AUTHOR=Mama Olouwafemi Mistourath , Aspiroz Carmen , Ruiz-Ripa Laura , Ceballos Sara , Iñiguez-Barrio Maria , Cercenado Emilia , Azcona José Manuel , López-Cerero Lorena , Seral Cristina , López-Calleja Ana Isabel , Belles-Belles Alba , Berdonces Pilar , Siller María , Zarazaga Myriam , Torres Carmen ,  the Study Group of clinical S. aureus CC398 

TITLE=Prevalence and Genetic Characteristics of Staphylococcus aureus CC398 Isolates From Invasive Infections in Spanish Hospitals, Focusing on the Livestock-Independent CC398-MSSA Clade

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.623108

DOI=10.3389/fmicb.2021.623108

ISSN=1664-302X

ABSTRACT=<sec><title>Background</title><p>Livestock-associated (LA)-CC398-MRSA is closely related to pigs, being unfrequently detected in human invasive infections. CC398-MSSA is emerging in human invasive infections in some countries, but genetic and epidemiological characteristics are still scarcely reported.</p></sec><sec><title>Objectives</title><p>To determine the prevalence of <italic>Staphylococcus aureus</italic> (SA) CC398, both MRSA and MSSA, among blood cultures SA isolates recovered in Spanish hospitals located in regions with different pig-farming densities (PD) and characterize the recovered isolates.</p></sec><sec><title>Methods</title><p>One thousand twenty-two SA isolates (761 MSSA, 261 MRSA) recovered from blood cultures during 6–12 months in 17 Spanish hospitals (2018–2019) were studied. CC398 lineage identification, detection of <italic>spa</italic>-types, and antibiotic resistance, virulence and human immune evasion cluster (IEC) genes were analyzed by PCR/sequencing.</p></sec><sec><title>Results</title><p>Forty-four CC398-MSSA isolates (4.3% of SA; 5.8% of MSSA) and 10 CC398-MRSA isolates (1% of SA; 3.8% of MRSA) were detected. Eleven <italic>spa</italic>-types were found among the CC398-MSSA isolates with t571 and t1451 the most frequent <italic>spa</italic>-types detected (75%). Most of CC398-MSSA isolates were Immune-Evasion-Cluster (IEC)-positive (88.6%), tetracycline-susceptible (95.5%) and erythromycin/clindamycin<sup>–inducible</sup>-resistant/<italic>erm</italic>(T)-positive (75%). No statistical significance was detected when the CC398-MSSA/MSSA rate was correlated to PD (pigs/km<sup>2</sup>) (<italic>p</italic> = 0.108). On the contrary, CC398-MRSA isolates were all IEC-negative, predominately <italic>spa</italic>-t011 (70%), and the CC398-MRSA/MRSA rate was significantly associated to PD (<italic>p</italic> &lt; 0.005).</p></sec><sec><title>Conclusion</title><p>CC398-MSSA is an emerging clade in invasive infections in Spanish hospitals. CC398-MRSA (mostly t011) and CC398-MSSA (mostly t571 and t1451) show important differences, possibly suggesting divergent steps in host-adaptation evolutionary processes. While CC398-MRSA is livestock-associated (lacking IEC-system), CC398-MSSA seems to be mostly livestock-independent, carrying human-adaptation markers.</p></sec>