An analysis of group B streptococcus infections has revealed unexpected transmission events.

The research, published in the journal Clinical Infectious Diseases, may open new avenues for preventing certain types of group B streptococcus infection.

Group B streptococcus bacteria are carried harmlessly in the body in around 20% of people. The bacteria are usually found in the rectum or vagina, and, in rare cases, can transfer from mother to baby during birth and cause serious infection.

In addition, group B streptococcus may cause so-called ‘late onset’ infections which occur up to three months after birth.

We hope that by publishing the outcome of this work, more units will undertake similar investigations enabling better understanding of transmission routes Professor Shiranee Sriskandan Study author

The route of infection for late-onset infections is not clearly defined, with infections thought to be potentially acquired from the mother, other contacts, or rarely, the hospital environment.

However, the new research suggests a greater potential role for spread of the bacteria within a hospital setting.

The team analysed 11 late-onset cases, clustered into four groups over the course of two years. 

The scientists performed genomic analysis on the bacteria and found that although each cluster was caused by different strains of group B streptococcus, each case within the same cluster was caused by the same strain. This suggests the bacteria could have been transmitted between patients.

A number of possible routes of transmission were investigated but no one method of transmission could be pinned down; as a precaution a range of interventions were introduced to reduce risk to patients.

The team behind the study say more research is now needed into how group B streptococcus bacteria could spread in hospital settings.

Professor Shiranee Sriskandan, lead author of the study from the Department of Medicine at Imperial College London, said: “We hope that by publishing the outcome of this work, more units will undertake similar investigations enabling better understanding of transmission routes, and more effective preventative measures where applicable.”

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"Serial Clustering of Late-Onset Group B Streptococcal Infections in the Neonatal Unit: A Genomic Re-evaluation of Causality" by E. Jauneikaite et al. is published in the journal Clinical Infectious Diseases