NDM-1-producing Escherichia coli Isolated from a Case Patient's Environment
Methods: A CRE case is defined as Enterobacteriaceae non-susceptible to all third-generation cephalosporins and ≥1 carbapenem tested. CRE isolates are routinely characterized via Carba NP test and PCR for carbapenemase genes. In addition, this isolate underwent pulsed-field gel electrophoresis (PFGE), strain and plasmid identification, and whole genome sequencing. We conducted laboratory and chart reviews, case and health care provider interviews, contact screenings, site visits, and environmental testing.
Results: In November 2013, testing confirmed a NDM-1 positive, CTX-M-27-producing E. coli O25b-ST131 isolated from an outpatient shin wound culture taken from a rural Oregon county resident. Review of regional laboratory reports did not identify other NDM-positive CRE during the preceding year. The case and spouse denied international travel or visitors, and we confirmed only outpatient clinic visits during the previous year. CRE rectal swabs from the resident (N =3) and spouse (N = 1) were negative. Other possible sources such as laboratory error, food contamination, animal shedding, outpatient clinic contamination, or household water contamination were extensively reviewed. Spice (N = 14), nutritional supplement (N = 15), indoor environmental (N = 13), outdoor environmental (N = 18), and vacuum dust (N = 4) samples were collected two months after case confirmation. An NDM-1-producing E. coli isolate indistinguishable from the resident’s isolate by PFGE was extracted and cultured from a household vacuum dust sample.
Conclusion: Though CRE are associated with exposure to health care in CRE endemic regions, we could not identify any previously described sources in this low-prevalence region. Recovery of a matching strain from a vacuum environmental sample raises concern about the persistence of pathogenic strains in a household environment and an as yet unidentified origin.
G. L. Buser,
C. Pfeiffer, None
J. M. Townes, None
K. E. Morey, None
J. Rayar, None
K. K. Kutumbaka, Molecular Epidemiology Inc.: Employee, Salary
S. Han, Molecular Epidemiology Inc.: Employee, Salary
C. Nadala, Molecular Epidemiology Inc.: Employee, Salary
M. Samadpour, Molecular Epidemiology Inc.: Consultant, None
S. Weissman, None
R. Vega, None
Z. G. Beldavs, None
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