Changing epidemiology of MRSA clones in Argentina: community-associated MRSA strains as main culprit for hospital-onset infections

CORSO A; BARCUDI D; GAGETTI P; LAMBERGHINI R; FACCONE D; LUCERO C; CERIANA P; EGEA AL; SARKIS C; PASTERAN F; MRSA GROUP AR; BOCCO JL; SOLA C

Madrid

Congreso; European Congress of Clinical Microbiology and Infectious Diseases 2018; 2018

European Society of Clinical Microbiology and Infectious Diseases ESCMID

Background: The emergence of community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) has transformed the epidemiology of MRSA over the last 15 years. In Argentina, the spread of the CA- ST5-IV and CA-ST30-IV clones in the community and, hospital-associated (HA)-ST5-I in the hospital setting has been reported. We aimed to investigate the molecular epidemiology of MRSA infections in both community and hospital setting in Argentina.Materials/methods: Consecutive S.aureus clinical isolates were collected during May-2015 from 61 hospitals in 21 Argentinian provinces and BA city and subjected to antimicrobial susceptibility testing. Healthcare-onset (HO)/community-onset (CO) infections were defined when MRSA was obtained after/before 48 hours of hospitalization. MRSA strains were genetically typed as CA-MRSA and HA-MRSA by SCCmec, spa-typing, PVL, PFGE and MLST.Results: A total of 668 S.aureus were collected; 471 (70%) were from CO infections and 341 (51%) were MRSA (45.2% CA- and 5.8% HA-).Of all patients, 251 were children (<19 years) (38%) and 394 were female (59%). MRSA percentages were higher in pediatric (59%) than adult patients (46.3%), p=0.0015.The proportion of MRSA differed from Northern (72.9%) to Centre (48.4%) and Southern (25.6%) regions of Argentina (p<0.0001). In contrast, no differences were found in the MRSA proportion among CO- (50.7%) and HO- (51.8%) infections. Among MRSA infections, 159 (47%) were invasive and 176 (52%) were non-complicated skin and soft-tissue infections. CO-MRSA infections were mainly associated to CA-ST30-SCCmecIVc-t019-PVL+ (South-West Pacific) (72%), CA-ST5-SCCmecIVa-t311-PVL+(12.6%) and CA-ST8-SCCmecIVc-t008-PVL+-ACME¯(USA300-LA,Latin-American variant) (4.6%). In the other side, HO-MRSA infections were mainly associated with CA-ST30-SCCmecIVc-t019-PVL+(40.2%), HA-ST5-SCCmecI-t149 (Cordobes/Chilean) (17.6%), CA-ST5-SCCmecIVa-t311-PVL+(15.7%), HA-ST100-SCCmecIVNv-t002-PVL¯(Pediatric) (7.8%), CA-ST97-SCCmecIVa (Livestock-Associated) (7.8%) and CA-ST8-SCCmecIVc-t008-PVL+-ACME¯ (6.9%) clones.Conclusions: The epidemiology of MRSA is continuously changing in Argentina, particularly due to the spread of CA-ST30-IV and CA-ST5-IV clones. CA-MRSA clones are responsible of the 95% of the CO- and 75% of HO-MRSA infections. The replace of HA- by CA-MRSA clones in the hospital setting along with an important reservoir of CA-MRSA clones in the community, strongly suggest to the community as the main source of MRSA in the hospitals.