-

. Objective: Study on antimicrobial drug resistance and transfer of resistance factor among Escherichia coli.
Design: Laboratory study.
Samples: Twenty five Escherichia coli isolated from cases
of colibacilosis from chicken farms (as donors of R- Factor) and Salmonella typhimurium RITCC173O (as acceptor of R-Factor) were used.
Procedure: Twenty five Escherichia coli isolated from
100 cases of colibacilosis from chicken farms were tested for sensitivity to 10 antimicrobial drugs and their ability to
transfer the resistance determinants.
The antimicrobial agents were Tetracycline (Te),
Ampicillin (Am), Neomycin (N), Chloramphenicol (C), Tiamulin (TM), Enrofloxacin (NFX), Flumequine(FM), Linco Spectine(LS), Nalidixic acid(Na), Gentamycin(G).
Results: A total of 25 samples 96ko¾l were resistant to at
least one of the antimicrobial agents. Four different
patterns of resistance to antimicrobial agents were observed, of which thple pattern and more than triple
pattern were most frequently encountered (32ko¾l).
Resistance to Nalidixic acid was maximum (88ko¾l) among all the agents used. Among resistant strains, 62/5ko¾l were able to transfer the resistance determinants. The majority of the isolates
carried triple resistance determinants. Conclusion: The results of this study and other researches indicat that the R- Factor may transfer among the gram negative bacteria specially in the family of
Enterobacteriaceae J.Fac. Vet.Med.Univ. Tehran.60, 1:71-77, 2005.