TRANSFERABILITY OF MULTIPLE RESISTANCE TO ANTIBIOTICS IN WATER

A clinical isolate of Enterobacter cloacae resistant to at least 12 an tibiotics transferred en bloc all the twelve resistance determinants t o E. coli K-12 recipient strain with a relatively high frequency of tr ansfer (10(-3)) in full nutrient medium and with the same high frequen cy in fresh drinking water. Also in a second cycle of transfers, i.e., between E. coli K-12 strains, the transfer frequency remained high in both media and, simultaneously, no signs of segregation of individual resistance determinants were observed. In the third cycle of transfer s, the frequency of transfer in the water was by one logarithm lower t han in full medium, and some resistance determinants segregated. It se ems that the fertility factor, tra(+), which mediates the transfer of these resistances, is firmly associated with the cefotaxime resistance determinant.