Rapid and widespread dissemination of multidrug-resistant blaCMY-2 Salmonella Typhimurium in Mexico

Typhimurium in humans, retail meat and food animals from Yucatan, Mexico. Methods: Salmonella Typhimurium isolates were collected through an active surveillance system and tested for susceptibility to 12 antimicrobial agents. Isolates that were non-susceptible to ceftriaxone were tested with 10 additional antimicrobials and assayed by PCR for the presence of CMY, CTX-M, SHV, TEM and OXA b-lactamase genes. Plasmid-borne phenotypes were identified by transfer to sus-ceptible Escherichia coli. Isolates from humans, retail meat and food animals were compared by PFGE to determine genetic relatedness. Results: MDR Salmonella Typhimurium containing a plasmid-mediated blaCMY-2 AmpC b-lactamas