ARS | Publication request: HIGH-LEVEL AMINOGLYCOSIDE RESISTANT ENTEROCOCCI ISOLATED FROM SWINE

Submitted to: Epidemiology and Infection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 13, 2004
Publication Date: December 13, 2004
Citation: Jackson, C.R., Cray, P.J., Barrett, J.B., Ladely, S.R. 2004. High-level aminoglycoside resistant enterococci isolated from swine. Epidemiology and Infection. V. 133. P. 367-371.

Interpretive Summary: One problem inhibiting the effective study of the potential transfer of resistance from animals to humans is the lack of information of antimicrobial resistance in animal bacterial isolates. Aminoglycosides antimicrobials are of interest due to their use in both animals and humans. In this study, resistance to aminoglycosides in enterococci from swine samples was examined. High-level gentamicin, kanamycin, and streptomycin resistance was found in 6%, 30%, and 32% of the isolates, respectively. Of the 13 genes tested, 8 resistance genes [ant(6)-Ia, ant(9)-Ia, ant(4')-Ia, aph(3')-IIIa, aac(6')-Ie-aph(2")-Ia, aph(2")-Id, and aac(6')-Ii] were identified in the isolates using PCR. This data suggests that although enterococci from animals represent a diverse population of aminoglycoside resistance, some resistance genes have not yet spread to animal isolates. This data will be useful for researchers due to the need to understand where antimicrobial resistance is harbored and where it originates.

Technical Abstract: Approximately 42% (187/444) of swine enterococci collected between 1999-2000 exhibited high-level resistance to gentamicin, kanamycin (MIC greater than or equal to 500 ug/ml), or streptomycin (MIC greater than or equal to 1000 ug/ml). Eight aminoglycoside resistance genes were detected, most frequently ant(6)-Ia and aac(6')-Ii from Enterococcus faecium. Twenty-four percent (45/187) of total isolates and 26% (4/15) of isolates resistant to high-levels of all three antimicrobials were negative for all genes tested. These data suggest that enterococci from swine contain diverse and possibly unidentified aminoglycoside resistance genes.