LAUSR

OBJECTIVES To monitor quantitatively the extent of intestinal colonization by KPC-producing Klebsiella pneumoniae (KPC-Kp) in colonized patients who receive selective digestive decontamination (SDD) with oral gentamicin. METHODS We developed a real-time quantitative PCR (qPCR) method for determination of the relative load of blaKPC (RLKPC) within the gut microbiota. Clinical validation was performed using a culture method as gold-standard and receiver-operating-curve (ROC) analysis. Fifteen patients were observationally and prospectively followed for one year. Clinical, microbiological variables and rectal swab samples were collected at 0 (baseline), 14, 30 days and monthly thereafter. RESULTS Clinical validation performed on 111 rectal swab samples demonstrated that the PCR method detected 17% more positives than the culture method. ROC analysis documented excellent agreement between both methods (area under the curve, 0.96; 95% confidence interval 0.93-0.99). The RLKPC decreased in 6/15(40%) and 7/12(58.3%) patients on days 14 and 30, respectively. Persistent eradication was observed in 2/12(16.7%), 3/9(33.3%), 4/8(50%) and 7/8(87.5%) patients at one, three, six and twelve months, respectively, with a median time of 150 days (range 30-270) to persistent eradication. Gentamicin-resistant KPC-Kp isolates were identified in 4/15(26.7%) patients. The rates of infections (57.1% versus 12.5%, p=0.119) and deaths (71.4% versus 0%, p=0.007) were higher among patients with high baseline RLKPC. CONCLUSIONS Following SDD, a rapid reduction on intestinal load is observed when the colonizing KPC-Kp isolate is susceptibile to gentamicin, however persitent eradication at the end of SDD is low. Intestinal carriage of KPC-Kp persists after three months in about one third of patients.