Duration of antimicrobial therapy for Gram-negative infections

Navigating the Current Treatment Landscape of Metallo-β-Lactamase-Producing Gram-Negative Infections: What are the Limitations?

The spread of carbapenemase-producing gram-negative pathogens, especially those producing metallo-β-lactamases (MBLs), has become a major health concern. MBLs are molecularly the most diverse carbapenemases, produced by a wide spectrum of gram-negative organisms, including the Enterobacterales, Pseudomonas spp., Acinetobacter baumannii, and Stenotrophomonas maltophilia, and can hydrolyze most β-lactams using metal ion cofactors in their active sites. Over the years, the prevalence of MBL-carrying isolates has increased globally, particularly in Asia. MBL infections are associated with adverse clinical outcomes including longer length of hospital stay, ICU admission, and increased mortality across the globe. The optimal treatment for MBL infections not only depends on the pathogen but also on the underlying resistance mechanisms. Currently, there are only few drugs or drug combinations that can efficiently offset MBL-mediated resistance, which makes the treatment of MBL infections challenging. The rising concern of MBLs along with the limited treatment options has led to the need and development of drugs that are specifically targeted towards MBLs. This review discusses the prevalence of MBLs, their clinical impact, and the current treatment options for MBL infections and their limitations. Furthermore, this review will discuss agents currently in the pipeline for treatment of MBL infections.

Is there evidence on the optimal duration of aminoglycoside therapy in β-lactam/aminoglycoside combination regimens used for the treatment of gram-negative bacterial infections? A systematic review

BACKGROUND

The optimal duration of therapy of aminoglycosides in combination regimens is expected to be different from that of monotherapy regimens, and shorter durations could help minimize toxicity without compromising efficacy. The aim of this review was to assess the evidence for the optimal duration of aminoglycosides in β-lactam/aminoglycoside combinations used for the treatment of Gram-negative bacterial infections.

MATERIALS AND METHODS

PubMed, Cochrane, Embase, Scopus, Web of Science, and CINHAL databases were searched. Covidence software was used for article screening and management. Studies were included if they clearly reported the duration of therapy of aminoglycosides in β-lactam/aminoglycoside combinations used against Gram-negative bacteria. The protocol is registered with PROSPERO (CRD42023392709).

RESULTS

A total of 45 β-lactam/aminoglycoside combination courses from 32 articles were evaluated. The duration of therapy of aminoglycosides in combinations regimens ranged from 1 to 14 days, varying with the type of infection treated. In half (51.1%; (23/45) of the combinations, aminoglycosides were administered for a duration ranging from 6 to 9 days. In 26.7% (12/45) of the combinations, the duration of aminoglycoside therapy was ≤ 5 days. In the remaining 22.2% (10/45) of these combinations, the aminoglycosides were administered for a duration of ≥ 10 days. Aminoglycosides were administered for a longer duration of 7-14 days in 12 (75%) of the 16 combination courses that induced toxicity.

CONCLUSIONS

Long duration of aminoglycoside use is associated with increased risk of toxicity. However, there is a lack of evidence on defining an optimal duration of aminoglycoside therapy in β-lactam/aminoglycoside combination regimens that ensures clinical efficacy outcomes whilst minimizing toxicity outcomes.

Use of Antimicrobials for Bloodstream Infections in the Intensive Care Unit, a Clinically Oriented Review

Bloodstream infections (BSIs) in critically ill patients are associated with significant mortality. For patients with septic shock, antibiotics should be administered within the hour. Probabilistic treatment should be targeted to the most likely pathogens, considering the source and risk factors for bacterial resistance including local epidemiology. Source control is a critical component of the management. Sending blood cultures (BCs) and other specimens before antibiotic administration, without delaying them, is key to microbiological diagnosis and subsequent opportunities for antimicrobial stewardship. Molecular rapid diagnostic testing may provide faster identification of pathogens and specific resistance patterns from the initial positive BC. Results allow for antibiotic optimisation, targeting the causative pathogen with escalation or de-escalation as required. Through this clinically oriented narrative review, we provide expert commentary for empirical and targeted antibiotic choice, including a review of the evidence and recommendations for the treatments of extended-spectrum β-lactamase-producing, AmpC-hyperproducing and carbapenem-resistant Enterobacterales; carbapenem-resistant Acinetobacter baumannii; and Staphylococcus aureus. In order to improve clinical outcomes, dosing recommendations and pharmacokinetics/pharmacodynamics specific to ICU patients must be followed, alongside therapeutic drug monitoring.

Treatment of Severe Infections Due to Metallo-Betalactamases Enterobacterales in Critically Ill Patients

Metallo-beta-lactamases-producing (MBL) Enterobacterales is a growing problem worldwide. The optimization of antibiotic therapy is challenging. The pivotal available therapeutic options are either the combination of ceftazidime/avibactam and aztreonam or cefiderocol. Colistin, fosfomycin, tetracyclines and aminoglycosides are also frequently effective in vitro, but are associated with less bactericidal activity or more toxicity. Prior to the availability of antibiotic susceptibility testing, severe infections should be treated with a combination therapy. A careful optimization of the pharmacokinetic/pharmacodynamic properties of antimicrobials is instrumental in severe infections. The rules of antibiotic therapy are also reported and discussed. To conclude, treatment of severe MBL infections in critically ill patients is difficult. It should be individualized with a close collaboration of intensivists with microbiologists, pharmacists and infection control practitioners.

How Antibiotics Stewardship Can Be Safely Implemented in Patients with Septic Shock?

In critically ill patients with sepsis and septic shock, the need for prompt and adequate antibiotic therapy is balanced by the risk of excessive antibiotic exposure that leads to emergence of multidrug-resistant pathogens. As such, antibiotic stewardship programs propose a set of operating rules from antibiotic treatment initiation to de-escalation and finally cessation. In this review, we will describe the rationale for early antibiotic treatment in septic patients, how to optimize initial antibiotic treatment, rules for early treatment discontinuation in pathogen-negative sepsis, and optimal duration of antimicrobial therapy.