Program Schedule

Detection of Carbapenemase-Producing Aeromonas hydrophila on Perirectal Surveillance Culture

Session: Poster Abstract Session: Multidrug-resistant Organisms: Epidemiology and Prevention
Thursday, October 9, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
  • Aeromonas_IDWeek_2014_FinalDraft.pdf (1.9 MB)
  • Background: Aeromonas species are Gram-negative organisms found in aquatic environments. Antibiotic resistance genes have been detected in clinical and environmental isolates, including strains that confer carbapenem resistance. Although rarely reported, Aeromonas can acquire blaKPC genes. We describe a patient who had intestinal colonization with blaKPC-carrying Aeromonas hydrophila and our use of whole-genome sequencing (WGS) to clarify relatedness to other Aeromonas isolates and other blaKPC-carrying organisms in our hospital.

    Methods: Surveillance perirectal swabs were inoculated on carbapenem-selective, chromogenic agar. Isolates underwent MALDI-TOF identification; suspected carbapenem-resistant Enterobacteriaceae (CRE) underwent blaKPC-PCR testing. WGS was performed on Aeromonas isolates. Water and environmental samples were inoculated on MacConkey agar.

    Results: Perirectal swabs from two adult patients grew carbapenem-resistant Aeromonas spp. within a 3-week period. Both patients occupied the same room at different times, but had no other epidemiological links. MALDI-TOF could not reliably differentiate the isolates to the species level. To investigate possible nosocomial transmission, WGS was performed. WGS identified them as most closely matching A. hydrophila and A. veroni. Unexpectedly, WGS also identified the presence of a KPC-2 gene on an uncharacterized plasmid within the A. hydrophila isolate (retrospectively confirmed by blaKPC PCR); the A. veroni isolate contained no blaKPC. The plasmid was not similar to other KPC-carrying isolates identified in our hospital. Environmental cultures were negative for Aeromonas spp. or other carbapenem-resistant organisms.

    Conclusion: To our knowledge, there are few reports of KPC-carrying Aeromonas spp. in clinical settings. The source(s) of our patients’ Aeromonas isolates is unknown, but WGS confirmed that they were unrelated. As a result of these cases, the standard workup of organisms growing on CRE perirectal surveillance cultures at our institution now includes real-time colony blaKPC PCR on Aeromonas and Enterobacteriaceae. Hospital surveillance for CRE must consider that non-Enterobacteriaceae isolates may serve as hosts of these epidemiologically important carbapenemases.

    Heather Y. Hughes, MD1, Angela V. Michelin, M.P.H.2, Anna F. Lau, Ph.D.3, John Dekker, MD, PhD3, Karen Frank, MD, PhD3, Sean Conlan, PhD4, Julia Segre, PhD4, David K. Henderson, M.D., FIDSA5 and Tara N. Palmore, M.D.6, (1)National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, (2)Hospital Epidemiology Service, National Institutes of Health Clinical Center, NIH, Bethesda, MD, (3)Department of Laboratory Medicine, NIH, Bethesda, MD, (4)National Human Genome Research Institute, NIH, Bethesda, MD, (5)NIH Clinical Center, Bethesda, MD, (6)National Institutes of Health Clinical Center and National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD


    H. Y. Hughes, None

    A. V. Michelin, None

    A. F. Lau, Bruker Corp: Collaborator, Research support

    J. Dekker, Bruker Corp: Collaborator, Research support

    K. Frank, Bruker Corp: Collaborator, Research support

    S. Conlan, None

    J. Segre, None

    D. K. Henderson, None

    T. N. Palmore, None

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