Rapid antibiotic susceptibility testing (RAST) of blood cultures in enterobacteria with inducible chromosomal AmpC-type B-lactamase / Pruebas rápidas de sensibilidad antibiótica de hemocultivos con enterobacterias portadoras de B-lactamasa tipo AmpC cromosómica inducible

Introduction: Early and adequate treatment of bloodstream infections decreases patient morbidity and mortality. The objective is to develop a preliminary method for rapid antibiotic susceptibility testing (RAST) in enterobacteria with inducible chromosomal AmpC. Methods: RAST was performed directly on spiked blood cultures of 49 enterobacteria with inducible chromosomal AmpC. Results were read at 4, 6 and 8h of incubation. Commercial broth microdilution was considered the reference method. Disks of 10 antibiotics were evaluated. Results: The proportion of readable tests at 4h was 85%. All RAST could be read at 6 and 8h. For most antibiotics, the S or R result at 4, 6 and 8h was greater than 80% after tentative breakpoints were established and Area of Technical Uncertainty was defined. Conclusions: This preliminary method seems to be of practical use, although it should be extended to adjust the breakpoints and differentiate them by species.(AU)

Introducción: El tratamiento precoz y adecuado de las bacteriemias disminuye la morbilidad y mortalidad de los pacientes. El objetivo es desarrollar un método preliminar de pruebas rápidas de sensibilidad antibiótica (PRSA) en enterobacterias con AmpC cromosómica inducible. Métodos: Las PRSA se realizaron directamente de hemocultivos simulados positivos para 49 enterobacterias con AmpC cromosómica inducible. Los resultados se leyeron a las 4, 6 y 8 horas de incubación. La microdilución en caldo comercial se consideró el método de referencia. Se evaluaron discos de 10 antibióticos. Resultados: La proporción de pruebas legibles a las 4 horas fue del 85%. Todas las PRSA pudieron leerse a las 6 y 8 horas. Para la mayoría de los antibióticos, el resultado S o R a las 4, 6 y 8 horas fue superior al 80%, después de que se establecieran puntos de corte provisionales y se definiera el área de incertidumbre técnica. Conclusiones: Este método preliminar parece ser de utilidad práctica, aunque debería ampliarse para ajustar los puntos de corte y diferenciar por especies.(AU)

Factors associated with non-carbapenemase mediated carbapenem resistance of Gram-negative bacteria: a retrospective case-control study

Infections with carbapenemase-producing Gram-negative bacteria are related to increased morbidity and mortality, yet little is known regarding infections caused by non-beta-lactamase mediated carbapenem-resistant bacteria. Our objective was to identify risk factors for, and the clinical impact of infections caused by carbapenem-resistant carbapenemase-negative Enterobacterales and Pseudomonas aeruginosa. This retrospective matched case-control study was performed at the University Hospital of Basel, Switzerland, in 2016. We focused on other resistance mechanisms by excluding laboratory-confirmed carbapenemase-positive cases. Carbapenem resistance was set as the primary endpoint, and important risk factors were investigated by conditional logistic regression. The clinical impact of carbapenem resistance was estimated using regression models containing the resistance indicator as explanatory factor and adjusting for potential confounders. Seventy-five cases of infections with carbapenem-resistant, carbapenemase-negative bacteria were identified and matched with 75 controls with carbapenem-susceptible infections. The matched data set was well-balanced regarding age, gender, and comorbidity. Duration of prior carbapenem treatment (OR 1.15, [1.01, 1.31]) correlated with resistance to carbapenems. Our study showed that patients with carbapenem-resistant bacteria stayed 1.59 times (CI [0.81, 3.14]) longer in an ICU. The analyzed dataset did not provide evidence for strong clinical implications of resistance to carbapenems or increased mortality. The duration of prior carbapenem treatment seems to be a strong risk factor for the development of carbapenem resistance. The higher risk for a longer ICU stay could be a consequence of a carbapenem resistance. In contrast to carbapenemase-producers, the clinical impact of carbapenamase-negative, carbapenem-resistant strains may be limited... (AU)

Review of carbapenemics de-escalation in extended-spectrum b-lactamases producing enterobacteriaceae urinary tract infections in clinical practice / Revisión de la desescalada de carbapenémicos en las infecciones del tracto urinario por enterobacterias productoras de betalactamasas

The indiscriminate use of carbapenem antibiotics in urinary tract infections poses a risk of increasing antimicrobial resistance to them. The use of carbapenem antibiotics should be reserved for those urinary tract infections caused by extended-spectrum β-lactamases -producing Enterobacteriaceae. However, there is sufficient evidence of the possibility of using different therapeutic options to carbapenems in certain infections with extended-expectrum β-lactamases isolation and sensitivity data. Of the patients analysed in the study, those with urinary tract infection by extended-spectrum β-lactamases -producing Enterobacteriaceae treated with antibiotics other than carbapenemics based on susceptibility data, achieved resolution of infection in those cases where they were clinically well, so the use of these alternatives would be an appropriate optimisation and rational use of carbapenemic. (AU)

