Combination Therapy with Aminoglycoside in Bacteremiasdue to ESBL-Producing Enterobacteriaceae in ICU

Antibiotic Prescriptions in Critically Ill Patients with Bloodstream Infection Due to ESBL-Producing Enterobacteriaceae: Compliance with the French Guidelines for the Treatment of Infections with Third-Generation Cephalosporin-Resistant Enterobacteriaceae-A Multicentric Retrospective Cohort Study

National and international guidelines were recently published regarding the treatment of Enterobacteriaceae resistant to third-generation cephalosporins infections. We aimed to assess the implementation of the French guidelines in critically ill patients suffering from extended-spectrum β-lactamase-producing Enterobacteriaceae bloodstream infection (ESBL-E BSI). We conducted a retrospective observational cohort study in the ICU of three French hospitals. Patients treated between 2018 and 2022 for ESBL-E BSI were included. The primary assessment criterion was the proportion of adequate empirical carbapenem prescriptions, defined as prescriptions consistent with the French guidelines. Among the 185 included patients, 175 received an empirical anti-biotherapy within 24 h of ESBL-E BSI onset, with a carbapenem for 100 of them. The proportion of carbapenem prescriptions consistent with the guidelines was 81%. Inconsistent prescriptions were due to a lack of prescriptions of a carbapenem, while it was recommended in 25% of cases. The only factor independently associated with adequate empirical carbapenem prescription was ESBL-E colonization (OR: 107.921 [9.303-1251.910], p = 0.0002). The initial empirical anti-biotherapy was found to be appropriate in 83/98 patients (85%) receiving anti-biotherapy in line with the guidelines and in 56/77 (73%) patients receiving inadequate anti-biotherapy (p = 0.06). Our results illustrate the willingness of intensivists to spare carbapenems. Promoting implementation of the guidelines could improve the proportion of initial appropriate anti-biotherapy in critically ill patients with ESBL-E BSI.

Carbapenem-sparing beta-lactam/beta-lactamase inhibitors versus carbapenems for bloodstream infections caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae: a systematic review and meta-analysis

OBJECTIVES

Bloodstream infections (BSIs) caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) have become a worldwide public health threat, and beta-lactam/beta-lactamase inhibitor combinations (BLBLIs) are considered as one reliable carbapenem-sparing antibiotic. However, it is still controversial whether BLBLIs are truly noninferior to carbapenems. Therefore, we conducted this meta-analysis to compare the efficacy of BLBLIs with carbapenems for ESBL-PE BSIs.

METHODS

A systematic search of PubMed, Cochrane Library, and Embase was conducted until December 2021 to enroll studies comparing BLBLIs with carbapenems for ESBL-PE BSIs. A subgroup analysis was performed based on the choice of therapy (empirical, definitive, and mixed therapy). The protocol was registered in the International Prospective Register of Systematic Reviews (#CRD42022316011).

RESULTS

A total of 2786 patients from one randomized clinical trial and 25 cohorts were included. There was no statistically significant difference between BLBLIs and carbapenems groups in therapeutical response (odds ratio [OR] = 1.19, P = 0.45) and mortality (OR = 1.06, P = 0.68). Furthermore, although the statistical difference was also not found in the subgroup analysis, BLBLIs performed better in definitive therapy than empirical therapy than carbapenems, with a numerically higher therapeutical response (OR = 1.42 vs 0.89) and a mildly lower mortality (OR = 0.85 vs 1.14).

CONCLUSION

BLBLIs were noninferior to carbapenems for ESBL-PE BSIs, especially in definitive therapy. BLBLIs may be a valid alternative to spare the use of carbapenems.

Pharmacodynamics of Piperacillin-Tazobactam/Amikacin Combination versus Meropenem against Extended-Spectrum β-Lactamase-Producing Escherichia coli in a Hollow Fiber Infection Model

Carbapenems are recommended for the treatment of urosepsis caused by extended-spectrum β-lactamase (ESBL)-producing, multidrug-resistant Escherichia coli; however, due to selection of carbapenem resistance, there is an increasing interest in alternative treatment regimens including the use of β-lactam-aminoglycoside combinations. We compared the pharmacodynamic activity of piperacillin-tazobactam and amikacin as mono and combination therapy versus meropenem monotherapy against extended-spectrum β-lactamase (ESBL)-producing, piperacillin-tazobactam resistant E. coli using a dynamic hollow fiber infection model (HFIM) over 7 days. Broth-microdilution was performed to determine the MIC of E. coli isolates. Whole genome sequencing was conducted. Four E. coli isolates were tested in HFIM with an initial inoculum of ~107 CFU/mL. Dosing regimens tested were piperacillin-tazobactam 4.5 g, 6-hourly, plus amikacin 30 mg/kg, 24-hourly, as combination therapy, and piperacillin-tazobactam 4.5 g, 6-hourly, amikacin 30 mg/kg, 24-hourly, and meropenem 1 g, 8-hourly, each as monotherapy. We observed that piperacillin-tazobactam and amikacin monotherapy demonstrated initial rapid bacterial killing but then led to amplification of resistant subpopulations. The piperacillin-tazobactam/amikacin combination and meropenem experiments both attained a rapid bacterial killing (~4-5 log10) within 24 h and did not result in any emergence of resistant subpopulations. Genome sequencing demonstrated that all ESBL-producing E. coli clinical isolates carried multiple antibiotic resistance genes including blaCTX-M-15, blaOXA-1, blaEC, blaTEM-1, and aac(6')-Ib-cr. These results suggest that the combination of piperacillin-tazobactam/amikacin may have a potential role as a carbapenem-sparing regimen, which should be tested in future urosepsis clinical trials.

