CDC recommendations to stop resistant staph
To prevent the spread of staphylococci with reduced susceptibility to vancomycin within and between facilities, and to minimize the potential for the organism to become endemic, the Centers for Disease Control and Prevention recommends the following steps be taken whenever such an organism is isolated:1
• The laboratory should immediately notify infection control personnel, the clinical unit, and the attending physician.
• Infection control personnel, in collaboration with appropriate authorities (including the state health department and CDC), should initiate an epidemiologic and laboratory investigation.
• Medical and nursing staff should isolate the patient in a private room and use contact precautions, including gown, mask, glove, and antibacterial soap for hand washing;
minimize the number of people with access to colonized/infected patients;
dedicate specific health-care workers to provide one-on-one care for the colonized/ infec ted patient or the cohort of colonized/ infected patients.
• Infection control personnel should inform all personnel providing direct patient care of the epidemiologic implications of such strains and of the infection control precautions necessary for their containment;
monitor and strictly enforce compliance with contact precautions and other recommended infection control practices;
determine whether transmission has already occurred by obtaining baseline cultures (before initiation of precautions) for staphylococci with reduced susceptibility to vancomycin from the anterior nares and hands of all health-care workers, roommates, and others with direct patient contact;
assess efficacy of precautions by monitoring health care personnel for acquisition of staphylococci with reduced susceptibility to vancomycin as recommended by consultants from the state health department or CDC;
avoid transferring infected patients within or between facilities, and if transfer is necessary, fully inform the receiving institution or unit of the patient’s colonization/infection status and appropriate precautions;
consult with state health department and CDC before discharge of the colonized/infected patient.
Detecting staphylococci
Use of recommended laboratory methods (including media and incubation methods, antimicrobial susceptibility testing methods, and susceptibility breakpoints) for identifying such strains is essential.
• The most accurate form of antimicrobial susceptibility testing for staphylococci is a minimal inhibitory concentration method (broth dilution, agar dilution, or agar-gradient diffusion) using a full 24-hour incubation. Strains of staphylococci with a MIC [minimal inhibitory concentration] =8 µg/mL (classified as intermediate using National Committee for Clinical Laboratory Standards breakpoints) were not detected by using the current disk diffusion procedure.
• All strains with a MIC greater than or equal to 4 µg/mL should be considered candidate strains for reduced vancomycin susceptibility. Other than the isolate reported in Japan, all S. aureus strains with putative reduced vancomycin susceptibility sent to CDC for confirmation have been misidentified or mixed with other microorganisms. Thus, the laboratory should ensure that the strain is in pure culture and reconfirm the genus and species of the organism; then repeat the susceptibility test for vancomycin using a minimal inhibitory concentration method.
• After repeat testing, if species identification and vancomycin test results are consistent, immediately contact the state health department and the CDC hospital infections program in the National Center for Infectious Diseases [telephone: (404) 639-6400] to report the occurrence of a "presumptive" staphylococcal strain with reduced susceptibility to vancomycin and to obtain epidemiologic and laboratory assistance.
• Retest staphylococci isolated from patients who fail to respond to vancomycin therapy because resistance may have emerged during therapy.
Reference
1. Centers for Disease Control and Prevention. Interim guidelines for prevention and control of staphylococcal infection associated with reduced susceptibility to vancomycin. MMWR 1997; 46:626-628.
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