A 2019 Prospective Survey of Staphylococcus aureus in South America reveals distinct populations of MRSA and MSSA: Results from the frst StaphNET-SA network study

VIELMA VALLENILLA J; DI GREGORIO S; HAIM MS; RAGO L; CAMPOS J; STAPHNET-SA CONSORTIUM; ARGIMON S; AANENSEN DM; MOLLERACH M

Bath

Congreso; 13th International Meeting on Microbial Epidemiological Markers; 2022

European Society of Clinical Microbiology and Infectious Diseases

Although WGS has been implemented as a tool for surveillance, the genomic epidemiology of S. aureus in South America (SA) has been scarcely investigated. We hereby report genomic 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 five MSSA primary isolates from bacteremia between April and October 2019. DNA was sequenced using the Illumina HiSeq platform and, following quality control, we extracted clinically relevant information [i.e., resistome, sequence types (STs), SCCmec and spa type]with public and custom-built pipelines and databases. Several hospitals were unable to submit 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 greater diversity of clonal complexes (CC) among the MSSA population (15 CCs) than the MRSA population (8 CCs). CC30, CC5, CC8 and CC398 were the most prevalent lineages and where 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 a narrow resistome, was the most frequent MRSA genotype (18/50, 36%), found in northwestern 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 the predominant clone in Bolivia, but sporadic in other countries. Noteworthy, we also found the LA variant of USA300 (USA300-LV) within this clone. Strikingly, CC398 was the most frequent CC among MSSA (45/405, 11.1%) but absent among MRSA. The most common CC398-MSSA-t1451 (32/45) genotype was present in all countries, and all but one isolate presented the macrolide resistance ermT gene.This study provides valuable genomic information of MRSA and MSSA lineages circulating in SA in the pre-COVID 19 period. A greater genetic diversity among MSSA compared to MRSA populations is highlighted, with epidemiological associations in each country exhibiting local trends.