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Methicillin-resistant Staphylococcus aureus Infections: A
Public Health Update
From Navy Environmental and Preventive Medicine
Unit #2 (NEPMU-2), Norfolk, VA
Issue
Between August 2001 and November 2002, a growing number of community-acquired
methicillin-resistant Staphylococcus aureus (MRSA) skin infections
were diagnosed among Navy and Marine Corps service members and recruits.
This update provides guidance on the treatment and response to MRSA
cases occurring aboard Navy operational and training platforms.
Background
NEPMU-2 and a large military training facility recently completed
a survey of nasal colonization among recruits. 790 recruits from
three separate battalions were tested upon initial entry into training.
They were also tested just before and shortly after a final training
exercise that is held in the final week of training. The prevalence
of nasal colonization upon entry was initially high for two of the
battalions (7.5% and 5.1%) but dropped markedly when tested prior
to the final recruit training exercise (0% and 2.3%). Prevalence
for the third battalion was initially low (0.9%) but actually rose
during training (5.4% prior to the final exercise). Prevalence rates
for all three battalions rose when tested after the final training
exercise (5%, 13.9%, 7.9%). The reasons for the disparity between
battalions are unclear but may be related to weather changes, geographic
origin of the recruits, or other factors. 67 Staff members were
tested including barbershop, medical, dental, and training staff.
One staff member working in the Physical Therapy Department was
positive for MRSA (1.49%). 119 Environmental samples were collected
from areas recruits frequently use such as barracks, clinic, barbershop,
in-processing center, training pool, weapon ranges, and chapel.
Two environmental samples were positive (2.13%). Subsequent to this
survey, several training and recruit sites have experienced dramatic
increases in community acquired MRSA skin and soft tissue infections.
Based on this survey and the investigations into these outbreaks,
NEPMU2 recommends the following actions be taken in response to
MRSA cases.
Recommendations
- Maintain and enforce good hygiene.
a. Implement program of required and frequent hand-washing (i.e.
require hand-washing at several points throughout the day including
but not limited to before and after all meals).
b. Ensure staff/supervisors observe for cleanliness and require
hand-washing when needed. Emphasize proper technique and adequate
duration (i.e. scrubbing for 30 to 60 seconds). Consider issuing
alcohol based hand sanitizer to all students.
c. Enforce a regimen of daily showers, emphasizing adequate duration.
d. Consider use of Hibiclens washings at some point or points
during training (i.e., upon entry).
e. Clean medical spaces, barracks rooms, heads and common areas
with a one to ten percent bleach solution.
- Immediately report localized cluster of cases.
a. Notify cognizant NEPMU for any concerns about new cases, clusters,
or outbreaks.
b. For small populations, consider universal screening with nasal
cultures. Individuals found to be carriers can be treated for
nasal eradication (see below for regimens).
c. If appropriate, obtain environmental samples of barracks/ equipment
of platoon/BN involved.
- Raise awareness among residents and staff of
high density living environments.
a. Educate recruits about methods of S. aureus transmission; importance
of proper hygiene and frequent hand-washing.
b. Educate recruits on signs and symptoms of infected wounds/abrasions
and the importance of immediately reporting such lesions.
- Implement enhanced surveillance among health
care providers.
a. Increase awareness of MRSA among providers to improve diagnosis
and identification of organism.
b. Establish a clear case definition of MRSA infection: Any skin
or soft tissue infection with a culture positive for MRSA from
the site of infection. Infections in individuals who have a MRSA
positive nasal culture are not confirmed MRSA infections.
c. Encourage providers to have high index of suspicion for MRSA
(see below for diagnosis and treatment).
d. Demographic information about laboratory positive cultures
(date, location, etc.) should be collected and forwarded to Preventive
Medicine personnel in a timely manner (i.e. weekly).
