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Letter to the Editor| Volume 16, ISSUE 7, e570-e571, July 2012

Vir typing for the analysis of group C and group G streptococcal genotypes

  • D. Prabu
    Affiliations
    Department of Microbiology, Dr. AL Mudaliar Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai 113, India
    Search for articles by this author
  • Thangam Menon
    Correspondence
    Corresponding author. Tel.: +91 044 24547100; fax: +91 044 24540709.
    Affiliations
    Department of Microbiology, Dr. AL Mudaliar Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai 113, India
    Search for articles by this author
Open ArchivePublished:May 10, 2012DOI:https://doi.org/10.1016/j.ijid.2011.10.010
Vir typing for the analysis of group C and group G streptococcal genotypes
Previous ArticleRepeated dengue shock syndrome and ‘dengue myocarditis’ responding dramatically to a single dose of methyl prednisolone
      Group C and group G streptococci (GCS and GGS) cause a wide variety of suppurative and nonsuppurative infections.
      • Baracco G.J.
      • Bisno A.L.
      Group C and group G streptococcal infections: epidemiologic and clinical aspects.
      in: Fischetti V.A. Novick R.P. Ferretti J.J. Portnoy D.A. Rood J.I. Gram-positive pathogens. ASM press, Washington, DC2006: 222-229
      The epidemiology of GCS and GGS is considered to be important, since infections caused by GCS and GGS have increased in recent years.
      • Broyles L.N.
      • Van Beneden C.
      • Beall B.
      • Facklam R.
      • Shewmaker P.L.
      • Malpiedi P.
      • et al.
      Population-based study of invasive disease due to β-hemolytic streptococci of groups other than A and B.
      Clin Infect Dis. 2009; 48: 706-712
      , 
      • Sylvetsky N.
      • Raveh D.
      • Schlesinger Y.
      • Rudensky B.
      • Yinnon A.M.
      Bacteremia due to β-hemolytic Streptococcus group G: increasing incidence and clinical characteristics of patients.
      Am J Med. 2002; 112: 622-626
      Studies in the Aboriginal population of Australia suggest that they may also have rheumatogenic potential.
      • Haidan A.
      • Talay S.R.
      • Rohde M.
      • Sriprakash K.S.
      • Currie B.J.
      • Chhatwal G.S.
      Pharyngeal carriage of group C and group G streptococci and acute rheumatic fever in an Aboriginal population.
      Lancet. 2000; 356: 1167-1169
      Vir typing is considered to be a good epidemiological tool for the identification of group A Streptococcus (GAS) genotypes and involves strain discrimination based on the vir regulon, which consists of structurally related genes of the emm family.
      • Lloyd C.
      • Balakrishnan N.
      • Menon T.
      Vir types of Streptococcus pyogenes in Chennai, South India.
      J Med Microbiol. 2008; 57: 1176-1177
      The vir regulon of GCS and GGS can also be amplified using GAS-specific primers.
      • Hartas J.
      • Hibble M.
      • Sriprakash K.S.
      Simplification of a locus-specific DNA typing method (Vir typing) for Streptococcus pyogenes.
      J Clin Microbiol. 1998; 36: 1428-1429
      Hence the present study was aimed to determine the genetic variability among the GCS and GGS by vir typing.
      A total of 117 GCS and GGS isolates were included in the study. The majority of the isolates (n = 88) were from throat cultures of asymptomatic children attending four different schools in Chennai City. The remaining isolates were from pharyngotonsillitis/pyoderma (n = 26), blood (n = 2), and aspirated fluid (n = 1). DNA was extracted from fresh subcultures of bacterial isolates by alkali lysis method.
      • Hartas J.
      • Hibble M.
      • Sriprakash K.S.
      Simplification of a locus-specific DNA typing method (Vir typing) for Streptococcus pyogenes.
      J Clin Microbiol. 1998; 36: 1428-1429
      PCR for vir regulon amplification and subsequent digestion with HaeIII for analysis of restriction fragment length polymorphism (RFLP) was performed using previously described primers and conditions.
      • Lloyd C.
      • Balakrishnan N.
      • Menon T.
      Vir types of Streptococcus pyogenes in Chennai, South India.
      J Med Microbiol. 2008; 57: 1176-1177
