Coagulase-positive staphylococci were isolated from 63 of 74 raw milk samples collected from two milk plants in November, 1971, when Staphylococcus 110 medium was used.
Two-peak resistance was presented by the isolated strains to penicillin (PC) and tetracycline (TC)(0.05 and 12.5 mcg/m
l), to streptomycin (SM)(12.5 and 100), and to oleandomycin (OM)(0.8 and 50). Onepeak resistance was exhibited by these strains to leucomycin leucomycin (LM)(0.4), kanamycin (KM)(6.2), furagiomycin (FM)(1.6), and chloramphenicol (CP)(1.6).
The frequency of isolation of resistant staphylococci was 100% to sulfamonomethoxine sodium (AS), 69.6% to PC, 17.8% to SM, 3.1% to TC, and 0.5% to OM. No strains were resistant to CP, FM, KM, or LM. The frequency of isolation of strains highly resistant to PC and SM was 33.5 and 15.2 %, respectively.
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