Short-course aminoglycosides as adjunctive empirical therapy in patients with Gram-negative bloodstream infection, a cohort study.

OBJECTIVE: Short-course aminoglycosides as adjunctive empirical therapy to ß-lactams in patients with a clinical suspicion of sepsis are used to broaden antibiotic susceptibility coverage and to enhance bacterial killing. We quantified the impact of this approach on 30-day mortality in a subset of sepsis patients with a Gram-negative bloodstream infection. METHODS: From a prospective cohort study conducted in seven hospitals in the Netherlands between June 2013 and November 2015, we selected all patients with Gram-negative bloodstream infection (GN-BSI). Short-course aminoglycoside therapy was defined as tobramycin, gentamicin or amikacin initiated within a 48-hour time window around blood-culture obtainment, and prescribed for a maximum of 2 days. The outcome of interest was 30-day all-cause mortality. Confounders were selected a priori for adjustment using a propensity score analysis with inverse probability weighting. RESULTS: A total of 626 individuals with GN-BSI who received ß-lactams were included; 156 (24.9%) also received aminoglycosides for a median of 1 day. Patients receiving aminoglycosides more often had septic shock (31/156, 19.9% versus 34/470, 7.2%) and had an eight-fold lower risk of inappropriate treatment (3/156, 1.9% versus 69/470, 14.7%). Thirty-day mortality was 17.3% (27/156) and 13.6% (64/470) for patients receiving and not receiving aminoglycosides, respectively; yielding crude and adjusted odds ratios for 30-day mortality for patients treated with aminoglycosides of 1.33 (95% CI 0.80-2.15) and 1.57 (0.84-2.93), respectively. CONCLUSIONS: Short-course adjunctive aminoglycoside treatment as part of empirical therapy with ß-lactam antibiotics in patients with GN-BSI did not result in improved outcomes, despite better antibiotic coverage of pathogens.

An International Prospective Cohort Study To Validate 2 Prediction Rules for Infections Caused by Third-generation Cephalosporin-resistant Enterobacterales.

BACKGROUND: The possibility of bloodstream infections caused by third-generation cephalosporin-resistant Enterobacterales (3GC-R-BSI) leads to a trade-off between empiric inappropriate treatment (IAT) and unnecessary carbapenem use (UCU). Accurately predicting 3GC-R-BSI could reduce IAT and UCU. We externally validate 2 previously derived prediction rules for community-onset (CO) and hospital-onset (HO) suspected bloodstream infections. METHODS: In 33 hospitals in 13 countries we prospectively enrolled 200 patients per hospital in whom blood cultures were obtained and intravenous antibiotics with coverage for Enterobacterales were empirically started. Cases were defined as 3GC-R-BSI or 3GC-R gram-negative infection (3GC-R-GNI) (analysis 2); all other outcomes served as a comparator. Model discrimination and calibration were assessed. Impact on carbapenem use was assessed at several cutoff points. RESULTS: 4650 CO infection episodes were included and the prevalence of 3GC-R-BSI was 2.1% (n = 97). IAT occurred in 69 of 97 (71.1%) 3GC-R-BSI and UCU in 398 of 4553 non-3GC-R-BSI patients (8.7%). Model calibration was good, and the AUC was .79 (95% CI, .75-.83) for 3GC-R-BSI. The prediction rule potentially reduced IAT to 62% (60/97) while keeping UCU comparable at 8.4% or could reduce UCU to 6.3% (287/4553) while keeping IAT equal. IAT and UCU in all 3GC-R-GNIs (analysis 2) improved at similar percentages. 1683 HO infection episodes were included and the prevalence of 3GC-R-BSI was 4.9% (n = 83). Here model calibration was insufficient. CONCLUSIONS: A prediction rule for CO 3GC-R infection was validated in an international cohort and could improve empirical antibiotic use. Validation of the HO rule yielded suboptimal performance.

The burden of bacteremic and non-bacteremic Gram-negative infections: A prospective multicenter cohort study in a low-resistance country.

Objectives There is a global increase in infections caused by Gram-negative bacteria. The majority of research is on bacteremic Gram-negative infections (GNI), leaving a knowledge gap on the burden of non-bacteremic GNI. Our aim is to describe characteristics and determine the burden of bacteremic and non-bacteremic GNI in hospitalized patients in the Netherlands. Methods We conducted a prospective cohort study of patients in eight hospitals with microbiologically confirmed GNI, between June 2013 and November 2015. In each hospital the first five adults meeting the eligibility criteria per week were enrolled. We estimated the national incidence and mortality of GNI by combining the cohort data with a national surveillance database for antimicrobial resistance. Results 1,954 patients with GNI were included of which 758 (39%) were bloodstream infections (BSI). 243 GNI (12%) involved multi-drug resistant pathogens. 30-day mortality rate was 11.1% (n = 217) Estimated national incidences of non-bacteremic GNI and bacteremic GNI in hospitalized adults were 74 (95% CI 58 - 89) and 86 (95% CI 72-100) per 100,000 person years, yielding estimated annual numbers of 30-day all-cause mortality deaths of 1,528 (95% CI 1,102-1,954) for bacteremic and 982 (95% CI 688 - 1,276) for non-bacteremic GNI. Conclusion GNI form a large mortality burden in a low-resistance country. A third of the associated mortality occurs after non-bacteremic GNI.

Attributable mortality of antibiotic resistance in gram-negative infections in the Netherlands: a parallel matched cohort study.

OBJECTIVES: Antibiotic resistance in Gram-negative bacteria has been associated with increased mortality. This was demonstrated mostly for third-generation cephalosporin-resistant (3GC-R) Enterobacterales bacteraemia in international studies. Yet, the burden of resistance specifically in the Netherlands and created by all types of Gram-negative infection has not been quantified. We therefore investigated the attributable mortality of antibiotic resistance in Gram-negative infections in the Netherlands. METHODS: In eight hospitals, a sample of Gram-negative infections was identified between 2013 and 2016, and separated into resistant and susceptible infection cohorts. Both cohorts were matched 1:1 to non-infected control patients on hospital, length of stay at infection onset, and age. In this parallel matched cohort set-up, 30-day mortality was compared between infected and non-infected patients. The impact of resistance was then assessed by dividing the two separate risk ratios (RRs) for mortality attributable to Gram-negative infection. RESULTS: We identified 1954 Gram-negative infections, of which 1190 (61%) involved Escherichia coli, 210 (11%) Pseudomonas aeruginosa, and 758 (39%) bacteraemia. Resistant Gram-negatives caused 243 infections (12%; 189 (78%) 3GC-R Enterobacterales, nine (4%) multidrug-resistant P. aeruginosa, no carbapenemase-producing Enterobacterales). Subsequently, we matched 1941 non-infected controls. After adjustment, point estimates for RRs comparing mortality between infections and controls were similarly higher than 1 in case of resistant infections and susceptible infections (1.42 (95% confidence interval 0.66-3.09) and 1.32 (1.06-1.65), respectively). By dividing these, the RR reflecting attributable mortality of resistance was calculated as 1.08 (0.48-2.41). CONCLUSIONS: In the Netherlands, antibiotic resistance did not increase 30-day mortality in Gram-negative infections.