title: Changing clonal patterns of Salmonella enteritidis in Maryland: evaluation of strains isolated between 1985 and 1990.
abstract: We examined isolates from 203 sporadic and outbreak-associated Salmonella enteritidis cases occurring in Maryland between 1985 and 1990. Plasmid profiles were determined for all isolates; 52 isolates were phage typed. Ten plasmid profiles were identified. A single profile (consisting of a single ca. 55-kb plasmid) emerged as the predominant profile in Maryland during the study period. This profile (which was closely associated with phage type 8) accounted for 86% of a group of isolates from sporadic cases in 1988 and 1989, compared with 43% of the 1985 isolates. Strains with this profile were identified in four of nine outbreaks, including one of three outbreaks in which eggs were implicated as a vehicle. While plasmid profiles and phage typing appear to provide complementary means of identifying specific strains of S. enteritidis, the emergence of what appears to be a single predominant clone has reduced the discriminant ability of both typing systems. The factors be a single predominant clone has reduced the discriminant ability of both typing systems. The factors contributing to the emergence of this one clone are still not well understood.
authors.affiliation: Department of Medicine, University of Maryland School of Medicine, Baltimore.
authors.forename: J G
authors.initials: JG
authors.lastname: Morris
authors.forename: D M
authors.initials: DM
authors.lastname: Dwyer
authors.forename: C W
authors.initials: CW
authors.lastname: Hoge
authors.forename: A D
authors.initials: AD
authors.lastname: Stubbs
authors.forename: D
authors.initials: D
authors.lastname: Tilghman
authors.forename: C
authors.initials: C
authors.lastname: Groves
authors.forename: E
authors.initials: E
authors.lastname: Israel
authors.forename: J P
authors.initials: JP
authors.lastname: Libonati
mesh_terms: D001434:Bacteriophage Typing; D006801:Humans; D008396:Maryland; D010957:Plasmids; D012477:Salmonella enteritidis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D013997:Time Factors