Differentiation of Streptococcus sanguis and S. mitior by whole-cell rhamnose content and possession of arginine dihydrolase

Abstract

Summary. Whole-cell rhamnose concentrations were measured in 48 strains of streptococci resembling Streptococcus sanguis and S. mitior. Physiological characteristics were tested by the API-20/Strep system, and it was found that "typical" S. sanguis (arginine positive, aesculin positive) contained significant amounts of rhamnose, while "typical" S. mitior (arginine negative, aesculin negative) contained very low or undetectable amounts of rhamnose. Both groups contained dextran-positive and dextran-negative strains. Organisms that were more difficult to speciate (those giving positive results in the arginine or the aesculin test, but not in both) could also be divided into a rhamnose-positive and a rhamnose-negative group; with one exception, all of the rhamnose-positive strains gave a positive result with arginine in the API-20/ Strep test.There were several discrepancies between the results of conventional tests for arginine and aesculin hydrolysis and those of the corresponding API test. The results of conventional tests for arginine hydrolysis did not correlate closely with rhamnose content, and conventional tests for aesculin hydrolysis were less sensitive than API tests. With the API-20/Strep system, S. sanguis can almost always be distinguished from S. mitior by its ability to hydrolyse arginine.

Characterisation of and polysaccharide production by amoxycillin-resistant streptococci

“…Dextran-negative erythromycin-resistant strains of S. sanguis have also been described recently (Harrison et al,198%). This is surprising because although dextran-negative S. sanguis have been reported, they are relatively uncommon and most strains characteristically synthesise polysaccharides (Price et al, 1986). In our previous study, bacteria were isolated that could grow on agar supplemented with amoxycillin 40 mg/L and, as this concentration corresponds to the peak serum levels of the antibiotic, they were considered to pose a potentially significant threat to the patient.…”

“…Although dextran-negative S . sanguis strains have been described (Price et al, 1986), most studies report that an overwhelming majority of strains produce extracellular polysaccharides from sucrose. Some of the highly amoxycillin-resistant streptococci from our recent study (Woodman et al, 1985) have now been identified.…”

Identification of viridans streptococci by pyrolysis-gas chromatography

“…The atypical S . mitior-like strain STH 135(J), arginine-negative but containing large amounts of rhamnose (Price et al, 1986), was classified intuitively as S . mitior on the basis of physiological reactions but grouped with S .…”

Effects of Arginine and Arginyl·-L- Arginine on the Glucose-Mediated pH Fall of Streptococcus rattus and Streptococcus milleri (Short Communication)

“…Many species of oral bacteria, some of which are dom inant plaque microorganisms, utilize arginine by hydroly sis yielding ammonia [Hardie and Bowden, 1976;Price et al, 1986;Krai and Daneo-Moore, 1981;Coykendall, 1989].…”