High level methicillin resistance correlates with reduced Staphylococcus aureus endothelial cell damage

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• 作者：Kati Seidl ; ^{kati.seidlspirig@usz.ch} ; Michè ; le Leemann ; Miguel Palheiros Marques ; Carole Rachmü ; hl ; Nadja Leimer ; Federica Andreoni ; Yvonne Achermann ; Annelies S. Zinkernagel
• 关键词：Staphylococcus aureus ; Methicillin resistance ; Virulence ; Endothelial cell damage
• 刊名：International Journal of Medical Microbiology
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：307
• 期：1
• 页码：11-20
• 全文大小：998 K
• 卷排序：307

文摘

There has been controversy about the intrinsic virulence of methicillin-resistant Staphylococcus aureus (MRSA) as compared to methicillin-susceptible S. aureus (MSSA). To address this discrepancy, the intrinsic virulence of 42 MRSA and 40 MSSA clinical isolates was assessed by testing endothelial cell (EC) damage, a surrogate marker for virulence in blood stream infections. Since these clinical isolates represent a heterogeneous group, well characterized S. aureus laboratory strains with SCCmec loss- and gain-of-function mutations were used in addition. The clinical MRSA isolates carrying typical hospital acquired SCCmec types (I, II or III) induced significantly less damage (47.8%) as compared to isolates with other SCCmec types (62.3%, p = 0.03) and MSSA isolates (64.2%, p < 0.01). There was a strong inverse correlation between high-level oxacillin resistance and low EC damage induction (R2 = 0.4464, p < 0.001). High-level oxacillin resistant strains (MIC >32 μ/ml) grew significantly slower as compared to isolates with low-level resistance (p = 0.047). The level of EC damage positively correlated with α- and δ-toxin production (p < 0.0001 and p < 0.05, respectively) but not with β-toxin production. Invasive MRSA isolates (n = 21, 56.3%) were significantly less cytotoxic as compared to invasive MSSA isolates (n = 20, 68.0%, p < 0.05). There was no difference between EC damage induced by superficial versus invasive isolates in either MRSA or MSSA strains. Our data suggest that the intrinsic virulence of MRSA is similar or even reduced as compared to MSSA strains but is linked to the level of methicillin resistance.