Modulation of mgrB gene expression as a source of colistin resistance in Klebsiella oxytoca

Gene modifications in the PmrAB and PhoPQ two-component regulatory systems, as well as inactivation of the mgrB gene, are known to be causes of colistin resistance in Klebsiella pneumoniae. The objective of this study was to characterise the mechanism involved in colistin resistance in a Klebsiella oxytoca isolate. A K. oxytoca clinical isolate showing resistance to colistin was recovered in Cali, Colombia. The pmrA, pmrB, phoP, phoQ and mgrB genes were amplified and sequenced. Wild-type mgrB genes from K. pneumoniae and K. oxytoca were cloned, and corresponding recombinant plasmids were used for complementation assays. By analysing the mgrB gene of the K. oxytoca isolate and its flanking sequences, an insertion sequence (IS) of 1196 bp was identified in its promoter region. The insertion was located between nucleotides −39 and −38 when referring to the start codon of the mgrB gene, thus negatively interfering with expression of the mgrB gene by modifying its promoter structure. This IS was very similar to ISKpn26 (99% nucleotide identity) belonging to the IS5 family. Complementation assays with mgrB genes from wild-type K. pneumoniae or K. oxytoca restored full susceptibility to colistin. In conclusion, here we identified the mechanism involved in colistin resistance in a K. oxytoca isolate. Modulation of mgrB gene expression was the key factor for this acquired resistance to colistin

Resistance to colistin associated with a single amino acid change in protein PmrB among Klebsiella pneumoniae isolates of worldwide Origin

A series of colistin-resistant Klebsiella pneumoniae isolates recovered from different countries was investigated in order to evaluate the involvement of the PmrA/PmrB two-component system in this resistance. Six isolates possessed a mutated PmrB protein, which is encoded by the pmrB gene, part of the pmrCAB operon involved in lipopolysaccharide modification. The same amino acid substitution (Thr157Pro) in PmrB was identified in the six isolates. The six isolates belonged to four distinct clonal groups, recovered in South Africa (sequence type 14 [ST14]), Turkey (ST101), and Colombia (ST258 and ST15). Three out of the four clones produced a carbapenemase, OXA-181, OXA-48, or KPC-3, while a single isolate did not produce any carbapenemase. Expression assays revealed an overexpression of the pmrA (70-fold), pmrB (70-fold), pmrC (170-fold), and pmrK (40-fold) genes in the pmrB-mutated isolate compared to expression of the pmrB wild-type isogenic K. pneumoniae isolate, confirming that the PmrB substitution was responsible for increased expression levels of those genes. Complementation assays leading to the expression of a wild-type PmrB protein restored the susceptibility to colistin in all isolates, confirming that the substitution in PmrB was responsible for the resistance phenotype. This study identified a key amino acid located in the PmrB protein as being responsible for the overexpression of pmrCAB and pmrHFIJKLM operons, leading to resistance to colistin

Lagunas y obstáculos en la aplicación y el funcionamiento de los programas de administración de antimicrobianos: Resultados de una evaluación de necesidades con métodos mixtos educativos y conductuales en Francia, Estados Unidos, México e India