El uso indiscriminado de antibióticos carbapenémicos en infecciones del tracto urinario supone un riesgo de aumento de la resistencia antimicrobiana a los mismos. El uso de antibióticos carbapenémicos debe reservarse para aquellas infecciones del tracto urinario causadas por Enterobacterias productoras de betalactamasas de espectro extendido. Sin embargo, existe evidencia suficiente de la posibilidad de utilizar opciones terapéuticas diferentes a los carbapenémicos en determinadas infecciones con datos de sensibilidad. De los pacientes analizados en el estudio, aquellos con infección del tracto urinario por Enterobacterias productoras de betalactamasas de espectro extendido y tratados con antibióticos distintos a los carbapenémicos según datos de sensibilidad, consiguieron resolver la infección en aquellos casos en los que presentaban buen estado clínico por lo que el uso de estas alternativas supondría una adecuada optimización y uso racional de carbapenémicos. (AU)

Plasmids of the incompatibility group FIBK occur in Klebsiella variicola from diverse ecological niches / Los plásmidos del grupo de incompatibilidad FIBK se encuentran en Klebsiella variicola en diversos nichos ecológicos

Plasmids play a fundamental role in the evolution of bacteria by allowing them to adapt to different environments and acquire, through horizontal transfer, genes that confer resistance to different classes of antibiotics. Using the available in vitro and in silico plasmid typing systems, we analyzed a set of isolates and public genomes of K. variicola to study its plasmid diversity. The resistome, the plasmid multilocus sequence typing (pMLST), and molecular epidemiology using the MLST system were also studied. A high frequency of IncF plasmids from human isolates but lower frequency from plant isolates were found in our strain collection. In silico detection revealed 297 incompatibility (Inc) groups, but the IncFIBK (216/297) predominated in plasmids from human and environmental samples, followed by IncFIIK (89/297) and IncFIA/FIA(HI1) (75/297). These Inc groups were associated with clinically important ESBL (CTX-M-15), carbapenemases (KPC-2 and NDM-1), and colistin-resistant genes which were associated with major sequence types (ST): ST60, ST20, and ST10. In silico MOB typing showed 76% (311/404) of the genomes contained one or more of the six relaxase families with MOBF being most abundant. We identified untypeable plasmids carrying blaKPC-2, blaIMP-1, and blaSHV-187 but for which a relaxase was found; this may suggest that novel plasmid structures could be emerging in this bacterial species. The plasmid content in K. variicola has limited diversity, predominantly composed of IncFIBK plasmids dispersed in different STs. Plasmid detection using the replicon and MOB typing scheme provide a broader context of the plasmids in K. variicola. This study showed that whole-sequence-based typing provides current insights of the prevalence of plasmid types and their association with antimicrobial resistant genes in K. variicola obtained from humans and environmental niches.(AU)

Virulence, antimicrobial resistance, and molecular characteristics of carbapenem-resistant Klebsiella pneumoniae in a hospital in Shijiazhuang City from China / Virulencia, resistencia a los antimicrobianos y características moleculares de Klebsiella pneumoniae resistente a carbapenémicos en un hospital de la ciudad de Shijiazhuang de China

Carbapenem-resistant Klebsiella pneumoniae (CRKP), as one of the most common drug-resistant bacteria threatening human health, is hyper-resistant to multiple antimicrobial drugs and carbapenems, which can be dealt with only limited clinical treatment options. This study described the epidemiological characteristics of CRKP in this tertiary care hospital from 2016 to 2020. Specimen sources included blood, sputum, alveolar lavage fluid, puncture fluid, secretions from a burn wound, and urine. Among the 87 carbapenem-resistant strains, ST11 was the predominant isolate, followed by ST15, ST273, ST340, and ST626. These STs were in broad agreement with the STs defined by pulsed-field gel electrophoresis clustering analysis in discriminating clusters of related strains. Most CRKP isolates contained the blaKPC-2 gene, some isolates carried the blaOXA-1, blaNDM-1, and blaNDM-5 genes, and the isolates carrying carbapenem resistance genes were more resistant to the antimicrobials of β-lactams, carbapenems, macrolides, and fluoroquinolone. The OmpK35 and OmpK37 genes were detected in all CRKP strains, and the Ompk36 gene was detected in some CRKP strains. All detected OmpK37 had 4 mutant sites, and OmpK36 had 11 mutant sites, while no mutant sites were found in OmpK35. More than half of the CRKP strains contained the OqxA and OqxB efflux pump genes. The virulence genes were most commonly combined with urea-wabG-fimH-entB-ybtS-uge-ycf. Only one CRKP isolate was detected with the K54 podoconjugate serotype. This study elucidated the clinical epidemiological features and molecular typing of CRKP, and grasped the distribution of drug-resistant genotypes, podocyte serotypes, and virulence genes of CRKP, providing some guidance for the subsequent treatment of CRKP infection.(AU)

Reconstrucción ancestral de una B-lactamasa y comparativa con sus homólogos actuales / Ancestral reconstruction of a B-lactamase and comparison with its extant proteins

