Abstract
Staphylococcus aureus (SA) belonging to the clonal complex 398 (CC398) took a special place within the species due to its spread throughout the world. SA CC398 is broadly separated in two subpopulations: livestock-associated methicillin-resistant SA (MRSA) and human-associated methicillin-susceptible SA (MSSA). Here, we reviewed the global epidemiology of SA CC398 in human clinical infections and focused on MSSA CC398. The last common ancestor of SA CC398 was probably a human-adapted prophage φSa3-positive MSSA CC398 strain, but the multiple transmissions between human and animal made its evolution complex. MSSA and MRSA CC398 had different geographical evolutions. Although MSSA was present in several countries all over the world, it was mainly reported in China and in France with a prevalence about 20%. MSSA CC398 was frequently implicated in severe infections such as bloodstream infections, endocarditis, and bone joint infections whereas MRSA CC398 was mainly reported in skin and soft tissue. The spread of the MSSA CC398 clone is worldwide but with a heterogeneous prevalence. The prophage φSa3 played a crucial role in the adaptation to the human niche and in the virulence of MSSA CC398. However, the biological features that allowed the recent spread of this lineage are still far from being fully understood.
Highlights
Staphylococcus aureus (SA) is a leading cause of morbidity worldwide [1]
Recent genomic analyses have demonstrated the existence of two main subpopulations within the clonal complex 398 (CC398): an ancestral human-adapted clade with the integrase group 3 prophage containing the immune evasion cluster (IEC) genes and the erythromycin-resistant gene erm(T) and an animal-associated clade associated with the absence of φSa3, and the acquisition of resistance to tetracycline and methicillin [1,3,4]
methicillin-susceptible SA (MSSA) CC398 bloodstream infection (BSI) were more frequent in patients with surgical site infection (SSI) (22.4 vs. 11.2%) and another study found that patients with MSSA CC398 infections were more likely hospitalized in the past 6 months, suggesting a nosocomial transmission (41 vs. 22%, p < 0.01) [8,17]
Summary
Staphylococcus aureus (SA) is a leading cause of morbidity worldwide [1]. During the past 20 years, livestock animals, especially pigs, have been identified as a reservoir of methicillin-resistant SA (MRSA) isolates that clustered in clonal complex 398 (CC398). Recent genomic analyses have demonstrated the existence of two main subpopulations within the CC398: an ancestral human-adapted clade with the integrase group 3 prophage (φSa3) containing the immune evasion cluster (IEC) genes and the erythromycin-resistant gene erm(T) and an animal-associated clade associated with the absence of φSa3, and the acquisition of resistance to tetracycline and methicillin [1,3,4]. Severe infections, such as bloodstream infection (BSI), endocarditis, osteomyelitis and necrotizing pneumonia or mild infections such as skin and soft-tissue infections (SSTI) were reported in both populations of CC398. We first discussed the evolution of SA CC398 and its epidemiology in clinical infections in human and focused on methicillin-susceptible SA (MSSA) CC398
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