Background The increasing incidence of carbapenem-resistant Klebsiella pneumoniae (CR-KP) has become a significant problem and treatment of infections caused by these pathogens is a major challenge for clinicians.

Purpose To describe infections caused by CR-KP in the setting of a single tertiary Spanish hospital outbreak between June 2012 and February 2013.

Material and methods Eighty-one patients with confirmed KPC-producing isolates were included. Demographic and clinical records, antibiotic use and patient outcomes were collected retrospectively.

Results Eighty-one patients with confirmed CR-KP-producing isolates were included. Post-antibiogram treatment data were collected from 69 patients. The most used antibiotics were tigecycline (n = 44, 63.8%), gentamicin (n = 36, 52.2%), meropenem (n = 13, 18.8%), fosfomycin (n = 11, 15.9%) and colistin (n = 8, 11.6%). In 28 patients (40.6%) the regimen consisted of a single drug. Most patients (n = 41, 59.4%) received ≥2 drugs against the CR-KP isolate. The most common combination was tigecycline plus gentamicin, which was used in a total of 23 cases, alone (n = 19), or with a third drug (n = 4).

The most active agent against CR-KP was tigecycline (72.8% susceptibility). Resistance rates to gentamicin, fosfomycin and colistin were 64.2%, 82.7% and 93.8%, respectively.

The mean initial dose of gentamicin was 4.1 ± 1.4 mg/kg/day with a mean Cmax = 10.7 ± 5.6 mcg/ml and mean Cmin = 0.9 ± 1.3 mcg/ml. The pharmacokinetic monitoring of gentamicin allowed the mean daily dose to be increased to 5.5 ± 1.2 mg/kg reaching a mean Cmax = 16.5 ± 2.7 mcg/ml and mean Cmin = 0.6 ± 0.4 mcg/ml.

We recorded a clinical cure or improvement in 44 patients (54.3%) and microbiological cure in 14 patients (17.3%). The overall mortality of the 81 patients was 27.2%, but just 13.6% of deaths were considered attributable to infection.

Conclusion To our knowledge this is the largest reported series of infections caused by CR-KP in the setting of a single-centre outbreak with such high levels of resistance and provides further input on the clinical management of this type of infection.

References and/or Acknowledgements No conflict of interest.