INVESTIGADORES
MOLLERACH Marta Eugenia
congresos y reuniones científicas
Título:
Comparative genomics of hetero and homogeneous methicillin resistant Staphylococcus aureus strains
Autor/es:
VIELMA VALLENILLA J; FERNÁNDEZ S; CUIROLO A; FERNÁNDEZ CANIGGIA L; RAGO L; HAIM MS; DI GREGORIO S; MOLLERACH M
Reunión:
Congreso; Reunión Anual de Sociedades de Biociencias SAIC SAI SAFIS 2020; 2020
Institución organizadora:
SAIC SAI SAFIS
Resumen:
S. aureus is a major human pathogen. Misidentification of heterogeneous Methicillin Resistant S. aureus isolates (HeMRSA) may lead to inappropriate clinical treatments. We study a clinical mecA positive HeMRSA strain (SA454He), susceptible to betalactams and two in vitro derivatives obtained from SA454He under oxacillin and rifampin selective pressure (SA454Ho and SA454RIF) expressing an homogeneously MRSA (hoMRSA) phenotype. The aim of this study is to unravel genetic changes associated with the phenotypes observed for the aforementioned strains using whole-genome sequencing (WGS). WGS was conducted on genomic DNA using Illumina MiSeq. Quality control (QC) of reads was carried out with FastQC and Kraken, the novo assembly with SPAdes, assemblies´ QC with QUAST and annotated with Prokka. ARIBA with different databases was used for the analysis of antimicrobial resistance determinants, plasmids, and MLST. Snippy was used to determine single nucleotide polymorphisms (SNPs) and INDELs against S. aureus MW2 and SA454He as reference sequences. All strains belong to ST1, harbour mecA on SCCmecV and carry an average of 1576 SNPs each when compared to MW2. The blaZ operon was detected in SA454He, in a rep5a plasmid of approximately 22 kb, with a truncated blaR1 gene. This operon was absent in SA454Ho and SA454RIF genomes. SA454RIF and SA454Ho only carried one SNP each in rpoB, when compared with SA454He (Ser486Leu and Ala576Val, respectively). Both the loss of blaZ operon and rpoB mutations might be related to the hoMRSA phenotype in mutant strains, which could possibly be selected in clinical settings. We highlight the potential use of WGS to identify genetic mechanisms of heteroresistance in routine bacteriology laboratories and to detect these types of strains which represent a diagnostic and epidemiological challenge.