Characterization of a Salmonella enterica serovar Agona strain harbouring a class 1 integron containing novel OXA-type beta-lactamase (blaOXA-53) and 6'-N-aminoglycoside acetyltransferase genes [aac(6')-I30].
OBJECTIVE
To characterize by molecular methods a multidrug-resistant Salmonella enterica serovar Agona (S. enterica Agona) isolated from a hospitalized patient in Rio de Janeiro, Brazil.


METHODS
The S. enterica Agona strain was screened by PCR and DNA sequencing for TEM, SHV and CTX-M-type beta-lactamase genes, tet(A), (B), (C) and (D) tetracycline resistance genes, chloramphenicol resistance genes and class 1 integrons. Plasmid characterization was carried out by PCR and Southern hybridization analysis. PCR and PFGE were used to characterize nine other S. enterica Agona strains collected from hospitals in Rio de Janeiro.


RESULTS
The study strain was found to harbour a 105 kb plasmid, which contained catA1, bla(TEM-1), a class 1 integron with two novel genes labelled bla(OXA-53) and aac(6')-I30, respectively, and an additional unidentified aminoglycoside resistance gene. A second 53 kb plasmid from the same strain contained tet(D) and bla(SHV-5). OXA-53 was shown to provide reduced susceptibility to ceftazidime, and its activity was inhibited in the presence of clavulanic acid. PFGE analysis of the nine other S. enterica Agona strains revealed two clusters of related strains (78% similarity), and PCR analysis showed that all strains contained the novel integron.


CONCLUSIONS
An S. enterica Agona strain was found to harbour three plasmid-encoded beta-lactamases, one (OXA-53) on a novel class 1 integron that also contains a new aminoglycoside resistance gene, aac(6')-I30. The multidrug resistance plasmids appear to have disseminated to other city hospitals via other S. enterica Agona strains.
Mulvey
Michael R
MR
Bacterial and Enteric Diseases Program, National Microbiology Laboratory, Health Canada, 1015 Arlington St., Winnipeg, Manitoba, Canada, R3E 3R2. michael_mulvey@hc-sc.gc.ca
Boyd
David A
DA
Baker
Lorea
L
Mykytczuk
Oksana
O
Reis
E M F
EM
Asensi
M D
MD
Rodrigues
D P
DP
Ng
Lai-King
LK
D000123:Acetyltransferases / Q000235:genetics*; D000595:Amino Acid Sequence; D001938:Brazil; D003001:Cloning, Molecular; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D006801:Humans; D032023:Integrons / Q000235:genetics*; D007525:Isoelectric Focusing; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012480:Salmonella Infections / Q000188:drug therapy / Q000382:microbiology; D019779:Salmonella enterica / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics*
D017931:DNA Primers; D004269:DNA, Bacterial; C492228:6'-N-aminoglycoside acetyltransferase aac(6')-I30, Salmonella enterica; D000123:Acetyltransferases; D001618:beta-Lactamases; C492227:beta-lactamase OXA-53, Salmonella enterica