Las B-lactamasas son proteínas de origen bacteriano que se caracterizan por hidrolizar los antibióticos B-lactámicos, confiriendo resistencia microbiana ante estos. Son una familia heterogénea de proteínas muy relevantes desde el punto de vista sanitario debido a la facilidad que presentan para adquirir resistencia a nuevos fármacos por su alta capacidad de evolución.La evolución in vitro de estas proteínas ha servido, no solo para desarrollar su caracterización y mejorar su conocimiento, sino como una nueva línea de investigación que permite identificar de manera predictiva residuos implicados en la adquisición de resistencia frente antibióticos. Al mismo tiempo, el método de reconstrucción ancestral de proteínas se ha revelado como una herramienta novedosa y útil para comprender la evolución de las β- lactamasas y entender algunas de sus características como es su promiscuidad. En este trabajo, se ha realizado un estudio de B-lactamasas ancestrales reconstruidas a partir de la filogenia de B-lactamasas existentes de clase A. De las cuatro proteínas ancestrales estudiadas, se ha obtenido una que es funcional y se ha comparado su actividad hidrolítica con la de cuatro de sus homólogos actuales frente a ocho fármacos B-lactámicos. Se ha comprobado que esta proteína ancestral tiene una actividad frente aantibióticos más generalista que cualquier de las proteínas actuales estudiadas. Además, la proteína ancestral activa mostró más resistencia frente a uno de los fármacos utilizados que el resto de B-lactamasas existentes. Finalmente se han discutido estos resultados y a partir de ellos se argumenta por qué las secuencias ancestrales reconstruidas pueden ser un punto de partida muy atractivo a la hora de realizar evolución dirigida de proteínas para la obtención de proteínas de interés biotecnológico. (AU)

The B-lactamases are proteins of bacterial origin that are characterized by hydrolyzing antibiotics B-lactams, conferring microbial resistance against them. They are a heterogeneous family of proteins very relevant from a health point of view due to the ease they present to acquire resistance to new drugs due to their high capacity for evolution.The in vitro evolution of these proteins has served not only to develop their characterization and improve their knowledge, but as a new line of research that allows to predictively identify residues involved in the acquisition of antibiotic resistance.At the same time, the method of ancestral protein reconstruction has been revealed as a novel and useful tool to understand the evolution of B-lactamases and understand some of their characteristics such as their promiscuity.In this work, a study of ancestral B-lactamases reconstructed from the phylogeny of existing class A B-lactamases has been carried out. Of the four ancestral proteins studied, one has been obtained that is functional and has compared its hydrolytic activity with that of four of its current counterparts against eight β-lactam drugs. This ancestral protein has been shown to have a more generalistic antibiotic activity than any of the current proteins studied. In addition, the active ancestral protein showed more resistance to one of the drugs used than the rest of B-lactamases existing. Finally these results have been discussed and from them it is argued why reconstructed ancestral sequences can be a very attractive starting point when it comes to direct evolution of proteins for obtaining proteins of biotechnological interest.

Treatment of infections caused by carbapenemase-producing Enterobacterales

Antibiotic resistance is one of the main menaces to public and individual health worldwide. In the last two decades, an increase in the detection of arbapenem-resistant Enterobacterales has been reported. The treatment of infections caused by these strains is a therapeutic challenge. The use of carbapenems may be beneficial depending on MIC value and source of infection. New drugs, with different activity against the different classes of carbapenemases, are developed showing significant benefits. (AU)

Antibacterial spectrum of cefiderocol

Cefiderocol, a siderophore catechol cephalosporin, recently introduced in the market has been developed to enhance the in vitro activity of extended spectrum cephalosporins and to avoid resistance mechanisms affecting cephalosporins and carbapenems. The in vitro study of cefiderocol in the laboratory requires iron depleted media when MIC values are determined by broth microdilution. Disk diffusion presents good correlation with MIC values. In surveillance studies and in clinical trials it has been demonstrated excellent activity against Gram-negatives, including carbapenemase producers and non-fermenters such as Pseudomonas aeruginosa, Acinetobacter baumannii and Stenotrophomonas maltophilia. Few cefiderocol resistant isolates have been found in surveillance studies. Resistance mechanisms are not directly associated with porin deficiency and or efflux pumps. On the contrary, they are related with gene mutations affecting iron transporters, AmpC mutations in the omega loop and with certain beta-lactamases such us KPC-variants determining also ceftazidime-avibactam resistance, certain infrequent extended-spectrum betalactamases (PER, BEL) and metallo-beta-lactamases (certain NDM variants and SPM enzyme). (AU)

In vitro activity of six biocides against carbapenemase-producing Klebsiella pneumoniae and presence of genes encoding efflux pumps / Actividad in vitro de seis biocidas frente a Klebsiella pneumoniae productora de carbapenemasa y presencia de genes codificantes de bombas de expulsión

Introduction: Acquisition of reduced susceptibility to biocides may contribute to the dissemination of high-risk (HR) clones of carbapenemase-producing Klebsiella pneumoniae (CP-Kp). The aim of this study was (a) to determinate the activity of biocides against CP-Kp, and (b) to analyse the relationship between biocide activity and the presence of efflux pumps. Methods: The minimal inhibitory concentrations (MICs) of 6 biocides (sodium hypochlorite, chlorhexidine digluconate, benzalkonium chloride, povidone-iodine, ethanol and triclosan) were determined in triplicate at 25°C and 37°C in Mueller-Hinton broth (MHB) and M9 minimum medium, against 17 CP-Kp isolates representing different clones (HR and no-HR), sequence-types (STs) and carbapenemases. Efflux pumps genes were detected by whole genome sequencing (MiSeq). Results: Median MICs were slightly higher at 37°C than at 25°C (p≤0.05), except for benzalkonium chloride, triclosan and ethanol. MIC medians were much higher in MHB than in M9, except for triclosan. No significant differences were observed in the median MICs, regarding the type of clone, ST or carbapenemase; cepA, acrAB, kpnEF and oqxAB genes were detected in all isolates, whereas qacE and qacA were not detected; smvAR, and qacΔE genes were detected in 94% and 47% of isolates, respectively. Conclusions: Triclosan, chlorhexidine digluconate, benzalkonium chloride and ethanol were the most active biocides. The activity of some biocides is affected by temperature and growth media, suggesting that standardised procedures for biocide susceptibility testing based on MIC determination are required. This activity, in terms of MICs, are not related to the type of clone, ST, carbapenemase or the presence of the efflux pump genes.(AU)

