Evaluación de la sensibilidad de cepas de Pseudomonas aeruginosa multi-resistentes frente a ceftolozano/tazobactam / Evaluation of susceptibility of multidrug-resistant Pseudomonas aeruginosa strains against ceftolozane/tazobactam

Resumen Introducción: Pseudomonas aeruginosa es un patógeno oportunista asociado a alta morbi-mortalidad. Para cepas multi-resistentes (MDR), ceftolozano/tazobactam (CTZ) se ha autorizado por la Agencia Europea del Medicamento (EMA) para infecciones del tracto urinario complicadas, pielonefritis aguda e infecciones intra-abdominales complicadas. Objetivo: Determinar la sensibilidad a CTZ de P. aeruginosa MDR en muestras clínicas aisladas en el Hospital Universitario Puerto Real. Material y Métodos: Se estudió la sensibilidad según criterios EUCAST a CTZ de cepas de P. aeruginosa MDR, entre enero de 2015 y agosto de 2017. Los criterios de multi-resistencia fueron definidos por el Centers for Disease Control and Prevention. La sensibilidad antimicrobiana se obtuvo mediante sistema MicroScan® (Beckman Coulter). La sensibilidad a CTZ se determinó mediante tiras de gradiente (Liofilchem®, Werfen). Resultados: De 1253 cepas, 7% fueron MDR. Se estudió la sensibilidad de 78 cepas de P. aeruginosa MDR, de las cuales cinco (6,4%) resultaron resistentes a CTZ según criterios EUCAST. Conclusiones: En nuestro medio la resistencia in vitro a CTZ en cepas de P. aeruginosa MDR es aproximadamente 6%; CTZ es una opción de tratamiento de infecciones por cepas de P. aeruginosa MDR cuando no exista otra alternativa y se haya comprobado su sensibilidad in vitro.

Background: Pseudomonas aeruginosa is an opportunistic pathogen associated with high morbidity and mortality. For multidrug-resistant strains (MDR), ceftolozane/tazobactam (CTZ) has been authorized by the European Medicines Agency (EMA) for complicated urinary tract infections, acute pyelonephritis, and complicated intraabdominal infections. Aim: To determine the susceptibility to CTZ of P. aeruginosa MDR in isolated clinical samples at the University Hospital Puerto Real. Methods: The susceptibility according to the EUCAST to CTZ criteria of strains of P. aeruginosa MDR, between January 2015 and August 2017 has been studied. The multiresistance criteria were those defined by the Centers for Disease Control and Prevention. The antibiotic susceptibility was obtained by automated MicroScan® system (Beckman Coulter). Susceptibility to CTZ was determined using gradient strips (Liofilchem®, Werfen). Results: Of 1253 strains isolated, 7% presented MDR. We studied the susceptibility of a total of 78 strains of MDR P. aeruginosa, of which 5 (6.4%) were resistant to CTZ according to the EUCAST criteria. Conclusions: In our environment, the in vitro resistance to CTZ in MDR P. aeruginosa strains is approximately 6%. CTZ is an option for the treatment of infections by MDR P. aeruginosa when there is no other alternative and its in-vitro susceptibility has been proven.

Evaluation of INNO-LiPA mycobacteria v2 assay for identification of rapidly growing mycobacteria

A total of 54 rapidly growing mycobacteria (RGM) isolated from patients attended in the two hospitals of Cádiz Bay (Spain) were selected during a seven-year-period (2000-2006) in order to evaluate the INNO-LiPA Mycobacteria v2 assay for mycobacterial identification, based on the reverse hybridization principle. The strains were cultured in Lõwenstein-Jensen and Middlebrook 7H9 media and identified to the species level by sequencing of the 16S rRNA, PCR-restriction enzyme analysis of the hsp65 gene, conventional tests and INNO-LiPA Mycobacteria v2 assay. By the molecular methods we identified a total of 12 different species: 23 Mycobacterium fortuitum, 11 M. chelonae, 10 M. abscessus, 2 M. senegalense, 1 M. alvei, 1 M. brumae, 1 M. mageritense, 1 M. mucogenicum, 1 M. neoaurum, 1 M. peregrinum, 1 M. septicum and 1 M. smegmatis. Fifty two strains (96.3 percent) were correctly identified by conventional techniques and 47 strains (87.0 percent) by INNO-LiPA Mycobacteria v2 assay. We find INNO-LiPA Mycobacteria v2 assay simple to perform but it provides few advantages in comparison with conventional methods and sometimes needs complementary tests to identify Mycobacterium fortuitum complex, M. chelonae complex and specific species due to the great heterogeneity in the RGM group.

Sensibilidad a los antimicrobianos de micobacterias de crecimiento rápido mediante el método E-test / Assessment of in vitro susceptibility to antimicrobials of rapidly growing mycobacteria by E-test

Background: Rapidly growing mycobacteria (RGM) are considered opportunistic pathogens. An increasing number of post traumatic or surgical infections are caused by these microorganisms. Aim: To determine the antimicrobial susceptibility of RGM using the E-test method. Material and methods: A total of 54 isolates of RGM was obtained from several clinical samples and selected for this study Strains were identified to the species level by phenotypic and biochemical characteristics, PCR-restriction enzyme analysis of the hsp65 gene (PRA) and sequencing of the 16S rRNA. Susceptibility was investigated by E-test to amikacin, cefoxitin, ciprofioxacin, clarithromycin, imipenem, quinupristin/dalfopristin, linezolid and tigecycline. Results: Twelve different species of RGM were identified: Mycobacterium fortuitum (23 strains), M chelonae (11), M abscessus (10), Msenegalense (2), Malvei (1), Mbrumae (1), Mmageritense (1), mucogenicum (1), M neoaurum (1), Mperegrinum (1), M septicum (1) y M smegmatis (1). All the strains were inhibited by low concentrations of amikacin and tigecycline. Susceptibility to cefoxitin, fluoroquinolones, clarithromycin, imipenem and linezolid was variable. All but two strains were resistant to quinupristin/ dalfopristin. Conclusions: Due to the uneven antimicrobial susceptibility of different species of RGM, an antimicrobial susceptibility test is mandatory for these microorganisms. The E-test method is well suited to determine minimum inhibitory concentrations.