      The RFLP patterns were visually compared. VT8 was the most common (18.8%), followed by VT37 (4.3%), VT1 (3.4%), and VT28 (3.4%). A total of 61 vir type (VT) patterns were obtained from the 117 strains by RFLP analysis, accounting for 52.13% diversity. Thirty-three emm types and subtypes were identified among these 61 vir types. Since the majority of the strains had been emm sequence typed we attempted to compare the emm type with the vir type, but found virtually no concordance (Table 1). Previous studies on GAS have shown that emm types could be related to vir types in the majority of cases.
      • Gardiner D.L.
      • Goodfellow A.M.
      • Martin D.R.
      • Sriprakash K.S.
      Group A streptococcal vir types are M-protein gene (emm) sequence type specific.
      J Clin Microbiol. 1998; 36: 902-907
      However no study has so far compared emm types and vir types of GGS and GCS. Vir typing also appeared to be less discriminatory than emm typing in this study, since some of the common types such as VT8 were represented by more than one emm type. However this could have been because of the fact that our RFLP patterns were based on digests using only one enzyme (HaeIII). Use of the second enzyme HinfI is known to increase the discriminatory power of vir typing and yield information on subtypes.
      • Gardiner D.L.
      • Goodfellow A.M.
      • Martin D.R.
      • Sriprakash K.S.
      Group A streptococcal vir types are M-protein gene (emm) sequence type specific.
      J Clin Microbiol. 1998; 36: 902-907
      Table 1Distribution of vir types among group C Streptococcus and group G Streptococcus strains
      Vir typeNo. of isolatesSource of isolation (throat/skin/invasive)BiotypeEmm type
      VT142/1/1SDSD, SDSE, and SESZstG6792.3, stG2574.0, stG866.0
      VT211/0/0SESZstG652.0
      VT333/0/0SDSD, SDSE, and SESZstG866.0, stG6792.3, stC36.0b
      VT422/0/0SDSD and SESZstG866.0, stG485.0
      VT520/2/0SDS and SDSEstG652.1, emm80.0
      VT611/0/0SESZstC1400.0
      VT711/0/0SDSEstG4974.0
      VT82221/1/0SDSD, SDSE, and SESZstC2Sk.0, stC5345.1, stG166b, stG245.0, stG4974.0, stG2574.0, stG653.1, stG840.0, stGLp1.0
      VT922/0/0SDSEstG6792.3
      VT1011/0/0SDSEstG485.0
      VT1111/0/0SDSDstG245.0
      VT1211/0/0SDSEstG7882.1
      VT1311/0/0SDSEstG480.0
      VT1422/0/0SDSE and SESZstC36.4
      VT1511/0/0SDSEEmm gene not amplified
      VT1611/0/0SDSEstC345.1
      VT1722/0/0SDSEstG245.0
      VT1811/0/0SESZstC1400.0
      VT1933/0/0SDSE and SESZemm103.0, stG245.1, stC839.4
      VT2010/1/0SDSEstG1750.0
      VT2111/0/0SESZstC5345.1
      VT2211/0/0SDSEstC5345.1
      VT2322/0/0SDSEstG643.0, stG653.0
      VT2411/0/0SDSEstG653.0
      VT2511/0/0SDSEstC1400.0
      VT2622/0/0SDSE and SESZstG4974.0, stG485.0
      VT2711/0/0SDSEstG6792.3
      VT2844/0/0SDSEstG653.0, stG2574.0, stG4974.0, stG866.0
      VT2944/0/0SESZ and SDSEstG1750.0, stG866.0, stG10.0, stG653.0
      VT3011/0/0SDSEstC6792.3
      VT3111/0/0SDSEstC1400.0
      VT3233/0/0SDSEstG652.0, stC1400.0
      VT3311/0/0SDSEstGM220.0
      VT3411/0/0SDSEstC36.4
      VT3521/0/1SDSEstC6979.0, stG6792.3
      VT3610/0/1SDSEstG6792.3
      VT3755/0/0SDSE and SESZstC5345.0, stGLp1.0, stG245.0, stG4974.0, stC1400.0
      VT3811/0/0SDSEstC1400.0
      VT3922/0/0SDSEstGLp1.0
      VT4011/0/0SDSDstG643.0
      VT4122/0/0SDSEstG6792.3
      VT4221/1/0SDSDstC1400.0
      VT4311/0/0SDSEstC1400.0
      VT4411/0/0SDSEstC5345.1
      VT4511/0/0SESZstG6792.3
      VT4633/0/0SDSEstC36.4
      VT4722/0/0SDSEstG653.2
      VT4811/0/0SDSEstC36.0b
      VT4911/0/0SDSEstG4974.0
      VT5011/0/0SDSEstC36.4
      VT5111/0/0SDSEstGLp1.0
      VT5211/0/0SDSEstC5345.1
      VT5311/0/0SDSEEmm gene not amplified
      VT5411/0/0SDSEemm113.0
      VT5522/0/0SDSDstG6792.3
      VT5610/1/0SDSEstG1750.0
      VT5711/0/0SDSEEmm gene not amplified
      VT5812/0/0SDSE and SESZstG6792.3, stG653.0
      VT5911/0/0SDSEstG480.0
      VT6011/0/0SDSEstC1400.0
      VT6111/0/0SDSEstG1750.0
      SDSD, Streptococcus dysgalactiae subsp. dysgalactiae; SDSE, Streptococcus dysgalactiae subsp. equisimilis; SESZ, Streptococcus equi subsp. zooepidemicus.
      In conclusion, vir typing could be an alternative genotyping method for GCS and GGS isolates.
      Conflict of interest: No conflict of interest to declare.
      Ethics considerations: This work was approved by the institutional ethics committee and subjects gave informed consent to the work.

