Genetic Relatedness of Salmonella Isolates from Nondomestic Birds in Southeastern United States

Abstract

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 epidemiology of Salmonellainfection among domestic fowl, we know little about the incidence, epidemiology, and genetic relatedness of salmonellae in nondomestic birds. To gain further insight into salmonellae in these hosts, 22Salmonella isolates from diseased nondomestic birds were screened for the presence of virulence and antibiotic resistance-associated genes and compared genetically using pulsed-field gel electrophoresis (PFGE) and random amplified polymorphic DNA analysis. Of the 22 Salmonella isolates examined, 15 were positive for the invasion gene invA and the virulence plasmid-associated genes spvC and pef. Most (15 of 22) were generally sensitive to antibiotics. However, twoSalmonella isolates from pet birds were identified asSalmonella enterica serovar Typhimurium DT104. Despite the general susceptibility of these Salmonella isolates to most antimicrobial agents, antibiotic resistance-associated genesintI1, merA, and aadA1 were identified in a number of these isolates. Five distinctXbaI and nine distinct BlnI DNA patterns were observed for the 22 Salmonella isolates typed by PFGE. PFGE analysis determined that Salmonella isolates from passerines in Georgia and Wyoming were genetically related.

Epidemiology of Subclinical Salmonellosis in Wild Birds from an Area of High Prevalence of Pig Salmonellosis: Phenotypic and Genetic Profiles of Salmonella Isolates

“…As it happens is in other countries (Hudson et al., 2000; Kobayashi et al., 2007; Lawson et al., 2011; Palmgren et al., 2006), Salmonella Typhimurium was the most prevalent serotype in the bird samples. Interestingly, the monophasic variant of S .…”

Bacterial pathogens in wild birds: a review of the frequency and effects of infection

“…Canada geese Branta canadensis containing antibiotic‐resistant E. coli use farmland for grazing, creating the opportunity for transfer of drug‐resistant bacteria to cattle and other livestock (Cole et al , 2005). Although wild animals do not naturally come into contact with antibiotics, they can become infected with resistant bacteria disseminated by wild birds, and act as reservoirs and vectors of resistant bacterial pathogens, encouraging new health problems in wildlife populations to emerge, as well as novel reservoirs of zoonotic disease to form (Cole et al , 2005; Hudson et al , 2000; Sayah et al , 2005).…”

Towards more virulent and antibiotic-resistantSalmonella?

“…The nature of the gene cassettes in the other integron carrying isolates was unknown. Two additional isolates from diseased pet birds belonged to S. enterica serovar Typhimurium DT104, which contained SGI1 (Salmonella Genomic Island 1, which encodes antibiotic resistance; see below) [11]. Sequence analysis of the approximately 50 kb pKDSC50 virulence plasmid from a S. enterica serovar Choleraesuis strain showed the presence of the spv operon, but absence of pef and rck genes (see also below).…”