Detection of Carbapenemase-Producing Aeromonas hydrophila on Perirectal Surveillance Culture
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.
H. Y. Hughes,
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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