Introduction: The aim of this study was to determine the antimicrobial resistance rates and their evolution in clinical isolates of Pseudomonas aeruginosa causing invasive infections in the south of Spain between 2012 and 2017. Methods: Retrospective study consisting of the collection of microbiological data from 20 hospitals (14 from Andalucía, 5 from Extremadura and 1 from Ceuta) between 2012 and 2017. The main variables studied were the antimicrobial susceptibility testing system used, interpretation criteria (CLSI or EUCAST) and the rate or percentage of resistant isolates. Results: The most widely used antimicrobial susceptibility testing system was MicroScan (58%). The global resistance rates varied between 25% (ciprofloxacin) and 4% (colistin) using EUCAST, and between 19% (ciprofloxacin and imipenem) and 3% (amikacin) using CLSI. The antimicrobial resistance rates were relatively stable throughout the period 2012-2017. 14% of isolates were MDR and 7% were XDR. Respiratory isolates were more resistant, particularly to ciprofloxacin and colistin, than isolates from urine or blood. Conclusions: The antimicrobial resistance rates in P. aeruginosa are not particularly high in the south of Spain. The highest resistance rates were observed with ciprofloxacin, piperacillin/tazobactam and meropenem, whereas the more active antimicrobials were colistin, tobramycin and amikacin. The highest resistance rates were seen in respiratory isolates. In general, the resistance rates remained stable during the study period for most of the antimicrobials studied.

Miembros del Grupo GRAM: Eugenio Garduño, Purificación Hernández Pérez, José Román Muñoz Sanz, Carmen González Velasco, Saray Rodríguez, José M.Navarro Marí, María Dolores Rojo Martín, Marta Álvarez Estévez, Alejandro Peña Monje, Waldo Sánchez Yebra, Carolina Roldán Fontana, Lina Martín Hita, Encarnación Clavijo Frutos, María Gracia Ortega, Begoña Palop Borrás, Pilar Bermúdez Ruiz, José Antonio Lepes, Javier Aznar, M.Carmen Domínguez, Irene Gracia Ahufingeru, Fernando Rodríguez, Ana Domínguez Castaño, Manuel Rodríguez Iglesias, Fátima Galán Sánchez, M.Dolores López Prieto, Juan Manuel Sánchez Calvo, José Luis López Barba, Carmen Martínez Rubio.