Bloodstream infections among carriers of carbapenem-resistant Klebsiella pneumoniae: etiology, incidence and predictors

Carriers of carbapenem-resistant Klebsiella pneumoniae (CRKP) are increasingly recognised through active surveillance in much of the world. We studied incidence, aetiology and predictors of bloodstream infections (BSI) among such carriers. Via a retrospective cohort study conducted in a tertiary care teaching hospital, we examined occurrence of BSI within 45 days of CRKP carrier detection. Three nested case-control studies were conducted to analyse parameters associated with all-cause (ALL), Gram-negative rod (GNR) and CRKP BSI. Cases and controls were compared with respect to demographics, clinical parameters and recent receipt of antibiotics. A total of 431 patients were identified as CRKP carriers (28% by clinical culture, 72% by rectal surveillance), mean age was 75.2 years. Twenty percent of the patients (n = 85) developed BSI, of them 80% (n = 68) with GNR. Of 83 GNR isolates, 58 (70%) were Enterobacteriaceae, of which 19 were CRKP and 20 were extended-spectrum β-lactamase (ESBL) producers (23% and 24% of total GNR, respectively); 29% of the GNR isolates were nonfermenters (14.5% Pseudomonas aeruginosa, 14.5% Acinetobacter baumannii). Mechanical ventilation predicted ALL BSI (p = 0.04), whereas Clostridium difficile–associated diarrhoea predicted GNR BSI (p = 0.04). Receipt of broad-spectrum antibiotics (piperacillin-tazobactam, amikacin, imipenem) was significantly associated with ALL BSI or GNR BSI. No exposure independently predicted CRKP BSI. We conclude that patients detected as CRKP carriers are at high risk for BSI within 45 days of detection, primarily with multidrug-resistant GNR. Lack of predictive factors differentiating between pathogens and associated high mortality raises once more the dilemma regarding the appropriate empiric therapy for CRKP carriers who develop severe sepsis.