Prevalence and antimicrobial resistance of Salmonella serovars in conventional and organic chickens from Louisiana retail stores.

In this 1-year survey from October 2006 to September 2007, we isolated and characterized 126 Salmonella isolates from conventionally raised (n = 141) and organically raised (n = 53) chicken carcasses obtained from 27 retail stores in Baton Rouge, Louisiana. Salmonella was isolated from 22% of conventional and from 20.8% of organic chicken samples. Eight Salmonella serovars were identified; predominant ones included Kentucky, Hadar, and Enteritidis. The vast majority of isolates within the same chicken sample possessed the same pulsed-field gel pattern. All Salmonella isolates were susceptible to amikacin, ceftriaxone, and ciprofloxacin; however, decreased susceptibility to quinolones (7.1 %) or extended-spectrum cephalosporins (45.2%) was observed. Resistance to multiple antimicrobials (two or more) was found among 52.4% of the Salmonella isolates. Antimicrobial resistance profiles differed greatly among Salmonella serovars and also depended on the type of chicken from which they were recovered. Salmonella Kentucky isolates from organic chicken samples were susceptible to 11 of the antimicrobials tested, whereas those from conventional chickens were only susceptible to 4 antimicrobials. Three Salmonella Kentucky isolates from conventional chickens possessed multidrug resistance phenotype MDR-AmpC. Results of this study provide baseline data on both prevalence and antimicrobial resistance of Salmonella in retail chickens in this region and emphasize the need for implementing effective control measures to reduce Salmonella contamination and the levels of antimicrobial-resistant Salmonella in both conventionally and organically raised poultry products. Further studies involving larger sample sizes over time are needed to better monitor and assess the trend of prevalence and antimicrobial susceptibility among Salmonella serovars in retail chickens.