Proof­of­concept study to quantify changes in intestinal loads of KPC-producing Klebsiella pneumoniae in colonised patients following selective digestive decontamination with oral gentamicin.

OBJECTIVES: To monitor quantitatively the extent of intestinal colonisation by KPC-producing Klebsiella pneumoniae (KPC-Kp) in colonised 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 the 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 and 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 curve 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 1, 3, 6 and 12 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% vs. 12.5%, P = 0.119) and deaths (71.4% vs. 0%, P = 0.007) were higher among patients with high baseline RLKPC. CONCLUSION: Following SDD, a rapid reduction on intestinal load is observed when the colonising KPC-Kp isolate is susceptible to gentamicin; however, persistent eradication at the end of SDD is low. Intestinal carriage of KPC-Kp persists after three months in about one third of patients.

Prognostic Significance of the Relative Load of KPC-Producing Klebsiella pneumoniae within the Intestinal Microbiota in a Prospective Cohort of Colonized Patients.

Increased relative bacterial load of KPC-producing Klebsiella pneumoniae (KPC-KP) within the intestinal microbiota has been associated with KPC-KP bacteremia. Prospective observational study of KPC-KP adult carriers with a hospital admission at recruitment or within the three prior months (January 2018 to February 2019). A qPCR-based assay was developed to measure the relative load of KPC-KP in rectal swabs (RLKPC, proportion of blaKPC relative to 16S rRNA gene copy number). We generated Fine-Gray competing risk and Cox regression models for survival analysis of all-site KPC-KP infection and all-cause mortality, respectively, at 90 and 30 days. The median RLKPC at baseline among 80 KPC-KP adult carriers was 0.28% (range 0.001% to 2.70%). Giannella Risk Score (GRS) was independently associated with 90-day and 30-day all-site infection (adjusted subdistribution hazard ratio [aHR] 1.23, 95% CI = 1.15 to 1.32, P < 0.001). RLKPC (adjusted hazard ratio [aHR] 1.04, 95% CI = 1.01 to 1.07, P = 0.008) and age (aHR 1.05, 95% CI = 1.01 to 1.10, P = 0.008) were independent predictors of 90-day all-cause mortality in a Cox model stratified by length of hospital stay (LOHS) ≥20 days. An adjusted Cox model for 30-day all-cause mortality, stratified by LOHS ≥14 days, included RLKPC (aHR 1.03, 95% CI = 1.00 to 1.06, P = 0.027), age (aHR 1.10, 95% CI = 1.03 to 1.18, P = 0.004), and severe KPC-KP infection (INCREMENT-CPE score >7, aHR 2.96, 95% CI = 0.97 to 9.07, P = 0.057). KPC-KP relative intestinal load was independently associated with all-cause mortality in our clinical setting, after adjusting for age and severe KPC-KP infection. Our study confirms the utility of GRS to predict infection risk in patients colonized by KPC-KP. IMPORTANCE The rapid dissemination of carbapenemase-producing Enterobacterales represents a global public health threat. Increased relative load of KPC-producing Klebsiella pneumoniae (KPC-KP) within the intestinal microbiota has been associated with an increased risk of bloodstream infection by KPC-KP. We developed a qPCR assay for quantification of the relative KPC-KP intestinal load (RLKPC) in 80 colonized patients and examined its association with subsequent all-site KPC-KP infection and all-cause mortality within 90 days. Giannella Risk Score, which predicts infection risk in colonized patients, was independently associated with the development of all-site KPC-KP infection. RLKPC was not associated with all-site KPC-KP infection, possibly reflecting the large heterogeneity in patient clinical conditions and infection types. RLKPC was an independent predictor of all-cause mortality within 90 and 30 days in our clinical setting. We hypothesize that KPC-KP load may behave as a surrogate marker for the severity of the patient's clinical condition.