Genetic heterogeneity among nutritionally deficient streptococci

Genetic heterogeneities and phenotypic characteristics of strains of the genus Abiotrophia and proposal of Abiotrophia para-adiacens sp. nov

The genus Abiotrophia represents a heterogeneous group of fastidious cocci that show a dependence on pyridoxal hydrochloride analogs for growth. The genetic heterogeneity in the genus Abiotrophia was examined by DNA-DNA hybridization, PCR assay of genomic DNA sequences, and restriction fragment length polymorphism and sequence homology analyses of the PCR-amplified 16S rRNA gene. Nine type or reference strains of Abiotrophia defectiva, Abiotrophia adiacens, and Abiotrophia elegans and 36 oral Abiotrophia isolates including the ones presumptively identified as Gemella morbillorum by the rapid ID32 STREP system were divided into four groups: A. defectiva (genotype 1), A. adiacens (genotype 2), A. elegans (genotype 4), and a fourth species (genotype 3) which we propose be named Abiotrophia para-adiacens sp. nov. A PCR assay specific for detection and identification of the novel Abiotrophia species was developed. A. para-adiacens generally produced beta-glucosidase but did not produce alpha- or beta-galactosidase or arginine dihydrolase, did not ferment, trehalose, pullulan, or tagatose, and was serotype IV, V, or VI. Thus, it was distinguished phenotypically from A. adiacens, A. elegans, and A. defectiva as well as, apparently, from the recently described species Abiotrophia balaenopterae sp. nov., which produces arginine dihydrolase and which ferments pullulan but not sucrose (P. A. Lawson et al., Int. J. Syst. Bacteriol. 49:503-506, 1999). Strain ATCC 27527, currently listed as G. morbillorum, was a member of the species A. para-adiacens.

Isolation and properties of bacteriolytic enzyme-producing cocci from the human mouth

One-hundred-and-one bacteriolytic enzyme producing organisms were isolated from various sites of the mouth. All were non-hemolytic, Gram-positive, and chain-forming cocci. Ninety-one strains, like the reference strains of Streptococcus defectivus and S. adjacens, were dependent on pyridoxal for growth and produced a chromophore. The Rapid ID32 STREP system speciated these isolates as S. defectivus, S. adjacens or Gemella morbillorum. The remaining 10 bacteriolytic isolates were pyridoxal-independent and 8 belonged to S. intermediate. Some pyridoxal-independent S. intermedius reference strains including ATCC27335T and all group D Enterococcus strains tested were also bacteriolytic. Thus, bacteriolytic enzyme production is common to nutritionally variant streptococci but not unique to S. defectives and S. adjacens. The nutritionally variant strains generally had arylamidases but not alkaline phosphatase. The S. defectivus strains produced alpha-and beta-galactosidases (biotype 1) whereas the S. adjacens strains generally produced N-acetyl-beta-glucosaminidase and some had beta-glucuronidase but others did not (biotypes 2 and 3). The C. morbillorum strains had no detectable activity of these glycosidases (biotype 4) but produced a chromophore and an arginine dihydrolase, exhibiting a physiological profile atypical of the Gemella species. This indicates the possible presence of an additional phenotypic group or a new species among the nutritionally variant streptococci.