Last update July 17, 2023

Group B Streptococcus agalactiae (GBS) in breast milk


Safe substance and/or breastfeeding is the best option.

Mastitis is an inflammation of the breast that, if mishandled, can end up becoming infected. When there is infection, the most frequently implicated germ is Staphylococcus aureus (Cullinane 2022, Paricio 2017, Amir 2016, Espinola 2016, Baeza 2015, Amir 2014, Spencer 2008).

Coagulase negative staphylococci (CoNS) such as S. epidermidis are not associated with mastitis (Culinane 2022). There is also no evidence that bacterial biofilms are a cause of blocked ducts and mastitis. (Douglas 2022). Studies are needed to determine the aetiological role of Candida albicans, which appears to be a minority. (Amir 2014, Hanna 2011, Carmichael 2002, Brent 2001)

Damaged nipple, infrequent feedings, scheduled frequency or duration of feedings, missed feedings and poor latch are risk factors for mastitis. (Wilson 2020, Amir 2014)

Effective treatment requires resting of the mother, a frequent emptying of the breast, use of anti-inflammatory drugs and in case of no amelioration, it should be necessary a course of antibiotics that must be effectively active against Staphylococcus aureus. (Paricio 2017, Espinola 2016, Amir 2014, Cabou 2011, Spencer 2008). High-quality double-blind RCTs are needed to determine the use of antibiotics in mastitis. (Jahanfar 2013)

The nursing infant may be latched on to the inflamed breast without bad consequences for the child (Amir 2014, Lawrence 2013, WHO 2000). Emptying of the breast is important for treatment, with the baby being the most effective extractor. Better results are obtained with a continued lactation during the treatment with antibiotics. Incidentally, the baby may refuse sucking the breast because a salted flavor of the milk, in which case, it should be manually or mechanically pumped.

Medication used for the treatment of mastitis, such as antibiotics and anti-inflammatory drugs, is compatible with breastfeeding.

Breast milk culture is only indicated if (Paricio 2017, Espínola 2016, Amir 2014)

  • no response to antibiotic therapy within 48 hours
  • return or recurrence of mastitis
  • nosocomial mastitis (hospital-acquired)
  • patient allergic to beta-lactam antibiotics
  • population with excessive frequency of methicillin-resistant Staphylococcus isolates
  • serious or unusual case of entry
  • Late or recurrent group B streptococcal infection in the breastfed infant

As of the last review, there is no valid scientific evidence that the use of probiotics is effective in treating mastitis or breast pain in women (WHO 2022, Crepinsek 2020, Barker 2020, Paricio 2017, Espínola 2016, Amir 2016, Baeza 2015, Amir 2014). Its indiscriminate use can delay other treatments and be financially burdensome (WHO 2022, Amir 2016).Evidence that orally administered can get into the milk is lacking. (Elias 2011)

The use of presumably preventive probiotics during pregnancy was associated with an increased risk of mastitis and other complications of breastfeeding during the first month of breastfeeding. (Karlsson 2019)

Only in the rare case of tuberculosis mastitis are both direct breastfeeding and the administration of expressed milk contraindicated. (Red Book 2021-24 p.110)

Group B Streptococcus agalactiae (GBS) in breast milk (Nicolini 2018, Zimmermann 2017, Filleron 2014, Davanzo 2013, Kotiw 2003, Rench 1989):

GBS can be isolated in breast milk from healthy, mastitis-free women.

The pathogenesis of late onset and/or recurrent GBS infection (sepsis-meningitis) in the infant and its relationship to the occurrence of GBS in breast milk is unclear. Several authors advocate a retrograde and circular mechanism of infection: GBS from the oral mucosa of the late-infected infant (by contamination during delivery or by subsequent infection from other sources outside or not from the mother) would colonize milk and breast tissue, causing an increase of GBS colonies in breast milk and making possible the appearance of recurrent GBS infection in the infant and an increased risk of mastitis occurrence.

Milk culture is indicated in case of late or recurrent GBS infection in an infant and to treat or not to treat asymptomatic mothers depending on the GBS bacterial load found. Suspending lactation could favor the development of mastitis or complications such as abscess.

