FRIDAY, June 8, 2012 (MedPage Today) — In rare cases, the bacteria responsible for causing strep throat — group A Streptococcus — can penetrate beyond the superficial surfaces of the body and lead to necrotizing fasciitis, toxic shock syndrome, and even death.

But, but because most strep infections are treated easily with antibiotics, there are challenges in identifying which patients will progress to the more severe invasive infections, according to Rodney Willoughby, MD, a pediatric infectious disease specialist at Children's Hospital of Wisconsin.

"These are rare lightning strikes, but they're devastating to the families involved," said Willoughby, who sits on the infectious diseases committee of the American Academy of Pediatrics.

Such was the case for the family of 12-year-old Rory Staunton. It's believed that streptococcal toxic shock claimed his life just 5 days after he got a small cut while playing basketball.

Scope of the Problem

Although exact statistics are hard to come by, Stanford Shulman, MD, chief of infectious diseases at Lurie Children's Hospital of Chicago (formerly Children's Memorial Hospital), estimated that there are about 10,000 cases of invasive streptococcal infection each year among all age groups in the U.S., about one-third of which progress to toxic shock.

Older and very young individuals are particularly vulnerable.

From the pediatric perspective, Willoughby estimated that among a birth cohort of about four million children in the U.S. each year, there might be 80 to 100 cases of invasive streptococcal infection, about 30 to 40 that progress to toxic shock.

Historically, invasive streptococcal infections were often associated with chicken pox, because of the increased areas of broken skin allowing potential access for the bacteria. Since the introduction of the varicella vaccine in 1995, there's been a decrease in the numbers of invasive group A streptococcal infections in the pediatric population, but they haven't been eliminated, Shulman said.

The mortality rate can reach 60 percent or higher for patients who develop both necrotizing fasciitis and toxic shock syndrome, according to Shulman. Those who have toxic shock alone will die 15 percent to 20 percent of the time.

Developing Toxic Shock Syndrome

Why some invasive streptococcal infections progress to toxic shock is not fully known, but there is evidence that both genetic susceptibility and differences among particular strains of group A Streptococcus are involved.

Willoughby said that after an infection enters the bloodstream or soft tissues there might be certain people who are genetically predisposed to having an exaggerated immune response to the toxins released by the bacteria.

"Then you essentially hurt yourself," he said. "Your immune response actually goes against you and it develops such a massive inflammation that it's actually hard for you to recover from it. So you literally go into shock and die."

Challenging Identification

The circumstances of Rory Staunton's illness and death are not unusual for these types of extreme infections, Willoughby said.

A child or teenager may get checked out for an infection and a general feeling of being unwell. The doctor may decide it's a gastrointestinal illness and send the patient home. Over the next 3 or 4 days, the patient may return to the doctor 2 or 3 more times with nonspecific symptoms that don't point to a looming invasive infection. What usually happens is that the doctor does extra tests but can't find anything wrong, Willoughby said.

Part of the problem among younger patients is that they are generally healthy and robust, so their bodies are able to compensate initially for the damage caused by the infection, he said. Eventually, however, the infection will overcome the ability of the body to mask it.

"There's nothing to be feared more than the teenage patient who's sick, because ... you really don't find things until [he or she is] in real trouble," Willoughby said. "And so it's very scary."

At the point that it becomes clear the young patient is very sick and he or she is headed to intensive care, there might be little the medical system can do, he said.

"With the retrospectoscope and with lawyers abounding you can almost always find something that could have been done slightly better," he said, but at the point the patient is going to the ICU "a lot of times essentially your fate has been already determined."

Stopping It Before It Starts

Willoughby highlighted two potential approaches to preventing these extreme cases — vaccination or an advancement in genetic testing that would allow clinicians to know which patients are genetically susceptible to toxic shock.

There are some vaccines in development for group A Streptococcus, but none is close to market. Willoughby said a strep vaccine would require a larger number of components than existing vaccines against pneumococcal disease or Haemophilus influenzae type B.

Thus, the technical challenge of creating the vaccine may render that approach too expensive. Willoughby and Shulman agreed that vaccinating a large number of children to prevent a rare, but serious event is also controversial.

Now that genetic testing is being used more frequently, Willoughby said, it might be possible someday to identify patients with a "genetic chink in the armor" that allows the more serious streptococcal infections to develop.

Armed with that information, he said, clinicians may be able to raise the alert, perform more extensive testing, and start antibiotics sooner in susceptible individuals than they would in others.

But that approach is still in the future, he said, leaving clinicians in the position of not knowing what the appropriate response should be.

"So you're left essentially knowing that there are evil things out there in the world, but they're rare enough and inefficient enough as spreaders [that there may not] be anything to be done about it," Willoughby said.

"There are hundreds of conditions that are relatively uncommon or rare, and the lay public can't be concerned about every one of them," Shulman added. "But I do think that parents need to be taught that when their children are manifesting signs of more-than-trivial illness they really ought to be checked out by a doctor, preferably their pediatrician, to make sure there is no indication of anything more serious going on."

Source: Toxic Shock from Strep: a ‘Lightning Strike’