described strains with the same ST and none of them was MBL-positive learn more [17]. Three of our five isolates were non-MBLs producers. In a previous study performed in another Majorcan hospital, ST-235 has been described as a VIM-13 producing β-lactamase [19]. ST-179, previously described in Mallorca as VIM-2 producer, was also MBL-positive [19]. The third most abundant sequence type was ST-253, with four isolates. These isolates were isolated from two patients; two isolates were MDR, and two were non-MDR. Only one isolate was colistin-resistant, corresponding to ST-244 reported previously in Korea as the isolate most frequently colistin non-susceptible and sensitive to

other antibiotics [20]. Our isolate was isolated in a mixed culture with Morganella morganii and Serratia marcescens, both inherently resistant to colistin. The high discriminatory SB-715992 power of the MLST profiling allowed the differentiation among isolates obtained from the same

patient at different dates and sampling sites. When the specimen was associated with the site of infection, the sequence type or clonal complex obtained and the antibiotic resistance profiles were the same. Conclusions The present results indicate that P. aeruginosa isolates revealed a significant frequency of recombination and a panmictic net-like population structure, as was suggested by Kiewitz and Tümler [21]. The population structure of clinical P. aeruginosa present in our hospital indicates the coexistence of nonresistant and resistant isolates with the same sequence type. The multiresistant isolates

studied are grouped in the prevalent sequence types found in other Spanish hospitals and at the international level, and the susceptible isolates correspond mainly to singleton sequence types. Acknowledgments This work was supported by the General Board click here for Evaluation and Accreditation of the Department of Health and Consume of the Autonomous Community of the Balearic Islands (Dirección General de Evaluación y Acreditación, de la Conselleria de Salut i Consum, de la Comunidad Autónoma de las Islas Baleares). M. Gomila is the recipient of a postdoctoral contract from the Juan de la Cierva Programme of the Spanish Ministerio de Ciencia e Innovación. E. García-Valdés and J. Lalucat want to thank the support of the projects CGL2008-03242 and CSD2009-00006 from the Ministerio de Economia y Competitividad (Spain) and Fondo Europeo de Desarrollo Regional (FEDER) funding. The authors want to thank the critical revision of Dr. A. Oliver. All authors report no conflicts of interest relevant to this article. References 1. Cramer N, Wiehlmann L, Tümmler B: Clonal epidemiology of Pseudomonas aeruginosa in cystic fibrosis. Int J Med Microbiol 2010, 300:526–533.PubMedCrossRef 2. Renom F, Yáñez A, Garau M, et al.