373. Surveillance for Multidrug-Resistant Gram-negative Bacilli: Use of Selective Screening Agar Increases the Rate of Detection and Decreases Cost of Screening
Session: Poster Abstract Session: HAI: Multi Drug Resistant Gram Negatives
Thursday, October 27, 2016
Room: Poster Hall
Posters
  • VACC Poster Kaur 36X60.pdf (828.4 kB)
  • Background: Infections with multidrug resistant gram negative bacilli (MDRGNB) are increasing. The roles of surveillance cultures to aid management of individual patients and to reduce spread of MDRGNB are controversial. Lack of standardized screening methods further complicates decision making. Objective was to compare traditional screening method [MacConkey (MAC) agar] vs selective screening method {VACC [vancomycin, amphotericin B, ceftazidime (³2_g/ml), clindamycin] agar, Thermo Fisher Scientific} to detect MDRGNB in surveillance cultures.

    Methods: Study was performed at clinical microbiology laboratory of a tertiary care childrenÕs hospital between Dec Õ13- Feb Ô14 & Oct Ô15-Dec Ô15. Surveillance cultures for MDRGNB were performed on high-risk patients (pts) according to hospital policy. Individual swabs of nares, axilla and rectum were obtained. MDRGNB include (i) extended spectrum _-lactamase (ESBL) production, (ii) carbapenem resistance, and (iii) high-level resistance to cephalosporins & cephamycins (HLCR), likely to represent AmpC-_-lactamase production. Traditional and selective screening methods start with inoculation onto MAC agar and VACC agar, resp, followed by Vitek2 identification (ID) and antimicrobial susceptibility testing (AST) of isolates for MDRGNB confirmation.

    Results: 180 swabs from 60 pts were screened by parallel inoculation on MAC & VACC agars. 28 MDRGNB were detected in 20 pts. Majority were HLCR. (Fig 1). E. cloacae (54%) was predominant MDRGNB. (Fig 2). MAC agar detected 14 MDRGNB (all 14 detected with VACC agar also). VACC agar detected 14 additional MDRGNB (in 11 additional patients) that were missed with MAC agar. Selective screening method was less costly. (Table 1).

    Conclusion: Use of a selective screening medium increased rate of detection of MDRGNB by 50% and decreased cost of screening.

     

    Table 1. Cost of Screening Methods

     

    Traditional

    Selective

    Screening agar (cost/plate)

    $0.21 (MAC)

    $1.80 (VACC)

    MDRGNB confirmation

    (Vitek2 ID & AST)  (cost/test)

    $6.00

    $6.00

    Swabs screened

    n=180

    n=180

    Cost for swabs screened

    $37.80 (=180 x $0.21)

    $324 (=180 x $1.80)

    Isolates on screening agar

    n=116

    n=43

    Cost for MDRGNB confirmation

    $696 (=116 x $6.00)

    $258 (=43 x $6.00)

    Total cost

    $733.88

    $582

    MDRGNB detected

    n=14

    n=28

     

    Ishminder Kaur, M.D.1, Jennifer Vodzak, MD1, Kaushik Patel, MT2, Sarah S. Long, MD3, Jane M. Gould, MD4 and Alan T. Evangelista, PhD5, (1)Infectious Diseases, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA, (2)Microbiology, Virology and Molecular Diagnostics, St. Christopher's Hospital for Children, Philadelphia, PA, (3)St. Christopher's Hospital for Children, Philadelphia, PA, (4)Infectious Diseases and Infection Prevention, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA, (5)Microbiology, Virology and Molecular Diagnostics, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA

    Disclosures:

    I. Kaur, None

    J. Vodzak, None

    K. Patel, None

    S. S. Long, None

    J. M. Gould, None

    A. T. Evangelista, None

    Findings in the abstracts are embargoed until 12:01 a.m. CDT, Wednesday Oct. 26th with the exception of research findings presented at the IDWeek press conferences.