title: Stored-product insects carry antibiotic-resistant and potentially virulent enterococci.
abstract: A total of 154 enterococcal isolates from 95 stored-product insects collected from a feed mill, a grain storage silo, and a retail store were isolated and identified to the species level using PCR. Enterococcus casseliflavus represented 51% of the total isolates, followed by Enterococcus gallinarum (24%), Enterococcus faecium (14%), Enterococcus faecalis (7%), and Enterococcus hirae (5%). Many isolates were resistant to tetracycline (48%), followed by streptomycin (21%), erythromycin (14%), kanamycin (13%), ciprofloxacin (12%), ampicillin (4%), and chloramphenicol (<1%). Enterococci carried genes coding for virulence factors, including the gelatinase gene gelE (26% of isolates), an enterococcal surface protein gene esp (1%), and the cytolysin gene cylA (2%). An aggregation substance (asa1) gene was detected in six out of 10 E. faecalis isolates and five of these were positive for the aggregation substance. Enterococci were positive for hemolytic (57% of isolates) and gelatinolytic (23%) activity. The filter-mating assay showed that the tetracycline resistance gene, tetM, was transferable among E. faecalis by conjugation. These data demonstrated that stored-product insects can serve as potential vectors in disseminating antibiotic-resistant and potentially virulent enterococci.
authors.affiliation: Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506-2201, USA.
authors.forename: Lakshmikantha H
authors.initials: LH
authors.lastname: Channaiah
authors.forename: Bhadriraju
authors.initials: B
authors.lastname: Subramanyam
authors.forename: Leland J
authors.initials: LJ
authors.lastname: McKinney
authors.forename: Ludek
authors.initials: L
authors.lastname: Zurek
mesh_terms: D000818:Animals; D024881:Drug Resistance, Bacterial; D002523:Edible Grain / Q000382:microbiology; D016983:Enterococcus / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D007313:Insecta / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors