Glycopeptide Intermediate-Resistant Staphylococcus Aureus

Trends

Staphylococcus aureus is one of the most common causes of community- and hospital-acquired infection. In the 1980s, methicillin-resistant S. aureus (MRSA) emerged and became endemic in many U.S. hospitals. Vancomycin was the only antimicrobial agent with uniform effectiveness against MRSA. In the 1990s, vancomycin-resistant enterococci (VRE) emerged and also became endemic in many U.S. hospitals. In 1996, the first S. aureus strain with decreased susceptibility to vancomycin (glycopeptide intermediate-resistant S. aureus [GISA]) was reported in Japan. In 1997, the first GISA strains were reported in the United States.

Scope Of Problem

The spread of antimicrobial-resistant nosocomial pathogens such as MRSA, VRE and GISA is secondary to both over- and misuse of antimicrobials and incomplete compliance with recommended infection control precautions. Some studies have documented that as much as 63 percent of vancomycin use is inappropriate. Other studies show that health care workers often fail to wash their hands as recommended or to fully implement recommended infection control precautions.

Sequelae

GISA (and other antibiotic-resistant pathogens) cause serious morbidity and mortality. Treatment requires removal of colonized invasive devices, therapy with agents to which the organism is susceptible and monitoring of drug levels to ensure that adequate levels are maintained. If the prevalence of GISA strains increases, they may lead to increased health care costs, since the infected patients will require combined antimicrobial therapy.

Challenges and Goals

In 1997, the Hospital Infections Program, Centers for Disease Control and Prevention, issued interim recommendations for the prevention and control of S. aureus with reduced susceptibility to vancomycin. These recommendations highlight the importance of improving the appropriate use of antimicrobials, provide guidance for when vancomycin should and should not be used and describe the enhanced isolation precautions that patients colonized or infected with GISA strains should be placed in. In addition, these recommendations describe the microbiologic methods needed to identify these strains. Educational programs for physicians and other health care workers are needed to ensure that these recommendations are understood and fully implemented.

Risk Groups

Patients at greatest risk are those who are severely ill, those receiving prolonged courses of vancomycin, those with prior colonization with MRSA or VRE and particularly those with peritoneal catheters.

Research Priorities

• To educate physicians to improve appropriateness of antimicrobial use.
• To enhance laboratory capability to detect GISA.
• To improve compliance with recommended infection control precautions for GISA.
• To develop a nationwide surveillance system for GISA.
• To determine the mechanism of GISA development.
• To enhance the public awareness of GISA and antimicrobial use and resistance and encourage more appropriate use of antimicrobials.

April 1998