FREQUENCY OF ANTIMICROBIAL RESISTANCE AND PLASMID PROFILES OF BACILLUS-CEREUS STRAINS ISOLATED FROM MILK

Plasmid profile analysis and susceptibility to eight commonly used ant imicrobial agents was done on sixty Bacillus cereus (B. cereus) strain s isolated from milk. About seventy two percent (71.7%) of the isolate s contained plasmids. The number of plasmids per isolate ranged betwee n 1 and 5, while plasmid sizes ranged between 60 and 0.1 megadaltons ( Mda), All isolates were resistant to ampicillin with a relatively high rate of resistance to cotrimoxazole and sulphamethoxazole. The isolat es showed a low frequency of resistance to the other antimicrobial age nts, with all of them being susceptible to streptomycin. Approximately ninety one (90.7%) percent of the isolates showed multiple resistance , There was no apparent relationship between carriage of plasmids and drug resistance.