Science / Medicine : Strep Bacteria Have Split Personality : Disease: They seem to be evolving into more virulent form. Group A strain causes pneumonia that killed Jim Henson of Muppets fame. It also triggers other disorders from mild to deadly.

The same bacteria that commonly cause relatively innocuous cases of strep throat in school-age children and young adults appears to be evolving into a menacing, more virulent form. In recent years, it has produced a severe and potentially lethal--though rare--infection, most often in adults.

The ubiquitous strain of bacteria known as Group A streptococcus causes the pneumonia that swiftly killed Muppeteer Jim Henson in May. It also triggers a variety of other disorders ranging from a relatively mild skin infection, impetigo, to potentially deadly ailments such as scarlet fever, rheumatic fever, respiratory disease and a newly described infection called severe streptococcal syndrome.

Ironically, the devastating syndrome often starts with a minor skin infection from a skinned elbow or a bruised knee, said Dr. Benjamin Schwartz, an epidemiologist in the respiratory diseases branch of the Centers for Disease Control in Atlanta. The Group A strep bacteria present on the skin penetrate the wound, infiltrating the blood stream. Within 48 to 72 hours the microbes can wreak havoc in the body.

The rapidly advancing infection often leads to a variety of symptoms including high fever, chills, extremely low blood pressure, muscle and tissue damage, a loss of circulation that may result in death or amputation, multiorgan failure of the kidneys, liver and lungs, and shock.

The CDC estimates that the syndrome occurs in four or five out of every 100,000 people. Of those infected, 30% die, Schwartz said. Twenty percent of those infected also seem to develop a more acute form of the syndrome, although researchers do not know why the infection is more severe in some people than others, he said.

Researchers speculate that a toxin produced by Group A strep is involved either directly or indirectly in triggering the characteristic adverse reactions within the body.

“The jury is still out. We don’t know which toxin, if any, is responsible (for the syndrome), but the infection almost has to be toxin mediated,” said Dr. Edward Kaplan, a pediatrician and director of the World Health Organization Collaborating Center for Reference and Research on Streptococci at the University of Minnesota. “Once the infection gets started, something other than just the presence of the bacteria has to account for its symptoms,” he said.

A report in the New England Journal of Medicine last year noted that eight of 10 people with the syndrome whose bacteria could be grown in the laboratory produced a protein called Toxin A, the same toxin that caused severe cases of scarlet fever earlier in the century. The toxin “disappeared” around 1940, as did acute cases of scarlet fever. Since then, milder forms of scarlet fever--caused by Group A strep bacteria producing Toxins B and C--have been documented.

The type of toxin produced, if any, in 10 other infected patients included in the study could not be determined, Stevens said.

The first U.S. cases of severe streptococcal syndrome are believed to have surfaced in 1984 in Boise, Ida. Since then, cases have been documented throughout the United States and in Scandinavia, East Germany, England, Australia, New Zealand and Canada.

In order to track the incidence of infection and gather clinical and epidemiological data, the CDC recently began working with local and state health departments in California, Arizona, Colorado, Alabama, Ohio and Maryland. Samples of the Group A strep bacteria from all patients infected with the syndrome in the surveillance areas will be collected and sent to the CDC.

According to Dr. Susan Lee, an epidemiologist with the Los Angeles County Health Department, earlier data collected by the department in January and February, 1989, detected seven cases of the syndrome. Five of the patients died, Lee said. “It is alarming.”

Even so, Schwartz said, “It is not a disease that mothers and fathers need to be especially concerned with. Although strep infections are common, the severe syndrome is very, very rare,” particularly in children.

While roughly 50% of the cases of the syndrome begin with skin injuries, none are believed to be associated with complications associated with strep throat, Schwartz said. In 35% of the cases, the site of infection cannot be determined and in 15% of the cases, the infection begins with pneumonia, he said.

Researchers understand little at the molecular level to explain how genetic switches might turn on, increasing the toxicity of bacteria that previously have been benign. They speculate that a population’s resistance to infection through acquired immunity--previous exposure to the strain of bacteria that causes infection--may cause the bacteria to modify itself over time to become more infectious.

Antibiotics, such as penicillin, have proved effective in treating the syndrome, but only if those infected seek treatment early, before the bacteria unleash their potent toxin or a related factor throughout the body. Once severe symptoms appear, simply killing the organism with antibiotics won’t cure the patient, Kaplan said. In that case, doctors must use other means to treat the severe symptoms of the disease, such as multiorgan failure and muscle damage from the toxin--a task that does not always end in success.

Early reports of the syndrome in the United States implicated Toxin A as the culprit responsible for mediating severe streptococcal syndrome. Because the toxin is well-known for causing the severe cases of scarlet fever in children earlier in the century, some researchers have suggested that the syndrome may be a return of scarlet fever.

Recent reports of the syndrome in Europe and in data collected by the CDC, however, indicate that far more patients diagnosed as having the syndrome are producing another bacterial toxin--Toxin B, either with or without Toxin C, rather than Toxin A. Toxins B and C are also capable of causing scarlet fever, but typically produce milder forms of the illness as well as milder forms of severe streptococcal syndrome. The new finding has led scientists to speculate that another yet unrecognized toxin may be involved in the syndrome or that two distinct forms of the syndrome exist.

Patrick Schlivert, a microbiologist at the University of Minnesota who has studied severe streptococcal syndrome since it was first reported, said he believes one form of the illness occurs in healthy individuals, typically under 50 years of age who aren’t old enough to have been exposed to earlier Toxin A cases of scarlet fever. These patients almost always produce Toxin A and seem to develop the most severe form of the syndrome, he said.

Schlivert speculates that a second form of the syndrome occurs more often in an older group of patients with underlying medical conditions that may predispose them to infection.

The first group may, in fact, have scarlet fever, while the second group appears to have something completely new, Schlivert speculates.

CDC’s Schwartz disagrees. Their data indicates that severe streptococcal syndrome is different epidemiologically and clinically from scarlet fever. “Severe scarlet fever with Toxin A-producing bacteria occurred in children with sore throats,” Schwartz said. “The new syndrome rarely occurs in children and it doesn’t occur with a throat infection.”

Muscle and tissue destruction, a hallmark signal of the severe streptococcal syndrome, did not occur in earlier cases of scarlet fever, he said.

“It is a major mystery why the overwhelming majority of strep infections occur in children, but the severe syndrome occurs most often in adults,” Schwartz said.

Although severe streptococcal syndrome is considered contagious, not everyone who comes into contact with an infected individual develops the syndrome, Schwartz said. Signs of the infection include a skin abrasion or cough that gets progressively worse within a relatively short time. Those infected typically develop signs of severe illness such as a fever and chills. Anyone with such symptoms should promptly seek medical attention, he said.

Severe Streptococcal Syndrome The syndrome occurs most often in adults, beginning with an infection or cough that progressively worsens, leading to severe illness and destruction of muscle tissue and organs. 1. The syndrome starts with a minor skin infection from an abrasion.

2. Group A streptococcal bacteria present on the skin penetrate the wound, infiltrating the blood stream.

3. Doctors believe the bacteria release toxins which cause the severe streptococcal syndrome.

4. Infection can lead to a variety of symptoms, including high fever, chills, low blood pressure, shock, muscle and tissue damage, and multiple organ failure of the kidneys, liver and lungs. Antibiotics have proved effective in treating the syndrome when diagnosed early, before the bacteria release the toxins.

The bacteria occur in chains. Several toxins are released by the bacteria, but doctors believe that toxin A causes the most severe form of the syndrome.