FREQUENCY OF AGGREGATION SUBSTANCE AND CYTOLYSIN GENES AMONG ENTEROCOCCAL ENDOCARDITIS ISOLATES

Enterococcus faecalis blood isolates were probed for the serine protea se activator of cytolysin (cylA) and aggregation substance (asal), tra its that generally reside on pheromone-responsive plasmids, to determi ne how commonly these genotypes were associated with disease. In dot b lot assays, no significant difference was found in the frequency of as al for blood isolates [55 of 103 (54%)] and isolates recovered from st ool [9 of 14 (60%); P > 0.1, chi(2) test]. In contrast, cylA occurred more frequently among bacteremia isolates [34 of 68 (50%)] than endoca rditis [4 of 35 (11%)] or stool isolates (0 of 14; P < 0.001; chi(2) L est). However, when the clonality of isolates was accounted for, the f requency of asal and cylA among unrelated strains was not significantl y different among the three sets of strains (P > 0.2, chi(2) test). Th e lack of enrichment for asal or cylA among clonally unrelated E. faec alis bloodstream isolates fails to support a role for plasmid-encoded aggregation substance or cytolysin in the transition from bacteremia t o endocarditis. Clonally related, cytolytic strains, however, demonstr ated an increased propensity to cause bloodstream infection. (C) 1995 Academic Press, Inc.