Rapid and quantitative detection of blood Serratia marcescens by a real-time PCR assay: Its clinical application and evaluation in a mouse infection model

Authors

  • Akira Iwaya,

    1. Division of Bacteriology, Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951–8510, Japan
    2. Department of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951–8510, Japan
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  • Saori Nakagawa,

    1. Division of Bacteriology, Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951–8510, Japan
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  • Nobuhiro Iwakura,

    1. Division of Bacteriology, Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951–8510, Japan
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  • Ikue Taneike,

    1. Division of Bacteriology, Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951–8510, Japan
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  • Mizuki Kurihara,

    1. Division of Bacteriology, Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951–8510, Japan
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  • Tomoko Kuwano,

    1. Division of Bacteriology, Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951–8510, Japan
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  • Fumio Gondaira,

    1. Division of Bacteriology, Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951–8510, Japan
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  • Miyoko Endo,

    1. Tokyo Metropolitan Research Laboratory of Public Health, Tokyo, Japan
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  • Katsuyoshi Hatakeyama,

    1. Department of Digestive and General Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951–8510, Japan
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  • Tatsuo Yamamoto

    Corresponding author
    1. Division of Bacteriology, Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951–8510, Japan
      *Corresponding author. Tel.: +81 25 227 2050; fax: +81 25 227 0762., E-mail address: tatsuoy@med.niigata-u.ac.jp
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  • Edited by P.H. Williams

*Corresponding author. Tel.: +81 25 227 2050; fax: +81 25 227 0762., E-mail address: tatsuoy@med.niigata-u.ac.jp

Abstract

Large-scale nosocomial outbreaks of Serratia marcescens septicaemia in Japan have had a fatality rate of 20–60% within 48 h. As a countermeasure, a real-time PCR assay was constructed for the rapid diagnosis of S. marcescens septicaemia. This assay indeed detected S. marcescens in clinical blood specimens (at ca. 102 CFU ml−1), at a frequency of 0.5% in suspected cases of septicaemia. In mice, the assay provided estimates of blood S. marcescens levels at various infectious stages: namely, 107 to 108 CFU ml−1 at a fatal stage (resulting in 100% death), 104–105 CFU ml−1 at a moderately fatal stage (resulting in 50% or more death), and <103 CFU ml−1 at a mild stage (resulting in 100% survival), consistent with actual CFU measurements. Blood bacterial levels could be an important clinical marker that reflects the severity of septicaemia. The simultaneous detection of S. marcescens and the carbapenem resistance gene was also demonstrated.

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