MOLECULAR CHARACTERISATION OF TETRACYCLINE RESISTANCE OF SOME AVIAN SALMONELLA TYPHJMURJUM AND SALMONELLA ENTERJTJDJS STRAINS

Genetic screening by hybridi zation with tet M and let 0 DNA probes demonstrated, in Salmonella strains iso lated in 1996, the following: 14/15 (93.3%) of S. enteritidis strains and 9/ 12 (75%) of S. typhimurium strains harbored the tet M determinant; I 0/15 (66.6%) ofS. enteritidis strains and 7112 (58.3%) of S. typhimurium harbored also the tet 0 determinant. The PCR screening, for which we used primers provided by Dr. Eli sabeth Chaslu s Dancla, !NRA Tours, France, and which underline a common fragment for the A,B,C,D,E determinants, was negative. The presence of the tel Mand tel 0 determinants, which code the re sistance mechani sm by ribosomal protection against all types of tetracycline (first generation and the analogues of the second generation) could be attributed to a genetic acq ui sition from Gram-positive bacteria. In conjugation te sts , with£. coli BM2 l (gyr A, Nair), tetracycline re sistance shown high transfer frequency, which suggests the possibility of high epidemiological ri sk. The origi n of strains - three Romanian geographical region s - suggests that the M and 0 tetracycline resistance determinants were widespread among avian S. typhimurium and S. enteritidis strain s.