Background: The natural history of carbapenem-resistant Enterobacteriaceae (CRE) carriage and the timing and procedures required to safely presume a CRE-free status are unclear.
Objective: To determine risk factors for recurrence of CRE among presumed CRE-free patients.
Methods: Case-control study including CRE carriers in whom CRE carriage presumably ended, following at least 2 negative screening samples on separate days. Recurrence of CRE carriage was identified through clinical samples and repeated rectal screening in subsequent admissions to any healthcare facility in Israel. Patients with CRE recurrence (cases) were compared with recurrence-free patients (controls). The duration of follow-up was 1 year for all surviving patients.
Results: Included were 276 prior CRE carriers who were declared CRE-free. Thirty-six persons (13%) experienced recurrence of CRE carriage within a year after presumed eradication. Factors significantly associated with CRE recurrence on multivariable analysis were the time in months between the last positive CRE sample and presumed eradication (odds ratio, 0.94 [95% CI, 0.89-0.99] per month), presence of foreign bodies at the time of presumed eradication (4.6 [1.64-12.85]), and recurrent admissions to healthcare facilities during follow-up (3.15 [1.05-9.47]). The rate of CRE recurrence was 25% (11/44) when the carrier status was presumed to be eradicated 6 months after the last known CRE-positive sample, compared with 7.5% (10/134) if presumed to be eradicated after 1 year.
Conclusions: We suggest that the CRE-carrier status be maintained for at least 1 year following the last positive sample. Screening of all prior CRE carriers regardless of current carriage status is advised.