Antibiotic Resistance: A Rising Concern In Marine Ecosystems

Scientists Find Threats As Well As Cures In Ocean

February 13, 2009

A team of scientists, speaking today at the annual meeting of the American
Association for the Advancement of Science, called for new awareness of the
potential for antibiotic-resistant illnesses from the marine environment,
and pointed to the marine realm as a source for possible cures of those
threats.

The group stated that newly completed studies of ocean beach users point to
an increasing risk of staph infections, and that current treatments for
seafood poisoning may be less effective due to higher than expected
antibiotic resistance. The group also asserts that new research has
identified sponge and coral-derived chemicals with the potential for
breaking down antibiotic resistant compounds and that could lead to new
personalized medical treatments.

"While the marine environment can indeed be hostile to humans, it may also
provide new resources to help reduce our risks from illnesses such as those
caused by water borne staph or seafood poisoning," stated Paul Sandifer,
Ph.D., former member of the U.S. Commission on Ocean Policy, chief scientist
of NOAA <http://www.eol.ucar.edu/projects/ohhi/> 's Oceans and Human Health
Initiative, and co-organizer of the symposium.  

Carolyn Sotka, also with the NOAA Oceans and Human Health Initiative and
lead organizer of the session, stated "It is critically important that we
continue research on the complex interactions between the condition of our
oceans and human health. Without doubt, this research will develop new
understandings of ocean health risks and perhaps more importantly crucial
discoveries that will lead to new solutions to looming public health
problems."

"We've found significant new tools to fight the antibiotic resistance war,"
says NOAA research scientist Peter Moeller, Ph.D., in describing the
identification of new compounds derived from a sea sponge and corals.

 "The first hit originates with new compounds that remove the shield
bacteria utilize to protect themselves from antibiotics. The second hit is
the discovery of novel antibiotics derived from marine organisms such as
corals, sponges and marine microbes that fight even some of the worst
infectious bacterial strains. With the variety of chemicals we find in the
sea and their highly specific activities, medicines in the near future can
be customized to individuals' needs, rather than relying on broad spectrum
antibiotics."

The research team, a collaboration between scientists at NOAA's Hollings
Marine Laboratory in Charleston, S.C., the Medical University of South
Carolina and researchers at North Carolina State University in Raleigh,
N.C., noticed a sponge that seemed to thrive despite being located in the
midst of a dying coral reef. After extraction, testing showed that one of
the isolated chemicals, algeliferin, breaks down a biofilm barrier that
bacteria use to protect themselves from threats including antibiotics.  The
same chemical can also disrupt or inhibit formation of biofilm on a variety
of bacteria previously resistant to antibiotics which could lead to both
palliative and curative response treatment depending on the problem being
addressed.

"This could lead to a new class of helper drugs and result in a rebirth for
antibiotics no longer thought effective," notes Moeller. "Its potential
application to prevent biofilm build-up in stents, intravenous lines and
other medical uses is incredible."

The compound is currently being tested for a variety of medical uses and has
gone through a second round of sophisticated toxicity screening and thus far
shows no toxic effects.

Research, funded by multiple agencies and conducted by the University of
Miami's Rosenstiel's School of Marine and Atmospheric Sciences and the
Leonard M. Miller School of Medicine, found that swimmers using public ocean
beaches increase their risk for exposure to staph organisms, and they may
increase their risk for potential staph infections once they enter the
water.

"Our study found that if you swim in subtropical marine waters, you have a
significant chance, approximately 37 percent, of being exposed to staph -
either yours or possibly that from someone else in the water with you,"
explained Dr. Lisa Plano, a pediatrician and microbiologist with the Miller
School of Medicine. Plano collaborated in the first large epidemiologic
survey of beach users in recreational marine waters without a sewage source
of pollution. "This exposure might lead to colonization or infection by
water-borne bacteria which are shed from every person who enters the water.
People who have open wounds or are immune-compromised are at greatest risk
of infection."

The Miami research team does not advise avoiding beaches, but recommends
that beach-goers take precautions to reduce risk by showering thoroughly
before entering the water and after getting out. They also point out that
while antibiotic resistant staph, commonly known as MRSA, has been
increasingly found in diverse environments, including the marine
environment, less than three percent of staph isolated from beach waters in
their study was of the potentially virulent MRSA variety. More research is
needed to understand how long staph (including MRSA) can live in coastal
waters, and human uptake and infection rates associated with beach
exposures.

Researchers at the Bigelow Laboratory for Ocean Science in West Boothbay
Harbor, Maine, report that the frequency of antibiotic resistance in vibrio
bacteria was significantly higher than expected. These findings suggest that
the current treatment of vibirio infections should be re-examined, since
these microbes are the leading cause of seafood-borne illness and death in
the United States. The severity of these infections makes antibiotic
resistance in vibrios a critical public health concern.

Naturally-occurring resistance to antibiotics among Vibrios may undermine
the effectiveness of antibiotic treatment, but as yet this has not been
extensively studied. Furthermore, antibiotics and other toxicants discharged
into the waste stream by humans may increase the frequency of
antibiotic-resistant Vibrio strains in contaminated coastal environments.

"We found resistance to all major classes of antibiotics routinely used to
treat Vibrio infections, including aminoglycosides, tetracyclines, and
cephalosporins," stated Bigelow's Ramunas Stepanauskas, Ph.D. "In contrast,
we found that Vibrios were highly susceptible to carbapenems and
new-generation fluoroquinolones, such as Imipenem and Ciprofloxacin. This
information may be used to design better strategies to treat Vibrio
infections."