- Diagnose and treat with appropriate antibiotics
and wound care.
a. In any setting where MRSA is occurring, all wound infections
and abscesses should be cultured. Infections known or suspected
to be MRSA should be treated with the following outpatient regimen:
(Rifampin 600 mg once a day for 10-14 days and Minocin 100mg twice
a day for 10-14 days) OR (Rifampin 600 mg once a day for 10-14
days and Septra DS twice a day for 10-14 days). Also administer
Mupirocin 2% nasal ointment twice a day for 10 days, and hibiclens
washings to cover the body from the neck down daily for 5 days.
This regimen will treat the infection and hopefully eliminate
carriage of the organism. Additional time on this antibiotic regimen
may be required, subject to clinical judgment. Consult ID for
questions.
b. Mild cellulitis may be treated initially with standard antibiotics
such as dicloxacillin. If possible, obtain cultures prior to the
initiation of therapy. If lesions are suspected to be MRSA or
if initial treatment fails, consider outpatient treatment with
the above regimen. Fluoroquinolones such as levofloxacin or ciprofloxacin
are not recommended as treatment for MRSA infections.
c. If eradication of nasal carriage is desired for individuals
who are found to be carriers but do not have active infection,
use the same regimen as above (5a).
d. Encourage providers to incise and drain abscesses to allow
for drainage.
e. Provide clean and adequate dressings for all wounds or abrasions.
Ensure dressings are changed by medical providers as frequently
as needed.
f. Ensure sites with environmental samples positive for MRSA are
thoroughly cleaned with bleach solution or similar agent and then
sampled again.
- Provide adequate hygiene and wound care during
field training evolutions.
a. Focus control efforts on field evolutions where most significant
increase in colonization was noted.
b. Ensure sufficient hand-washing and showering during these events.
Consider using alcohol-based sanitizers.
c. Although no specific documentation of environmental sources,
may need to consider routine cleaning of training gear and equipment.
Related MRSA Information
Recent outbreaks--Since October 2001, NEPMU-2 has been notified
of several outbreaks of MRSA skin and soft tissue infections. Clusters
of cases have occurred aboard a Norfolk area surface ship and, a
San Diego based aircraft carrier, at a recruit training center,
and at an advanced special warfare school.
Disease--The vast majority of MRSA infections are skin and
soft tissue infections such as impetigo, cellulitis, furuncles,
and abscesses. Complications of severe or ineffectively treated
infections can include osteomyelitis and sepsis. Infections that
are widespread may cause constitutional symptoms such as fever,
malaise, headache, and anorexia.
Occurrence--Previously considered a hospital-acquired pathogen,
MRSA has now been noted to occur with increasing frequency in the
general community. Community acquired MRSA infections often occur
in individuals without the traditional risk factors (recent hospitalization,
dialysis, residence in a long-term care facility, and intravenous
drug use).
Transmission--The primary method of transmission is by direct
contact with a person who is colonized or infected. The most common
site of asymptomatic colonization is the anterior nares. Transmission
primarily occurs from the hands of healthy carriers but may also
occur from infected wounds. Infection from an environmental source
is not believed to be the primary method of transmission but does
occur. Close quarters, sharing personal items, warm weather, and
poor hygiene may contribute to transmission and subsequent infection.
Prevalence--The prevalence of MRSA colonization or infection
among the general community or among military populations is unknown.
However, surveillance of special warfare trainees from (1999-2001)
revealed that approximately 40% of trainees were nasal carriers
of S. aureus and less than 1% were MRSA carriers. Roughly
90% of S. aureus isolates were resistant to penicillin prior
to receiving bicillin prophylaxis. A prevalence survey was also
conducted aboard a US Navy surface ship after the discovery of a
cluster of four MRSA cases in 2001. In the departments in which
the infections occurred, 3.3% of crewmembers were found to be nasal
carriers.
For questions, contact NEPMU-2, Norfolk, VA. Phone Number: (757)
444-7671; DSN 564-7671.
REFERENCE: Chin J. Control of Communicable Diseases Manual,
17th edition. Baltimore: United Book Press, Inc.; 2000: 460-470.
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