Severe infections with flesh-eating bacteria are considerably more common than expected

Sep 16 2004

Severe infections with Group A streptococci, sometimes called "flesh-eating killer bacteria," are considerably more common than expected in many countries.

In an EU project covering 11 countries, headed by Lund University in Sweden, it was calculated that some 1,000 cases would be found over an initial 1½-year period. Fully 5,000 were identified.

Group A streptococci, GAS, can sometimes occur in the throat without the carrier noticing anything. In other cases, the bacteria can cause a benign form of strep throat or skin infection. But in some cases, partly depending on the nature of the bacterial strain, a throat or skin infection can lead to serious consequences, with chronic heart and kidney damage. An acute GAS infection of the skin, for instance, can also dig deeper and lead to the muscles' being virtually eaten up by the bacteria. In other cases the bacteria can spread rapidly and the body's fine blood vessels start to leak fluids, which can lead to loss of blood pressure and rapid death, even in a young and previously healthy person.

"Our study has attracted a lot of attention, and we have had to turn down a number of countries that have wanted to be included in the project afterward," says Aftab Jasir from the Section for Bacteriology at Lund University. She and her colleague Claes Schalén act as coordinators of the EU study.

"Some of these 11 countries, like Italy and Romania, initially claimed that they had almost no severe GAS infections whatsoever. But once they started looking, they found a huge number of cases. In Sweden there are some 300-400 severe GAS infections every year. In relation to population size, the incidence is roughly the same in the rest of Scandinavia, Great Britain, and the Czech Republic, which also have well-functioning systems for reporting these things. If we assume that this is the true incidence rate, then the enlarged EU should have 18-20,000 cases per year of severe streptococcal infections."

"We'll probably never arrive at the exact figure. But there are also a large number of cases we never find out about," says Claes Schalén. "We therefore hope that the study will lead to pan-European monitoring of these infections, and to more uniform laboratory methods."

The study also shows that not merely the number of cases but also the number of different types of bacteria is greater than previously recorded. In the past scientists have estimated that there are some 50 types of GAS. Now the number has reached nearly 200, and new forms are turning up all the time. Moreover, different types often dominate different countries.

"The US has invested a lot of money and time in the development of vaccines against the GAS types that were previously seen as the most common. But our results indicate that this is not a fruitful path. If a vaccine is to work, it has to be based on some very basic property of GAS," says Aftab Jasir.

Severe streptococcal infections are treated with penicillin in combination with a more rapidly working antibiotic called clindamycin. But the EU study has uncovered a few cases of clindamycin resistance, which in a worst-case scenario could spread quickly and render the bacteria resistant to this treatment.

If clindamycin should become useless, there is one more move for severe cases, a drug called vancomycin. After that, there are no more antibiotics available. Therefore, not only Aftab Jasir and her associates but many others place their hopes in a substance that the Lund team has developed, called Cystapep. It is a substance that attacks several kinds of dangerous bacteria, and bacteria apparently cannot develop any resistance to it. This research is still in its early stages, however, and clinical use of Cystapep can only become a reality in about 5-10 years' time.