Introducción: La adquisición de sensibilidad reducida a los biocidas puede contribuir a la diseminación de clones de alto riesgo (HR) de Klebsiella pneumoniae productor de carbapenemasa (Kp-PC). El objetivo de este trabajo fue: (a) determinar la actividad de varios biocidas frente a Kp-PC, y (b) analizar la relación de dicha actividad con la presencia de genes codificantes de bombas de expulsión. Métodos: Las concentraciones mínimas inhibitorias (CMI) de 6 biocidas (hipoclorito de sodio, digluconato de clorhexidina, cloruro de benzalconio, povidona yodada, etanol y triclosán) se determinaron por triplicado a 25 y 37°C, tanto en caldo Mueller-Hinton (MHB) como en medio mínimo M9, frente a 17 aislados de Kp-PC representativos de diferentes clones (HR y no HR), secuenciotipos (ST) y carbapenemasas. Los genes de bombas de expulsión se detectaron mediante secuenciación masiva del genoma completo (MiSeq). Resultados: Las medianas de las CMI fueron ligeramente superiores a 37°C que a 25°C, excepto para cloruro de benzalconio, etanol y triclosán. Las medianas de las CMI fueron considerablemente superiores en MHB que en M9, excepto para triclosán; cepA, acrAB, kpnEF y oqxAB se detectaron en todos los aislados, mientras que qacE y qacA no se detectaron; smvAR y qacΔE se detectaron en el 94% y en el 47% de los aislados, respectivamente. Conclusiones: La actividad de algunos biocidas se afecta por la temperatura y el medio de crecimiento. Esta actividad, en términos de CMI, no se relaciona con el tipo de clon, ST, carbapenemasa, ni con la presencia de genes que codifican bombas de expulsión.(AU)

Evaluation of a lateral flow immunoassay to detectCTX-M extended-spectrum B-lactamases (ESBL)directly from positive blood cultures for its potentialuse in Antimicrobial Stewardship programs / Evaluación de una inmunocromatografía paradetectar beta-lactamasas de espectro extendidoCTX-M directamente de hemocultivos positivospara su potencial uso en programas deoptimización de antibioterapia

Background. Bloodstream infections (BSI) caused by extended-spectrum beta-lactamases Enterobacteriaceae (ESBL-E) are associated with high rates of treatment failure andincreased mortality, especially when appropriate antimicrobialtherapy is delayed. Our aim was to evaluate the anticipationof ESBLs detection and the potential improvement of the timeresponse of the Vitek 2 System (BioMérieux; France).Methods. We compared this lateral flow immunoassaywhen used directly on fluid from positive blood cultures to theVITEK2 AST system. We evaluated 80 isolates, 61 tested directlyon fluid from positive blood cultures and 19 tested on fluidfrom blood cultures spiked with known ESBL positive and negative organisms.Results. The concordance between the CTX-LFIA and thereference method (Vitek 2) had a Cohen´s Kappa coefficient of0.97, indicating a particularly good correlation between bothcompared methods.Conclusion. This lateral flow immunoassay can be morerapid than the Vitek 2 for earlier presumptive identification ofCTX- M ESBLs and can be useful to anticipate results and theadjustment of antimicrobial therapy. (AU)

Antecedentes. Las bacteriemias causadas por Enterobacteriaceae productoras beta-lactamasas de espectro extendido(BLEE) están asociadas con altas tasas de fallo de tratamientoy mortalidad, especialmente cuando se retrasa el tratamientoapropiado. Nuestro objetivo ha sido evaluar la anticipación dela detección de estas BLEE y la potencial mejora en el tiempode respuesta respecto al VITEK2 System (Biomerieux; Francia).Métodos. Se comparó una inmunocromatografía para sudetección con el VITEK2 AST system directamente del hemocultivo. Se evaluaton 80 aislados, 61 evaluados directamentede hemocultivos positivos y 19 de la misma manera pero inoculados con microorganismos productores y no productores deBLEE.Resultados. La concordancia entre la inmunocromatografía y el VITEK2 AST mostró un coeficiente Kappa de 0,97,indicando una buena correlación entre ambas técnicas.Conclusión. Esta inmunocromatografía puede ser másrápida que el VITEK2 para una identificación de BLEE tipo CTXM y puede ser útil para anticipar resultados y ajustar la terapiaantimicrobiana. (AU)

Ceftazidime-avibactam

The increase in nosocomial infections by beta-lactamaseproducing Gram-negative bacilli constitutes a therapeuticchallenge. The combination of ceftazidime-avibactam offers avery interesting therapeutic option for nosocomial pneumoniacaused by extended-spectrum beta-lactamase-producingKlebsiella pneumoniae, multidrug-resistant Pseudomonasaeruginosa, and other enterobacteria. Compared to carbapenems,ceftazidime-avibactam has demonstrated non-inferiority in thetreatment of nosocomial pneumonia including better clinical andmicrobiological cure rates and mortality compared to colistin. Thelimitation of ceftazidime-avibactam in the treatment of infectionscaused by metallo-beta-lactamase-producing Enterobacteriaceaecan be overcome with the addition of aztreonam (AU)

