US Centers for Disease Control
Staphylococcus aureus with reduced susceptibility to
vancomycin -- U.S.
Morb Mort Weekly Rep
(Aug) 46:No.33 1997
Reproduced from the CDC in full text below:
Staphylococcus aureus is one of the most common causes of both hospital-
and community-acquired infections worldwide, and the antimicrobial agent
vancomycin has been used to treat many S. aureus infections,
particularly those caused by methicillin-resistant S. aureus (MRSA).
1996, the first documented case of infection caused by a strain of S.
aureus with intermediate levels of resistance to vancomycin (VISA;
minimum inhibitory concentration [MIC]=8 mg/mL) was reported from Japan
( 1 ).
This report describes the first isolation of VISA from a patient
in the United States, which may be an early warning that S. aureus
strains with full resistance to vancomycin will emerge.
In July 1997,
VISA-associated peritonitis was diagnosed in a patient who was being
treated with long-term ambulatory peritoneal dialysis. During January
1996 - June 1997, the patient had been treated with multiple courses of
both intraperitoneal and intravenous vancomycin for repeated episodes of
MRSA-associated peritonitis. The patient received medical care primarily
at home; when hospitalized, the patient had been placed on contact
isolation precautions because of known MRSA.
Six isolates of S. aureus
obtained from one specimen from this patient in July were sent to CDC
for species confirmation and antimicrobial susceptibility testing. The
identity of these isolates was confirmed, and of the six, one
demonstrated a vancomycin MIC of 8 mg/mL (National Committee for
Clinical Laboratory Standards break-points for susceptibility:
=32 mg/mL) ( 2 ).
The VISA isolate was susceptible to rifampin,
chloramphenicol, trimethoprim-sulfamethoxazole, and tetracycline. The
patient is continuing to receive antimicrobial therapy. Epidemiologic
and laboratory investigations are under way to assess the risk for
person-to-person transmission of VISA and to determine the mechanism(s)
by which these strains develop resistance.
Editorial Note: Since the 1980s, when MRSA emerged in the United States,
vancomycin has been the last uniformly effective antimicrobial
available for treatment of serious S. aureus infections. This report
documents the emergence of VISA in the United States and may signal the
eventual emergence of S. aureus strains with full resistance to
Widespread use of antimicrobials, such as vancomycin, is a
major contributing factor for the emergence of vancomycin-resistant
organisms, in-cluding vancomycin-resistant enterococci. To accurately
detect staphylococci with reduced susceptibility to vancomycin,
antimicrobial susceptibility should be determined with a quantitative
method (broth dilution, agar dilution, or agar gradient diffusion) using
a full 24 hours of incubation at 95 F (35 C). Strains of staphylococci
with vancomycin MICs of 8 mg/mL were not de-tected using disk-diffusion
To prevent the spread of these organisms within and between
facilities, health-care providers and facilities are advised to 1)
ensure the appropriate use of vancomycin ( 3 ); 2) educate those
personnel who provide direct patient care about the epidemiologic
implications of such strains and the infection-control precautions
nec-essary for containment; 3) strictly adhere to and monitor compliance
with contact iso-lation precautions and other recommended
infection-control practices, and 4) conduct surveillance to monitor the
emergence of resistant strains. Detailed recommendations for the
prevention, detection, and control of S. aureus strains with reduced
susceptibility to vancomycin are outlined in
Interim Guidelines for
Prevention and Control of Staphylococcal Infection Associated with
Reduced Susceptibility to Vancomycin, published previously in MMWR (4),
July 11, 1997 / Vol. 46 / No. 27 (.pdf format) .
The isolation of S. aureus with confirmed or "presumptive" reduced
vancomycin susceptibility should be reported through state and local
health departments to CDC+s Investigation and Prevention Branch,
Hospital Infections Program, National Center for Infectious Diseases,
Mailstop E69, 1600 Clifton Road, NE, Atlanta, GA 30333; telephone (404)
639-6413. Physicians treating patients with infections caused by
staphylococci with reduced susceptibility to vancomycin can obtain
information about investigational drug therapies from the Food and Drug
Administration+s Division of Anti-Infective Drug Products, telephone
1. CDC. Reduced susceptibility of Staphylococcus aureus to
vancomycin -- Japan, 1996. MMWR 1997;46:624-6.
2. National Committee for Clinical Laboratory Standards. Methods for
dilution antimicrobial sus-ceptibility tests for bacteria that grow
aerobically, fourth edition: approved standard, M7-A4. Villanova,
Pennsylvania: National Committee for Clinical Laboratory Standards,
3. CDC. Recommendations for preventing the spread of vancomycin
resistance: recommendations of the Hospital Infection Control Practices
Advisory Committee (HICPAC). MMWR 1995; 44(no. RR-12).
4. CDC. Interim guidelines for prevention and control of staphylococcal
infection associated with reduced susceptibility to vancomycin. MMWR
HDCN Editor's note:
See also the
NEPHROL thread on this subject.