Figure 5: Susceptibility test with antimicrobial arrangement proposed by the CLSI to detect extended spectrum beta lactamases. The antimicrobials were added each alone or in combination with clavulanic acid (4 μg/ml) at each concentration to the suspension antimicrobial combination with clavulanic acid showed significant depolarisation in the samples at minimal concentrations whereas the samples with antimicrobials alone showed no or marginal depolarisation. The strain H 018 was an E. coli with CTX-M-type resistance.