Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2004
Publication Date: 1/1/2004
Citation: Jackson, C.R., Cray, P.J., Barrett, J.B., Ladely, S.R. 2004. Genetic relatedness of high-level aminoglycoside resistant enterococci isolated from poultry carcasses. Avian Diseases. 48(1):100-107.
Technical Abstract: Approximately 46% (75/162) of poultry enterococci collected between 1999-2000 exhibited high-level resistance to gentamicin (MIC greater than 500 ug/ml), kanamycin (MIC greater than 500 ug/ml), or streptomycin (MIC greater than 1000 ug/ml). Forty-one percent of the isolates were resistant to kanamycin (n=67) while 23% and 19% were resistant to gentamicin (n=37) and streptomycin (n=31), respectively. The predominant species identified was Enterococcus faecium (n=105), followed by Enterococcus faecalis (n=40) and Enterococcus durans (n=8). Using PCR, the isolates were examined for the presence of ten aminoglycoside resistance genes [ant(6)-Ia, ant(9)-Ia, ant(4')-Ia, aph(3')-IIIa, aph(2')-Ib, aph(2')-Ic, aph(2')-Id, aac(6')-Ie-aph(2')-Ia, and aac(6')-Ii]. Five aminoglycoside resistance genes were detected, most frequently aac(6')-Ii and ant(6)-Ia from E. faecium. Seven E. faecalis isolates resistant to gentamicin, kanamycin, or streptomycin were negative for all genes tested suggesting that additional resistance genes may exist. Phylogenetic analysis revealed that the isolates were genetically different with little clonality. These data suggest that enterococci from poultry are diverse and contain potentially unidentified aminoglycoside resistance genes.