Use of the Rapid STREP system for identification of viridans streptococcal species

A commercially available streptococcal identification system, Rapid STREP (API System S.A., Montalieu-Vercieu, France), was used to identify 119 viridans strains at the species level. A total of 92% of the strains tested were identified correctly with the Rapid STREP system, and 81% of the correct identifications were made at percentages of identification of 90 or greater. From these data it appears that the Rapid STREP system is a fairly accurate and rapid (24-h incubation) method for identifying species of viridans streptococci.

Multiply resistant viridans streptococci: susceptibility to beta-lactam antibiotics and comparison of penicillin-binding protein patterns

A unique group of viridans streptococci has been found in South Africa. These organisms were isolated in close temporal and physical proximity to the isolation of penicillin-resistant pneumococci. The strains were resistant to penicillin, oxacillin, the cephalosporins (all generations), piperacillin, azlocillin, and mezlocillin but were susceptible to vancomycin. Penicillin-binding proteins of two penicillin-resistant South African strains of Streptococcus mitis differed markedly from those of two penicillin-susceptible strains but were identical to those seen in a penicillin-resistant strain isolated in Boston. Although both susceptible strains were identified as S. mitis with identical biochemical profiles, their penicillin-binding protein patterns differed from each other. This finding may have significance with regard to the need for additional taxonomic classification of the viridans streptococci.

Automated identification of gram-positive bacteria

A total of 451 strains of gram-positive bacteria were identified with a prototype of the Gram-Positive Identification card used in conjunction with the AutoMicrobic system (Vitek Systems, Inc., Hazelwood, Mo.). Of the species that the Gram-Positive Identification card is capable of identifying, 85% of staphylococcal, 50% of beta-hemolytic group A, B, C, F, and G streptococcal, 91% of group D streptococcal, 100% of pneumococcal, 63% of viridans streptococcal, and 100% of Listeria monocytogenes strains tested displayed Gram-Positive Identification card identifications that were in agreement with identifications obtained by conventional methods.

Identification of viridans streptococci isolated from clinical specimens

Of 532 strains of viridans streptococci isolated from clinical specimens, 517 were identified by using a scheme based on the work of Facklam (R. R. Facklam, J. Clin. Microbiol. 5:184-201, 1977). The strains were distributed among nine of the species described by Facklam and an additional group of physiologically homogeneous streptococci not recognized in Facklam's scheme. The method for identification involves a battery of 10 tests that employ both conventional media and commercially prepared disks. The identification of most of the isolates was accomplished within 48 h.

Nitrate-reductase electron-transport cofactors in Veillonella alcalescens

Studies on the effects of inhibitors of the nitrate-reducing activity of Veillonella alcalescens extracts suggest the participation of a naphthoquinone, a b-type cytochrome, and non-heme iron in electron transport to nitrate. A nitrate-reductase-deficient mutant displayed a longer doubling time and a decreased molar growth yield on nitrate media. This mutant was phenotypically restored by the addition of molybdate to the growth medium, giving evidence for the functioning of molybdenum in the nitrate-reductase enzyme of V. alcalescens.