New evidence in severe pneumonia: meropenem-vaborbactam

The appearance and spread of new mechanisms of bacterial resistance to antibiotics is a serious health problem. Oneof the most difficult resistance mechanisms to treat is theproduction of carbapenemases. Carbapenemase KPC is one ofthose mechanisms with few therapeutic options. Meropenem-vaborbactam has shown great efficacy against this type ofmicroorganism, both from a clinical and microbiological pointof view. Its good pharmacokinetics, including in the lung, andits safety profile make meropenem-vaborbactam an excellenttherapeutic option. Finally, the absence of resistance genesisduring treatment seems to indicate that its efficacy will belong-lasting. (AU)

Implementation of contact isolation strategy for the containment of extended - spectrum beta lactamase carriers in a University Hospital positively affects the epidemiology of carbapenemase-producing Enterobacterales / La implementación de la estrategia de aislamiento de contacto para la contención de portadores de beta lactamasas de espectro extendido en un hospital universitario afecta positivamente a la epidemiología de las enterobacterias productoras de carbapenemasas

Introduction: The lack of consensus of control measures to prevent extended-spectrum β-lactamase producing Enterobacterales (ESBL-E) transmission in the hospital setting is of great concern. We describe the prevalence and species distribution of ESBL-E and carbapenemase producing Enterobacterales (CPE) in patients admitted in a tertiary Hospital during an active surveillance screening program for detecting ESBL-E carriers and reducing the ESBL-E transmission (R-GNOSIS Project). Methods: From March-2014 to March-2016, 15,556 rectal swabs were collected from 8209 patients admitted in two medical (Gastroenterology, Pneumology) and two surgical (Neurosurgery, Urology) wards. Swabs were seeded onto ChromoID-ESBL and -CARB/OXA-48 agar plates. Growing colonies were identified by MALDI-TOF MS. ESBL and carbapenemases were phenotypically detected. Changes in species diversity (SDI) and distribution over time were analyzed. Results: ESBL-E incidence (8.4%) tended to decrease over time (p=0.003) and CPE carrier prevalence remained unchanged during the study (2%). The contact isolation strategy targeted to reduce ESBL-E transmission was ineffective in reducing ESBL-E carriers but significant differences were observed with CPE (p=0.017). SDI did not change among ESBL-E and E. coli was predominant (78.5%) during the study. K. pneumoniae (54%) was the most frequent CPE species, followed by E. coli (19%). SDI decreased among the CPE population over time mainly due to K. pneumoniae dominance and increased E. coli prevalence in the last part of the study. Conclusions: During the R-GNOSIS project, contact precautions were not effective in reducing the ESBL-E transmission but may have had a positive collateral effect on the CPE containment.(AU)

Introducción: La falta de consenso en las medidas de control necesarias para prevenir la transmisión de enterobacterias productoras de β-lactamasas de espectro extendido (BLEE-E) en el entorno hospitalario es muy preocupante. En este trabajo describimos la prevalencia y la distribución de especies de BLEE-E y las enterobacterias productoras de carbapenemasas (EPC) en pacientes ingresados en un hospital terciario durante un programa de vigilancia activa para detectar portadores de BLEE-E y reducir su transmisión (Proyecto R-GNOSIS). Métodos: Entre marzo-2014 y marzo-2016 se recogieron 15.556 hisopos rectales de 8.209 pacientes ingresados en 2 servicios médicos (Gastroenterología, Neumología) y 2 quirúrgicos (Neurocirugía, Urología). Los hisopos se sembraron en las placas de agar ChromoID-ESBL y CARB/OXA-48. Las colonias crecidas fueron identificadas por MALDI-TOF MS. La producción de BLEE y carbapenemasas se confirmó fenotípicamente. Se analizaron los cambios en la diversidad de especies (SDI) y su distribución en el tiempo. Resultados: La incidencia de BLEE-E (8,4%) tendió a disminuir (p=0,003) y la prevalencia de portadores de CPE permaneció sin cambios durante el estudio (2%). La estrategia de aislamiento de contacto dirigida a reducir la transmisión de BLEE-E fue ineficaz, pero se observaron diferencias significativas en las EPC (p=0,017). La SDI de las BLEE-E no cambió durante el estudio y E. coli fue la especie predominante (78,5%). K. pneumoniae (54%) fue la especie de EPC más frecuente, seguida de E. coli (19%). El SDI disminuyó entre la población de EPC, principalmente debido al dominio de K. pneumoniae y al aumento de la prevalencia de E. coli en la última parte del estudio. Conclusiones: Durante el proyecto R-GNOSIS, las precauciones de contacto no fueron efectivas para reducir la transmisión de BLEE-E, pero pudo haber tenido un efecto colateral positivo en la contención de EPC.(AU)

Perfil etiológico y sensibilidad antimicrobiana en 1740 infecciones urinarias de la comunidad en la ciudad de Córdoba, Argentina / Etiological profile and antimicrobial susceptibility in 1740 community urinary tract infections in the city of Córdoba, Argentina

