285. Detection in Blood of Dominant Carried Pneumococcal Serotype with Quantitative Serotype-Specific PCR in Adult Pneumonia
Session: Poster Abstract Session: Diagnostic Microbiology; Novel Molecular Methods
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Posters
  • 285_Detection_blood_dominant_carried_pneumococcal_serotype_Pneumonia_Albrich.png (333.4 kB)
  • Background: We recently reported a critical nasopharyngeal colonization density cut-off as a diagnostic for pneumococcal pneumonia. Here we analyzed the serotype-specific genomic pneumococcal density in blood with regards to colonization density.

    Methods: Quantitative realtime (rt) PCR for the 40 most prevalent pneumococcal serotypes was performed in the cps locus and lytAPCR was used as internal control on whole blood and nasopharyngeal washes (NW) in adults hospitalized for pneumonia in Soweto, South Africa. For serotyping 11 series of quadruplex rtPCR were performed.

    Results: Of 514 patients with pneumonia, lytA and serotyping rtPCR were positive from 82 (16.3%) and 49 (9.8%) of 502 available blood and from 226 (56.8%) and 179 (45.0%) of 398 available NW specimens. At least 2 different pneumococcal serotypes were detected in 34 (19.0%) NW and in 2 (4.1%; p=0.02) blood specimens; 3 (4.5%) serotypes in 8 NW and in 0 (0%; p=0.29) blood specimens. At least 1 identical serotype was found in 37 (9.5%) of 390 patients with both specimens available (75.5% of patients with serotype from blood). The bacterial genomic load was at least as high in the NW (0 to 104cfu/ml higher) as in blood. This difference was only significant for serotype 1 (p=0.012). There was a trend for higher pneumococcal density of NW in patients with a simultaneous positive blood specimen for serotypes considered “invasive”. If there was more than one serotype in the NW, the serotype detected in blood corresponded to the NW serotype with the higher genomic count.

    Conclusion: A quantitative serotyping PCR found at least one identical serotype in NW and blood in most cases. Our results provide important insight into pneumococcal pathogenesis. While the frequency of multiple serotype carriage is high, usually only the dominant serotype with the highest colonization density was detected in blood.

    Werner Albrich, MD, MCSR1,2, Jean-Noel Telles, PhD3, Shabir Madhi, MD, PhD4, Melina Messaoudi3, Milen Milenkov3, Peter Adrian, PhD2, Sandra Dollet3, Nadia Van Niekerk2, Glaucia Paranhos-Baccala, PhD3 and Keith Klugman, MD, PhD, FIDSA5, (1)Division of Infectious Diseases and Hospital Epidemiology, Cantonal Hospital St. Gallen, St. Gallen, Switzerland, (2)DST/NRF Vaccine Preventable Diseases, University of the Witwatersrand, Bertsham, South Africa, (3)Emerging Pathogens Laboratory, Lyon, France, (4)Respiratory and Meningeal Pathogens Research Unit, University of the Witwatersrand, Bertsham, South Africa, (5)Pneumonia, Bill & Melinda Gates Foundation, Seattle, WA

    Disclosures:

    W. Albrich, GSK: Scientific Advisor, Consulting fee
    Pfizer: Investigator, Research support
    BRAHMS Thermo Fisher: Investigator, Research support, Speaker honorarium and support to attend meetings
    bioMérieux: Investigator, Research support and support to attend meetings

    J. N. Telles, None

    S. Madhi, GSK: Investigator, Research support
    Pfizer: Consultant, Research support

    M. Messaoudi, None

    M. Milenkov, None

    P. Adrian, None

    S. Dollet, None

    N. Van Niekerk, None

    G. Paranhos-Baccala, None

    K. Klugman, None

    Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 2nd with the exception of research findings presented at the IDWeek press conferences.