Antibiotic resistance and transfer factor in Salmonella, United States 1967

Four hundred Salmonella strains isolated during 1967 from clinical sources throughout the United States were examined for resistance to 11 antibiotics, and suitable strains were tested for resistance transfer factor (RTF). Only 89 (22%) of the strains were resistant to one or more of the antibiotics. Resistance was most common to streptomycin (14.2%), tetracycline (12.5%), and sulfathiazole (11.5%). None of the strains were resistant to chloramphenicol, nalidixic acid, or colistin sulfate. Resistance was significantly more common in strains ofSalmonella typhimuriumthan in the otherSalmonellaserotypes. Of 52 multiply resistant strains, 41 (79%) demonstrated RTF. Comparison with previous studies suggests that no significant change in the incidence of resistantSalmonellahas occurred during the past five years.