Identification of clinically relevant viridans group streptococci by phenotypic and genotypic analysis

Teles, Cristina; Smith, Andrew; Ramage, Gordon; Lang, Sue

doi:10.1007/s10096-010-1076-y

Cited by 50 publications

(52 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The housekeeping gene sodA has frequently been studied as a genotypic method for identifying VGS strains to the species level and has shown to be one of the most effective single-gene analyses, correctly identifying most VGS strains approximately 95% of the time (8-10, 19, 23). However, shortcomings in the ability of sodA sequencing to accurately resolve some S. mitis and S. oralis strains have been reported (3,(8)(9)(10)19). Thus, we next sought to determine how accurate sodA sequence analysis would be for our strains.…”

Section: Resultsmentioning

confidence: 99%

“…The inherent problems with these approaches lie in the variability of traits within VGS species, poor reproducibility, subjectivity of interpretation, and the lack of availability of up-todate phenotypic information in the databases on more recently described or reevaluated species (7,8,10). Sequence analysis of the 16S rRNA gene has been utilized for VGS species-level identification; however, there is no agreement on a universal cutoff for species delineation (11).…”

mentioning

confidence: 99%

“…Routine tests and commercial kits used in clinical practice based on the phenotypic and biochemical traits of individual species, such as API Rapid ID32 Strep, Vitek 2, and Streptogram, have only a 30% to 80% accuracy rate for VGS, depending on the species (7)(8)(9)(10). The inherent problems with these approaches lie in the variability of traits within VGS species, poor reproducibility, subjectivity of interpretation, and the lack of availability of up-todate phenotypic information in the databases on more recently described or reevaluated species (7,8,10).…”

mentioning

confidence: 99%

“…MLSA assigns VGS strains to a species by comparing the concatenated partial sequences of seven housekeeping genes to a database of VGS strains, including type strains (3). Although this approach produces well-resolved species clusters, MLSA is not feasible in a routine clinical microbiology setting due to the time, workload, expense, and difficulty in reliably amplifying all the genes (10,31). Therefore, there is still a need for a simple and dependable method for identifying VGS strains to the species level.…”

mentioning

confidence: 99%

See 3 more Smart Citations

GyrB Polymorphisms Accurately Assign Invasive Viridans Group Streptococcal Species

et al. 2014

View full text Add to dashboard Cite

Viridans group streptococci (VGS) are a heterogeneous group of medically important bacteria that cannot be accurately assigned to a particular species using conventional phenotypic methods. Although multilocus sequence analysis (MLSA) is considered the gold standard for VGS species-level identification, MLSA is not yet feasible in the clinical setting. Conversely, molecular methods, such as sodA and 16S rRNA gene sequencing, are clinically practical but not sufficiently accurate for VGS species-level identification. Here, we present data regarding the use of an ϳ400-nucleotide internal fragment of the gene encoding DNA gyrase subunit B (GyrB) for VGS species-level identification. MLSA, internal gyrB, sodA, full-length, and 5= 16S gene sequences were used to characterize 102 unique VGS blood isolates collected from 2011 to 2012. When using the MLSA species assignment as a reference, full-length and 5= partial 16S gene and sodA sequence analyses failed to correctly assign all strains to a species. Precise species determination was particularly problematic for Streptococcus mitis and Streptococcus oralis isolates. However, the internal gyrB fragment allowed for accurate species designations for all 102 strains. We validated these findings using 54 VGS strains for which MLSA, 16S gene, sodA, and gyrB data are available at the NCBI, showing that gyrB is superior to 16S gene and sodA sequence analyses for VGS species identification. We also observed that specific polymorphisms in the 133-amino acid sequence of the internal GyrB fragment can be used to identify invasive VGS species. Thus, the GyrB amino acid sequence may offer a more practical and accurate method for classifying invasive VGS strains to the species level.V iridans group streptococci (VGS) are a genetically heterogeneous group of commensal bacteria that cause a wide range of infections in humans, particularly in persons with hematologic disease or neutropenia as a result of chemotherapy (1, 2). Although Ͼ25 VGS species have been described, rapid and reliable identification to the species level eludes this group of organisms (3, 4). Accurate species identification is pertinent not only for epidemiological purposes but has potential implications for the clinical management of VGS infections. For example, recent studies show that Streptococcus mitis strains cause a higher incidence of severe clinical disease and have higher rates of resistance to penicillin and fluoroquinolones than do other VGS species (2, 4-6). Additionally, other VGS species have predilections to cause distinct types of infections, such as endocarditis by Streptococcus sanguinis and gastrointestinal infections by Streptococcus anginosus (2, 6).Routine tests and commercial kits used in clinical practice based on the phenotypic and biochemical traits of individual species, such as API Rapid ID32 Strep, Vitek 2, and Streptogram, have only a 30% to 80% accuracy rate for VGS, depending on the species (7-10). The inherent problems with these approaches lie in the variability of traits within V...

