VUMC Researchers Find Drug-resistant Bacteria MRSA To Be A Growing
Threat: Bacteria's rising threat studied
by John Howser, March 18, 2005, The Vanderbilt Reporter
Infectious diseases researchers at Vanderbilt University Medical
Center are noticing a significant increase in the number of infections
due to Methicillin-Resistant Staphylococcus aureus (MRSA), and the
number of asymptomatic individuals who harbor the organism in their
bodies.
In fact, in a recent analysis of children seen at the Monroe Carell
Jr. Children's Hospital at Vanderbilt Emergency Department in 2003,
approximately 60 percent of the skin infections due to the
staphylococcus germ were, indeed, MRSA. Now, a new study done by VUMC
researchers confirms a dramatic spread of the organism that is being
harbored in the noses of healthy children. What this tells us is that
we're more likely to find MRSA in this population than we are the
typical staphylococcus organism that is susceptible to methicillin,"
said Buddy Creech, M.D., a fellow in pediatric infectious diseases and
the lead investigator on the study.
"The problem with this organism is that it seems to behave
differently, with a tendency to cause skin abscesses and pneumonia."
According to the Centers for Disease Control and Prevention, MRSA is a
type of bacteria that is resistant to a class of antibiotics that
include methicillin and other more commonly prescribed variants such
as oxacillin and other penicillin-based drugs. Previously, MRSA was
seen only in the hospital in patients with underlying diseases or
compromised immune systems. Now the organism appears to be common
among people everywhere, including those in communal settings such as
the military, prisons, daycare facilities, and on athletic teams.
The CDC estimates that roughly 130,000 people are hospitalized with
MRSA each year. MRSA can enter the body through even the smallest
opening in the skin and infiltrate the bloodstream. Once MRSA enters
the bloodstream the bacteria can cause devastating staph infections.
The organism can be difficult to control because its early symptoms
are so benign, and because those who are infected frequently delay
seeking medical intervention until the organism has begun to spread.
Creech and colleagues visited one of Nashville's large community
pediatric practices, and the Children's Hospital Outpatient Pediatric
Clinic, to swab the noses of 500 otherwise healthy children to collect
samples.
Three years earlier a similar study had been done in the same
practices and Creech wanted to see whether things had changed. "We
were just trying to get a sense of how common MRSA actually is in the
community," he said. "We've known for over a half-century that
staphylococcus likes to live in the nose and that's where it thrives.
If it's not in the nose, you probably don't have it. So we went out
and collected these samples." What Creech and colleagues discovered
was that 9.2 percent of the children from this sampling were positive
for MRSA in their noses. "That's up dramatically from three years ago
when only one percent had MRSA," he said. "What we are able to show is
that the increasing incidence of this organism is not just an isolated
phenomenon among football players, prisoners and others in close
communal settings," he said. "These are young, healthy children who
are coming in for well-child visits and they have the resistant
organisms in their noses."
Creech says the next mystery to be solved is why MRSA is increasing in
healthy people "This study tells us there are a lot of children
walking around with MRSA who are healthy, but we are also seeing this
germ cause infections. What we are trying to understand is why some
children go on to develop a serious infection and others don't." MRSA
is an organism that can produce a variety of physical manifestations
across a wide spectrum, from the very minor, all the way to causing
death. Children's Hospital has had adolescents in the intensive care
units suffering from pneumonia and others with the organism in the
bloodstream. As noted earlier, in both the Emergency Department and
outpatient clinics, MRSA skin abscesses and bone infections have also
been seen. Creech says the take-home message for this organism is that
the typical problem associated with MRSA is skin abscesses that often
require drainage and antibiotics. "We are yet to understand why some
children just have MRSA in their nose, causing no disease, while
others are severely ill," he said. Still, Creech says parents should
not be alarmed, but consult their physician if their child develops
skin infections, fever or other signs of illness.
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