Introducción: Las infecciones deltracto urinario (ITU) son una de las infecciones más comunes que afectan al ser humano a lo largo de su viday constituyen un problema de salud frecuente tanto en elámbito comunitario como nosocomial. El conocimientode las características microbiológicas, perfil de sensibilidad y factores de riesgo permiten optimizar el manejode las ITU minimizando el incremento de resistencia antibiótica (RA), estableciendo tratamientos precoces parareducir la morbilidad y la gravedad de la infección.Este estudio tiene como objetivo establecer cuáles sonlos microorganismos responsables de las infecciones urinarias de la comunidad en nuestro medio y determinarsu RA. Pacientes y métodos: Estudio observacional, descriptivo, transversal, retrospectivo de todos los pacientescon primer episodio de ITU registrado en el SanatorioAllende de la ciudad de Córdoba, Argentina a loscuales se les solicitó urocultivo (URC), desde enero de2016 a diciembre 2017.Resultados: Se analizaron 3636 URC positivos delos cuales 1740 cumplieron con los criterios de inclusión. Del total analizado 90,2% (n=1570) fueron desexo femenino. El promedio de edad fue 37,8 años(DE=15,2).Escherichia coli fue el microorganismo aislado en mayorfrecuencia en un 80,3% seguido de S. saprophyticusen un 8,0 %. El grupo etario de 18-30 años (40,1%)demostró la mayor proporción de microorganismos, endonde observamos mayor prevalencia de E. coli y S.saprophyticus. Del total de aislamientos se obtuvieronlas siguientes resistencias adquiridas: 47,6% de los microorganismos fueron resistentes a ampicilina, 29,6%a cotrimoxazol, 15,2% a ciprofloxacina, 4,6% a cefalosporinas de 1° generación, 3,4% a cefixima, 2,3%a amoxicilina-clavulánico, 1,2% a gentamicina y 1% anitrofurantoína.Conclusion: E. Coli fue el patógeno más frecuente en nuestro entorno, con altas tasas de resistencia aampicilina, fluoroquinolonas y TMS...(AU)

Introduction: Urinary tract infections(Uti) are one of the most common infections that affecthumans throughout their lives and are a common healthproblem both at the community and at the nosocomiallevel. Knowing microbiological characteristics, sensitivity profile and risk factors allow to optimize the management of Utis minimizing the increase of antibiotic resistance (AR) and establishing early treatments to reducethe morbidity and severity of infection. This study aimsto establish which microorganisms are responsible forurinary tract infections in our community and determinetheir AR.Patients and methods: An observational, descriptive, cross-sectional, retrospective study of all patientswith the first episode of UTI recorded at the SanatorioAllende in the city of Cordoba, Argentina, who wererequested to undergo urine culture (URC), from January2016 to December 2017.Results: 3636 positive URC were analyzed, of which1740 met the inclusion criteria. Of the total analyzed90.2 % (n=1570) were female. The average age was37.8 years (SD=15.2).Escherichia coli was the microorganism most frequentlyisolated in 80.3% followed by S. saprophyticus in 8.0%.The age group of 18-30 years (40.1%) showed the highest proportion of microorganisms, where we observedthe highest prevalence of E. coli and S. saprophyticus.The following acquired resistances were obtained fromthe total isolations: 47.6% of the microorganisms wereresistant to ampicillin, 29.6% to cotrimoxazole, 15.2%to ciprofloxacin, 4.6% to first generation of cephalosporins, 3.4% to cefixime, 2.3% to amoxicillin-clavulanic, 1,2% to gentamicin and 1% to nitrofurantoin.Conclusion: E. Coli was the most prevalent pathogen in our environment, with high rates of resistanceto ampicillin, fluoroquinolones and trimethoprim-sulfamethoxazole, confirming the need for periodic studiesto determine the most optimal empirical antibiotic treatment.(AU)

Reconstrucción ancestral de una beta-lactamasa y comparativa con sus homólogos actuales / Ancestral reconstruction of a beta-lactamase and comparison with its extant proteins

Las β-lactamasas son proteínas de origen bacteriano que se caracterizan por hidrolizar los antibióticos β-lactámicos, confiriendo resistencia microbiana ante estos. Son una familia heterogénea de proteínas muy relevantes desde el punto de vista sanitario debido a la facilidad que presentan para adquirir resistencia a nuevos fármacos por su alta capacidad de evolución. La evolución in vitro de estas proteínas ha servido, no solo para desarrollar su caracterización y mejorar su conocimiento, sino como una nueva línea de investigación que permite identificar de manera predictiva residuos implicados en la adquisición de resistencia frente antibióticos. Al mismo tiempo, el método de reconstrucción ancestral de proteínas se ha revelado como una herramienta novedosa y útil para comprender la evolución de las β- lactamasas y entender algunas de sus características como es su promiscuidad. En este trabajo, se ha realizado un estudio de β-lactamasas ancestrales reconstruidas a partir de la filogenia de β-lactamasas existentes de clase A. De las cuatro proteínas ancestrales estudiadas, se ha obtenido una que es funcional y se ha comparado su actividad hidrolítica con la de cuatro de sus homólogos actuales frente a ocho fármacos β-lactámicos. Se ha comprobado que esta proteína ancestral tiene una actividad frente a antibióticos más generalista que cualquier de las proteínas actuales estudiadas. Además, la proteína ancestral activa mostró más resistencia frente a uno de los fármacos utilizados que el resto de β-lactamasas existentes. Finalmente se han discutido estos resultados y a partir de ellos se argumenta por qué las secuencias ancestrales reconstruidas pueden ser un punto de partida muy atractivo a la hora de realizar evolución dirigida de proteínas para la obtención de proteínas de interés biotecnológico.(AU)

