionales sanitarios y autoridades implicadas, así como una adaptación de los sistemas de salud que permita su control precoz y minimice su impacto
The emergence and spread of carbapenemase-producing Enterobacteriaceae (CPE), as the current paradigm of extensive drug-resistance and multi-drug resistance to antibiotics, is a serious threat to patient health and public health. The increase in OXA-48- and VIM-1-producing Klebsiella pneumoniae isolates represents the greatest impact of CPE in Spain. This evidence has lead the members of a representative panel of the Spanish Study Groups of Nosocomial Infections and Mechanisms of Action and Resistance to Antimicrobials of the Spanish Society of Clinical Microbiology and Infectious Diseases (GEIH/GEMARA-SEIMC) to make a position statement expressing the need for: (i) definitive and coordinated action by all health professionals and authorities involved, and (ii) an adaptation of health systems to facilitate their early control and minimize their impact
Subject(s)
Humans , Male , Female , Enterobacteriaceae/isolation & purification , Enterobacteriaceae/metabolism , Carbapenems/metabolism , Carbapenems/therapeutic use , Anti-Bacterial Agents/therapeutic use , Drug Resistance, Microbial , Enterobacteriaceae , Drug Resistance, Bacterial , Bacteria/isolation & purification , Bacteria/pathogenicityABSTRACT
Las β-lactamasas AmpC pueden hidrolizar penicilinas, cefamicinas, oximinocefalosporinas y monobactams, pero no son activas frente a cefalosporinas de cuarta generación y carbapenémicos. Los genes blaAmpC, que se encuentran en el cromosoma de algunos bacilos gramnegativos, se han integrado en elementos genéticos transferibles, lo que ha permitido su difusión a microorganismos que carecen de forma natural de ampC cromosómico o lo expresan a bajo nivel. La prevalencia de las infecciones causadas por bacterias productoras de AmpC plasmídica (pAmpC) varía en función del tipo de enzima y la localización geográfica, siendo blaCMY-2 la enzima de distribución más universal. Los aislados clínicos productores de pAmpC son con frecuencia resistentes a otros antimicrobianos, lo que reduce de manera importante las opciones terapéuticas. Se describen los métodos fenotípicos y genotípicos que permiten su detección y se analiza el papel que pueden desempeñar diferentes antimicrobianos en el tratamiento de las infecciones que producen. Este mecanismo emergente de resistencia requiere detectar y vigilar su evolución en los aislados clínicos y evaluar la sensibilidad in vitro y la eficacia clínica de otras opciones terapéuticas(AU)
AmpC β-lactamases can hydrolyze penicillins, oxyimino-, 7-α-methoxycephalosporins and monobactams. Susceptibility to cefepime or cefpirome is little affected and is unchanged for carbapenems. Originally such genes are thought to have been mobilized to mobile genetic elements from the chromosomal ampC genes from members of Enterobacteriaceae facilitating their spread and now they can appear in bacterial lacking or poorly expressing a chromosomal ampC gene. The prevalence of infection by plasmid mediated AmpC (pAmpC) varies depending on the type of enzyme and geographical location and blaCMY-2 is the most frequently detected worldwide. Typically, pAmpC producing isolates are associated with resistance to multiple antibiotics making the selection of an effective antibiotic difficult. Phenotypic and molecular methods to detect pAmpC are described and the role of different antibiotics in the treatment of these infections is examined. Surveillance studies about the evolution of this emerging resistant mechanism are important in clinical isolates. Evaluate the in vitro susceptibility of these isolates and the clinical efficacy of other therapeutic options is required(AU)
Subject(s)
Humans , Male , Female , Ambulatory Care , Emergency Medicine/methods , beta-Lactamases/therapeutic use , 3',5'-Cyclic-AMP Phosphodiesterases/therapeutic use , Infections/drug therapy , Cloxacillin/therapeutic use , Fosfomycin/therapeutic use , beta-Lactamases/pharmacology , Carbapenems/metabolism , Carbapenems/pharmacology , Carbapenems/pharmacokineticsABSTRACT
Abstract: Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae is spreading globally and represents achallenge in infection control and treatment. Solid organtransplant (SOT) recipients are especially at risk for infection bymultidrug-resistant bacteria, and little is known about infectionwith KPC-producing organisms in this setting. The aim of thisstudy was to describe the clinical and microbiologic aspects ofKPC-producing K. pneumoniae infections in SOT recipients. AKPC-2-producing K. pneumoniae outbreak was identified in apublic teaching tertiary care hospital in Sao Paulo, Brazil, in June2009. During the outbreak, cases of KPC-2-producing K.pneumoniae infection in SOT recipients occurred between July2009 and February 2010; these cases were retrospectivelyreviewed. Overall, 12 episodes of infection with KPC-producingK. pneumoniae occurred in 2 heart, 4 liver, and 6 kidneytransplant recipients with incidence rates of 16.7%, 12.9%, and26.3% in heart, liver, and kidney transplantation, respectively.Infection occurred at a median time of 20 days aftertransplantation. Primary infection sites were as follows: 4 urinarytract infections, 4 bloodstream infections, 2 pneumonias, and 2surgical site infections. All patients except one had receivedantibiotics in the last 30 days, mostly piperacillin-tazobactam orglycopeptides. All strains exhibited susceptibility to amikacin andgentamicin. Patients were treated with tigecycline plus polymyxinB (3 cases), polymyxin B plus carbapenem (3 cases), polymyxin Balone (3 cases), or tigecycline plus imipenem (1 case). In 2 cases,patients received only carbapenem, and death occurred before thefinal culture result. The overall 30-day mortality rate was 42%. Inthis series of KPC-producing K. pneumoniae infection in SOTrecipients, the infection occurrence was high during aninstitutional outbreak and was potentially life threatening.
