Investigators Warn: Group A Strep Could Be On Its Way to Antibiotic-Resistance

New research finds a small fraction of group A streptococcus strains are showing mutations that could lead to lower antibiotic susceptibility, and possibly someday resistance.

Public health officials need to prepare—now—for the possibility that group A streptococcus (GAS) could soon become antibiotic-resistant.

That’s the message from a new study published last week in the Journal of Clinical Microbiology.

“All of us in the field of infectious diseases and microbiology and so forth were raised on the concept—and it was an unshakeable truth—that group A strep was universally susceptible to β-lactam antibiotics,” James M. Musser, MD, PhD, the study’s lead author, told Contagion®.

Those days may not last, though, said Musser, chair of the Department of Pathology and Genomic Medicine at Houston Methodist Hospital.

Prompted by research published last year that found resistance-promoting mutations in 2 Streptococcus pyogenes strains, Musser and colleagues in the US and Europe decided to study a library of 7025 genome sequences of type emm1, emm28, and emm89 S. pyogenes clinical strains in search of mutations in the pbp2x gene. The group found that about 2% of the strains had mutations warranting further study. Subsequent analysis found many of those strains had decreased susceptibility in vitro to β-lactam antibiotics.

Musser said those findings are striking because they suggest that the linchpin of the medical community’s defense against GAS—penicillin and related antibiotics—might eventually be rendered obsolete.

“If we would lose those beta-lactams as frontline agents, then that’s a real problem, not only in the US but in Canada, Europe and globally for that matter,” he said.

Six hundred million people globally are estimated to be infected with GAS each year. Its most well-known symptom is a sore throat, which the US Centers for Disease Control and Prevention estimates leads to 20-30% of sore throat cases in children, and 5-15% of sore throats in adults.

Left untreated, Musser said GAS can lead to much more serious problems, such as rheumatic fever and rheumatic heart disease.

“That’s a huge problem globally and it remains the most common preventable cause of childhood heart problems globally,” he said.

Last year, public health officials in the United Kingdom reported that 12 people died from an outbreak of invasive GAS.

For Musser, the solution is to be proactive. He believes a GAS vaccine will necessary to subdue the bacteria.

“Importantly, really, I think we’ve got to be honest here that the only reasonable long-term approach to controlling group A strep is through a successful human vaccine,” he said.

Unfortunately, that’s not easy to do. He said there are a handful of groups -- including his own -- who are working on developing a vaccine.

“But let’s put it this way, there’s not an effective one that’s going to be on the immediate horizon,” he said. “We’re years away from an effective group A strep.”

The good news is that we still have time.

“What we and others have found so far is what I would call sort of a partial resistance,” he said. “[GAS] is still susceptible, but it’s going in the direction of resistance,” he said.

By raising the alarm now, he hopes more people will turn their attention to studying GAS, including questions of how mutations occur in humans, and how these mutations affect the virulence of GAS.

“We need to try to get ahead of the curve on this,” he said.