The concept of bacterial resistance is defined as the set of genetic changes experienced by microorganisms which gives them tools to efficiently evade the antimicrobial action.Resistance mechanisms occur by multiple processes, such as mutation of chromosome material and acquisition of extra-chromosomic material.The first descriptions were found in Staphylococcus spp., but in the last two decades there has been an increase of Gram-negative bacteria isolates with some kind of resistance [1].Data from the Bacterial Resistance Surveillance System from the Capital District (SIVIBAC), Colombia, shows a percentage of 13.19% of isolates of E. coli, 8.11% of K. pneumoniae and 5.2% of P. aeruginosa in ICUs during the year 2006 [2].The data mentioned directly impacts patient morbi-mortality and hospitalization conditions.[3] Fifty Eight Gram-negative isolated strains from patients in the hospitalization service from a third level complexity institution in 2012 were considered.Using a recollection instrument created by the researchers, the information was put on a database taking into account the type of bacterial isolation and type of resistance.