INTERACTIONS BETWEEN EIKENELLA-CORRODENS AND STREPTOCOCCUS MILLERI-GROUP ORGANISMS - POSSIBLE MECHANISMS OF PATHOGENICITY IN MIXED INFECTIONS

Interactions between the 'Streptococcus milleri-group' organisms ( SMG ; S. intemedius, S. constellatus and S. anginosus) and Eikenella corro dens were investigated. Coaggregation reactions occurred frequently be tween S. anginosus (83% of strain combinations) or S. constellatus (87 %) and E. corrodens isolates, but were infrequent between S. intermedi us and E. corrodens (28%). No enhancement of enzyme activities against lipid, phosphate, peptide and saccharide substrates tested were detec ted with combinations of species in comparison to the species alone. E xponential growth of S. constellatus and S. intermedius, in mixed cult ure with E. corrodens, occurred within 6h post inoculation, in compari son to 25h without E. corrodens. No growth stimulation of S. anginosus was observed. It is concluded that both coaggregation and growth stim ulation occur between E. corrodens and SMG isolates, and may be import ant mechanisms in the establishment of mixed infections involving thes e bacteria.