Genetic relatedness of Salmonella isolates from nondomestic birds in southeastern united states

Salmonella infections have been implicated in large-scale die-offs of wild birds in the United States. Although we know quite a bit about the epidemio logy of Salmonella infection among domestic fowl, we know little about the incidence, epidemiology, and genetic relatedness of salmonellae in nondomes tic birds. To gain further insight into salmonellae in these hosts, 22 Salm onella isolates from diseased nondomestic birds were screened for the prese nce of virulence and antibiotic resistance-associated genes and compared ge netically using pulsed-field gel electrophoresis (PFGE) and random amplifie d polymorphic DNA analysis. Of the 22 Salmonella isolates examined, 15 were positive for the invasion gene invA and the virulence plasmid-associated g enes spvC and pef. Most (15 of 22) were generally sensitive to antibiotics. However, two Salmonella isolates from pet birds were identified as Salmone lla enterica serovar Typhimurium DT104. Despite the general susceptibility of these Salmonella isolates to most antimicrobial agents, antibiotic resis tance-associated genes int11, merA, and aadA1 were identified in a number o f these isolates. Five distinct XbaI and nine distinct BlnI DNA patterns we re observed for the 22 Salmonella isolates typed by PFGE. PFGE analysis det ermined that Salmonella isolates from passerines in Georgia and Wyoming wer e genetically related.