      References

        • Baracco G.J.
        • Bisno A.L.
        Group C and group G streptococcal infections: epidemiologic and clinical aspects.
        in: Fischetti V.A. Novick R.P. Ferretti J.J. Portnoy D.A. Rood J.I. Gram-positive pathogens. ASM press, Washington, DC2006: 222-229
        View in Article
        • Broyles L.N.
        • Van Beneden C.
        • Beall B.
        • Facklam R.
        • Shewmaker P.L.
        • Malpiedi P.
        • et al.
        Population-based study of invasive disease due to β-hemolytic streptococci of groups other than A and B.
        Clin Infect Dis. 2009; 48: 706-712
        View in Article
        • Sylvetsky N.
        • Raveh D.
        • Schlesinger Y.
        • Rudensky B.
        • Yinnon A.M.
        Bacteremia due to β-hemolytic Streptococcus group G: increasing incidence and clinical characteristics of patients.
        Am J Med. 2002; 112: 622-626
        View in Article
        • Haidan A.
        • Talay S.R.
        • Rohde M.
        • Sriprakash K.S.
        • Currie B.J.
        • Chhatwal G.S.
        Pharyngeal carriage of group C and group G streptococci and acute rheumatic fever in an Aboriginal population.
        Lancet. 2000; 356: 1167-1169
        View in Article
        • Lloyd C.
        • Balakrishnan N.
        • Menon T.
        Vir types of Streptococcus pyogenes in Chennai, South India.
        J Med Microbiol. 2008; 57: 1176-1177
        View in Article
        • Hartas J.
        • Hibble M.
        • Sriprakash K.S.
        Simplification of a locus-specific DNA typing method (Vir typing) for Streptococcus pyogenes.
        J Clin Microbiol. 1998; 36: 1428-1429
        View in Article
        • Gardiner D.L.
        • Goodfellow A.M.
        • Martin D.R.
        • Sriprakash K.S.
        Group A streptococcal vir types are M-protein gene (emm) sequence type specific.
        J Clin Microbiol. 1998; 36: 902-907
        View in Article

      Article info

      Publication history

      Published online: May 10, 2012
      Received: May 31, 2011
      Corresponding Editor: Karamchand Ramotar, Ottawa, Canada

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      DOI: https://doi.org/10.1016/j.ijid.2011.10.010

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      © 2012 International Society for Infectious Diseases. Published by Elsevier Inc.

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