CONTACT: JENNIFER BROWN
Iowa City IA 52242
(319) 335-9917; fax(319) 384-4638
Release: June 13, 2002
(Photo: Loreen Herwaldt, M.D., UI associate professor of internal medicine
and public health)
NOTE TO EDITORS: Parts of this release are adapted from a release issued
by Johns Hopkins Medical Institution.
Nasal antibiotic ointment reduces hospital-acquired, post-surgery infections
new study conducted by researchers from the University of Iowa and Johns Hopkins
Medical Institution finds that applying an antibiotic ointment inside the
noses of surgery patients helps protect them from acquiring a post-operative
infection. The study is published in the June 13 issue of the New England
Journal of Medicine.
The antibiotic ointment, mupirocin, is effective for treating a bacterium
known as Staphylococcus aureus (S. aureus), which resides in the nostrils
of an estimated 25 to 30 percent of the general population. Usually, S. aureus
nasal colonization is temporary and harmless, but bacteria from the nose can
contaminate surgical sites, causing severe and often deadly infections. S.
aureus causes one fourth of all hospital-acquired infections, which can result
in prolonged hospital stays and substantially increased health care costs.
"It has been known for a while that patients who have S. aureus in their
nose have a substantially higher risk of getting a S. aureus surgical wound
infection after a surgical procedure than patients who don't have the bacteria
in their noses," said Loreen Herwaldt, M.D., UI associate professor of
internal medicine and public health and an author on the study. "Mupirocin
really is the most effective agent that we have for eliminating S. aureus
bacteria from the nose."
The study known as MARS (Mupirocin and the Risk of Staphyloccus aureus infections)
may be the largest trial to date to investigate the effectiveness of an antibiotic
in preventing post-operative infection. More than 4,000 adult patients undergoing
elective surgery at UI Hospitals and Clinics and the Veteran Affairs Medical
Center (VAMC) in Iowa City were enrolled.
The study had several goals. It aimed to find out if using mupirocin to
kill nasal bacteria in patients before they had surgery would reduce S. aureus
surgical-site infections. The study also examined whether mupirocin treatment
could reduce surgical-site infections caused by other kinds of bacteria. Finally
the study investigated whether mupirocin could reduce the overall incidence
of hospital-acquired infection caused by S. aureus, including surgical site
infection, pneumonia, bloodstream infections, and urinary tract infection.
Patients were randomly assigned to one of two groups. One group had mupirocin
ointment applied to the inside of their nostrils twice daily for five days
before surgery. The other group received a placebo treatment, which consisted
of an ointment that did not contain the antibiotic substance. Neither patients
nor physicians knew who received the mupirocin and who got the placebo. The
patients were assessed for an average of 30 days after their operations to
determine whether they acquired infections. Study participants included general
surgery patients, neurosurgery patients, gynecology patients and cardiothoracic
"When we looked at all S. aureus hospital-acquired infections, there
was a significant decrease in infection rates for the treated group compared
with the non-treated group," Herwaldt said.
The study also showed nearly a 50 percent decrease in surgical-site infections
in the patients who received the mupirocin. Herwaldt commented that the researchers
believed that this decrease was clinically important, but added that due to
several factors in the study, the result was not statistically significant.
"We are excited to find that mupirocin did decrease the overall rate
of S. aureus hospital-acquired infection," Herwaldt said. "However,
we think that it is too early to say which patients are going to benefit the
most, and we have to use mupirocin cautiously to protect against the development
of antibiotic resistance."
Antibiotic resistance is a problem associated with increased use of any
antibiotic. Although the research team found that a short, carefully planned
mupirocin treatment, like that used in the study, did not appear to contribute
to antibiotic resistance, Herwaldt explained that targeting mupirocin treatment
only to patients most likely to benefit would also help prevent antibiotic
resistance. The researchers hope to identify risk factors that increase patients'
likelihood of carrying S. aureus in their nose so they can identify the patients
who are at highest risk of acquiring an infection after an operation.
"Mupirocin is the only drug of its kind," Herwaldt said. "We
don't want to lose it by causing antibiotic resistance through overuse. We
definitely need to use mupirocin wisely."
Lead author on the study Trish Perl, M.D., associate professor of medicine,
director of Hospital Epidemiology and Infection Control at Johns Hopkins,
was at the University of Iowa when the study was done. In addition to Herwaldt
and Perl, other UI authors of the study include
Joseph Cullen, M.D., associate professor of surgery, Michael Pfaller, M.D.,
professor of pathology and public health, M. Bridget Zimmerman, Ph.D., Deborah
Sheppard, and Jennifer Twombley. Richard Wenzel, M.D., professor and head
of internal medicine at Virginia Commonwealth University, Richmond Va., and
Pamela French, M.D., at GlaxoSmithKline, also were authors. Herwaldt, Cullen
and Pfaller all hold physician appointments at the VAMC.
Mupirocin ointment is made by GlaxoSmithKline. The study was funded by a
research grant from GlaxoSmithKline, and both Herwaldt and Perl have consulted
for the company.
University of Iowa Health Care describes the partnership between the
UI Roy J. and Lucille A. Carver College of Medicine and UI Hospitals and Clinics
and the patient care, medical education and research programs and services
they provide. Visit UI Health Care online at www.uihealthcare.com.