Identification and characterization of Salmonella enterica subsp. enterica serovar Derby isolates carrying a new aadA26 gene cassette in a class 1 integron obtained at pig slaughterhouses.
Salmonella enterica subsp. enterica (S.) serovar Derby is one of the most prevalent serovars in pigs. Twenty-seven multiresistant S. Derby isolates, obtained at two pig slaughterhouses in Southern Brazil, were investigated for their molecular relationships, genotypic resistance and presence of class 1 and 2 integrons. All isolates shared the same XbaI-macrorestriction pattern and showed a common resistance genotype with resistance to streptomycin/spectinomycin (aadA variant), sulphonamides (sul1) and tetracycline [tet(A)]. They carried chromosome-located class 1 integrons with a new aadA gene variant, designated aadA26, as part of a gene cassette. The sequence of the flanking regions of this integron and the amplification of the merA gene may indicate the location of the class 1 integron into a Tn21-related transposon. The close relationships among these isolates and isolates from an earlier study suggest the persistence of a resistant clone of S. Derby in the pig production chain in Southern Brazil.
Departamento de Medicina Veterinária Preventiva, Universidade Federal do Rio Grande do Sul (UFGRS), Porto Alegre, Brazil; Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut (FLI), Neustadt-Mariensee, Germany.
Graciela Volz
GV
Lopes
Geovana Brenner
GB
Michael
Marisa
M
Cardoso
Stefan
S
Schwarz
D000003:Abattoirs; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004783:Environmental Microbiology; D005798:Genes, Bacterial; D032023:Integrons; D007422:Intestines / Q000382:microbiology; D019779:Salmonella enterica / Q000235:genetics* / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D013307:Streptomycin / Q000494:pharmacology; D034421:Sus scrofa / Q000382:microbiology
D000900:Anti-Bacterial Agents; D013307:Streptomycin
antimicrobial resistance; macrorestriction analysis; pig slaughterhouse; pork; transposon