Antimicrobial drugs are widely used in poultry industry as growth promoters or to control infectious diseases. However, this practice is reported to have caused high resistance to antimicrobial drugs in normal chicken flora and pathogens. Antimicrobial resistance to Escherichia coli (E. coli) from chicken has been mainly reported in normal flora, but rare in pathogenic organism in Korea, recently. Therefore, this study was conducted to investigate prevalence of antimicrobials resistance, transfer of R plasmid, and association between antimicrobial drug resistance and O serotype of 203 pathogenic E. coli from poultry in Korea during the period from April 2003 to December 2005. These isolate showed a high resistance to tetracycline (Tc, 92.6%), streptomycin (Sm. 81.8%), ampicillin (Ap, 77.3%), ciprofloxacin (Ci, 70.9%), sulfisoxazole (Su, 66.5%), and trimethoprim (Tp, 58.1%). Two hundred-one (99.0%) of the isolates were resistant to one or more drugs. They showed 57 different resistant patterns, and the most prevalent resistant pattern among them was Tc, Sm, Su, Ap, Tp, Ci, Na. Sixty-eight (33.8%) of the isolates transferred all or a part of their antimicrobial resistant pattern to the recipient strain by R plasmid. The most common antinicrobial resistant pattern was Tc, Sm, Su, Ap, Tp, Ci, Na in serotype O78, O88 and O15, respectively. These results exhibit high individual and multiple resistance to antimicrobials of pathogenic E. coli from poultry in Korea. They also suggest the needs for surveillance to monitor antimicrobial resistance in pathogenic bacteria that can be potentially transmitted to humans from food animals and to regulate the abuse of antimicrobials in food-producing animals in Korea.

This study was conducted to investigate incidence of extended-spectrum β-lactamase (ESBL) producing strains and characteristics of ESBL gene in pathogenic Escherichia coli isolated from poultry during the period from April 2003 to December 2005 in Korea. Among 203 isolates, 4 isolates (3 from broilers and 1 from layer) were confirmed as ESBL producing strains by double disk synergy test, polymerase chain reaction and sequencing for β-lactamase genes. bla∧CTX-M-15 and bla∧CMY-2 were detected in these 4 isolates and were transferred to recipient by conjugation, respectively. Also, these ESBL producing strains were associated with multiple drug resistance. In conclusion, these results exhibit incidence of CTX-M and CMY-2 β-lactamase in pathogenic E coli from poultry in Korea, and clinically important meaning in human. And they also suggest the needs for rapid and broad surveillance to monitor ESBL genes and R plasmid transferring resistant gene in poultry.