252. Investigation at a Veterans Affairs Medical Center (VAMC) of Spurious Legionella Environmental Testing Results and High Lab-to-Lab Variability among Four Commercial Laboratories
Session: Poster Abstract Session: HAI: Environment and Device Cleaning
Thursday, October 27, 2016
Room: Poster Hall
  • IDSA SHEA 2016 - 252 HAI Enviornment - Legionella.pdf (841.8 kB)
  • Background: The Dept. of Veterans Affairs (VA) requires quarterly water Legionella environmental testing (LET). The Minneapolis VAMC (MVAMC) began LET in 2008. All results were neg. until 11/2015, when a new (CDC ELITE-certified) LET lab (lab1) reported Legionella spp. (Lsp) in 12/40 (30%) MVAMC samples. Healthcare-associated legionellosis (HAL) and LET reliability were investigated.

    Methods: Records of all 2015 MVAMC Lsp cases and potentially exposed patients were reviewed. In 1/2016, test and control water samples were sent to 4 contract LET labs. MVAMC water samples were collected from 5 purportedly Lsp-pos. sites. A sterilized-water neg. control and 3 pos. controls (10x dilutions of L. pnueumophila type 1 [Lp1] stock culture) were created. Each LET lab received 18 masked samples: 1 neg. control, 3 pos. controls, and 5 test samples, all in duplicate. Purported Lsp isolates underwent Matrix Assisted Laser Desorption/Ionization Time of Flight (MALDI).

    Results: During intensified LET (11/6/15-1/11/16), Lab1 ostensibly found Lsp in 77 (26%) of 296 MVAMC water samples. Mitigation and remediation was performed. No HAL was identified. The 4 LET labs' blinded test results (cfu/mL) were as shown:


    Definitions: Lp2-15, Lp serotypes 2-15; Lnp= Lsp, not pneumophila

    In 2/2016 Lab3 tested all sites Lab1 had reported as Lsp pos. including areas not remediated; all were neg. for Lsp. By MALDI, 18 purported MVAMC Lsp isolates from Lab1 were all diverse non-Lsp environmental organisms. After learning of these results, Lab1 withdrew from its LET contract. CDC and VA experts were notified

    Conclusion: A CDC-ELITE certified LET lab provided spurious results, with enormous consequent costs to MVAMC. Lab-to-lab differences were found between the remaining 3 labs, raising concern about accuracy for both pos. and neg. LET results. Healthcare systems must be cautious in deciding when to perform LET and how to interpret the results.

    Aaron S. Devries, MD, MPH, FIDSA1, Daniel Meredith, RN1, John Holter, MT (ASCP)2, Jane Harper, BSN, MS, CIC1, Connie Clabots, BS MT(ASCP)1, Ryan Van Schyndel, BS, PE3 and James R. Johnson, MD, FIDSA, FACP, FRCPE4, (1)Minneapolis Veterans Affairs Medical Center, Minneapolis, MN, (2)Clinical Microbiology Laboratory, Minneapolis Veterans Affairs Medical Center, Minneapolis, MN, (3)Minneapolis Veteran Affairs Healthcare Center, Minneapolis, MN, (4)Department of Medicine, Division of Infectious Diseases and International Medicine, University of Minnesota, Minneapolis, MN


    A. S. Devries, None

    D. Meredith, None

    J. Holter, None

    J. Harper, None

    C. Clabots, None

    R. Van Schyndel, None

    J. R. Johnson, 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.