Pregledni rad
Detection and Typing Methods of Methicillin-Resistant Strains of Staphylococcus aureus
Ana Budimir
; Department for Medical Microbiology and Parasitology, University of Zagreb, Faculty of Medicine, Zagreb, Croatia
Sažetak
Staphylococcus aureus is one of the most important pathogens in hospital infections and its importance in the community is also prominent, especially since the 1990’s. Today methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common causes of hospital infection, causing 40-70% of staphylococcal infections in intensive care units. Data on the prevalence of MRSA isolates differ in various parts of the world, as well as between hospitals, from 0.6% in Norway to 66.8% in Japan, and in 2008 a trend was noticed of a fall in the number of MRSA infections in various European countries. It is possible to isolate MRSA from clinical isolates, as part of the procedure of diagnostics of the infection, or as isolates from the site of colonization through MRSA screening procedures. Identification of S. aureus is based mainly on production of catalase, coagulase and DNA-se and with latex agglutination test based on detection of specific S. aureus antigens (e.g. protein A). Methicillin-resistance can be detected by susceptibility testing to cefoxitine or by using molecular tests to confirm the presence of mecA gene, responsible for methicillin-resistance. There are also some automated laboratory systems that can combine identification and susceptibility testing of MRSA and other bacteria. Detection of MRSA in screening samples is challenged by presence of other bacterial flora and can be overcome by use of different selective broth for initial (overnight) incubation and / or different selective agar plates (e.g. chromogenic plates). Screening can also be performed with molecular tests and new, third generation PCR detects the whole region of genome between SCCmec fragment and orfX (not only mecA gene). Typing is important for MRSA in order to investigate the correlation between different isolates, are they same, similar, do they origin from the same pathogen source etc. One group of methods is phenotypic typing, which is very much substituted with genotypic methods. Among genotypic methods, the most widely used are Pulse–Field Gel Electrophoresis (PFGE), Multi-Locus Sequence Type (MLST) analysis and sequencing of protein A region of Staphylococcus aureus. It is very important for laboratory and hospitals to be able to detect MRSA in samples, accurately and reasonably fast, in clinical samples or as a part of screening strategy. It is up to laboratory to choose which method to use, following guidelines and recommendations and depending on ability to afford different tests.
Ključne riječi
MRSA; detection; typing methods
Hrčak ID:
84029
URI
Datum izdavanja:
21.5.2012.
Posjeta: 2.962 *