1736. Propionibacterium acnes - Time-to-positivity of Cultures from Different Clinical Sites
Session: Poster Abstract Session: Novel Diagnostics for Uncommon Bacteria
Saturday, October 10, 2015
Room: Poster Hall
Posters
  • Propionibacterium_ID_Week_2015_abdulmassih_poster_MJC_Revisions.pdf (610.5 kB)
  • Background: Infections from Propionibacterium acnes are generally uncommon. Reasons for this may be underestimation since this microbe is often not recovered in cultures until after 5 days, and often dismissal as a contaminant. The objectives of our quality improvement project were to: 1) determine time-to-positivity (TTP) of P. acnes growth and 2) identify P. acnes from clinically relevant sites in suspected infections.

    Methods: All cultures positive for P. acnes from 2010 to 2014 were retrieved through the laboratory database. Specimen sources and TTP were recorded. Electronic chart review was conducted to see which isolates were regarded as clinically relevant.

    Results: A total of 146 specimens from 121 patients were analyzed. Table (below) reveals sites of isolation and TTP. Both native tissue and prosthetic (orthopedic, cardiovascular, and CNS) infections were identified. Majority of positive cultures were from CNS, blood, and musculoskeletal sites (37.5%, 17.8%, and 16.3%, respectively). The maximum TTP from CNS and musculoskeletal cultures was 8 days. Overall, TTP ranged from 3 to 11 days (mean 5.73 +/- 1.25 days, median 6 days). Majority (86%) of the isolates were mono-microbial. In 37% (54/146) of instances, antibiotics were targeted solely against P. acnes.

    Conclusion: While we request our laboratory to hold cultures for 2 weeks for suspected P. acnes infection, limiting extension to 11 days may be sufficient. P. acnes infections are likely more varied than generally thought. Routine implementation of longer incubation periods should be considered especially in suspected cases of infection with negative cultures at day 5. Such information has implications to inform targeted, appropriate, and maximally effective antimicrobial therapy.

    Sites of Isolation

    (total: 146)

    N (%)

    TTP(range in days)

    Median(days)

    Blood

    26 (17.8)

    4-6

    5

    Central Nervous System

     

     

     

    a)      Epidural tissue

    12 (8.2)

     

    3-7

    6

    b)      Cerebrospinal fluid from Ventriculo-peritoneal shunt

    12 (8.2)

    3-7

    5.5

    c)      Craniotomy site

    29 (19.8)

    3-8

    6

    d)     Brain tissue

    1 (0.68)

    7

      -

    e)      Subdural Hematoma

    1 (0.68)

    7

      -

    Musculoskeletal

     

     

     

    a)      Native joints

    5 (3.4)

    4-7

    5

    b)      Prosthetic joints

    11 (7.5)

    5-6

    6

    c)      Vertebral spine tissue

    8 (5.4)

    5-8

    7

    Skin and Soft Tissue

    22 (15)

    3-11

    6

    Cardiac Device

    8 (5.4)

    5-10

    7

    Lymph node

    1 (0.68)

    6

      -

    Abdominal

     

     

     

    a)      Biliary Drain

    2 (1.36)

    7

    7

    b)      Peritoneal Fluid

    2 (1.36)

    6

    6

    Arteriovenous graft

    1 (0.68)

    5

      -

    Pleural Fluid

    5 (3.4)

    5-8

    6

    Rasha Abdulmassih, MD1, Jina Makadia, MD2, Zaw Min, MD, FACP3, James Como, MD4 and Nitin Bhanot, MD, MPH3, (1)Infectious Disease, Allegheny General Hospital, Pittsburgh, PA, (2)Infectious Disease, Allegheny General Hospital, Pitsburgh, PA, (3)Department of Medicine, Division of Infectious Diseases, Allegheny General Hospital, Pittsburgh, PA, (4)Allegheny General Hospital, Pittsburgh, PA

    Disclosures:

    R. Abdulmassih, None

    J. Makadia, None

    Z. Min, None

    J. Como, None

    N. Bhanot, None

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 7th with the exception of research findings presented at the IDWeek press conferences.