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The importance of diagnosing Streptococcus agalactiae as a public health policy

Streptococcus agalactiae is a Gram-positive Cocci, which was isolated for the first time in 1887, and for decades it was recognized as an etiological agent of bovine mastitis, however, it was not considered as a cause for humans infections (SILVEIRA, 2006). In 1933, Rebecca Lancefield developed a classification for these bacteria based on the antigenic characteristics of carbohydrate C in the cell wall. In 1934, she differentiated serologically the bovine hemolytic streptococcus, classifying it as belonging to Group B. From there, Streptococcus agalactiae was also called Lancefield Group B Streptococcus (EGB) (CASTELLANO FILHO, 2008).

 

Streptococcus agalactiae can cause mild infections, as vaginal and urinary or even serious infections such as cellulitis and fascitis; in pregnancy, in addition it can cause puerperal endometritis, amnionitis and infection wounds in the mother. Its highest incidence is septicemia and meningitis in newborns, in addition to premature births or birth of children with low weight. Many newborns, specially premature ones, born from mothers infected by Group B Streptococcus that were, perhaps, infected in the womb, may be critically ill at birth, with a mortality incidence of 15% to 20% (BORGER, 2005).

 

To prevent newborn infection, chemoprophylaxis is recommended for pregnant women who are infected by Streptococcus agalactiae or who are in risk  of contamination; however, several studies have shown that B Streptococcus detection in the genital/anal tract in the final period of pregnancy is the most effective way to prevent diseases than procedures based only on risk factors, thus avoiding possible complications for the child and elevated costs for hospitals (BORGER, 2005).

 

It is important that the investigation of this microorganism is done at the end of pregnancy, between 35th and 37th week, as infection can be intermitente in this period. Therefore, pregnant women who were not infected in the middle of pregnancy, may have a positive culture at the end of the pregnancy and vice versa; colonized and treated women at the beginning or middle of pregnancy can be infected again at the end of pregnancy (CENTERS FOR DISEASE CONTROL AND PRESENTION Conduct Guide, 2002).

 

The isolation incidence of the microorganism depends on the laboratory method and the anatomical sites from which the samples are collected. About the biological material, the collect performed at both sites, the lower vagina region and anus, increases the chances of identifying Streptococcus agalactiae by 5% to 27% when compared to the collect only from the lower vagina region (ALMEIDA, 2009 ; BORGER, 2005; POGERE, 2005; SILVEIRA, 2006). The collect must be made with swabs and they must be put in transport medium for a period of up to 4 days. After collect, the swab must be removed from the transport medium case and incubated in Todd Hewitt Broth for 18-24h at 35-37ºC. After this period, perform the subculture on Chromogenic Agar for Strepto B. The characteristic of the colonies must be evaluated after 24-48 hours.

 

At Renylab you will find all the necessary material for the diagnosis of Streptococcus agalactiae:

  • Swab with transport medium (code 3739,3740,3741);
  • Todd Hewitt broth (code 1266);
  • Chromogenic agar for Strepto B (code 3471).

 

References:

  1. https://www.portaleducacao.com.br/conteudo/artigos/moda/pesquisa-de-streptococcus-agalactiae-em-gestantes-como-rotina-laboratorial/29013
  2. SILVEIRA, J. L. S. Prevalence of Streptococcus agalactiae in pregnant women detected by the Polymerase Chain Reaction (PCR) technique. Master’s thesis, Pontifícia Universidade do Rio Grande do Sul, Porto Alegre, 2006.
  3. CASTELLANO FILHO, D. S.; TIBIRIÇÁ, S. H. C.; DINIZ, C. G. Perinatal disease associated with Group B streptococci: clinical-microbiological aspects and prevention. HU Magazine (Juiz de Fora). 2008; v.34: p.127-134.
  4. POGERE, A.; ZOCCOLI, C. M.; TOBOUTI, N. R.; FREITAS, P. F.; D’ACAMPORA, A. J., ZUNINO, J. N. Prevalence of colonization by group B streptococcus in pregnant women attended at the prenatal clinic. Brazilian Journal of Obstetrics Gynecology 2005; 27(4): p. 174-180.
  5. BORGER, I. L. Study of colonization by Streptococcus agalactiae in pregnant women attended maternity school at UFRJ. Master’s thesis, Universidade Federal Fluminense, Niterói, 2005.
  6. COSTA, H. P. F.; BRITO, A. S. Prevention of Perinatal Disease by Group B Streptococcus. Educação Médica Continuada, Sociedade de Pediatria (Continuing Medical Education, Pediatric Society), 2009.
  7. MIURA, E; MARTIN, M. C. Group B streptococcal neonatal infections in Rio Grande do Sul, Brasil. Revista do inst. de Med. Trop. de SP. São Paulo, 2001; v.43, n.5, p.243-246.
  8. BERALDO, C.; BRITO, A. S.; SARIDAKIS, H. O.; MATSUO, T. Prevalence of vaginal and anorectal colonization by group B streptococcus in pregnant women in the third trimester. Brazilian Journal of Obstetrics Gynecology. 2004; 26(7): p. 543-549.
  9. CENTERS FOR DISEASE CONTROL AND PREVENTION. Prevention of Perinatal Group B Streptococcal Disease. – Revised Guidelines from CDC. Morbidity and Mortality and Mortality Weekly Report, Atlanta, 2002; v. 51, n. RR-11, p. 01-22.
  10. COSTA, A. L. R.; FILHO, F. L.; CHEIN, M. B. C.; BRITO, L. M. O.; LAMY, Z. C.; ANDRADE, K. L. Prevalence of colonization by group B streptococci in pregnant women attended at a public maternity hospital in Northeastern Brazil. Brazilian Journal of Obstetrics Gynecology. 2008; v.30, p. 274-280.
  11. ALMEIDA, A.; AGRO, J.; FERREIRA, L. Group B Hemolytic Streptococcus – Perinatal Disease Screening and Prevention Protocol. Consensus in Neonatology. Portuguese Society of Neonatology, 2009, p.191-197.
  12. Ministry of Health. Health Care Secretariat. Department of Strategic Programmatic Actions. Prenatal and Puerperium – Qualified and Humanized Care – Technical Manual. 3º ed. Brasília: MS Publishing company, 2006.