Genetic and phenotypic characterization of the bla(CMY) gene from Escherichia coli and Salmonella enterica isolated from food-producing animals, humans, the environment, and retail meat.
The bla(CMY-2) family of the ampC beta-lactamase genes confer broad-spectrum resistance to beta-lactam antimicrobials, including ceftriaxone and ceftiofur, as well as to beta-lactamase inhibitors, such as clavulanic acid. Organisms with the bla(CMY-2) phenotype have been recovered from the environment and from retail meat products, posing a potential public health risk. The objectives of this study were to sequence the bla(CMY-2) gene from Escherichia coli and Salmonella enterica from multiple sources that had a reduced susceptibility to ceftriaxone and to determine the effect of observed mutations in the bla(CMY-2) gene on the antimicrobial resistance phenotype (spectrum and minimum inhibitory concentration/susceptibility patterns) of the isolates. The bla(CMY-2) genes from 52 bacterial isolates were sequenced for this study. Sixty-two percent (32/52) were E. coli and 38% (20/52) were S. enterica. Of the 32 E. coli isolates, 30 were found to carry a beta-lactamase gene that was 100% homologous to bla(CMY-2). One of the E. coli isolates was found to contain a gene that was 90% homologous to bla(CMY-2). This isolate also had lower minimum inhibitory concentrations to tetracyclines, streptomycin, and the sulfonamide antimicrobials than are commonly expected for isolates containing the bla(CMY-2). Of the 20 genes obtained from Salmonella isolates, 8 (40%) were found to be homologous to bla(CMY-2), with no altered susceptibility phenotypes observed.
Heider
Luke C
LC
Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210, USA. heider.11@osu.edu
Hoet
Armando E
AE
Wittum
Thomas E
TE
Khaitsa
Margaret L
ML
Love
Brenda C
BC
Huston
Carla L
CL
Morley
Paul S
PS
Funk
Julie A
JA
Gebreyes
Wondwossen A
WA
D000483:Alleles; D000818:Animals; D000829:Animals, Domestic / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics*; D018550:Cephalosporin Resistance / Q000235:genetics*; D004269:DNA, Bacterial / Q000737:chemistry; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D005506:Food Contamination / Q000517:prevention & control; D056726:Genetic Association Studies; D006801:Humans; D008460:Meat / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D019779:Salmonella enterica / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D014481:United States; D001618:beta-Lactamases / Q000235:genetics*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; C103022:beta-lactamase CMY-2; D001618:beta-Lactamases