Published March 1, 2012
UB researchers are studying a hypervirulent strain of a common
bacterium with the potential to become a superbug that is
difficult, if not impossible, to treat.
Most antibiotic-resistant bacteria do not infect healthy people. The strain of Klebsiella pneumoniae that UB researchers are investigating could prove an exception.
”In the last 10 to 15 years, this new variant of the
bacterium has begun causing community-acquired infection in young,
healthy individuals,” says Thomas
Russo, MD, professor in the Department of
Medicine and head of its Division
of Infectious Disease.
“It causes serious, life-threatening, invasive infections
and is able to spread to other organs from the initial site of
“If it also becomes highly resistant to antimicrobials, we will have a significant problem to manage.”
Under a program to fund high-risk, high-reward research, the National Institutes of Health has awarded Russo and his UB colleagues a $238,000 grant so they can try to identify the genes that make the new variant of Klebsiella pneumoniae hypervirulent.
It is important to better understand this bacterial species because it can easily acquire mobile genetic units, called plasmids, that contain multiple genes conferring high levels of antimicrobial resistance.
The UB team has already begun to develop a clearer picture of the formidable bacterium.
In October, Russo and his colleagues published a PLoS
ONE paper that showed that hypervirulent Klebsiella pneumoniae
acquires iron more efficiently than the usual strains. With the NIH
grant, they hope to further elucidate the bacterial factors
responsible for this process.
“The goal of this line of research is that these iron-acquisition factors possessed by hypervirulent Klebsiella pneumoniae will then lend themselves as therapeutic or vaccine targets so that we can better treat or prevent infection.”
While the hypervirulent variant of Klebsiella pneumoniae was first seen exclusively in the Pacific Rim, it has since been found in several cities in North America, including Buffalo, and in Europe, Canada, Israel and South Africa.
In Buffalo, the variant was identified in an otherwise healthy young man several years ago. The patient, in his 20s, was hospitalized for several months before fully recovering.
Similar cases are causing concern throughout the international infectious disease community.
UB researchers say that the new strain is underrecognized by physicians and microbiology laboratories.
The disease most commonly presents as a liver abscess, which is not typical for otherwise healthy patients.
It has a propensity for metastatic spread to other parts of the
body, including the lungs, the central nervous system and the eye,
potentially causing vision loss.
“If infection spreads to the brain, there can be brain damage as well,” Russo says. “Between 10 and 30 percent of cases are fatal.”
In the laboratory, an important characteristic of these
hypervirulent strains, also known as hypermucoviscous strains, is
the viscous “string” that forms: When bacterial
colonies grown on a solid surface are stretched by an inoculation
loop, they form a string longer than five millimeters.
Currently, Russo notes, most cases of hypervirulent Klebsiella
pneumoniae resolve if treated aggressively with antibiotics and
drainage of abscesses. Despite optimal treatment, some infections
result in a persistent morbidity or death.