A multicentre cohort study on colonization and infection with ESBL-producing Enterobacteriaceae in high-risk patients with haematological malignancies.

Background: Bloodstream infections (BSIs) caused by enterobacteria remain a leading cause of mortality in patients with chemotherapy-induced neutropenia. The rate and type of colonization and infection with ESBL-producing Enterobacteriaceae (ESBL-E) and their mode of transmission in German cancer centres is largely unknown.

Methods: We performed a prospective, observational study at five German university-based haematology departments. Participating sites screened for intestinal ESBL-E colonization within 72 h of admission, every 10 ± 2 days thereafter and before discharge. Three of the five centres performed contact isolation for patients colonized or infected with ESBL-E. Molecular characterization of resistance mechanisms and epidemiological typing of isolates by repetitive extragenic palindromic PCR (rep-PCR) and PFGE was performed to assess strain transmission between patients.

Results: Between October 2011 and December 2012, 719 hospitalizations of 497 haematological high-risk patients comprising 20,143 patient-days were analysed. Mean duration of in-hospital stay was 36.6 days (range: 2-159 days). ESBL-E were identified from screening samples (82.8% Escherichia coli and 14.6% Klebsiella pneumoniae) in 55/497 patients (11.1%; range by centre: 5.8%-23.1%). PFGE and rep-PCR revealed only a single case of potential cross-transmission among two patients colonized with K. pneumoniae. Six episodes of BSI with ESBL-E were observed. Multivariate analysis revealed previous colonization with ESBL-E as the most important risk factor for BSI with ESBL-E (OR 52.00; 95% CI 5.71-473.89).

Conclusions: Even though BSI with ESBL-E is still rare in this high-risk population, colonization rates are substantial and vary considerably between centres. In-hospital transmission of ESBL-E as assessed by molecular typing was the exception.