| Description |
Staphylococcus aureus is globally a leading cause of death due to bacterial infection. The majority of invasive staphylococcal infections in Europe are caused by methicillin sensitive strains of S. aureus (MSSA). The goal of this study was to analyze clonal structure, resistance and virulence gene carriage among MSSA isolates causing infection in Czech hospitals. Methods From October to December 2023, fourteen hospitals across the Czech Republic were asked to collect MSSA clinical isolates and provide the basic demographic data. The antimicrobial susceptibility was tested by disc diffusion according to EUCAST criteria. Sequencing libraries were prepared using DNA prep and sequenced on NextSeq 2000 instrument (Illumina). Raw reads were assembled by SPAdes v 3.15.5. The presence of resistance and virulence gene as well as MLST were assessed using the bioinformatic tools available at the Centre for genomic epidemiology. The wgMLST- based minimum spanning tree was constructed using Bionumerics v8.1(Applied Maths, Belgium) using 3,897 loci. Results The tested isolates (n=143) have been causing infection of bloodstream (n=70), skin and soft tissue (n=51), respiratory tract (n=6), bone and joint (n=6), and other (n=10). Resistances to penicillin, erythromycin, clindamycin, ofloxacin, gentamicin, and tetracycline, were detected with identi f ication of corresponding genetic markers. Isolates were separated into 32 STs. Among them, ST398 (n=25), ST45 (n=20), ST5 (n=11), ST30 (n=10), and ST97 (n=10) were most frequent (Figure 2). Genes codding for Panton-Valentine leukocidin (PVL) were detected in nine (6.3%) isolates belonging to ST15, ST30, ST88, ST152, and ST1232. Gene for TSST-1 was detected in six (4.2%) isolates belonging to ST30 and ST152. Our study revealed genetic heterogeneity among MSSA, with no lineage forming more than 20% of isolates. This is in striking contrast with a highly clonal structure of MRSA circulating in Czech hospitals as revealed in our previous study. However, some MSSA lineages like ST398 and ST45 were found in multiple hospitals across the country. Resistance to antimicrobials was rare. Full and/or penicillin susceptibility were found in half of the isolates.
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