Antecedentes: La evidencia muestra una adherencia limitada a los principios de administración antimicrobiana (AMS). Objetivos: Identificar las lagunas educativas y las barreras sistémicas que obstaculizan la adhesión a los principios de la AMS. Métodos: Se realizó un estudio de métodos mixtos que combina un análisis temático de entrevistas cualitativas (enero-febrero de 2021) y un análisis inferencial de encuestas cuantitativas (mayo-junio de 2021). Se seleccionaron deliberadamente participantes de Francia, EE.UU., México y la India a partir de paneles en línea de profesionales de la salud para incluir a médicos infectólogos, especialistas en control de infecciones, microbiólogos clínicos, farmacólogos o farmacéuticos que se espera que apliquen los principios de la MGA en su entorno de práctica (por ejemplo, clínica, hospital académico o comunitario). Este estudio se ha guiado por un marco de análisis de carencias. Resultados: La muestra final incluyó 383 participantes (n = 33 entrevistas; n = 350 encuestas). Los resultados de los métodos mixtos indicaron que los conocimientos y habilidades de los participantes no eran óptimos para facilitar la aplicación personal y colectiva de los principios de la MGA. Los datos de la encuesta indicaron un desfase entre el conocimiento ideal y el actual de los protocolos de MGA, especialmente entre los farmacólogos (Δ0,95/4,00, p < 0,001). También se midieron las diferencias entre los niveles de conocimientos ideales y los actuales, que fueron mayores entre los especialistas en control infeccioso (Δ1,15/4,00, P < 0,001), para convencer a los directivos de los hospitales de que asignen recursos a los programas de MGA. Los obstáculos sistémicos ya existentes (por ejemplo, tiempo, financiación o formación insuficientes) se percibieron como agravados durante la pandemia COVID-19 (el 72% de los participantes en la encuesta estuvieron de acuerdo). Las deficiencias más acusadas se registraron en India y Francia. Conclusiones: Las necesidades educativas de los profesionales y los países incluidos en este estudio pueden informar las futuras actividades de desarrollo profesional continuo en AMS. Debería considerarse la posibilidad de obtener financiación adicional para abordar las barreras sistémicas percibidas. Las evaluaciones locales están justificadas para validar los resultados y la idoneidad de las intervenciones.Background: Evidence shows limited adherence to antimicrobial stewardship (AMS) principles. Objectives: To identify educational gaps and systemic barriers obstructing adherence to AMS principles. Methods: A mixed-methods study combining a thematic analysis of qualitative interviews (January-February 2021) and inferential analysis of quantitative surveys (May-June 2021) was conducted. Participants from France, the USA, Mexico and India were purposively sampled from online panels of healthcare professionals to include infectious disease physicians, infection control specialists, clinical microbiologists, pharmacologists or pharmacists expected to apply AMS principles in their practice setting (e.g. clinic, academic-affiliated or community-based hospital). A gap analysis framework guided this study. Results: The final sample included 383 participants (n = 33 interviews; n = 350 surveys). Mixed-methods findings indicated suboptimal knowledge and skills amongst participants to facilitate personal and collective application of AMS principles. Survey data indicated a gap in ideal versus current knowledge of AMS protocols, especially amongst pharmacologists (Δ0.95/4.00, P < 0.001). Gaps in ideal versus current skill levels were also measured and were highest amongst infectious control specialists (Δ1.15/4.00, P < 0.001), for convincing hospital executives to allocate resources to AMS programmes. Already existing systemic barriers (e.g. insufficient dedicated time/funding/training) were perceived as being aggravated during the COVID-19 pandemic (72% of survey participants agreed). Reported gaps were highest in India and France. Conclusions: The educational needs of professionals and countries included in this study can inform future continuous professional development activities in AMS. Additional funding should be considered to address perceived systemic barriers. Local assessments are warranted to validate results and suitability of interventions

The mgrB gene as a key target for acquired resistance to colistin in Klebsiella pneumoniae

Objectives Alterations in the PhoPQ two-component regulatory system may be associated with colistin resistance in Klebsiella pneumoniae. MgrB is a small transmembrane protein produced upon activation of the PhoPQ signalling system, and acts as a negative regulator on this system. We investigated the role of the MgrB protein as a source of colistin resistance in a series of K. pneumoniae.Methods Colistin-resistant K. pneumoniae isolates were recovered from hospitalized patients worldwide (France, Turkey, Colombia and South Africa). The mgrB gene was amplified and sequenced. A wild-type mgrB gene was cloned and the corresponding recombinant plasmid was used for complementation assays. Clonal diversity was evaluated by MLST and Diversilab analysis.Results Of 47 colistin-resistant isolates, 12 were identified as having a mutated mgrB gene. Five clonally unrelated isolates had an mgrB gene truncated by an IS5-like IS, while one clone also harboured an insertional inactivation at the exact same position of the mgrB gene, but with ISKpn13. Another clone harboured an insertional inactivation due to ISKpn14 at another location of the mgrB gene. Two clonally related isolates harboured an IS (IS10R) in the promoter region of mgrB. Finally, three clonally unrelated isolates harboured substitutions leading to anticipated stop codon in the MgrB protein. Complementation assays with a wild-type MgrB protein restored full susceptibility to colistin for all colistin-resistant isolates identified with qualitative or quantitative MgrB modifications.Conclusion The inactivation or down-regulation of the mgrB gene was shown to be a source of colistin resistance in K. pneumoniae. Interestingly, identical genetic events were identified among clonally unrelated isolates

The mgrB gene as a key target for acquired resistance to colistin in Klebsiella pneumoniae

