A method for determining the presence of extended spectrum beta-lactamases (ESBL) nucleic acids in a sample, comprising the steps of: (a) extracting nucleic acids from micro-organisms, said nucleic acids comprising target ESBL nucleic acids, (b) performing a ligase detection reaction on said target ESBL nucleic acids, comprising: contacting a plurality of different probe pairs with said target ESBL nucleic acid(s), wherein each probe pair comprises a first nucleic acid probe and a second nucleic acid probe, wherein each probe pair being specific for a particular target ESBL nucleic acid, wherein for each probe pair, the first nucleic acid probe and the second nucleic acid probe are configured to be essentially adjacent when hybridized with the particular target ESBL nucleic acid; incubating said target ESBL nucleic acid with said plurality of different probe pairs under conditions allowing to hybridize said particular target ESBL nucleic acid with at least one probe pair, ligating any essentially adjacent identifiable first nucleic acid probe and identifiable second nucleic acid probe of a probe pair, to form a connected probe assembly; providing at least a set of two amplification primers configured to amplify the connected probe assembly of step, amplifying the connected probe assembly of step using the amplification primers of step, thereby providing amplified target ESBL nucleic acids [ESBL amplicon], (c) detecting the amplified target ESBL nucleic acids [ESBL amplicon] by performing Real Time detection and a hybridization to a capture probe, wherein the hybridization to the capture probe is performed when the RT detection determines that ESBL nucleic acid(s) is present, whereby the presence of an ESBL nucleic acid in a sample is determined. (a) extracting nucleic acids from micro-organisms, said nucleic acids comprising target ESBL nucleic acids, (b) performing a ligase detection reaction on said target ESBL nucleic acids, comprising: contacting a plurality of different probe pairs with said target ESBL nucleic acid(s), wherein each probe pair comprises a first nucleic acid probe and a second nucleic acid probe, wherein each probe pair being specific for a particular target ESBL nucleic acid, wherein for each probe pair, the first nucleic acid probe and the second nucleic acid probe are configured to be essentially adjacent when hybridized with the particular target ESBL nucleic acid; incubating said target ESBL nucleic acid with said plurality of different probe pairs under conditions allowing to hybridize said particular target ESBL nucleic acid with at least one probe pair, ligating any essentially adjacent identifiable first nucleic acid probe and identifiable second nucleic acid probe of a probe pair, to form a connected probe assembly; providing at least a set of two amplification primers configured to amplify the connected probe assembly of step, amplifying the connected probe assembly of step using the amplification primers of step, thereby providing amplified target ESBL nucleic acids [ESBL amplicon], contacting a plurality of different probe pairs with said target ESBL nucleic acid(s), wherein each probe pair comprises a first nucleic acid probe and a second nucleic acid probe, wherein each probe pair being specific for a particular target ESBL nucleic acid, wherein for each probe pair, the first nucleic acid probe and the second nucleic acid probe are configured to be essentially adjacent when hybridized with the particular target ESBL nucleic acid; incubating said target ESBL nucleic acid with said plurality of different probe pairs under conditions allowing to hybridize said particular target ESBL nucleic acid with at least one probe pair, ligating any essentially adjacent identifiable first nucleic acid probe and identifiable second nucleic acid probe of a probe pair, to form a connected probe assembly; providing at least a set of two amplification primers configured to amplify the connected probe assembly of step, amplifying the connected probe assembly of step using the amplification primers of step, thereby providing amplified target ESBL nucleic acids [ESBL amplicon], (c) detecting the amplified target ESBL nucleic acids [ESBL amplicon] by performing Real Time detection and a hybridization to a capture probe, wherein the hybridization to the capture probe is performed when the RT detection determines that ESBL nucleic acid(s) is present, whereby the presence of an ESBL nucleic acid in a sample is determined.