MICROBIOLOGICAL STUDIES. All procedures will be performed locally using accepted, standard microbiological protocols. Isolates identified as CRE or CRAB according to above criteria will be locally studied for carbapenemase production using the CARBA-NP test. Susceptibility tests to key antimicrobial agents will be collected. Isolates preservation CRE and CRAB isolates will be preserved locally at least at -20ºC.