The production of ESBL was confirmed by
double disk synergy test ( DDST) . Single colony of
each bacterial were cultured in 5 ml of MH broth and
incubated at 37ºC for 5 hours with continuous
shaking at 150 rpm until turbidity of bacterial
suspension reach 0.5 McFarland and swab on MH
agar. Both cefotaxime ( 30 μg) and ceftazidime ( 30
μg) alone and combination of amoxicillin/clavulanic acid
(20 μg/10 μg) were used. These plates were incubated
at 37 ºC for 18 hr. Enhancement of the inhibition zone
between the disk containing clavulanic acid and
cefotaxime or ceftazidime indicated the presence of
ESBL production.