Suspension of breastfeeding would only be indicated in the case of high-risk preterm infants admitted to the ICU and in the case of recurrent infection of the infant; until milk cultures were negative for GBS, pasteurized breast milk could be fed. (Davanzo 2013)

See below the information of these related products:

  • Cefadroxil (Safe substance and/or breastfeeding is the best option.)
  • Cephalexin (Safe substance and/or breastfeeding is the best option.)
  • Cloxacillin; Cloxacillin Sodium (Safe substance and/or breastfeeding is the best option.)
  • Ibuprofen (Safe substance and/or breastfeeding is the best option.)
  • Paracetamol (Safe substance and/or breastfeeding is the best option.)
  • Probiotics (Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.)

Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Group B Streptococcus agalactiae (GBS) in breast milk is also known as Maternal Mastitis. Here it is a list of alternative known names::


Group B Streptococcus agalactiae (GBS) in breast milk belongs to this group or family:


  1. WHO. WHO recommendations on maternal and newborn care for a positive postnatal experience. Geneva: World Health Organization; 2022. Licence: CC BY-NC-SA 3.0 IGO. Consulted on June 6, 2022 Abstract Full text (link to original source) Full text (in our servers)
  2. Cullinane M, Scofield L, Murray GL, Payne MS, Bennett CM, Garland SM, Amir LH; CASTLE Study team.. Random amplified polymorphic DNA analysis reveals no clear link between Staphylococcus epidermidis and acute mastitis. Aust N Z J Obstet Gynaecol. 2022 Mar 1. Consulted on June 4, 2022 Abstract Full text (link to original source) Full text (in our servers)
  3. (Red Book). AAP. Kimberlin DW, Barnett ED, , Lynfield R, Sawyer MH eds. Red Book: 2021-2024. Report of the Committee on Infectious Diseases. 32th ed. Elk Grove Village, - 2021
  4. Wilson E, Woodd SL, Benova L. Incidence of and Risk Factors for Lactational Mastitis: A Systematic Review. J Hum Lact. 2020 Nov;36(4):673-686. Abstract Full text (link to original source)
  5. Crepinsek MA, Taylor EA, Michener K, Stewart F. Interventions for preventing mastitis after childbirth. Cochrane Database Syst Rev. 2020 Sep 29;9:CD007239. Abstract Full text (link to original source)
  6. Barker M, Adelson P, Peters MDJ, Steen M. Probiotics and human lactational mastitis: A scoping review. Women Birth. 2020 Nov;33(6):e483-e491. Abstract
  7. Karlsson S, Brantsæter AL, Meltzer HM, Jacobsson B, Barman M, Sengpiel V. Maternal probiotic milk intake during pregnancy and breastfeeding complications in the Norwegian Mother and Child Cohort Study. Eur J Nutr. 2019 Sep 10. Abstract
  8. Nicolini G, Borellini M, Loizzo V, Creti R, Memo L, Berardi A. Group B streptococcus late-onset disease,contaminated breast milk and mothers persistently GBS negative: report of 3cases. BMC Pediatr. 2018 Jul 5;18(1):214. Abstract Full text (link to original source)
  9. Paricio Talayero JM. Diagnóstico y manejo de la mastitis en la madre lactante. Actualización. IX Congreso Español de Lactancia Materna. Mesa 6: Abordaje del dolor al amamantar. Zaragoza, 2017 Full text (link to original source) Full text (in our servers)
  10. Zimmermann P, Gwee A, Curtis N. The controversial role of breast milk in GBS late-onset disease. J Infect. 2017 Jun;74 Suppl 1:S34-S40. Abstract
  11. Amir LH, Griffin L, Cullinane M, Garland SM. Probiotics and mastitis: evidence-based marketing? Int Breastfeed J. 2016 Abstract Full text (link to original source) Full text (in our servers)
  12. Espínola-Docio B, Costa-Romero M, Díaz-Gómez NM, Paricio-Talayero JM; Comité de Lactancia Materna, Asociación Española de Pediatría.. Mastitis. Puesta al día. [Mastitis update.] Arch Argent Pediatr. 2016 Abstract Full text (link to original source) Full text (in our servers)