show abstract

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

GyrB Polymorphisms Accurately Assign Invasive Viridans Group Streptococcal Species

et al. 2014

View full text Add to dashboard Cite

show abstract

“…However, in another study (11), 21 optochin-susceptible isolates were identified as S. mitis by multilocus sequence analysis (MLSA). Also, commercial biochemical test panels have limitations in identifying streptococci to the species level (12)(13)(14)(15)(16).…”

mentioning

confidence: 99%

Improved Differentiation of Streptococcus pneumoniae and Other S. mitis Group Streptococci by MALDI Biotyper Using an Improved MALDI Biotyper Database Content and a Novel Result Interpretation Algorithm

et al. 2017

View full text Add to dashboard Cite

Reliable distinction of Streptococcus pneumoniae and viridans group streptococci is important because of the different pathogenic properties of these organisms. Differentiation between S. pneumoniae and closely related Sreptococcus mitis species group streptococci has always been challenging, even when using such modern methods as 16S rRNA gene sequencing or matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. In this study, a novel algorithm combined with an enhanced database was evaluated for differentiation between S. pneumoniae and S. mitis species group streptococci. One hundred one clinical S. mitis species group streptococcal strains and 188 clinical S. pneumoniae strains were identified by both the standard MALDI Biotyper database alone and that combined with a novel algorithm. The database update from 4,613 strains to 5,627 strains drastically improved the differentiation of S. pneumoniae and S. mitis species group streptococci: when the new database version containing 5,627 strains was used, only one of the 101 S. mitis species group isolates was misidentified as S. pneumoniae, whereas 66 of them were misidentified as S. pneumoniae when the earlier 4,613-strain MALDI Biotyper database version was used. The updated MALDI Biotyper database combined with the novel algorithm showed even better performance, producing no misidentifications of the S. mitis species group strains as S. pneumoniae. All S. pneumoniae strains were correctly identified as S. pneumoniae with both the standard MALDI Biotyper database and the standard MALDI Biotyper database combined with the novel algorithm. This new algorithm thus enables reliable differentiation between pneumococci and other S. mitis species group streptococci with the MALDI Biotyper.KEYWORDS MALDI-TOF, Streptococcus pneumoniae, algorithm, mitis group streptococci, phenotypic identification, pneumococcus T raditional classification of streptococci was based on the potential to cause hemolysis on sheep blood agar. The term "viridans" is used to refer to the greenish coloring (alpha-hemolysis) of the medium around the colonies due to partial lysis of red blood cells. Streptococcus pneumoniae, one of the most common causative agents of bacterial meningitis, community-acquired pneumonia, and otitis media, is clinically the most important alpha-hemolytic streptococcus. Because of the different pathogenic potentials of S. pneumoniae and other alpha-hemolytic streptococci, the practical dichotomy in clinical laboratories has been between S. pneumoniae and viridans group

show abstract

Evaluation of two matrix-assisted laser desorption ionization–time of flight mass spectrometry systems for identification of viridans group streptococci

Kärpänoja

Harju

Rantakokko‐Jalava

et al. 2013

Eur J Clin Microbiol Infect Dis

View full text Add to dashboard Cite

In this study, the performances of two matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) systems, MALDI Biotyper (Bruker Daltonics) and VITEK MS (bioMérieux), were evaluated in the identification of viridans group streptococci. Two collections of isolates were tested with both methods. From a panel of type collection strains (n = 54), MALDI Biotyper gave correct species-level identification for 51/54 (94 %) strains and 37/54 (69 %) strains for the VITEK MS in vitro diagnostic (IVD) method. Additionally, a collection of blood cultures isolates which had been characterized earlier with partial sequencing of 16S rRNA (n = 97) was analyzed. MALDI Biotyper classified 89 % and VITEK MS 93 % of these correctly to the group level. Comparison of species-level identification from the blood culture collection was possible for 36 strains. MALDI Biotyper identified 75 % and VITEK MS 97 % of these strains consistently. Among the clinical isolates, MALDI Biotyper misidentified 36 strains as Streptococcus pneumoniae. Nevertheless, our results suggest that the current MALDI-TOF methods are a good alternative for the identification of viridans streptococci and do perform as well as or better than commercial phenotypical methods.

show abstract

Identification of clinically relevant viridans group streptococci by phenotypic and genotypic analysis

Cited by 50 publications

References 32 publications

GyrB Polymorphisms Accurately Assign Invasive Viridans Group Streptococcal Species

GyrB Polymorphisms Accurately Assign Invasive Viridans Group Streptococcal Species

Improved Differentiation of Streptococcus pneumoniae and Other S. mitis Group Streptococci by MALDI Biotyper Using an Improved MALDI Biotyper Database Content and a Novel Result Interpretation Algorithm

Evaluation of two matrix-assisted laser desorption ionization–time of flight mass spectrometry systems for identification of viridans group streptococci

Contact Info

Product

Resources

About