Objectives Alterations in the PhoPQ two-component regulatory system may be associated with colistin resistance in Klebsiella pneumoniae. MgrB is a small transmembrane protein produced upon activation of the PhoPQ signalling system, and acts as a negative regulator on this system. We investigated the role of the MgrB protein as a source of colistin resistance in a series of K. pneumoniae. Methods Colistin-resistant K. pneumoniae isolates were recovered from hospitalized patients worldwide (France, Turkey, Colombia and South Africa). The mgrB gene was amplified and sequenced. A wild-type mgrB gene was cloned and the corresponding recombinant plasmid was used for complementation assays. Clonal diversity was evaluated by MLST and Diversilab analysis. Results Of 47 colistin-resistant isolates, 12 were identified as having a mutated mgrB gene. Five clonally unrelated isolates had an mgrB gene truncated by an IS5-like IS, while one clone also harboured an insertional inactivation at the exact same position of the mgrB gene, but with ISKpn13. Another clone harboured an insertional inactivation due to ISKpn14 at another location of the mgrB gene. Two clonally related isolates harboured an IS (IS10R) in the promoter region of mgrB. Finally, three clonally unrelated isolates harboured substitutions leading to anticipated stop codon in the MgrB protein. Complementation assays with a wild-type MgrB protein restored full susceptibility to colistin for all colistin-resistant isolates identified with qualitative or quantitative MgrB modifications. Conclusion The inactivation or down-regulation of the mgrB gene was shown to be a source of colistin resistance in K. pneumoniae. Interestingly, identical genetic events were identified among clonally unrelated isolate

Prevalencia de bacterias Gram negativas portadoras del gen blaKPC en hospitales de Colombia

Introduction: KPC enzymes are carbapenemases with a great capability to disseminate and to cause epidemics. They are frequently associated with higher mortality rates and prolonged hospital stay. In Colombia, they have been progressively reported since 2007; however, its prevalence in hospitals is not known.Objective: To estimate the prevalence of blaKPC gene in hospitals.Methods and materials: The presence of blaKPC gene and its clonality were evaluated in clinical isolates of Enterobacteriacea and Pseudomonas aeruginosa in hospitalized patients.Results: Of the 424 isolates tested during the study period, 273 met eligibility criteria, and 31.1% were positive for blaKPC gene; after clonality adjustment, positivity was 12.8%. The blaKPC gene was more frequent in Klebsiella pneumonia, followed by P. aeruginosa and other Enterobacteriacea. Although intensive care units (ICU) provided the majority of the isolates, the blaKPC pattern was not more prevalent in ICUs than in other wards. The respiratory tract was the anatomic source with the highest prevalence. No seasonality was observed associated with the frequency of isolation of microorganisms carrying blaKPC gene.Conclusion: This study revealed a high prevalence of blaKPC gene in microorganisms isolated from different hospitals in Colombia. The extraordinary ability of blaKPC gene to spread, the difficulties for its diagnosis and the limited antibiotics available for its treatment pose the urgent need to strengthen epidemiological surveillance systems, and to timely adjust institutional policies for rational use of antibiotics in order to limit its dissemination to other institutions in the country.Introducción. Las enzimas carbapenemasas de tipo KPC tienen gran capacidad de diseminación, son causantes de epidemias y se asocian a mayor mortalidad y estancia hospitalaria. En Colombia se han venido reportando cada vez más desde 2007, pero se desconoce la prevalencia hospitalaria.Objetivo. Estimar la prevalencia hospitalaria del gen blaKPC.Materiales y métodos. Se evaluó la presencia del gen blaKPC y su ‘clonalidad’ en aislamientos de enterobacterias y Pseudomonas aeruginosa de pacientes hospitalizados.Resultados. De los 424 aislamientos evaluados durante el periodo de estudio, 273 cumplieron con criterios de elegibilidad, 31,1 % fue positivo para el gen blaKPC y, al ajustar por ‘clonalidad’, la positividad fue de 12,8 %. El gen blaKPC se encontró con mayor frecuencia en Klebsiella pneumoniae seguido de P. aeruginosa y otras enterobacterias. A pesar de que la unidad de cuidados intensivos aportó el mayor número de aislamientos, no se encontró un patrón más prevalente del gen blaKPC en las ellas que en las otras salas. El aparato respiratorio fue el sitio anatómico de origen con la mayor prevalencia. No se presentó estacionalidad en la frecuencia de los aislamientos portadores del gen blaKPC.Conclusión. Este estudio reveló la alta prevalencia del gen blaKPC en diferentes microorganismos aislados en varias instituciones hospitalarias del país. La extraordinaria capacidad de propagación del gen blaKPC, las dificultades del diagnóstico y la limitada disponibilidad de antibióticos plantean la apremiante necesidad de fortalecer los sistemas de vigilancia epidemiológica y ajustar oportunamente las políticas institucionales de uso racional de antibióticos con el fin de contener su diseminación a otras instituciones de salud del país

