RESUMO
BACKGROUND: Mupirocin resistance of methicillin-resistant Staphylococcus aureus (MRSA) was frequently reported, but heterogeneous mupirocin resistance in Staphylococcus aureus (S. aureus) was rarely recognized. This study aims to investigate the prevalence of mupirocin heteroresistance among clinical S. aureus isolates and its possible molecular mechanism. METHODS: Disk diffusion and agar dilution were used to detect the resistance features of mupirocin resistant S. aureus isolates collected form a tertiary teaching hospital in China. Population analysis profiling was used to identify the mupirocin heteroresistant isolates. Multi locus sequence typing and Staphylococcus protein A gene molecular typing were used to discriminate the genetic features of the heteroresistant isolates. Mutations in the isoleucyl tRNA synthetase (ileS) gene of S. aureus isolates were detected by gene sequencing technique. RESULTS: Mupirocin heteroresistant isolates were identified in 27.67% (83/300) strains. The dominant clones with mupirocin heteroresistance were ST239-t030 MRSAs (25.30%, 21/83). Mutations of G1762T and A637G in ileS gene could be detected in the mupirocin resistant and heteroresistant isolates. The resistance of resistant subpopulations with mutation of G1762T in ileS gene could stabilize for at least 25 passages. CONCLUSIONS: This study first revealed a higher prevalence of mupirocin heteroresistance in S. aureus. The mutation of G1762T in ileS gene is closely correlated with both mupirocin resistant and heteroresistant S. aureus isolates, supportingo ileS as a potential marker for fast identification of mupirocin resistant S. aureus.
RESUMO
OBJECTIVES: This study set out to analyze the difference of heat shock protein 27 (HSP27) and its phosphorylation in patients with lower extremity arteriosclerosis obliterans (LEASO) at different stages. This research also examined their clinical significance in this disease. METHODS: Blood samples from 60 patients with LEASO were collected and divided into two groups according to ankle-brachial index (ABI): group A (ABI ≤ 0.43) and group B (ABI > 0.43). The expression of HSP27 in each stage of Fontaine was measured by ELISA, and the difference of HSP27 concentration and ABI between the two groups was analyzed. Meanwhile, three normal femoral artery specimens (normal group) and three atherosclerotic femoral artery specimens (lesion group) were collected, and HSP27 and its Phospho-HSP27 (Ser15), Phospho-HSP27 (Ser78) and Phospho-HSP27 (Ser82) were detected by western blotting. The data of the protein level between the normal group and the lesion group was made a statistical analysis. RESULTS: HSP27 concentration in group A was (40.73 ± 15.99) ng/ml, and ABI was 0.26 ± 0.20. HSP27 concentration in group B was (66.30 ± 24.70) ng/ml, and ABI was 0.64 ± 0.20. The protein expression of HSP27 and its phosphorylation in the normal group was 0.82 ± 0.13, 0.66 ± 0.12, 0.91 ± 0.24 and 0.90 ± 0.16, respectively; the protein expression of the lesion group was 0.45 ± 0.08, 0.42 ± 0.09, 0.39 ± 0.12 and 0.58 ± 0.11. CONCLUSION: Patients with higher LEASO Fontaine stage and lower ABI had a lower HSP27 concentration. Serum HSP27 concentration was negatively correlated with the severity of LEASO, while HSP27 concentration was positively correlated with ABI value. The content of HSP27 and its phosphorylation of lesion group is significantly lower than that of normal group, which may be closely related to the occurrence and development of atherosclerosis.
