OBJECTIVES: The double-disk synergy test was compared to the Mastdiscs ID AmpC and ESssL method for detection of ESssL production in rectal swab. METHODS: Two hundred and forty-nine rectal swabs were directly inoculated onto Mueller-Hinton plates and analyzed according to both methods. RESULTS: A total of 41 (16%) and 208 (84%) were positive and negative for ESssL, respectively. Twelve (29%) and 20 (49%) of the 41 rectal swabs positive for ESssL were detected after 24h of incubation with the double-disk synergy test and the Mastdiscs method, respectively (P=0.013). One hundred fifty-eight (76%) et 183 (88%) of the 208 rectal swabs were detected negative for ESssL after 24h of incubation with the double-disk synergy test and the Mastdiscs method, respectively (P<0.001). Finally, 79 (32%) and 46 (18%) rectal swabs respectively inoculated according to the double-disk synergy test and the Mastdiscs method were inconclusive after 24h of incubation. The better performance of the Mastdiscs method was due to an easier detection of cephalosporinase producing bacteria. CONCLUSIONS: The Mastdiscs method is a simple phenotypic method that detects more easily ESssL and non-ESssL producing bacteria in rectal swab.