Dissemination amongst humans and food products of animal origin of a Salmonella typhimurium clone expressing an integron-borne OXA-30 beta-lactamase.
OBJECTIVE
Characterization of the molecular basis for beta-lactam resistance and evaluation of the clonal relatedness among nine isolates of multidrug-resistant Salmonella typhimurium recovered from seven clinical human samples and two pork end products.


METHODS
The isolates were examined for susceptibility to antimicrobial agents. The relationships between resistance genes, class 1 integrons, plasmids and isolates were screened by molecular methods such as polymerase chain reaction and restriction fragment length analysis.


RESULTS
A bla(OXA-30) gene, located in a class 1 integron, was detected in all isolates. This integron was present on a conjugative plasmid in all but one isolate. By pulsed-field gel electrophoresis, it was determined that all strains share the same chromosomal type.


CONCLUSIONS
This study demonstrates the spread of an OXA-30-producing S. typhimurium in Portugal, suggesting dissemination of a resistant clone through the food chain.
Antunes
Patrícia
P
Faculdade de Ciências da Nutrição e Alimentação, Universidade do Porto, Porto, Portugal.
Machado
Jorge
J
Sousa
João Carlos
JC
Peixe
Luísa
L
D000818:Animals; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000096:biosynthesis / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D005516:Food Microbiology; D006801:Humans; D032023:Integrons / Q000235:genetics; D008460:Meat / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D011174:Portugal / Q000453:epidemiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012480:Salmonella Infections / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D013552:Swine; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000096:biosynthesis*
D004269:DNA, Bacterial; C413936:beta-lactamase OXA-30; D001618:beta-Lactamases