Diagnosis and susceptibility testing of methicillin-resistant Staphylococcus aureus in Latin America

Diagnosis and susceptibility testing of methicillin-resistant Staphylococcus aureus in Latin America Abstract Strategies to monitor and control the spread of methicillin-resistant Staphylococcus aureus (MRSA) infections are dependent on accurate and timely diagnosis of MRSA in both hospital and community settings. In Latin America, significant diversity in diagnostic and susceptibility testing procedures exists at the regional, national and local levels. Various tests for S. aureus and MRSA are available in clinical settings, but the application of these techniques differs between and within countries, and quality control measures are not uniformly applied to verify diagnoses. To optimize the diagnosis of MRSA infections across Latin America, a more consistent approach is required. This may include: adoption and appropriate adaption of specific guidelines for MRSA testing, depending on local resources; establishment of a coordinated system for quality control; regional access to central reference facilities; education of medical and healthcare professionals in best practices; and development of systems to evaluate the implementation of guidelines and best practices. Authors Jeannete Zurita1 Carlos Mejía2 Manuel GuzmánBlanco3 on behalf of the Latin American Working Group on Gram Positive Resistance. 1 Hospital Vozandes, Quito, Ecuador. 2 Hospital Roosevelt, Guatemala City, Guatemala. 3 Centro Médico de Caracas, Caracas, Venezuela. Keywords: MRSA, diagnosis, susceptibility testing, Latin America. Introduction Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of infections globally and a growing problem across Latin America.1-3 Epidemiologic studies in the region have charted a significant rise in MRSA infections both in hospital and community settings.1 A key step in the successful treatment of these infections is early and accurate diagnosis. In clinical settings, diagnosis is based on a combination of epidemiologic information, clinical symptoms and characterization of the infecting MRSA strain. The Monitoring/Surveillance Network for Resistance to Antibiotics, set up with the support of the Pan-American Health Organization (PAHO), provides epidemiologic information on bacterial resistance across Latin America. In some countries, including Argentina, Chile, Ecuador, Uruguay and Venezuela, an organized quality control system is present to support local surveillance, but in others, the capacity for microbiologic diagnosis is limited to a few large university hospitals in the major cities, and limited data, especially regarding community-acquired MRSA, are available in these regions. Various international guidelines are available that provide recommendations for best practices in MRSA diagnosis and treatment. However, adoption of these recommendations can be sporadic, especially at regional levels where resources may be a significant limiting factor. Most guidelines provide a range of options for MRSA diagnosis that can be adapted for different regional requirements. However, it may not always be clear which tests are appropriate and sufficient in specific circumstances. Additional guidance is therefore required to establish consistency of approach across the region. Guidelines for diagnosis of MRSA Guideline documents have been published in a number of countries outlining recommended protocols and procedures for the identification of MRSA (Table 14-9). The Clinical and Laboratory Standards Institute (CLSI; formerly the National Committee on Correspondence to: Jeannete Zurita Directora del Servicio de Microbiología y Tuberculosis Hospital Vozandes Villalengua Oe2-37 Quito, Ecuador Phone: +593-2-2262142 Fax: +593-2-2269234 E-mail: jzurita@hcjb. org.ec S97 Diagnosis of MRSA in Latin America Table 1. Guidelines for diagnosis of MRSA4-9 Source Guidelines Clinical and Laboratory Standards Institute (CLSI) Performance Standards for Antimicrobial Susceptibility Testing4 Surveillance for Methicillin-Resistant Staphylococcus aureus: Principles, Practices, and Challenges5 European Antimicrobial Resistance Surveillance System (EARSS) New and updated protocols for antimicrobial susceptibility testing of pathogens under EARSS surveillance 20056 Sociedad Española de Infectologia y Microbiologia Clinica (SEIMC) Protocolos de diagnostico en Microbiologia7 British Society for Antimicrobial Chemotherapy (BSAC) BSAC standardized disc susceptibility testing method (version 7)8 Joint Working Party of the British Society for Antimicrobial Chemotherapy, the Hospital Infection Society and the Infection Control Nurses Association (BSAC/HIS/ICNA) Guidelines for the laboratory diagnosis and susceptibility testing of methicillin-resistant Staphylococcus aureus (MRSA)9 Clinical Laboratory Standards, NCCLS) in the USA has developed a range of best practice documents covering all aspects of microbiologic testing, including recent publications entitled ‘Performance Standards for Antimicrobial Susceptibility Testing’4 and ‘Surveillance for Methicillin-Resistant Staphylococcus aureus: Principles, Practices, and Challenges’.5 The European Antimicrobial Resistance Surveillance System (EARSS), funded by the European Commission, provides a comprehensive surveillance and information system on the spread of antimicrobial resistance in Europe. EARSS has published protocols for diagnostic testing of various organisms with antibiotic resistance traits, including MRSA, VISA and VRSA.6,10 Similarly, the Sociedad Española de Infectologia y Microbiologia Clinica (SEIMC), based in Spain, has published recommendations for the identification of various bacterial strains with antimicrobial resistance, including MRSA.7 In the UK, the British Society for Antimicrobial Chemotherapy (BSAC) published their first guidelines on microbial sensitivity testing in 1991, including minimum inhibitory concentration (MIC) breakpoints for clinically relevant bacteria, and more recently provided standardized methods for disc susceptibility testing for a range of organisms, including MRSA.8 A Joint Working Party of the BSAC, the Hospital Infection Society (HIS) and the Infection Control Nurses Association (ICNA) recently published evidence-based guidelines on the laboratory diagnosis of MRSA.9 These guidelines include recommendations on the identification of MRSA and methods of susceptibility testing and screening. Since the various guidelines differ in their scope and detail, and generally do not apply specifically to infections in Latin America, infection control teams are advised to choose guidelines to follow and to adapt them to their local situation, considering such factors as epidemiology, available antibiotics and resources, likely sources of infection, and risk factors associated with their specific patient population S98 and environment. The CLSI guidelines are the guidelines of choice in most Latin American countries. Evaluation of the implementation of guidelines is also important, (...truncated)