Misidentification of alpha-hemolytic streptococci by routine tests in clinical practice

Ikryannikova, Larisa N.; Lapin, K. N.; Malakhova, Maja V.; Filimonova, Alla V.; Ilina, Elena N.; Dubovickaya, V.A.; Сидоренко, С. В.; Govorun, Vadim M.

doi:10.1016/j.meegid.2011.07.010

Cited by 49 publications

(41 citation statements)

References 41 publications

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“…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%

“…Although a single-gene approach is practical, problems with singlegene techniques in VGS stem from a highly diverse population undergoing extensive rates of inter-and intraspecies homologous recombination and horizontal gene transfer, which minimizes the utility of identification procedures based on any one particular gene tested to date (3,8,9,(25)(26)(27)(28)(29)(30). Currently, only one methodology has proven successful for differentiating VGS isolates to the species level: multilocus sequence analysis (MLSA).…”

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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).…”

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confidence: 99%

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GyrB Polymorphisms Accurately Assign Invasive Viridans Group Streptococcal Species

et al. 2014

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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...

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Section: Resultsmentioning

confidence: 99%

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GyrB Polymorphisms Accurately Assign Invasive Viridans Group Streptococcal Species

et al. 2014

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“…MALDI-TOF MS analysis in this same study yielded 100% congruency with the typical genotypic and phenotypic identification tests at the species level, but only 4 out of 17 VGS were correctly identified and each of the 8 S. mitis isolates were incorrectly identified as being S. pneumoniae (Ikryannikova et al, 2011). Seven specific m/z peaks may prove beneficial in differentiating streptococcal species.…”

Section: Introductionmentioning

confidence: 53%

Mass spectrometry and tandem mass spectrometry characterization of protein patterns, protein markers and whole proteomes for pathogenic bacteria

Intelicato-Young

Fox

2013

Journal of Microbiological Methods

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“…Wessels and coworkers (10) reported that optochin testing in a CO 2 atmosphere and tube bile solubility testing give consistent results for S. pneumoniae. 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).…”

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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

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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

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Misidentification of alpha-hemolytic streptococci by routine tests in clinical practice

Cited by 49 publications

References 41 publications

GyrB Polymorphisms Accurately Assign Invasive Viridans Group Streptococcal Species

GyrB Polymorphisms Accurately Assign Invasive Viridans Group Streptococcal Species

Mass spectrometry and tandem mass spectrometry characterization of protein patterns, protein markers and whole proteomes for pathogenic bacteria

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

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