The β-lactamases are proteins of bacterial origin that are characterized by hydrolyzing antibiotics β-lactams, conferring microbial resistance against them. They are a heterogeneous family of proteins very relevant from a health point of view due to the ease they present to acquire resistance to new drugs due to their high capacity for evolution. The in vitro evolution of these proteins has served not only to develop their characterization and improve their knowledge, but as a new line of research that allows to predictively identify residues involved in the acquisition of antibiotic resistance. At the same time, the method of ancestral protein reconstruction has been revealed as a novel and useful tool to understand the evolution of β-lactamases and understand some of their characteristics such as their promiscuity. In this work, a study of ancestral β-lactamases reconstructed from the phylogeny of existing class A β-lactamases has been carried out. Of the four ancestral proteins studied, one has been obtained that is functional and has compared its hydrolytic activity with that of four of its current counterparts against eight β-lactam drugs. This ancestral protein has been shown to have a more generalistic antibiotic activity than any of the current proteins studied. In addition, the active ancestral protein showed more resistance to one of the drugs used than the rest of β-lactamases existing. Finally these results have been discussed and from them it is argued why reconstructed ancestral sequences can be a very attractive starting point when it comes to direct evolution of proteins for obtaining proteins of biotechnological interest.(AU)

Characterization of AmpC Beta-lactamase mutations of extensively drug-resistant Pseudomonas aeruginosa isolates that develop resistance to ceftolozane/tazobactam during therapy / Caracterización de las mutaciones en la betalactamasa AmpC de aislados de Pseudomonas aeruginosa XDR que desarrollaron resistencia a ceftolozano/tazobactam durante el tratamiento

INTRODUCTION: We characterized AmpC β-lactamase mutations that resulted in ceftolozane/tazobactam resistance in extensively drug-resistant (XDR) Pseudomonas aeruginosa isolates recovered from patients treated with this agent from June 2016 to December 2018. METHODS: Five pairs of ceftolozane/tazobactam susceptible/resistant P. aeruginosa XDR isolates were included among a total of 49 patients treated. Clonal relationship among isolates was first evaluated by pulsed-field gel electrophoresis (PFGE). Multilocus sequence typing (MLST) was further performed. AmpC mutations were investigated by PCR amplification of the blaPDC gene followed by sequencing. RESULTS: The ST175 high-risk clone was detected in four of the pairs of isolates and the ST1182 in the remaining one. All resistant isolates showed a mutation in AmpC: T96I in two of the isolates, and E247K, G183V, and a deletion of 19 amino acids (G229-E247) in the other three. The G183V mutation had not been described before. The five isolates resistant to ceftolozane/tazobactam showed cross-resistance to ceftazidime/avibactam and lower MICs of imipenem and piperacillin/tazobactam than the susceptible isolates. CONCLUSIONS: Ceftolozane/tazobactam resistance was associated in all of the cases with AmpC mutations, including a novel mutation (G183V) not previously described. There is a vital need for surveillance and characterization of emerging ceftolozane/tazobactam resistance, in order to preserve this valuable antipseudomonal agent

INTRODUCCIÓN: Se han caracterizado las mutaciones en la betalactamasa AmpC que han producido resistencia a ceftolozano/tazobactam en aislados de Pseudomonas aeruginosa extremadamente resistente (XDR) en pacientes tratados con este agente desde junio de 2016 hasta diciembre de 2018. MÉTODOS: Se incluyeron 5 pares de aislados (sensibles/resistentes a ceftolozano/tazobactam) de P. aeruginosa XDR entre un total de 49 pacientes tratados. Se estudió la relación clonal mediante electroforesis en campo pulsado y MLST. Las mutaciones en AmpC se caracterizaron mediante amplificación por PCR del gen blaPDC y posterior secuenciación. RESULTADOS: Se detectó el clon de alto riesgo ST175 en 4 pares de aislados y el ST1182 en el restante. Todos los aislados resistentes mostraron una mutación en AmpC: T96I en 2 aislados, E247K, G183V y una deleción de 19 aminoácidos (G229-E247) en los otros 3. La mutación G183V no había sido descrita antes. Los 5 aislados resistentes a ceftolozano/tazobactam mostraron resistencia cruzada a ceftazidima/avibactam y CMI inferiores de imipenem y piperacilina/tazobactam que los aislados sensibles. CONCLUSIONES: La resistencia a ceftolozano/tazobactam se asoció con mutaciones en AmpC en todos los casos, incluida una nueva mutación G183V no descrita con anterioridad. La vigilancia y caracterización de la resistencia emergente a ceftolozano/tazobactam es de gran importancia para preservar este nuevo agente antipseudomónico

Risk factors for methicillin-resistant Staphylococcus aureus and extended-spectrum Beta-lactamase-producing Enterobacterales in patients with diabetic foot infections requiring hospital admission / Factores de riesgo de infección por Staphylococcus aureus resistente a meticilina y enterobacterias productoras de betalactamasas en infecciones de pie diabético que requieren hospitalización

