Antibiogram of Staphylococcal Strains Isolated from Milk and Milk‐Products

Abstract
A study of the resistance patterns of 248 staphylococcal isolates from milk and milk products to eight antimicrobial agents using the disc method showed that 80 (32.3%) were resistant to sulphafurazole, 75 (30.2%) to penicillin G, 63 (25.4%) to ampicillin, 23 (9.3%) to cloxacillin, 19 (7.7%) to tetracycline, 17 (6.9%) to streptomycin, 14 (5.6%) to erythromycin and 12 (4.8%) to chloramphenicol. One hundred and sixteen (46.8%) of the 248 staphylococcal isolates were sensitive to all the agents tested. A significant percentage (P<0.05) of the isolates from raw milk were resistant to erythromycin, sulphafurazole, cloxacillin, penicillin G and streptomycin compared to isolates from fermented milk. The minimum inhibitory concentrations (MIC) as determined by the tube method for isolates resistant by the disc method, were .gtoreq. 16 .mu.g for ampicillin in 5 (11.9%) isolates; .gtoreq. .mu.g for cloxacillin, 9 (36.0%) and .gtoreq. 12 international units for penicillin G amongst 12 (22.2%) isolates. MIC values of .gtoreq. 40 .mu.g were recorded for 9 (90.0%), 9 (69.2%), 8 (73.7%) and 7 (70.0%) isolates to chloramphenicol, streptomycin, erythromycin and tetracycline respectively. The relatively high level of resistance to antimicrobial agents is a reflection of misuse or abuse of these agents in the environment.