Clinical Pharmacokinetics of Gentamicin in Various Patient Populations and Consequences for Optimal Dosing for Gram-Negative Infections: An Updated Review

Gentamicin is an aminoglycoside antibiotic with a small therapeutic window that is currently used primarily as part of short-term empirical combination therapy. Gentamicin dosing schemes still need refinement, especially for subpopulations where pharmacokinetics can differ from pharmacokinetics in the general adult population: obese patients, critically ill patients, paediatric patients, neonates, elderly patients and patients on dialysis. This review summarizes the clinical pharmacokinetics of gentamicin in these patient populations and the consequences for optimal dosing of gentamicin for infections caused by Gram-negative bacteria, highlighting new insights from the last 10 years. In this period, several new population pharmacokinetic studies have focused on these subpopulations, providing insights into the typical values of the most relevant pharmacokinetic parameters, the variability of these parameters and possible explanations for this variability, although unexplained variability often remains high. Both dosing schemes and pharmacokinetic/pharmacodynamic (PK/PD) targets varied widely between these studies. A gentamicin starting dose of 7 mg/kg based on total body weight (or on adjusted body weight in obese patients) appears to be the optimal strategy for increasing the probability of target attainment (PTA) after the first administration for the most commonly used PK/PD targets in adults and children older than 1 month, including critically ill patients. However, evidence that increasing the PTA results in higher efficacy is lacking; no studies were identified that show a correlation between estimated or predicted PK/PD target attainment and clinical success. Although it is unclear if performing therapeutic drug monitoring (TDM) for optimization of the PTA is of clinical value, it is recommended in patients with highly variable pharmacokinetics, including patients from all subpopulations that are critically ill (such as elderly, children and neonates) and patients on intermittent haemodialysis. In addition, TDM for optimization of the dosing interval, targeting a trough concentration of at least < 2 mg/L but preferably < 0.5–1 mg/L, has proven to reduce nephrotoxicity and is therefore recommended in all patients receiving more than one dose of gentamicin. The usefulness of the daily area under the plasma concentration–time curve for predicting nephrotoxicity should be further investigated. Additionally, more research is needed on the optimal PK/PD targets for efficacy in the clinical situations in which gentamicin is currently used, that is, as monotherapy for urinary tract infections or as part of short-term combination therapy.

Appropriateness of empirical antibiotic therapy and added value of adjunctive gentamicin in patients with septic shock: a prospective cohort study in the ICU

OBJECTIVES

To determine the appropriateness of empiric antibiotic therapy and the possible benefit of adding short-course gentamicin in septic shock patients with abdominal, urogenital, or an unknown focus. Secondary objectives were the effect of gentamicin addition on shock reversal and the incidence of a fungal infection.

METHODS

Microbiological cultures, antibiotic treatment, and antibiotic resistance patterns of the cultured microorganisms were recorded during the first 5 days of admission. Inappropriate antibiotic therapy was defined as a prescription within the first 24 h that did not cover cultured bacteria during the first 5 days of admission and was determined in the overall group and in patients receiving adjunctive gentamicin (combination therapy) versus patients receiving monotherapy. Binomial logistic regression analysis was used to investigate the association of gentamicin addition with shock reversal.

RESULTS

Of 203 septic shock patients, with abdominal (n = 143), urogenital (n = 27) or unknown (n = 33) focus, 115 patients received monotherapy, and 88 patients received combination therapy. Inappropriate therapy occurred in 29 patients (14%), more frequently in monotherapy (17%) versus combination therapy (10%). Combination therapy would have been effective in 55% of patients with inappropriate monotherapy. We found no association between gentamicin addition and shock reversal (p = .223). A fungal infection was present in 22 patients (11%).

CONCLUSION

Inappropriate empirical antibiotic therapy occurs in 17% of septic shock patients receiving monotherapy. In 55% of these patients, additional gentamicin would have resulted in appropriate therapy. When clinical course is unfavourable, lowering the threshold for administering adjunctive aminoglycoside and antifungal therapy should be considered.