Abstract
Objectives Staphylococcus aureus or methicillin-resistant Staphylococcus aureus (MRSA) has been an important pathogen causing bloodstream infections. Our study aimed to investigate the epidemiological and genetic diversity of clinical S. aureus isolates from patients with bloodstream infection in four hospitals of Shanghai from 2009 to 2011.MethodsA collection of S. aureus isolates causing bloodstream infection from four hospitals in the central part of Shanghai was carried out. Antimicrobial susceptibility testings of collected isolates were performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines, and spa-type, multi-locus sequence typing, agr type and toxin gene profiling were performed to explore the molecular diversity. Moreover, MRSA strains were also characterized by Staphylococcal cassette chromosome mec (SCCmec) typing.ResultsThe drugs such as linezolid, teicoplanin and vancomycin were efficacious for treating S. aureus including MRSA bloodstream infection. Methicillin-sensitive Staphylococcus aureus (MSSA) strains displayed distinct diversity in molecular characterization and toxin genes, and three virulent MSSA strains encoding at least five toxins were detected. Five community-associated MRSA (CA-MRSA) strains were found, but the majority (88.7%) of MRSA strains belonged to two epidemic clones (ST239-MRSA- III and ST5-MRSA- II) with different toxin gene profiles among patients with bloodstream infection.ConclusionsHealthcare-associated MRSA (HA-MRSA) strains were still the main pathogen causing bloodstream infections in spite of the emergence of CA-MRSA strains in hospital setting.
Highlights
Staphylococcus aureus or methicillin-resistant Staphylococcus aureus (MRSA) has been a major cause of nosocomial infections [1], and during the last two decades it increasingly causes infections in the community [2]
It is known that various MRSA clones circulate in different countries or regions, and that they differ in antimicrobial resistance pattern, molecular characterization and virulence factors [7]
A total of 108 non-duplicated S. aureus isolates from 108 patients with bloodstream infection were enrolled in this study, including 54 from Hospital A, 12 from Hospital B, 26 from Hospital C, 16 from Hospital D
Summary
Staphylococcus aureus or methicillin-resistant Staphylococcus aureus (MRSA) has been a major cause of nosocomial infections [1], and during the last two decades it increasingly causes infections in the community [2]. Patients with invasive MRSA infections such as bloodstream infection (BSI) show a high mortality [5,6]. Molecular epidemiology, antibiotic resistance pattern, virulence factors and clinical information of S. aureus bloodstream infection should be provided to clinicians or healthcare workers to improve prevention, control and treatment. It is known that various MRSA clones circulate in different countries or regions, and that they differ in antimicrobial resistance pattern, molecular characterization and virulence factors [7]. A thorough knowledge of S. aureus bloodstream infection will contribute to the clinical practice and outcome of patients
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