학술논문
Characterization of extended-spectrum cephalosporin-resistant Salmonella enterica serovar Heidelberg isolated from humans in the United States
Document Type
Report
Author
Source
Foodborne Pathogens and Disease. February 1, 2010, Vol. 7 Issue 2, p181, 7 p.
Subject
Language
English
ISSN
1535-3141
Abstract
Introduction The Gram-negative bacterium Salmonella enterica is one of the most common bacterial causes of foodborne illness worldwide. S. enterica is the causative agent of salmonellosis, usually a self-limiting gastroenteritis. [...]
During the past decade, extended-spectrum cephalosporin resistance has increased among human isolates of Salmonella enterica serovar Heidelberg, the fourth most common serotype in the United States. We therefore characterized 54 Heidelberg isolates with decreased susceptibility (minimum inhibitory concentrations ≥ 2mg/L) to ceftriaxone or ceftiofur; 49 (90.7%) contained the CMY-type β-lactamase ([bla.sub.CMY]) gene. The 49 [bla.sub.CMY]- positive human Heidelberg isolates demonstrated a high degree of relatedness; 4 clusters (25 isolates total) had indistinguishable XbaI and BlnI patterns by pulsed-field gel electrophoresis and were indistinguishable from 42 retail meat Heidelberg isolates. Further characterization of 15 of these isolates demonstrated that all of the bla genes were [bla.sub.CMY-2] and plasmid-encoded, and most (11/15) of the plasmids were approximately 100 kb in size and belong to the incompatibility group I1 (IncI1). All five IncI1 plasmids tested by plasmid multilocus sequence typing analysis were ST12. This report suggests that extended-spectrum cephalosporin resistance among human Heidelberg isolates is mediated by the spread of a common IncI1 [bla.sub.CMY-2] plasmid, which may have a preference for a particular genetic background.
During the past decade, extended-spectrum cephalosporin resistance has increased among human isolates of Salmonella enterica serovar Heidelberg, the fourth most common serotype in the United States. We therefore characterized 54 Heidelberg isolates with decreased susceptibility (minimum inhibitory concentrations ≥ 2mg/L) to ceftriaxone or ceftiofur; 49 (90.7%) contained the CMY-type β-lactamase ([bla.sub.CMY]) gene. The 49 [bla.sub.CMY]- positive human Heidelberg isolates demonstrated a high degree of relatedness; 4 clusters (25 isolates total) had indistinguishable XbaI and BlnI patterns by pulsed-field gel electrophoresis and were indistinguishable from 42 retail meat Heidelberg isolates. Further characterization of 15 of these isolates demonstrated that all of the bla genes were [bla.sub.CMY-2] and plasmid-encoded, and most (11/15) of the plasmids were approximately 100 kb in size and belong to the incompatibility group I1 (IncI1). All five IncI1 plasmids tested by plasmid multilocus sequence typing analysis were ST12. This report suggests that extended-spectrum cephalosporin resistance among human Heidelberg isolates is mediated by the spread of a common IncI1 [bla.sub.CMY-2] plasmid, which may have a preference for a particular genetic background.