In the current work 500µg/ml concentration was found the best in controlling the growth of Xoo isolates on NA plates while 31.25µg/ml concentration was found least effective on the basis of all treatment combinations. Results were matched with the study of Casandra and Bernal (2007) in which it was found that high levels of chloramphenicol and penicillin Gsodium/ dihydrostreptomycin decreased bacterial numbers during the first days of experimentation. Erasmus et al. (1997) also found that chloramphenicol and cefotaxime at 20 and 150-mg mL–1 respectively inhibit the growth of abalone enteric bacteria.