Isolation and characterization of Escherichia coli O157 : H7 from retail meats in Argentina

Citation
I. Chinen et al., Isolation and characterization of Escherichia coli O157 : H7 from retail meats in Argentina, J FOOD PROT, 64(9), 2001, pp. 1346-1351
Citations number
37
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Food Science/Nutrition
Journal title
JOURNAL OF FOOD PROTECTION
ISSN journal
0362-028X → ACNP
Volume
64
Issue
9
Year of publication
2001
Pages
1346 - 1351
Database
ISI
SICI code
0362-028X(200109)64:9<1346:IACOEC>2.0.ZU;2-U
Abstract
Between February and May 2000, 279 meat samples were collected from 136 ret ail stores in Gualeguaychu City, Argentina. Samples were assayed for Escher ichia coli O157:H7 by selective enrichment in modified EC broth containing novobiocin, followed by immunomagnetic separation (IMS) and plating onto bo th sorbitol MacConkey agar supplemented with cefixime and potassium telluri te and a chromogenic medium. Eleven E. coli O157:H7 isolates were detected in 6 (3.8%) of 160 ground beef samples, in 4 (4.8%) of 83 fresh sausages, a nd in 1 (3.3%) of 30 dry sausages. E. coli O157:H7 was not isolated from fi ve hamburger patties or one barbecue-type fresh sausage assayed. The isolat es were tested for virulence-related genes. Ten additional Shiga toxin-prod ucing E. coli (STEC) O157:H7 isolates of food origin, recovered from differ ent locations in Argentina, were included for comparison purposes. All 21 i solates harbored both eae and EHEC-hlyA genes, and 12 (57.1%) encoded stx2/ stx2vh-a. The isolates were of phage types 87 (seven strains), 14 (four str ains), 4 (three strains), and 26 (one strain). Six strains were nontypable by phage typing. Pulsed-field gel electrophoresis (PFGE) revealed 19 XbaI-P FGE profiles. Fifteen (71%) strains were grouped in four clusters. which sh ared more than 80% of DNA restriction fragments. The enrichment culture met hod with IMS was a sensitive procedure to detect E. coli O157:H7 strains in retail meats. Some of the isolates from different stores presented a high clonal relatedness, as determined by XbaI-PFGE and phage typing, and harbor ed the virulence factors associated with human illness.