Infection control experts at Johns Hopkins are
sounding the alarm for vulnerable health care workers to be
on the lookout for a more aggressive form of
methicillin-resistant Staphylococcus aureus, called
community-acquired MRSA, or CA-MRSA. MRSA infections are
resistant to commonly used antibiotics, including oxacillin
(Bactocil), penicillin and cephalexin (Keflex).
The warning follows a Johns Hopkins-funded
investigation of the infection in two health care workers
in a very busy outpatient clinic for people with HIV at The
Johns Hopkins Hospital in 2004, revealing contamination to
be widespread in the clinic and a greater potential risk to
staff and patient safety than previously thought. No
patients were found to be infected as a result of the
outbreak, but afflicted staffers required treatment, and
infection control resources were significantly increased to
lower the risk of a repeat outbreak.
Health experts fear that the rising trend of MRSA
infections in hospitals could render useless many of the
most widely available and effective drugs.
"Tighter infection control practices and policies are
needed by health care workers and hospitals to prevent
outbreaks and prevent staff from picking up the
community-acquired form of this bacterium from patients,"
said Cecilia Johnston, an infectious diseases instructor at
Johns Hopkins and leader of the investigation.
Senior hospital epidemiologist Trish Perl, an
associate professor of medicine and pathology at the School
of Medicine, said, "Community-acquired MRSA is an
increasing problem in inpatient and outpatient settings, as
exposure can occur in the workplace. Our experience shows
that health care workers need to be aware of the risk,
alert infection control staff immediately after an
infection is suspected and understand that tighter
infection control procedures can guard against subsequent
exposure."
High-risk patients in intensive care are monitored
regularly for contamination with MRSA, and Johnston said
the new study calls for increased vigilance in outpatient
treatment areas with high patient traffic. "Treatment areas
should be cleaned regularly and between each patient visit
with strong disinfectants," she said, adding that health
care workers should wear gowns and gloves and care for
exposed skin and other wounds in designated, confined
treatment spaces or separate rooms. Like most bacterial
infections, MRSA is usually picked up through direct
contact, by touching someone or a surface with it.
The Johns Hopkins team describes the outbreak of
community-acquired MRSA and the subsequent investigation,
which started in February 2004 and took five weeks to
complete, in a report published in the journal Infection
Control and Hospital Epidemiology online Sept. 18. Their
study is believed to be the first to evaluate just how
widespread CA-MRSA is during an outbreak in an outpatient
setting. Previous research has focused on hospital wards
and inpatient settings.
The study showed that the aggressive form of CA-MRSA,
which can cause disease in healthy people, including
children, was present throughout the clinic, on seven of 36
surfaces tested. The less dangerous, hospital-acquired form
of MRSA, or HA-MRSA for short, was not found on any of the
surfaces tested.
Though rarely fatal, infections with either form of
MRSA can lead to life-threatening complications in
patients. CA-MRSA is associated with abscesses, or pimples,
on the skin that must be drained to prevent those
complications, which include foul-smelling skin infections,
muscle swelling or lethal necrotizing pneumonia and septic
shock. It can also produce more kinds of toxins than its
less-virulent form. HA-MRSA, known to colonize the whole
body, can lead to dangerous blood stream infections.
Of added concern to infection control specialists is
that CA-MRSA infections in hospitals are frequently
misdiagnosed as the hospital-acquired kind, which is
treated differently. According to researchers, CA-MRSA
infections have been effectively treated with oral
antibiotics, such as trimethoprim-sulfamethoxazole
(Bactrim), minocycline (Minocin) and clindamycin (Cleocin),
whereas HA-MRSA infections have been known to be more
resistant to these drugs. Another antibiotic, vancomycin,
is usually required. And the researchers caution that it is
extremely important to identify which bacterium is there,
by obtaining cultures, to make sure the right antibiotic is
prescribed.
