Occurrence of tetracycline-resistant determinant classes among Enterobacteriaceae isolated from meat

Abstract

Total genomic DNA from 207 randomly screened tetracycline-resistant Enterobacteriaceae isolates from raw ground beef and chicken meat samples were examined for occurrence of tetracycline resistance classes A-C using nonradioactively labeled DNA probes and dot blot hybridization. 76 and 61% of the isolates examined from chicken meat and ground beef samples, respectively, carried resistance determinant class B. Resistance determinant class A showed an occurrence of 29% (chicken meat isolates) and 39% (ground beef isolates). The respective values for class C type determinant were 3 and 15% which displayed the least common occurrence. Cross-hybridization between A-C determinants was observed. The cross-hybridization between determinant classes A and B were found to be more common than others (12 and 15% in isolates from chicken meat and ground beef, respectively). The least percentages of cross-hybridization were observed between determinant classes B and C (2% in isolates from ground beef). 7% of tetracycline-resistant isolates (ground beef) displayed hybridization signals with all three resistance determinants. A few isolates, 3% (chicken meat) and 4% (ground beef), did not show hybridization with any of the determinants examined.