Molecular characterization of OXA-48 carbapenemase-producing Klebsiella pneumoniae strains after a carbapenem resistance increase in Catalonia / Caracterización molecular de las cepas de Klebsiella pneumoniae productoras de carbapenemasa OXA-48 tras un aumento de la resistencia a las carbapenemas en Cataluña

Introduction: To characterize OXA-48 carbapenemase-producing Klebsiella pneumoniae strains isolated after an increase in carbapenem resistance in Catalonia. Methodology: K. pneumoniae identification, antimicrobial susceptibility studies, the Modified Hodge Test method, amplification of antimicrobial resistance genes (against β-lactamases, quinolones and aminoglycosides), molecular typing (by PFGE and MLST), conjugation assays, plasmid characterization (PBRT-PCR and Southern blot), a description of mobile genetic elements and statistical analysis were done. Results: OXA-48 was the only carbapenemase detected, with a prevalence of 1.9%. The blaOXA-48 gene was located in an IncL conjugative plasmid of 62 kb and integrated into the transposons Tn1999.2 (91.7%) or Tn1999.1. Five PFGE profiles (A to E) were found, which exactly matched the MLST: ST101, ST17, ST1233, ST14 and ST405, respectively. ST1233 is described here for the first time. K. pneumoniae OXA-48-producing strains were also CTX-M-15 carriers, some producing OXA-1 and TEM-1 penicillinases. The acquired qnrB66 and qnrB1 and aac(3′)-IIa, aac(6′)-Ib genes were also identified. Conclusion: The K. pneumoniae ST405 clone has played an important role in the growing prevalence of OXA-48 in Catalonia. All clones described preserved the blaOXA-48 genetic environment and mobile genetic elements (Tn1999). Notably, the three strains with minor sequence types in this study are not multiresistant strains. These strains are expanding in elderly patients (average age of 76 years) with serious underlying diseases, mainly women (61.2%)

Introducción: El objetivo de este estudio fue caracterizar las cepas de Klebsiella pneumoniae productoras de carbapenemasa OXA-48 aisladas tras observar un aumento de estos aislados resistentes a los carbapenémicos en Cataluña. Métodos: Se realizó la identificación de K. pneumoniae, estudios de sensibilidad antimicrobiana, el test de Hodge modificado, amplificación de genes de resistencia antimicrobiana (contra β-lactamasas, quinolonas y aminoglucósidos), tipificación molecular (por PFGE y MLST), ensayos de conjugación, caracterización de plásmidos (PBRT-PCR y Southern blot), descripción de los elementos genéticos móviles y el análisis estadístico. Resultados: OXA-48 fue la única carbapenemasa presente, con una prevalencia del 1,9%. El gen blaOXA-48 se localizó en un plásmido conjugativo IncL de 62kb e integrado en los transposones Tn1999.2 (91,7%) o Tn1999.1. Se encontraron 5 perfiles diferentes de PFGE (A a E), que tenían una concordancia exacta con el MLST: ST101, ST17, ST1233, ST14 y ST405, respectivamente. El ST1233 se describe aquí por primera vez. Las cepas productoras de K. pneumoniae OXA-48 también fueron portadoras de CTX-M-15 y algunas de ellas productoras también de penicilinasas OXA-1 y TEM-1. Los genes adquiridos qnrB66 y qnrB1 y aac(3’)-IIa, aac(6’)-Ib también se identificaron. Conclusión: El clon K. pneumoniae ST405 tiene un papel importante en la creciente prevalencia de OXA-48 en Cataluña. Todos los clones descritos preservaron el entorno genético de blaOXA-48, así como los elementos genéticos móviles (Tn1999). Notablemente, las 3 cepas con tipos de secuencia menos prevalentes en este estudio no son cepas multirresistentes. Además, la expansión de estas cepas con blaOXA-48 se está produciendo en pacientes de edad avanzada (promedio de edad de 76 años), la mayoría mujeres (61,2%) con enfermedades subyacentes graves

Molecular characterization of OXA-48 carbapenemase-producing Klebsiella pneumoniae strains after a carbapenem resistance increase in Catalonia.

INTRODUCTION: To characterize OXA-48 carbapenemase-producing Klebsiella pneumoniae strains isolated after an increase in carbapenem resistance in Catalonia. METHODOLOGY: K. pneumoniae identification, antimicrobial susceptibility studies, the Modified Hodge Test method, amplification of antimicrobial resistance genes (against ß-lactamases, quinolones and aminoglycosides), molecular typing (by PFGE and MLST), conjugation assays, plasmid characterization (PBRT-PCR and Southern blot), a description of mobile genetic elements and statistical analysis were done. RESULTS: OXA-48 was the only carbapenemase detected, with a prevalence of 1.9%. The blaOXA-48 gene was located in an IncL conjugative plasmid of 62kb and integrated into the transposons Tn1999.2 (91.7%) or Tn1999.1. Five PFGE profiles (A to E) were found, which exactly matched the MLST: ST101, ST17, ST1233, ST14 and ST405, respectively. ST1233 is described here for the first time. K. pneumoniae OXA-48-producing strains were also CTX-M-15 carriers, some producing OXA-1 and TEM-1 penicillinases. The acquired qnrB66 and qnrB1 and aac(3')-IIa, aac(6')-Ib genes were also identified. CONCLUSION: The K. pneumoniae ST405 clone has played an important role in the growing prevalence of OXA-48 in Catalonia. All clones described preserved the blaOXA-48 genetic environment and mobile genetic elements (Tn1999). Notably, the three strains with minor sequence types in this study are not multiresistant strains. These strains are expanding in elderly patients (average age of 76 years) with serious underlying diseases, mainly women (61.2%).