GENETIC CHARACTERIZATION OF METHICILLIN-SUSCEPTIBLE AND METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS STRAINS ISOLATED FROM BLOODSTREAM INFECTIONS IN SLOVENE HOSPITALS USING SPA TYPING

Staphylococcus aureus is the second leading cause of invasive bacterial infections in Slovenia. The aims of this 6-month study were to identify the most prevalent spa types among invasive isolates of methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) in Slovene hospitals, to determine genetic diversity of MSSA and MRSA, and to test the applicability of spa typing to epidemiological studies of S. aureus in Slovenia. Over a period of six months(1 September 2006 - 28 February 2007), up to five successive methicillin-susceptible (MSSA) blood culture isolates and a maximum of five successive methicillin- resistant (MRSA) blood culture isolates per hospital were obtained from different patients with bacteremia. The isolates were characterized by spa typing based on sequencing of polymorphic region X of the S. aureus protein A gene. Among the 58 isolates collected 54 were succesfully spa typed. The predominant spa types among MSSA isolates were t091, t015, t005, and among MRSA, t041. The predominant spa types among invasive S. aureus strains isolated in Slovenia predominated also in the neighbouring countries. The study showed high genetic diversity of invasive MSSA isolates and lower genetic diversity of invasive MRSA isolates in Slovenia. Spa typing is a good typing method for short- and long-term epidemiological studies of MSSA on a local scale.