284. Development and validation of a multiplex PCR assay for rapid diagnosis of ventriculostomy-related infections
Session: Poster Abstract Session: Diagnostic Microbiology; Novel Molecular Methods
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Posters
  • VRI poster IDWeek Final.pdf (529.0 kB)
  • Background:

    Diagnosis of ventriculostomy-related infections (VRIs) can be challenging and is based upon interpretation of clinical and cerebrospinal fluid (CSF) parameters. We developed and validated a multiplex MassTag polymerase chain reaction (PCR) assay for the rapid diagnosis of VRIs utilizing organism-specific primers. 

    Methods:

    A 13-plex MassTag PCR panel was developed targeting the most common pathogens causing VRIs at our institution, as identified in a retrospective review of culture-positive ventricular device (VD) CSF specimens between 2001-2006. The panel was optimized using cloned template standards and spiked samples. The level of detection ranged from 102-104 organisms per mL. The MassTag panel was evaluated on serially collected CSF specimens sent to the clinical microbiology laboratory. A retrospective review was performed to determine CSF and clinical parameters. VD patients were grouped into (1) definite VRI, (2) possible VRI, or (3) no VRI; while non-VD patients were grouped into (1) definite central nervous system (CNS) infection, (2) possible CNS infection, or (3) no CNS infection. Contamination or colonization was defined as organism detection in a patient with no VRI or no CNS infection. 

    Results:

    CSF from 128 subjects were analyzed: 49 with a VD (median age 43 years; interquartile range [IQR] 30-62 years; males 49%), and 79 without a VD (median age 45 years; IQR 21-59 years; males 49%). Among subjects with a definite VRI or CNS infection due to a pathogen on the MassTag panel, the pathogen was identified in all cases (9/9). Among subjects with a possible VRI, the MassTag panel detected >1 pathogen in 33% of samples. Among subjects with no VRI or no VD and no CNS infection, an organism, mostly gram-positive bacteria was detected in 32% and 11%, respectively, representing either contamination or VD colonization. 

    Conclusion:

    The VRI MassTag panel performed well in definite VRI and CNS infection and detected potential pathogens in possible VRI cases. However, the false positive rate with Staphylococcus and Enterococcus species necessitates the need for further confirmatory testing if these organisms are detected. Nonetheless, the negative predictive value for gram-negative bacteria suggests that empiric antibiotics can be narrowed if no gram-negative bacteria are detected.

    Claire Gordon1,2, Rafal Tokarz3, Thomas Briese, PhD3, Susan Whittier, PhD4, Jayesh Shah1 and Michael Yin, MD5, (1)Division of Infectious Diseases, Department of Medicine, Columbia University Medical Center, New York, NY, (2)Department of Medicine, University of Melbourne, Heidelberg, Australia, (3)Center for Infection and Immunity, Mailman School of Public Health, Columbia University Medical Center, New York, NY, (4)Clinical Microbiology Service, New York Presbyterian Hospital, New York, NY, (5)Columbia University, New York, NY

    Disclosures:

    C. Gordon, None

    R. Tokarz, None

    T. Briese, None

    S. Whittier, None

    J. Shah, None

    M. Yin, None

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