The outbreak was detected soon after it began when two
staff members reported MRSA-like lesions to Johns Hopkins'
infection control team, which monitors hospital operations
daily for potential hazards to patient safety, and
immediately tested both workers. One staff member had
direct contact with patients who also had MRSA-like
infections, while the second had no direct patient
contact.
Once the infection of the two clinic workers was
confirmed, researchers sought the scope of contamination
and to identify any other health care workers who may have
been exposed. The clinic was one of Johns Hopkins' busiest,
providing outpatient care to the regional HIV population,
with some 20,000 patient visits each year.
For the investigation, all other clinic staff,
approximately 138 nurses, physicians and managers who
worked inside the clinic, were tested for MRSA colonization
or infection. Researchers swabbed noses, a soft tissue
where the bacteria readily colonize. They also dipped
hands, another region where bacteria live, into a vat of
bacterial growth media to see if the MRSA bacterium would
grow. Two additional health care workers were found to be
colonized with HA-MRSA, but they showed no signs of
infection. The two were treated with an antibiotic nasal
spray that rid them of the bacterium.
As part of the investigation, the team swabbed 36
separate surfaces in the clinic — especially commonly
used items such as phones, doorknobs, equipment and
furniture — and surveyed each clinic worker to assess
possible sources of the MRSA infection and what infection
control procedures were in practice. For example,
researchers asked the staff about how often they treated
patients with signs of CA-MRSA and if open wounds were
cleaned and drained in the room, and how often staff washed
their hands between patient visits and to what extent the
exam room was cleaned between patient visits. It is the
routine between patient visits for clinic workers to pull
down a fresh sheet of paper over the exam room and wash
their hands.
The investigation showed that no other workers had
been infected with either form of MRSA. However, cultures
of the workplace showed contamination with CA-MRSA to be
widespread, with seven surfaces testing positive, including
patient exam table surfaces, pulse oximeters (a device for
testing blood oxygen levels), countertops, computer
keyboards and patient chairs in the triage station, and
waiting and exam rooms. Surfaces not found to be
contaminated included doorknobs, phones, ophthalmoscopes
(to check eyes), otoscopes (to check ears), blood pressure
cuffs, thermometers and sinks.
Researchers were not able to determine why some
surfaces were contaminated and others were not.
Staff interviews also revealed that patients with
CA-MRSA infections had their abscesses drained and wounds
cleaned in whichever room was available, and that some
staff wore no protective gowns or masks during the
procedure.
After subsequent meetings with clinic staff and
hospital cleaning personnel, a number of changes were
introduced to the clinic in an attempt to cut back on
environmental contamination. Cleaning supplies were checked
and switched to make sure all included agents that contain
ethyl alcohol and quarternary ammonium, compounds that kill
MRSA. Sanitary wipes containing the compound were placed in
all exam rooms to encourage cleaning between patients.
Cleaning staff practices were also changed to include daily
cleaning of all surfaces. To reduce exposure from patients
already infected and undergoing wound cleaning, one room
was set aside for draining abscesses.
After two weeks of intense efforts to prevent the
spread of infection, another round of environmental testing
in April 2004 showed no positive cultures of CA-MRSA. The
outbreak was deemed to be over.
Researchers say their next step is to work with
municipal health officials and to continue to monitor
CA-MRSA in the community, evaluate how it spreads among
different populations and assess the risk this poses to
health care workers and patients in the hospital, as well
as what measures will work best to prevent outbreaks.
No firm estimates on the prevalence of MRSA exist, and
preliminary numbers vary widely from country to country and
between hospitals. In 2006, however, the Joint Commission
on Accreditation of Healthcare Organizations released an
estimate that 70 percent of the bacteria that cause
infections for 2 million hospitalized Americans each year
are resistant to at least one of the drugs most commonly
used to treat them.
Funding for the study was provided by The Johns
Hopkins Hospital. Besides Perl and Johnston, other members
of the team involved in this investigation and study were
Lisa Cooper, William Ruby, Karen Carroll and Sara
Cosgrove.