Distribución y caracterización molecular de betalactamasas en bacterias Gram negativas en Colombia, 2001-2016

Beta-lactamases are enzymes with hydrolytic activity over beta-lactam antibiotics and they are the main resistance mechanism in Gram-negative bacteria. Extended-spectrum beta-lactamases (ESBL), AmpC, and carbapenemases have the greatest clinical and epidemiological impact in hospital settings. The increasing frequency and worldwide spread of these enzymes have limited the therapeutic options in hospital-acquired infections and those originating in the community.In Colombia, surveillance networks and research groups began studying them in the late 90s. Different variants of these enzymes have been molecularly characterized and their high prevalence and dissemination in medium and high complexity hospitals, along with a high clinical impact, have been reported. Furthermore, many studies in Colombia have evidenced high endemicity for some of these beta-lactamases, which requires an urgent implementation of antimicrobial stewardship programs in order to preserve the few therapeutic options and infection control strategies to prevent and limit their dissemination.In this publication, we carried out a review of the different enzyme variants, geographic distribution, and molecular characterization of these beta-lactamases in Colombia. Additionally, we describe the available information in the literature regarding studies conducted between the late 1990s and 2016, which provide an overview of the beta-lactamases circulating in different regions of Colombia, their increase over time, and their clinical implications.Las betalactamasas, enzimas con capacidad hidrolítica frente a los antibióticos betalactámicos, son responsables del principal mecanismo de resistencia en bacterias Gram negativas; las de mayor impacto clínico y epidemiológico en los hospitales, son las betalactamasas de espectro extendido (BLEE), las de tipo AmpC y las carbapenemasas. El incremento en su frecuencia y su diseminación a nivel mundial ha limitado cada vez más las opciones terapéuticas tanto en infecciones adquiridas en los hospitales como las que se generan en la comunidad.En Colombia, las redes de vigilancia y los grupos de investigación iniciaron su estudio desde finales de los años 90 y, así, se logró la caracterización molecular de las diferentes variantes; además, se reportó una gran prevalencia y diseminación en los hospitales de mediana y alta complejidad, y se describió el impacto clínico de las infecciones que causan. Dichos estudios han evidenciado el alto grado de endemia de algunas de estas betalactamasas y, en consecuencia, la necesidad de una inmediata implementación de programas para inducir el uso prudente de los antibióticos y de medidas de vigilancia, que permitan controlar y prevenir su diseminación, con el fin de disminuir la morbimortalidad en los pacientes y preservar las opciones terapéuticas disponibles en la actualidad.En esta revisión, se recopiló la información sobre las variantes, la distribución geográfica y la caracterización molecular de las betalactamasas en Colombia, así como los estudios llevados a cabo desde finales de la década de 90 hasta el 2016

Worldwide Diversity of Klebsiella pneumoniae That Produce β-Lactamase blaKPC-2 Gene1

TOC summary: Clones harboring different plasmids with identical genetic structure could be the origin of worldwide spread

Fully automatic landmarking of 2D photographs identifies novel genetic loci influencing facial features

We report a genome-wide association study for facial features in > 6,000 Latin Americans. We placed 106 landmarks on 2D frontal photographs using the cloud service platform Face++. After Procrustes superposition, genome-wide association testing was performed for 301 inter-landmark distances. We detected nominally significant association (P-value < 5×10− 8) for 42 genome regions. Of these, 9 regions have been previously reported in GWAS of facial features. In follow-up analyses, we replicated 26 of the 33 novel regions (in East Asians or Europeans). The replicated regions include 1q32.3, 3q21.1, 8p11.21, 10p11.1, and 22q12.1, all comprising strong candidate genes involved in craniofacial development. Furthermore, the 1q32.3 region shows evidence of introgression from archaic humans. These results provide novel biological insights into facial variation and establish that automatic landmarking of standard 2D photographs is a simple and informative approach for the genetic analysis of facial variation, suitable for the rapid analysis of large population samples.- Introduction - Results And Discussion -- Study sample and phenotyping -- Trait/covariate correlation and heritability -- Overview of GWAS results and integration with the literature -- Follow-up of genomic regions newly associated with facial features: Replication in two human cohorts -- Follow-up of genomic regions newly associated with facial features: effects in the mouse -- Genome annotations at associated loci - Conclusion - Methods -- Study subjects -- Genotype data -- Phenotyping -- Statistical genetic analysis -- Interaction of EDAR with other genes -- Expression analysis for significant SNPs -- Detection of archaic introgression near ATF3 and association with facial features -- Annotation of SNPs in FUMA -- Shape GWAS in outbred mic