OBJETIVO: Staphylococcus aureus resistente a meticilina (MRSA) y las enterobacterias productoras de betalactamasas (ESBL-E) pueden complicar el tratamiento de las infecciones del pie del diabético (DFIs). El objetivo de este estudio fue determinar los factores de riesgo de las infecciones por estos microorganismos en el pie del diabético. MATERIAL Y MÉTODOS: Estudio observacional prospectivo de 167 pacientes consecutivos con infecciones del pie del diabético. El diagnóstico y gravedad de las infecciones se basó en la guía de la Infectious Disease Society of America (IDSA). Para identificar los factores de riesgo de las infecciones por MRSA y (ESBL-E) se llevó a cabo mediante un estudio multivariante. RESULTADOS: S. aureus fue el microorganismo más aislado (n= 82; 37,9 %) seguido por Escherichia coli (n= 40; 18,5%). El 57,3% de S. aureus fueron MRSA y el 70% de Klebsiella pneumoniae y el 25% de E. coli eran productores ESBL, respetivamente. Los factores de riesgo independientes de las infecciones por MRSA fueron las úlceras profundas [OR 8,563; IC 95% (1,068-4,727)], uso previo de fluoroquinolonas [OR 2,78; IC 95% (1,156-6,685)] y la vasculopatía periférica [OR 2,47; IC 95% (1.068-4.727)], mientras que para las infecciones por (ESBL-E) lo fueron osteomielitis [OR 6,351; 95% IC 95% (1,609-25,068)] y el uso previo de cefalosporinas [OR 5,824; IC 95% (1,517-22,361)]. CONCLUSIONES: MRSA y ESBL-E han adquirido una gran relevancia clínica en las DFIs. La disponibilidad de sus factores de riesgo es muy conveniente para elegir el tratamiento empírico en las formas graves

PURPOSE: Methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum Beta-lactamase-producing Enterobacterales (ESBL-E) may complicate the treatment of diabetic foot infections (DFIs). The aim of this study was to determine the risk factors for these pathogens in DFIs. MATERIAL AND METHODS: This was a prospective observational study of 167 consecutive adult patients with DFIs. The diagnosis and severity of DFIs were based on the Infectious Disease Society of America (IDSA) classification system. Multivariate analyses were performed in order to identify risk factors for MRSA and ESBL-E infections. RESULTS: S. aureus was the most isolated pathogen (n=82, 37.9 %) followed by Escherichia coli (n= 40, 18.5%). MRSA accounted for 57.3% of all S. aureus and 70% of Klebsiella pneumoniae and 25% of E. coli were ESBL producers, respectively. Deep ulcer [OR 8,563; 95% CI (1,068-4,727)], previous use of fluoroquinolones [OR 2,78; 95% CI (1,156-6,685)] and peripheral vasculopathy [OR 2,47; 95% CI (1.068-4.727)] were the independent predictors for MRSA infections; and osteomyelitis [OR 6,351; 95% CI (1,609-25,068)] and previous use of cephalosporins [OR 5,824; 95% CI (1,517-22,361)] for ESBL-E infections. CONCLUSIONS: MRSA and ESBL-E have adquired a great clinical relevance in DFIs. The availability of their risk factors is very convenient to choose the empirical treatment in severe forms

Assessment of a semi-automated enrichment system (Uroquattro HB&L) for detection of faecal carriers of ESBL-/AmpC-producing Enterobacterales / Evaluación de un sistema de enriquecimiento semiautomático (Uroquattro HB&L(TM)) para la detección de portadores fecales de Enterobacterales productoras de beta-lactamasas de espectro extendido (BLEE)/AmpC

INTRODUCTION: Early detection of patients carrying multiresistant bacteria is an effective implement in surveillance programs. Our objective was to compare the semi-automatic Uroquattro HB&L "ESBL/AmpC Screening" (Alifax®) system with the routine culture on selective media to detect ESBL/pAmpC-producing microorganisms (3CGRE). METHODS: A total of 201 rectal swabs samples were processed by inoculating them into the Uroquattro HB&L system, performing growth curve measurements at 6.5 and 10 h, and into direct culture medium. RESULTS: Thirty-five samples yielded 3CGRE. Measurements at 10 h incremented the positive 3GCRE detection 5.7% in comparison with routine culture medium. In negative rectal swabs, the overall percent agreement at 6.5 h and 10 h versus routine culture medium was 93% and 90%, respectively. CONCLUSIONS: The Uroquattro HB&L system increased the detection of ESBL/pAmpC-producing bacteria compared to direct plating with an incubation time of 10 h and shortens the time to report a negative sample

INTRODUCCIÓN: La detección temprana de pacientes portadores de bacterias multirresistentes es una medida eficaz de los programas de vigilancia. Nuestro objetivo fue comparar el sistema semiautomático Uroquattro HB&L™ «ESBL/AmpC screening» (Alifax®) frente al cultivo habitual en medios selectivos para detectar microorganismos productores de beta-lactamasas de espectro extendido (BLEE)/AmpC (3CGRE). MÉTODOS: Se procesaron 201 frotis rectales mediante inoculación en el sistema Uroquattro HB&L™, se midió el crecimiento a las 6,5 y 10 h, y en el medio de cultivo directo. RESULTADOS: Treinta y cinco muestras fueron positivas para 3CGRE. La lectura a las 10 h incrementó la detección un 5,7% en comparación con el medio habitual. En muestras rectales negativas, la concordancia de la lectura global a las 6,5 y 10 h con el medio de cultivo habitual fue del 93 y 90%, respectivamente. CONCLUSIONES: El sistema Uroquattro HB&L™ incrementó la detección de bacterias productoras de BLEE/pAmpC en comparación con el cultivo directo con un tiempo de incubación de 10 h y acorta los tiempos de detección de muestras negativas