Using a multichannel micropipette with six tips
attached to consecutive channels, the undiluted cultures
in row A were mixed. From this row 10 ml of each was
transferred to the wells of row B. Tips were discarded to
minimize carry over and six new tips were attached to
the multichannel pipette. Contents of row B were
thoroughly mixed. The above process was repeated until
12 serial dilutions had been made. To each well 10 ml of
bacterial suspension at a concentration of 5/106 cfu/ml
was added. To prevent dehydration, the plates were
covered with a plastic cover and then incubated at 35/
37 8C for 18/24 h. The plates were examined for
growth or inhibition after 18 and 24 h. Controls were
set up using corresponding solvents, normal saline and
ciprofloxacin.