ABSTRACT:

The invitro Bacteriocidal and bacteriostatic activities of normal bovine serum with and without added guinea-pig complement tested against nine serotypes of Escherichia coli was investigated. Bovine serum without added guinea-pig complement tested within 24 hours of collection inhibited the growth of all nine serotypes of E coli. Bovine serum with added guinea-pig complement also inhibited the growth of all E coli tested. However slightly greater inhibition was recorded in the later trial (with added complement). In both cases growth inhibition was dependent on the index of serum dilution. Significantly greater survival of the organisms was recorded at higher dilutions (1 16. 1 32) Survival percentage in both trials was lowest at the 1 2. dilutions for all the organisms. However. survival percentage was higher for 02a (421%) 0101 (38.7%) and 011 (33.3%) respectively. There was significant difference (p= 0 05) between the mean of E. coli tested in serum with and without complement