POPULATION STRUCTURE OF METHICILLIN-SUSCEPTIBLE S. AUREUS AND ITS RELATEDNESS WITH MRSA IN ARGENTINA.

EGEA AL; BARCUDI D; FACCONE D; CA-MRSA GROUP AR; BOCCO JL; CORSO A; SOLA C

Rosario

Congreso; Reunión anual de la Sociedad Argentina de investigación en Bioquímica y Biología Molecular (SAIB); 2014

SAIB

Since 1990s, methicillin resistant S. aureus (MRSA) emerged as a community associated pathogen (CA-MRSA) worldwide. In Argentina, two major Panton-Valentine leukocidin (PVL)(+) CA-MRSA clones were reported with significant differences by geographical regions: CC5-ST5-IV-t311 mainly in South and CC30-ST30-IV-t019 in North of this country. We aimed to describe the population structure of MSSA and to shed light on the origin of these CAMRSA clones. A total of 132 MSSA clinical isolates collected during Nov-2009 from 66 hospitals (20 provinces and Bs. As. City) were analyzed by spa-typing, PVL, PFGE and MLST. A total of 11 clonal complex (CC, MLST) and 65 spa-types (t) were identified. The proportion of isolates belonging to CC5 (t311 and t002) and CC30: (t012, t021 and t018) differed significantly between North and South of Argentina: 36% and 6% vs. 12% and 32 %, respectively.BURP analysis showed that MRSA (previously analyzed) and MSSA isolates belonging to CC5 shared related t (t311and t002), suggesting that these were closely related. Contrary, for MRSA (t019) and MSSA (mainly t012) isolates from ST30 no common t was found. These results suggest that: 1) CA-MRSA CC5-ST5-IV-t311-PVL(+) clone have emerged from MSSA CC5-t311-PVL(+) ancestor, already established in this country and 2) CA-MRSA CC30-ST30-IV-t019-PVL(+) clone was probably imported from neighboring countries.