Nav: Home

Drug-resistant 'nightmare bacteria' show worrisome ability to diversify and spread

January 16, 2017

Boston, MA - A family of highly drug-resistant and potentially deadly bacteria may be spreading more widely--and more stealthily -- than previously thought, according to a new study from Harvard T.H. Chan School of Public Health and the Broad Institute of MIT and Harvard.

Researchers examined carbapenem resistant Enterobacteriaceae (CRE) causing disease in four U.S. hospitals. They found a wide variety of CRE species. They also found a wide variety of genetic traits enabling CRE to resist antibiotics, and found that these traits are transferring easily among various CRE species. The findings suggest that CRE is more widespread than previously thought, that it may well be transmitting from person to person asymptomatically, and that genomic surveillance of these dangerous bacteria should be increased.

The study will appear online January 16, 2017 in PNAS (Proceedings of the National Academy of Sciences).

"While the typical focus has been on treating sick patients with CRE-related infections, our new findings suggest that CRE is spreading beyond the obvious cases of disease. We need to look harder for this unobserved transmission within our communities and healthcare facilities if we want to stamp it out," said William Hanage, associate professor of epidemiology at Harvard Chan School and senior author of the study.

CRE are a class of bacteria that are resistant to multiple antibiotics, including carbapenems, which are considered last-resort drugs when other antibiotics have failed. CRE, which tend to spread in hospitals and long-term care facilities, cause an estimated 9,300 infections and 600 deaths in the U.S. each year, according to the U.S. Centers for Disease Control and Prevention (CDC) -- and incidence is on the rise. Tom Frieden, director of the CDC, has called these 'nightmare bacteria' because they are resistant to some of the last-ditch treatments available to doctors battling resistant infections.

The researchers looked at about 250 samples of CRE from hospitalized patients from three Boston-area hospitals and from one California hospital. Their goal was to obtain a snapshot of the genetic diversity of CRE, to define the frequency and characteristics of outbreaks, to find evidence of strains being transmitted within and between hospitals, and to learn how resistance is being spread among species. Previous studies have typically examined just one outbreak at a time.

Researchers found what Hanage termed a "riot of diversity," both among CRE species and among carbapenem resistance genes. They also found that resistance genes are moving easily from species to species, contributing to a continually evolving threat from CRE.

In addition, the researchers found resistance mechanisms that hadn't been seen before--implying that there are more to be discovered. The finding highlights the need for vigilance in searching for as yet unknown forms of resistance as they evolve and emerge.

"The best way to stop CRE making people sick is to prevent transmission in the first place," said Hanage. "If it is right that we are missing a lot of transmission, then only focusing on cases of disease is like playing Whack-a-Mole; we can be sure the bacteria will pop up again somewhere else."
-end-
Lead authors were Gustavo Cerqueira and Ashlee Earl of the Broad Institute of Harvard and MIT. Yonatan Grad, assistant professor of immunology and infectious diseases at Harvard Chan School, was a co-author of the study.

Funding for the study came from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, under Contract No. HHSN272200900018C and Grant Number U19AI110818 to the Broad Institute. YHG was supported by K08AI104767 and JEK was supported by R21AI112694 and R21AI119114 from the NIH/NIAID. JLRC was supported by CAPES fellowship, process 99999.010768/2014-09.

"Multi-institute analysis of carbapenem resistance reveals remarkable diversity, unexplained mechanisms and limited clonal outbreaks," Gustavo C. Cerqueira, Ashlee M. Earl, Christoph M. Ernst, Yonatan H. Grad, John P. Dekker, Michael Feldgarden, Sinéad B. Chapman, João L. Reis-Cunha, Terrance P. Shea, Sarah K. Young, Qiandong Zeng, Mary L. Delaney, Diane Kim, Ellena M. Peterson, Thomas F. O'Brien, Mary J. Ferraro, David C. Hooper, Susan S. Huang, James E. Kirby, Andrew B. Onderdonk, Bruce W. Birren, Deborah T. Hung, Lisa A. Cosimi, Jennifer R. Wortman, Cheryl I. Murphy, William P. Hanage, PNAS, online January 16, 2017, doi: 10.1073/pnas.1616248114

Visit the Harvard Chan website for the latest news, press releases, and multimedia offerings.

Harvard T.H. Chan School of Public Health brings together dedicated experts from many disciplines to educate new generations of global health leaders and produce powerful ideas that improve the lives and health of people everywhere. As a community of leading scientists, educators, and students, we work together to take innovative ideas from the laboratory to people's lives -- not only making scientific breakthroughs, but also working to change individual behaviors, public policies, and health care practices. Each year, more than 400 faculty members at Harvard Chan School teach 1,000-plus full-time students from around the world and train thousands more through online and executive education courses. Founded in 1913 as the Harvard-MIT School of Health Officers, the School is recognized as America's oldest professional training program in public health.

Harvard T.H. Chan School of Public Health

Related Bacteria Articles:

Conducting shell for bacteria
Under anaerobic conditions, certain bacteria can produce electricity. This behavior can be exploited in microbial fuel cells, with a special focus on wastewater treatment schemes.
Controlling bacteria's necessary evil
Until now, scientists have only had a murky understanding of how these relationships arise.
Bacteria take a deadly risk to survive
Bacteria need mutations -- changes in their DNA code -- to survive under difficult circumstances.
How bacteria hunt other bacteria
A bacterial species that hunts other bacteria has attracted interest as a potential antibiotic, but exactly how this predator tracks down its prey has not been clear.
Chlamydia: How bacteria take over control
To survive in human cells, chlamydiae have a lot of tricks in store.
Stress may protect -- at least in bacteria
Antibiotics harm bacteria and stress them. Trimethoprim, an antibiotic, inhibits the growth of the bacterium Escherichia coli and induces a stress response.
'Pulling' bacteria out of blood
Magnets instead of antibiotics could provide a possible new treatment method for blood infection.
New findings detail how beneficial bacteria in the nose suppress pathogenic bacteria
Staphylococcus aureus is a common colonizer of the human body.
Understanding your bacteria
New insight into bacterial cell division could lead to advancements in the fight against harmful bacteria.
Bacteria are individualists
Cells respond differently to lack of nutrients.

Related Bacteria Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Bias And Perception
How does bias distort our thinking, our listening, our beliefs... and even our search results? How can we fight it? This hour, TED speakers explore ideas about the unconscious biases that shape us. Guests include writer and broadcaster Yassmin Abdel-Magied, climatologist J. Marshall Shepherd, journalist Andreas Ekström, and experimental psychologist Tony Salvador.
Now Playing: Science for the People

#513 Dinosaur Tails
This week: dinosaurs! We're discussing dinosaur tails, bipedalism, paleontology public outreach, dinosaur MOOCs, and other neat dinosaur related things with Dr. Scott Persons from the University of Alberta, who is also the author of the book "Dinosaurs of the Alberta Badlands".