Multidrug-resistant Salmonella isolates from retail chicken meat compared with human clinical isolates

Abstract

Aim: To examine the prevalence of antimicrobial-resistant Salmonella in chicken meat and correlate with isolates from ill humans.

Methods: We isolated Salmonella from raw chicken purchased from a randomly selected sample of retail outlets in central Pennsylvania during 2006-2007. Salmonella isolates from meat were compared, using pulsed-field gel electrophoresis, to isolates in the PulseNet database of Salmonella recovered from humans.

Results: Of 378 chicken meat samples, 84 (22%) contained Salmonella. Twenty-six (31%) of the Salmonella isolates were resistant to > or = 3 antimicrobials and 18 (21%) were resistant to ceftiofur. All ceftiofur-resistant isolates exhibited reduced susceptibility (minimum inhibitory concentration >2 microg/mL) to ceftriaxone and carried a bla(CMY) gene, as detected by polymerase chain reaction. Among the 28 Salmonella serovar Typhimurium isolates, 20 (71.4%) were resistant to > or = 3 antimicrobials and 12 (42.9%) were resistant to ceftiofur. One ceftiofur-resistant Salmonella serovar Typhimurium poultry isolate exhibited a rare pulsed-field gel electrophoresis pattern indistinguishable from a human isolate in PulseNet; both isolates carried the bla(CMY-2) gene.

Conclusions: These data demonstrate the presence of multidrug-resistant Salmonella in poultry meat, including bla(CMY) plasmid-mediated genes that confer resistance to both ceftiofur, used in poultry, and ceftriaxone, used for treating salmonellosis in humans. This study illustrates the potential for molecular subtyping databases to identify related Salmonella isolates from meat and ill humans, and suggests that chicken could be a source for multidrug-resistant salmonellosis in humans.