  13. Baeza C. Dolor en la mama lactante: claves etiológicas y manejo clínico (I). Monografías Clínicas en Lactancia Materna. Madrid: Centro Raíces 2015, p.3-13. 2015 Full text (link to original source) Full text (in our servers)
  14. Amir LH; Academy of Breastfeeding Medicine Protocol Committee. ABM Clinical Protocol #4: Mastitis, Revised March 2014. Breastfeed Med. 2014;9(5):239-243. Abstract Full text (link to original source) Full text (in our servers)
  15. Amir LH. y el Comité de protocolos de la Academy of Breastfeeding Medicine. Protocolo clínico de la ABM n.o 4: Mastitis, modi cado en marzo de 2014. Breastfeed Med. 2014;9(5):239-243. Abstract Full text (link to original source) Full text (in our servers)
  16. Filleron A, Lombard F, Jacquot A, Jumas-Bilak E, Rodière M, Cambonie G, Marchandin H. Group B streptococci in milk and late neonatal infections: an analysis of cases in the literature. Arch Dis Child Fetal Neonatal Ed. 2014 Jan;99(1):F41-7. Abstract
  17. Lawrence RM. Circumstances when breastfeeding is contraindicated. Pediatr Clin North Am. 2013 Feb;60(1):295-318. Abstract
  18. Davanzo R, De Cunto A, Travan L, Bacolla G, Creti R, Demarini S. To feed or not to feed? Case presentation and best practice guidance for human milk feeding and group B streptococcus in developed countries. J Hum Lact. 2013 Nov;29(4):452-7. Abstract
  19. Jahanfar S, Ng CJ, Teng CL. Antibiotics for mastitis in breastfeeding women. Cochrane Database Syst Rev. 2013 Feb 28; Abstract Full text (link to original source)
  20. Elias J, Bozzo P, Einarson A. Are probiotics safe for use during pregnancy and lactation? Can Fam Physician. 2011 Abstract Full text (link to original source) Full text (in our servers)
  21. Hanna L, Cruz SA. Candida mastitis: a case report. Perm J. 2011 Abstract Full text (link to original source) Full text (in our servers)
  22. Cabou A, Babineau S, St Anna L. Clinical inquiry: what's the best way to relieve mastitis in breastfeeding mothers? J Fam Pract. 2011 Abstract Full text (in our servers)
  23. Spencer JP. Management of mastitis in breastfeeding women. Am Fam Physician. 2008 Abstract Full text (link to original source) Full text (in our servers)
  24. Kotiw M, Zhang GW, Daggard G, Reiss-Levy E, Tapsall JW, Numa A. Late-onset and recurrent neonatal Group B streptococcal disease associated with breast-milk transmission. Pediatr Dev Pathol. 2003 May-Jun;6(3):251-6. Epub 2003 Apr 14. Abstract
  25. Carmichael AR, Dixon JM. Is lactation mastitis and shooting breast pain experienced by women during lactation caused by Candida albicans? Breast. 2002 Abstract
  26. Brent NB. Thrush in the breastfeeding dyad: results of a survey on diagnosis and treatment. Clin Pediatr (Phila). 2001 Abstract
  27. WHO-World Health Organization. Mastitis: Causes and Management. Publication number WHO/FCH/CAH/00.13. World Health Organization, Geneva, 2000. Abstract Full text (link to original source) Full text (in our servers)
  28. OMS. Organización Mundial de la Salud. Mastitis. Causas y manejo. Organización Mundial de la Salud, 2000 - Licence: CC BY-NC-SA 3.0 IGO Abstract Full text (link to original source) Full text (in our servers)
  29. Rench MA, Baker CJ. Group B streptococcal breast abscess in a mother and mastitis in her infant. Obstet Gynecol. 1989 May;73(5 Pt 2):875-7. Abstract

Total visits


Help us improve this entry

How to cite this entry

Do you need more information or did not found what you were looking for?

   Write us at

e-lactancia is a resource recommended by El Parto Es Nuestro of Spain

Would you like to recommend the use of e-lactancia? Write to us at corporate mail of APILAM