The Microbiology group at Vall d’Hebron Institute of Research (VHIR) has been awarded with the best communication of the 17th edition of the "http://www.seimc2013.com/index.php/bienvenida" Spanish Congress of Clinical Microbiology and Infectious Diseases "http://www.seimc2013.com/index.php/bienvenida" (SEIMC), hosted from the 29th to the 31st of May in Zaragoza. The awarded study is entitled "Dissemination of strains of Klebsiella pneumoniae and Citrobacter koseri producing OXA-48 among different units at Vall d’Hebron University Hospital".The study describes the first strains detected at Vall d’Hebron which produced OXA-48 carbapenemase, an enzyme able to hydrolyze nearly all ß-lactam antibiotics, its clonal relationship, the genetic environment where the gen is codified, the plasmid which bears this resistance mechanism as well as the virulence factors of the carbapenemase-producing strains.  For the first time, this study has identified this mechanism of resistance at the Citrobacter genus and at a new clonal group of K. pneumoniae. The OXA-48 gene was codified at a plasmid which was transmitted among isolates from patients hospitalized at different units at Vall d’Hebron. The awarded project also reveals some of the pathogenic mechanisms by which these strains may be able to colonize and invade host cells and tissues.The Microbiology research group at VHIR and the Microbiology Service at the hospital work closely in the early detection and in the study of strains carrying resistance mechanisms with great clinical importance. This is a decisive factor to adequate the antibiotic treatment and to avoid the dissemination of resistant strains inside and outside the hospital.