A 2019 Prospective Survey of Staphylococcus aureus in South America Reveals Distinct Populations of MRSA and MSSA: Results from the First StaphNET-SA Network Study

VIELMA VALLENILLA J; DI GREGORIO S; HAIM MS; RAGO L; FAMIGLIETTI A; FERNÁNDEZ CANIGGIA L; RUBINSTEIN G; VON SPECHT MARTHA; HERRERA M; ARO C; CAMPOS J; GALAS M; BALDERRAMA N; FIGUEIREDO A; LINCOPAN N; FALCON M; GUILLEN R; CAMOU T; VARELA G; CONSORCIO STAPHNET-SA; ARGIMON S; AANENSEN DM; MOLLERACH M

Washington DC

Congreso; ASM Microbe 2022; 2022

American Society for Microbiology

Staphylococcus aureus remains one of the leading causes of infections worldwide.Although WGS has been implemented as a tool for surveillance, the genomic epidemiologyof S. aureus in South America (SA) has been scarcely investigated. We hereby reportgenomic data from the StaphNET South America network.We prospectively characterized405 genomes from isolates recovered by 57 hospitals in Argentina, Bolivia, Brazil,Paraguay, and Uruguay. Hospitals aimed to collect the first five MRSA and the first fiveMSSA primary isolates from bacteremia between April and October 2019. DNA wassequenced using the Illumina HiSeq platform and, following quality control, we extractedclinically relevant information [i.e., resistome, sequence types (STs), SCCmec and spa type]with public and custom-built pipelines and databases. Several hospitals were unable tosubmit ten isolates and/or collect five MRSA isolates during the six-month survey. Thus,59.3% (240/405) of the isolates were MSSA and 40.7% MRSA. WGS revealed a greaterdiversity of clonal complexes (CC) among the MSSA population (15 CCs) than the MRSApopulation (8 CCs). CC30, CC5, CC8 and CC398 were the most prevalent lineages andwere found in all countries.CC30 was the most prevalent CC of the study 75/405 (18.5%),of which 57/75 (76%) were MRSA, with predominance of the CC30-MRSA-IV-t019 clone(51/57, 89.5%) characterized by a narrow resistome but broad geographic distribution. Ofthe 71 CC5 isolates, 50 (70.4%) were MRSA. The CC5-MRSA-IV-t002 clone, carrying anarrow resistome, was the most frequent MRSA genotype (18/50, 36%), found innorthwestern Argentina, Uruguay, Brazil, and Paraguay. Out of the 64 CC8 isolates, 37(57.8%) were MRSA. CC8-MRSA-IV-t008 presented a narrow resistome and was thepredominant clone in Bolivia, but sporadic in other countries. Noteworthy, we also foundthe LA variant of USA300 (USA300-LV) within this clone. Strikingly, CC398 was the mostfrequent CC among MSSA (45/405, 11.1%) but absent among MRSA. The most commonCC398-MSSA-t1451 (32/45) genotype was present in all countries, and all but one isolatepresented the macrolide resistance ermT gene.This study provides valuable genomicinformation of MRSA and MSSA lineages circulating in SA in the pre-COVID 19 period. Agreater genetic diversity among MSSA compared to MRSA populations is highlighted, withepidemiological associations in each country exhibiting local trends.