Cryptococcus infections misdiagnosed in many AIDS patients

September 1, 2011, Duke University Medical Center

Most AIDS patients, when diagnosed with a fungal infection known simply as cryptococcosis, are assumed to have an infection with Cryptococcus neoformans, but a recent study from Duke University Medical Center suggests that a sibling species, Cryptococcus gattii, is a more common cause than was previously known.

The difference between these strains could make a difference in treatment, clinical course, and outcome, said Joseph Heitman, M.D., Ph.D., senior author of the study and chair of the Duke Department of and Microbiology.

The study was published Sept. 1 in .

The study emphasizes that health professionals need more careful recording of the cryptococcal species to understand different clinical courses and possibly to change .

Researchers at Duke University Medical Center discovered that in the Los Angeles area, over 12 percent of diagnosed with Crypotococcus were infected with C. gattii, much higher than earlier studies, suggesting only about 1 percent have C. gattii. The researchers based these figures on molecular testing of fungal DNA barcodes.

This discovery comes at the same time as a C. gattii outbreak is expanding in the Pacific Northwest, spreading southward from Vancouver, British Columbia, through Washington, Oregon, and into northern California. Molecular testing is helping both and scientists gain a picture of how a formerly tropical fungus could find new territory, in temperate climates, for infection.

"Importantly, we found that isolates causing the outbreak and those infecting AIDS patients are completely different (VGII vs. VGIII)," said co-lead author Edmond Byrnes, Ph.D., a recently graduated student in the Heitman laboratory.

Wenjun Li, Ph.D., also a co-lead author and researcher in the Heitman laboratory, noted that, based on the fungal isolate samples taken from patients, those with C. gattii may experience resistance to the commonly used "azole" drugs that combat fungal infections, and clinicians might be better aware of potential treatment problems if they knew the species.

Because cryptococcal strains are responsible for over 620,000 deaths annually and responsible for one-third of all AIDS deaths, this species distinction may be of public health importance.

"There may be an unrecognized health burden in AIDS patients attributable to C. gattii rather than C. neoformans," Heitman said.

He said that while a simple test is all that is needed to distinguish the two strains, "few clinical microbiology labs or hospitals, even in developed countries, are equipped to distinguish C. neoformans from C. gattii."

Heitman said that he doesn't believe that there is any human-to-human transmission of C. gattii, but rather, patients are being exposed in the environment. For example, one AIDS patient from San Diego had an isolate that was traced back to a type of tree, which is a common place to find C. gattii, in Australia and elsewhere.

"This study clearly illustrates that AIDS patients in certain areas of the world might be infected by two different cryptococcal species," said John R. Perfect, M.D., professor of medicine at Duke University Medical Center. "Although the outcome of infection in comparison between the two species remains uncertain, this study shows that we need to carefully control for potential differences and study them further."

Medical management might be more complicated for C. gattii compared to C. neoformans, including the possibility of azole drug resistance and the formation of cryptococcomas in the central nervous system that can be difficult to treat and that cause abscesses. "Based on the prevalence we found, it makes sense to pursue further clinical studies, not just to find out the species, but also the molecular type, so we can learn all we can about how this pathogen is travelling and evolving," Heitman said.

Related Stories

Recommended for you

War in Ukraine has escalated HIV spread in the country: study

January 15, 2018
Conflict in Ukraine has increased the risk of HIV outbreaks throughout the country as displaced HIV-infected people move from war-affected regions to areas with higher risk of transmission, according to analysis by scientists.

Researchers offer new model for uncovering true HIV mortality rates in Zambia

January 12, 2018
A new study that seeks to better ascertain HIV mortality rates in Zambia could provide a model for improved national and regional surveillance approaches, and ultimately, more effective HIV treatment strategies.

New drug capsule may allow weekly HIV treatment

January 9, 2018
Researchers at MIT and Brigham and Women's Hospital have developed a capsule that can deliver a week's worth of HIV drugs in a single dose. This advance could make it much easier for patients to adhere to the strict schedule ...

New long-acting, less-toxic HIV drug suppresses virus in humanized mice

January 8, 2018
A team of Yale researchers tested a new chemical compound that suppresses HIV, protects immune cells, and remains effective for weeks with a single dose. In animal experiments, the compound proved to be a promising new candidate ...

Usage remains low for pill that can prevent HIV infection

January 8, 2018
From gritty neighborhoods in New York and Los Angeles to clinics in Kenya and Brazil, health workers are trying to popularize a pill that has proven highly effective in preventing HIV but which—in their view—remains woefully ...

Researchers find clues to AIDS resistance in sooty mangabey genome

January 3, 2018
Peaceful co-existence, rather than war: that's how sooty mangabeys, a monkey species found in West Africa, handle infection by SIV, a relative of HIV, and avoid developing AIDS-like disease.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.