Group B Streptococcus – an enemy waiting for newborns

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FACULTY OF MEDICINE

 

There is a certain microorganism called Streptococcus agalactiae that lurks in the reproductive tract yet does not present any symptoms of its presence. However, it constitutes a fatal threat to newborns. The need to scientifically analyze it remains important, as this microorganism occurs on average in one of four pregnant women.

In recent years, a significant increase in infection caused by these streptococci has been noted in European clinics, including those in Poland. The frequency of infection in newborns, depending on the analyzed population, ranges from 0.2 to 2 cases out of every 1000 live births, reaching the level of 6.6 cases in every 1000 live births in infants born prematurely. Another reason for concern is the fact that resistance to antibiotics among these bacteria is increasing, which results in the treatment's low efficacy rates.

How to win the battle?

Group B streptococcus is referred to as GBS, its acronym in English. The only representative of this group is Streptococcus agalactiae. It belongs to human natural flora and usually exists in the digestive and reproductive tracts (on average, in 10%-30% of tested individuals). These bacteria may cause dangerous infections in both the fetus and in newborns, infections that can be fatal. Another result of their activity is infection in women in the postpartum period, in elderly people, and in patients suffering from limited immunity (immunosuppression).

In order to prevent the occurrence of infection in newborns, pursuant to the recommendation of the Polish Gynecological Society, women in their third trimester of pregnancy should undergo a test aimed at determining the presence of these bacteria in the reproductive tract and anus. Treatment during pregnancy is not recommended, because soon after the medication is discontinued, the bacteria re-enter the body, are ingested with food, and recolonize the digestive tract; in pregnant women, this includes recolonizing in the reproductive tract. If the test result is positive, the patient receives an antibiotic during labor to prevent the newborn from developing infection.

Unfortunately, there are many instances in which such prophylaxis proves insufficient. Considering its limited efficacy, the best long-term solution would be vaccination. However, in spite of intense research being conducted by research teams around the world aimed at developing an effective vaccine, we still do not have a ready product. This is a result of the streptococci itself: its ability need to adapt to changeable environmental conditions resulted in its unique capability to adapt and change its genetic material.

The genetic variability of streptococci, often connected with the given geographical region, is the key problem for selecting suitable components used in creating an effective vaccine capable of protecting the entire population of patients instead of a small fraction.


Direct vaginal smear preparation colored with the Gram staining method.
The image shows an epithelial cell, group B streptococci (small cocci colored purple),
immune cells, and other elements of the physiological flora of the female
reproductive tract. Photo: M. Brzychczy-Włoch

Enemy better known

Research on group B streptococcus has been conducted at the Department of Microbiology (the Jagiellonian University Medical College) for 10 years. It was initially conducted within a project of the Ministry of Science and Higher Education. The research was then financed with funds from the National Centre for Science. "The results of the conducted research enabled us to obtain knowledge about the epidemiological situation and the frequency of colonization with these pathogens in pregnant women and newborns in the Kraków region. They also became an inspiration and a starting point for the development of Polish recommendations aimed at the prophylaxis of GBS infections in newborns. Moreover, the conducted molecular analyses made it possible to prepare very detailed characteristics of an enormous collection of group B streptococci obtained both from carriers and from newborns and adults in whom infection developed. This in turn enabled us to obtain comprehensive knowledge about group B streptococcus and to compare the collected data with the results obtained in clinical and academic centers in Europe or in the United States," Monika Brzychczy-Włoch, PhD, of the Department of Microbiology, explains. When seen in the context of the intensive work undertaken by scientists around the world to create a modern vaccine that protects against infections caused by GBS, the results obtained by scientists from Kraków seem unique not merely on the national scale.

For three years, microbiologists from the Jagiellonian University Medical College have been conducting research on the proteins present in streptococcus cells. These proteins are capable of stimulating the human immune system to produce antibodies targeted against these bacteria. "Our group is the only team in Poland and one of a few teams in the world conducting research on group B streptococci and their immunogenic proteins. In the course of our work we marked several proteins that are characteristic for group B streptococcus and occur in the whole species, regardless of the extremely high genetic variability of these bacteria. What is equally important, they are capable of strongly stimulating the immune system. The application of these proteins as elements of the anti-GBS vaccine seems very promising," Brzychczy-Włoch points out.

Detection first!

Rapid diagnosis aimed at detecting carriers and infections caused by GBS guarantees immediate implementation of the targeted prevention or treatment. Currently, however, no quick diagnostic tests are available that would confirm the infection was caused by Streptococcus agalactiae. Traditionally used diagnostic methods are based on the culture method, the results of which are characterized by low sensitivity and long wait periods (up to several days).

During our studies on innovative tests aimed at the detection of GBS carriers and infections, the team from the Department of Microbiology developed a molecular method that allows for the simultaneous determination of several markers that are important for epidemiological studies and the diagnostics of group B streptococcus. Another development is an innovation already submitted for patent protection at the Polish Patent Office. It concerns a new diagnostic test that enables GBS infection to be confirmed. It is based on the specific reaction between selected proteins present in group B streptococcus with antibodies existing in the serum of patients. These tests constitute an alternative to tests currently used in detecting carriers of group B streptococcus, thus allowing for the extension of diagnostics in the event of occurrence of infection.

Further research on group B streptococcus and its proteins and binding epitopes are being conducted at the Department of Microbiology in cooperation with the Institute of Immunology and Experimental Therapy of the Polish Academy of Sciences in Wrocław and the Centre for Innovation, Technology Transfer and University Development, which is looking for entities interested in the commercialization of the obtained results.


Research team (Department of Microbiology, Jagiellonian University Medical College): Monika Brzychczy-Włoch, PhD; Tomasz Gosiewski, PhD; Professor Piotr Heczko; Małgorzata Bulanda, PhD Research partners from Institute of Immunology and Experimental Therapy of the Polish Academy of Sciences in Wroclaw: Sabina Górska, PhD; Ewa Brzozowska, PhD; Professor Andrzej Gamian