Table 2. Penetration of antibiotics ciprofloxacin (CIP) and azithromycin (ATH) through pre-formed E. coli CFT073 biofilms in presence and absence of piperine (PIP) and reserpine (RES).

Compounds	Zone diameter (mm)
Antibiotics	Without biofilm	With biofilm
CIP (5 µg/disc)	30±1	24±2
ATH (15 µg/disc)	24±1	18±2
Alkaloids
PIP (5 µg)	0	0
RES (5 µg)	0	0
Combination
CIP + PIP	33±2	28±2*
CIP + RES	31±2	25±1
ATH + PIP	27±2	24±1*
ATH + RES	24±2	19±1

* Indicates statistically different values (p<0.05) when compared with antibiotic alone.