Isolates belonging to the “Streptococcus milleri” species group that appear to exhibit a gliding type of motility, which is expressed as spreading growth on certain types of agar media, are described. These strains resembled a biotype of “S. milleri” that is usually isolated from genitourinary sources and is notable for its ability to ferment a wide array of carbohydrates. This biotype, which is currently included in the species Streptococcus anginosus, has been implicated in cases of neonatal infection. The “S. milleri” isolates which we studied lacked any observable organelles of motility and gave negative results when they were tested in conventional motility test medium stab cultures. Colonies growing on certain agar media, however, spread over the surfaces of plates and increased in area with increasing time of incubation. Chocolate agar supported maximum spreading, while this characteristic was barely discernible on blood agar. Electron microscopy studies revealed that there was more production of extracellular glycocalyx by motile strains than by a nonmotile isolate having a similar biotype. The results of an analysis of 16S rRNA gene sequences suggested that the motile strains are closely related to S. anginosus and represent a distinct rRNA population within the “S. milleri” species complex.
CollinsM. D.,
AshC.,
FarrowJ. A. E.,
WallbanksS.,
WilliamsA. M.1989; 16S ribosomal ribonucleic acid sequence analyses of lactococci and related taxa. Description of Vagococcus fluvialis gen. nov., sp. nov. J. Appl. Bacteriol 67:453–4160
CoxR. A.,
ChenK.,
CoykendallA. L.,
WesbecherP.,
HersonV. C.1987; Fatal infection in neonates of 26 weeks’ gestation due to Streptococcus milleri: report of two cases. J. Clin. Pathol 40:190–193
FacklamR. R.,
WashingtonJ. A.II1991; Streptococcus and related catalase-negative Gram-positive cocci. 238–257BalowsA.,
HauslerW. J.Jr.,
HerrmannK. L.,
IsenbergH. D.,
ShadomyH. J.Manual of clinical microbiology, 5. American Society for Microbiology; Washington, D. C:
HussainM.,
HastingsJ. G. M.,
WhiteP. J.1991; Isolation and composition of the extracellular slime made by coagulase-negative staphylococci in a chemically defined medium. J. Infect. Dis 163:534–541
HutsonR. A.,
ThompsonD. E.,
CollinsM. D.1993; Genetic interrelationships of saccharolytic Clostridium botulinum types B, E and F and related clostridia as revealed by small-subunit rRNA gene sequences. FEMS Microbiol. Lett 108:103–110
KocurM.1986; Genus III. Planococcus Migula 1894, 236AL
. 1011–1013SneathP. H. A.,
MairN. S.,
SharpeM. E.,
HoltJ. G.Bergey’s manual of systematic bacteriology2 Williams and Wilkins; Baltimore:
LawsonP. A.,
GharbiaS. E.,
ShahH. N.,
ClarkD. J.1989; Recognition of Fusobacterium nucleatum subgroups Fn-1, Fn-2 and Fn-3 by ribosomal RNA gene restriction patterns. FEMS Microbiol. Lett 65:41–46
PetersG.,
LocciR.,
PulvererG.1982; Adherence and growth of coagulase-negative staphylococci on surfaces of intravenous catheters. J. Infect. Dis 146:479–482
RuoffK. L.,
de la MazaL.,
MurtaghM. J.,
SpargoJ. D.,
FerraroM. J.1990; Species identities of enterococci isolated from clinical specimens. J. Clin. Microbiol 28:435–437
RuoffK. L.,
FishmanJ. A.,
CalderwoodS. B.,
KunzL. J.1983; Distribution and incidence of viridans streptococcal species in routine clinical specimens. Am. J. Clin. Pathol 80:854–858
WhileyR. A.,
BeightonD.1991; Emended descriptions and recognition of Streptococcus constellatus, Streptococcus intermedius, and Streptococcus anginosus as distinct species. Int. J. Syst. Bacteriol 41:1–5