Subject(s)
Carbapenems/metabolism , Infections , Klebsiella pneumoniae , TransplantationABSTRACT
Objective. To determine the frequency of enzymatic mechanisms associated with reduced sensitivity to broad-spectrum beta-lactam antibiotics in enterobacteria isolates obtained at hospital centers in Caracas, Venezuela.Methods. A cross-sectional study was conducted on enterobacteria isolated from patients at eight hospital centers in Caracas, Venezuela, from 15 October 2009 to 15 January 2010. The species were identified using conventional biochemical tests, and their susceptibility to antimicrobial drugs was assessed by antibiogram (Kirby-Bauer method), using the 2010 performance standards published by the Clinical and Laboratory Standards Institute. Beta-lactam-resistant genes were detected using an enhanced polymerase chain reaction assay.Results. Of 1 235 isolates, 207 (16.8%) exhibited resistance to third- and fourthgeneration cephalosporins, carbapenems, or both. They presented the following phenotypes: extended-spectrum beta-lactamase (ESBL), 93.8%; depressed AmpC, 4.3%; and carbapenemase, 1.9%. Further characterization of the first two phenotypes yielded the following breakdown of types: SHV, 36.7%; CTX-M-1 group, 22.3%; TEM, 21.7%; CTX-M-1 group with impermeability, 5.2%; two-enzyme combinations, 4.5%;CTX-M-2 group, 4.3%; PER, 3.4%; and KPC, 1.9%. The SHV type was predominant in the public hospital strains, whereas the CTX-M-1 group was most common in the strains from the private hospitals. Conclusions. Of the enzymatic mechanisms investigated, the SHV type was the most frequent, followed by the CTX-M-1 group and the TEM type. Also, a high percentageof type KPC was found. The research reported here is one of only a few multicenter studies that have been conducted in Venezuela to evaluate the frequency of this type of antimicrobial resistance mechanism, including phenotypical and molecular characterization...
Objetivo. Determinar la frecuencia de los mecanismos enzimáticos asociados a sensibilidad disminuida a los antibióticos betalactámicos de amplio espectro en aislados de enterobacteriasobtenidos de centros hospitalarios de Caracas, Venezuela. Métodos. Se realizó un estudio transversal con enterobacterias aisladas de pacientes de ocho centros hospitalarios de Caracas, Venezuela, desde el 15 de octubre de 2009 al 15 de enero de2010. La identificación se realizó mediante pruebas bioquímicas convencionales, y la susceptibilidada los antimicrobianos mediante antibiograma (Kirby-Bauer), según las normas de 2010 del Instituto de Estándares Clínicos y de Laboratorio. La detección de los genes de resistenciaa betalactámicos se realizó mediante amplificación por reacción en cadena de polimerasa. Resultados. De 1 235 aislados, 207 (16,8%) mostraron resistencia a cefalosporinas de terceray cuarta generación o a carbapenemes o a ambos. De esos, 93,8% presentaron fenotipo betalactamasa de espectro extendido (BLEE); 4,3%, fenotipo AmpC derreprimido, y 1,9%, fenotipocarbapenemasa. La caracterización de los dos primeros fenotipos determinó que 36,7% eran tipo SHV; 22,3%, grupo CTX-M-1; 21,7%, tipo TEM; 5,2%, grupo CTX-M-1 + impermeabilidad; 4,5%, combinación de dos enzimas; 4,3%, grupo CTX-M-2; 3,4%, tipo PER, y 1,9%, tipo KPC.Se observó un predominio del tipo SHV en las cepas obtenidas de hospitales públicos y del grupo CTX-M-1, en los privados. Conclusiones. De los mecanismos enzimáticos investigados, el tipo SHV fue el más frecuente,seguido del grupo CTX-M-1 y tipo TEM. Asimismo, se encontró un alto porcentaje de carbapenemasas tipo KPC. Este es uno de los pocos estudios multicéntricos realizados enVenezuela donde se evalúa la frecuencia de este tipo de mecanismo de resistencia a los antimicrobianos,incluida la caracterización fenotípica y molecular...