You can't B. cereus!

There was an exciting piece in the NY Times this weekend about the new “Microbe Hunters”, focusing on the wider availability of rapid whole genome sequencing, and characterization of complex communities of microorganisms (e.g. our microbiome). One part of the article referenced a case of rapidly fatal necrotizing pneumonia in a welder, and the suspicion that it may have been due to B. anthracis—possibly bioterror-related. The article breathlessly described the need for rapid species identification of the microbe:

“A patient had just died from what looked like inhalation anthrax. What should she do?
“I said, ‘I know precisely what to do,’ ” Dr. Musser said. “ ‘We just spent three hours talking about it.’ ”
The questions were: Was it anthrax? If so, was it a genetically engineered bioterrorism strain, or a strain that normally lives in the soil? How dangerous was it?
And the answers, Dr. Musser realized, could come very quickly from newly available technology that would allow investigators to determine the entire genome sequence of the suspect micro-organism.”

But as the case report reveals, it should have been clear that this organism wasn’t B. anthracis pretty quickly, just by looking at the agar plate. B. anthracis is non-hemolytic, and non-motile. B. cereus is both beta-hemolytic and motile. In fact, the lab involved identified it presumptively as B. cereus long before the whole genome sequencing was done. Furthermore, the association between B. cereus and necrotizing pneumonia among welders is well described, as is the presence of B. anthracis toxin genes in pathogenic B. cereus isolates. I’m not discounting the importance of genomic pathology—I’m just sayin’, you can still get a long way with traditional microbiological techniques (like looking at an agar plate).

Image courtesy of the CDC Public Health Image Library